Safety system, method and computer program for remotely controlled work vehicles

专利摘要:
ABSTRACT The present disclosure relates to a safety system (100) for a remotely operated work vehicle(110). The safety system (100) works by continuously establishing a spatial relationshipbetween the work vehicle (110) and a wireless remote control unit (130), wherein at leastpart of the information needed to establish the spatial relationship is carried as data insignals. The established spatial relationship is then used to control the work vehicle (110). (Figure 1) 38
公开号:SE1650538A1
申请号:SE1650538
申请日:2016-04-21
公开日:2017-10-22
发明作者:IDBRANT Marcus；Elofsson Kristian；Sihm Henrik
申请人:Construction Tools Pc Ab；
IPC主号:

专利说明:

Safety system, method and computer program for remotely controlled work vehicles TECHNICAL FIELD The present disclosure relates to safety systems for remotely controlled work vehicles,methods performed in safety systems for remotely controlled work vehicles and corresponding computer programs.
BACKGROUND ART Remote operation of work vehicles offers many advantages in various work environments.For instance, by operating the work vehicle remotely, accommodation for an operator in oron the work vehicle is no longer necessary. I/Iany work vehicles are also subjected to varioustypes of stress, e.g., vibrations and noise. By remotely operating the work vehicle, the impact of such stresses on the operator can be reduced or eliminated.
However, the size and weight of many of the remotely operated work vehicles combinedwith the fact that they are mobile implies that there is a risk of injury due to collisionbetween the work vehicle and an operator of the vehicle. One of the most direct ways toreduce the risk of injury is to provide either the work vehicle or an associated wirelessremote control with an emergency stop. When the emergency stop is arranged on the workvehicle it is sometimes arranged to stop the work vehicle based on contact with a resistance.Other safety systems have relied on radar principles, wherein infrared or ultrasonic sensorsare used to help determining if there is a risk of collision. Such systems often suffer from problems due to interference or limitations in the area that is monitored.
US 8 672 582 B2 discloses an automatic safety system comprising a multipurpose compactorand a movable unit. The movable unit comprises a fixedly coupled transceiver configured toperiodically transmit an identification code for reception at the compactor. The transceiverutilizes radio-frequency identification, RFID, technology to communicate with at least onetransceiver on the compactor. The compactor comprises transceivers that are adapted toemit a spherical propagation of a protective field. The safety system continuously searchesfor the presence of an RFID tag within the spherical protective field. Upon detecting an RFID tag, the compactor is stopped. Additionally, if the identification code is not transmitted or received correctly, two drive stop commands to stop the drive of the compactor in both directions is generated.
US 8115 650 B2 discloses an automatic safety system for co|ision avoidance betweenpersonnel and articulated or mobile industrial machinery. A worker is equipped with an RFIDtag and the industrial machinery is equipped with two sensors, wherein the sensors arearranged to determine the distance between the mobile industrial machinery, in particular amoving component on which a sensor is mounted, and the RFID tag. Depending on thedetermined distance, warning signals are issued or the moving component is slowed down or stopped.
While safety systems based on RFID technology is an improvement over not using any typeof radio based safety system, there are drawbacks from using RFID technology, e.g., fromcharacteristics of the antenna of the RFID tag.. The power radiated from an antenna in theRFID tag is not isotropic, which means that determining the distance to the antenna iscomplicated by the lack of isotropic radiation. Furthermore, RFID tag-based distancedetermining systems depending on a Radio Signal Strength Indicator, RSSI, do not work verywell for longer distances, i.e., over about 3m, because the received signal power dropsexponentially with distance. The strong correlation between received power and distancealso means that RSSI-systems are quite sensitive to the surrounding geometry in the sense that the system will be more sensitive to reflections other than that of the main signal.
As the distance between a remotely controlled machine and a wireless remote controlincreases the signal strength between them decreases. Since safe operation of the remotelycontrolled machine is dependent on control signals from the remote control, there is a needfor a safety system operative also when the distance between the remotely controlledmachine and a wireless remote control increases and is approaching a maximum safetydistance. Thus, there is a need for an automatic safety system that enables varying thesafety distance between the work vehicle and the wireless remote control to take intoaccount both a minimum and a maximum safety distance interval, and wherein the distance determination is independent of transmitter strength or antenna shape.
SUMMARY OF THE INVENTION An object of the present disclosure is to provide systems and methods that enables varyingthe safety distance between a work vehicle and a wireless remote control to take intoaccount both a minimum and a maximum safety distance interval, and wherein the distance determination is independent of transmitter strength or antenna shape.
The disclosure proposes a safety system for a remotely operated work vehicle, the workvehicle being arranged to receive a first control signal from a wireless remote control unit.The first control signal is arranged to control a drive operation of the work vehicle. Thesafety system comprises a vehicle unit arranged at the work vehicle and an operator unitarranged at the wireless remote control unit. The vehicle unit is arranged to obtaininformation relating to a first position of the work vehicle. The operator unit is arranged totransmit at least one signal carrying information relevant for positioning of the wirelessremote control unit to the vehicle unit. The vehicle unit is further arranged to determine aspatial relationship between the work vehicle and the wireless remote control unit based onthe information relating to a first position of the work vehicle and the information relevantfor positioning of the wireless remote control unit. The vehicle unit is also arranged toperiodically determine if the spatial relationship meets a predetermined criterion. Thevehicle unit is additionally arranged to provide a second control signal to the work vehicle.The second control signal is arranged to control the drive operation of the work vehicle based on the periodic determination.
As has been described in the background section above, there is a need in the art for anautomatic safety system that enables varying the safety distance between the work vehicleand the wireless remote control to take into account both a minimum and a maximumsafety distance interval. The present disclosure remedies this by keeping the wireless remotecontrol and the vehicle unit in constant communication with each other, with the distancebetween them being determined periodically. ln other words, the wireless remote controlwill always be inside the protective field of the vehicle unit as long as the wireless remotecontrol and the vehicle unit are within signaling range of each other. Since the wirelessremote control is always in communication with the vehicle unit as long as they remain within range of each other, it is possible to introduce distance intervals where different types of control signals are transmitted to the drive control mechanism without having tointroduce additional measurement systems, such as e.g. short range radars. ln particular, thesafety system can be arranged to have an upper limit on the allowed distance, whicheffectively eliminates the risk of the wireless remote control losing contact with the vehicleunit. This prevents the work vehicle from moving out of range of the wireless remotecontrol, which is a particularly useful feature if the work vehicle is operating in a semi-autonomous mode. Additionally, a need to be able to determine the distance independentof transmitter strength or antenna shape has been identified. The present disclosureaddresses this need by relying on information within signals, and possibly informationavailable within or generated by system components, rather than physical properties of the signals, such as e.g. signal power.
According to some aspects, the vehicle unit further comprises a processing element, whereinthe processing element is communicatively connected to the drive operation, and whereinthe processing element is arranged to control the drive operation of the work vehicle byproviding the second control signal. According to some further aspects, the processingelement further comprises processing circuitry arranged to receive the information relatingto a first position of the work vehicle and the information relevant for positioning of thewireless remote control unit. The processing circuitry is further arranged to determine saidspatial relationship and generate the second signal based on whether the spatial relationshipthe spatial relationship meets the predetermined criterion. The processing element enablescoordination of a plurality of control signals and/or processing of information from aplurality of sources. The processing element may also be coupled to a signal receiving unit,e.g. transceiver of the vehicle unit to define a master node via which other nodes of thevehicle unit communicates. ln the presence of other work vehicles able to communicate withthe transceiver, the master node may also function as a master node for coordinatingcommunication of a plurality of work vehicles exchanging information using the same frequency resources as the transceiver.
According to some aspects, the spatial relationship relates to a first distance between thework vehicle and the wireless remote control unit and in that the predetermined criterioncomprises the first distance falling within a predetermined distance interval. According to some further aspects, the second control signal is arranged to stop the work vehicle if the 4 work vehicle enters the predetermined distance interval. The predetermined distanceinterval may be used to determine how close the operator may be to the work vehiclebefore it is stopped. The predetermined distance interval may include a maximum safetydistance interval, which is an object of the present disclosure. Alternatively, the secondcontrol signal is arranged to stop the work vehicle if the work vehicle leaves thepredetermined distance interval. The lower bound of the interval then corresponds to aminimum safety distance and the upper bound corresponds to a maximum safety distance.ln other words, the work vehicle is allowed to operate as long as the operator does not gettoo close or too far away from the work vehicle. According to a further aspect, the predetermined distance interval is between 2m and 50m.
According to some aspects, the vehicle unit is arranged to determine the first distance usingtwo-way ranging time of flight based on a time stamp based on the information relevant forpositioning of the work vehicle that is time stamped at an initial time of the two-way rangingand a and a time stamp based on a received signal that is time stamped at a finishing time ofthe two-way ranging. The use of a local coordinate system associated with the time of flightbased safety system draws on the predetermined spatial relationships between the point onthe vehicle unit where the signal initiating the two-way ranging is located with respect to thework vehicle as well as between the transceiver and the wireless remote control unit. Thedistance in the local system from the origin to the point on the vehicle unit is zero (or someknown arbitrary constant) by definition. The time stamp associated with the signal initiatingthe two way ranging is thus all the information needed to determine the position of thework vehicle at the time of the time stamp, since it is zero by definition. A time stamprequires a minimal amount of data to be stored and/or processed. The information relevantfor positioning of the work vehicle may thus only comprise one or more time stamps. Bothtime stamps can then be used to determine the distance signals have travelled and the workvehicle is stopped if the work vehicle enters the predetermined distance interval. Theassociated time stamps, in addition to requiring a minimal amount of data to be transferred,may also be used to check the status of the communication link between the vehicle unitand the operator unit. By adding time stamps it is possible to determine if the safety system is receiving reliable results by comparing the time stamps with the present time. Too long time between measurements could indicate problems and the safety system is preferably arranged to take actions to handle this.
According to some aspects, the vehicle unit comprises a first transceiver and the operatorunit comprises a second transceiver, wherein the first transceiver is arranged to transmit aninitiation signal at said initial time to the second transceiver, and wherein second transceiveris arranged to receive the initiation signal and transmit a response signal to the firsttransceiver, the response signal comprising said time stamp for finishing time. Alternatively,the signaling is initiated from the second transceiver. The first and second transceiversenable an implementation of a safety system based on time of flight to determine the spatialrelationship. ln other words, the transceivers enable an implementation of a local coordinatesystem based on the position of the transceiver at the operator unit with respect to the position of the transceiver at the vehicle unit.
According to some aspects, the information relevant for positioning of the work vehicle andinformation relevant for positioning of the wireless remote control unit comprise respectiveglobal navigational satellite system, GNSS, coordinates obtained from a global navigationalsatellite system. The GNSS data enables safety operating systems that operate at greatdistances with high precision. The high precision may be obtained by correcting data fromsatellites of the GNSS with data from stationary reference points. For instance, the globalcoordinates may be obtained from a differential global position system, DGPS, where GPScoordinates are corrected using data from fixed positions having known coordinates. Theuse of a GNSS system enables data relevant for positioning of the wireless device to be pushed, i.e. transmitted without being prompted to do so, to the vehicle unit.
According to some aspects, the vehicle unit comprises a first receiver arranged to receive avehicle coordinate signal comprising the GNSS coordinates of the position of the workvehicle. The operator unit comprises a second receiver arranged to receive an operatorcoordinate signal comprising the GNSS coordinates of the position of the wireless remotecontrol unit. According to some further aspects, the first and second receivers are furtherarranged to receive corrective information, the corrective information being based onpredetermined GNSS coordinates of at least one reference point. The vehicle unit is further arranged to improve the accuracy of the GNSS coordinates of the positions of the work vehicle and the wireless remote control unit based on the corrective information. The firstand second receivers enable an implementation of a safety system based on coordinatesfrom a global navigation satellite system. ln other words, the transceivers enable animplementation of a global coordinate system based on the received GNSS coordinates. The corrective information improves the accuracy of the GNSS coordinates.
According to some aspects, the information relevant for positioning of the work vehiclecomprises information relating to a second position of the work vehicle, wherein the spatialrelationship further relates to a second distance between the work vehicle and the wirelessremote control unit based on the second position. The predetermined criterion furthercomprises the second distance falling within a second predetermined distance interval.Determining two distances provides redundancy. ln other words, if one determined positionindicates a problem in determining that distance, the other determined distance mayprovide the necessary information for continued operational use of the safety system. Bydetermining two distances, it is possible to arrange the safety system to detect if theoperator (holding the wireless remote control unit) is standing in front or behind the workvehicle. ln aspects based on time of flight for distance determination between the workvehicle and the wireless remote control unit, additional determined distances reduce theimpact of human blocking, wherein human blocking refers to the time delay associated witha signal passing through the human body. Signals travelling along different paths will beaffected differently by human blocking and more determined distances may be used to reduce the probability that all signals will be affected by human blocking.
According to some aspects, the vehicle unit and the wireless remote control unit eachcomprises direction detection means arranged to determine a direction of the work vehicleand the wireless remote control unit, respectively, wherein the vehicle unit is furtherarranged to determine a relative direction between the determined directions of the workvehicle and the wireless remote control unit. The vehicle unit is also arranged to stop thework vehicle based on a predetermined relative direction criterion. This enables stoppingthe work vehicle if an operator holding the wireless remote control unit is facing in adirection deemed unsafe. For instance, the work vehicle may be stopped if the operator has his/her back to the work vehicle. lt further enables detecting if the operator is at risk of losing focus of the task of Operating the work vehicle, e.g. by rotating in a direction away from facing the work vehicle.
According to some aspects, the operator unit comprises a first orientation sensor, whereinthe first orientation sensor is arranged to determine an acceleration and/or a change inorientation of the wireless remote control unit, and wherein the vehicle unit is arranged tostop the work vehicle based on the determined acceleration and/or change in orientationmeeting at least one predetermined criterion. lt is possible that an operator falls or losescontrol of the wireless remote control. The first orientation sensor enables registeringunsafe changes in the conditions by which the wireless remote control is handled. Accordingto some aspects, a signal indicating that the wireless remote control has fallen is transmittedto the vehicle unit based on the predetermined criterion. The vehicle unit is arranged to stop the work vehicle in response to the received signal.
According to some aspects, the vehicle unit comprises a second orientation sensor arrangedto provide the vehicle unit with information relating to roll, pitch and heading of the workvehicle, wherein the vehicle unit is further arranged to stop the work vehicle based on theinformation relating to roll, pitch and heading of the work vehicle meeting at least one predetermined criterion.
According to some aspects, vehicle unit comprises a temperature sensor, wherein thetemperature sensor is arranged to provide the vehicle unit with information relating to atemperature of the work vehicle, wherein the vehicle unit is further arranged to provide atleast one second control signal based on the information relating to said temperature of the work vehicle meeting a predetermined criterion.
By taking into account temperature and/or roll, pitch and heading of the work vehicle theoperational status ofthe work vehicle may be factored in when determining whether to stopthe work vehicle. By monitoring the temperature, the internal components of the workvehicle can be kept in an interval that ensures proper functionality. ln particular, parts of thesafety system arranged at the work vehicle can be kept within a predetermined temperatureinterval suitable for reliable operation of the safety system. The roll, pitch and heading can be used to determine if the work vehicle is in danger of e.g. falling over.
The disclosure also relates to a method performed in a safety system for a remotelyoperated work vehicle, the work vehicle being arranged to receive a first control signal froma wireless remote control unit. The first control signal is arranged to control a driveoperation of the work vehicle. The safety system comprises a vehicle unit arranged at thework vehicle and an operator unit arranged at the wireless remote control unit. The methodcomprises obtaining information relating to a first position of the work vehicle. The methodfurther comprises transmitting at least one signal carrying information relevant forpositioning of the wireless remote control unit to the vehicle unit. The method alsocomprises determining a spatial relationship between the work vehicle and the wirelessremote control unit based on the information relating to a first position of the work vehicleand the information relevant for positioning of the wireless remote control unit. The methodadditionally comprises periodically determining if the spatial relationship meets apredetermined criterion and providing a second control signal to the work vehicle. Thesecond control signal is arranged to control the drive operation ofthe work vehicle based onthe periodic determination. The disclosed method carries out method steps corresponding to what the functional units of the disclosed safety system are arranged to perform. The disclosed method thus has all the advantages associated with the disclosed safety system.
According to some aspects, determining the spatial relationship further comprisesdetermining a first and a second distance between the work vehicle and the wireless remotecontrol unit. Periodically determining if the spatial relationship meets a predeterminedcriterion further comprises, for each of the first and second distances, determining if at leastone of the first and second distances falls within a predetermined distance interval.Providing a second control signal to the work vehicle further comprises arranging the at leastone second control signal to stop the work vehicle if at least one of the first and seconddistances fall within the predetermined distance interval and fall within a secondpredetermined distance interval. The first and distances provide redundancy to the method.By determining two distances between the work vehicle and the wireless remote controlunit, accuracy can be improved with respect to only determining a single distance. By alsoproviding a second predetermined distance interval, the method can take into account thepossibility of one of the two determined distances not being properly provided and that the accuracy related to having two distances is lost.
According to some aspects, the method further comprises obtaining information relating toroll, pitch and heading of the work vehicle and arranging the at least one second controlsignal to stop the work vehicle if at least one of the roll, pitch and heading meets apredetermined criterion. The associated advantages have been described above in relation to the second orientation sensor.
The disclosure also relates to a computer program comprising computer program codewhich, when executed, causes a safety system according to the present disclosure to carryout an aspect according to the disclosed method. The computer program has all the advantages of the disclosed method.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a safety system for a remotely operated work vehicle according to the present disclosure; Figure 2 illustrates a safety system for a remotely operated work vehicle according to the present disclosure; Figure 3 illustrates a safety system for a remotely operated work vehicle according to the present disclosure; Figure 4 illustrates preferred aspects of the safety system for a remotely operated work vehicle; Figure 5 illustrates method steps of a method performed in a safety system for a remotely operated work vehicle according to the present disclosure; Figure 6 illustrates a flow diagram according to some aspects of the present disclosure;Figure 7 illustrates a flow diagram relating to evaluation of determined distances; Figure 8 illustrates control signaling according to some aspects; Figure 9 illustrates a flow diagram according to some aspects ofthe present disclosure; and Figure 10 illustrates a flow diagram according to some aspects ofthe present disclosure.
DETAILED DESCRIPTION ln the following description the wording ”arranged at” is to be understood as comprising”arranged on” and ”arranged in” as well as being ”arranged in proximity to", e.g. by the useof a distancing element, unless otherwise stated. For instance, a transceiver ”arranged at”the work vehicle may be arranged partially or completely in the work vehicle. An example of”partially in” could be the transceiver being arranged in the work vehicle with an antenna ofthe transceiver extending outside of the work vehicle. The transceiver may also be arrangedon the work vehicle, e.g. mounted on a surface of the work vehicle. lt is sometimespreferable to mount e.g. a signal transmitting or receiving unit at a distance from the workvehicle to reduce the impact of signal obstruction from dirt and work vehicle components and ”arranged at” is to be understood to include such cases as well.
Figure 1 illustrates a safety system 100 for a remotely operated work vehicle 110. Figure 1illustrates the main principles of the disclosed safety system. The work vehicle 110 isarranged to receive a first control signal 170 from a wireless remote control unit 130, thefirst control signal 170 being arranged to control a drive operation 190 of the work vehicle110. The control of a drive operation may comprise affecting a functioning of engine. Forinstance, the engine may be regulated to slow down or stop the work vehicle. ln case theengine is a hydraulic engine, the control of the drive operation may comprise controlling ahydraulic valve arranged to control the flow of hydraulic fluid to and/or from the hydraulicengine. As will be illustrated further below, the safety system 100 works by continuouslyestablishing a spatial relationship between the work vehicle 110 and the wireless remotecontrol unit 130, wherein at least part of the information needed to establish the spatialrelationship is carried as data in signals. The established spatial relationship is then used to control the work vehicle 110.
The safety system 100 comprises a vehicle unit 150 arranged at the work vehicle 110 and anoperator unit 155 arranged at the wireless remote control unit 130. Both the vehicle unit150 and the operator unit 155 are functional units that are arranged to interact with thework vehicle 110 and the wireless remote control 130, respectively, and they may comprisea plurality of functional elements that are arranged at different parts of the work vehicle 110 and the wireless remote control unit 155, respectively. For instance, the vehicle unit 150 11 may comprise a pair of transceivers arranged at different positions of the work vehicle 110,which will be illustrated further below. The vehicle unit 150 is arranged to obtaininformation relating to a first position 160a of the work vehicle 110. Ways of obtaining saidinformation will be illustrated below in relation to following figures. The operator unit 155 isarranged to transmit at least one signal 120 carrying information relevant for positioning of the wireless remote control unit 130 to the vehicle unit 150.
The vehicle unit 150 is further arranged to determine a spatial relationship between thework vehicle 110 and the wireless remote control unit 130 based on the information relatingto a first position 160a of the work vehicle 110 and the information relevant for positioningof the wireless remote control unit 130. The vehicle unit 150 is also arranged to periodicallydetermine if the spatial relationship meets a predetermined criterion. The predeterminedcriterion may comprise a distance interval between the work vehicle 110 and the wirelessremote control unit 155 in which operational use of the work vehicle is considered safe. Thevehicle unit 150 is additionally arranged to provide a second control signal 180 to the workvehicle 110, wherein the second control signal 180 is arranged to control the drive operation 190 ofthe work vehicle 110 based on the periodic determination.
The spatial relationship may be a distance between the work vehicle 110 and the wirelessremote control unit 130. The predetermined criterion may be a distance interval in whichthe distance between the work vehicle 110 and the wireless remote control unit 130 isconsidered unsafe. ln other words, an operator holding the wireless remote control unit 130is considered to be too close to the work vehicle 110 for operational use of the work vehicle110 to be considered safe. Conversely, the predetermined criterion may be a distanceinterval at which operational use of the work vehicle 110 is considered safe. The safetysystem 100 may then slow down or stop the work vehicle 110 if the operator is either getting too close or too far away from the work vehicle 110.
The predetermined criterion may be stored in a dedicated memory arranged at the vehicleunit 150. The predetermined criterion may be arranged at the vehicle, e.g. stored in saidmemory, prior to initiating operational use of the safety system 100. According to someaspects, the vehicle unit 150 comprises an interface where the predetermined criterion may be defined. The interface may comprise a user interface, e.g. a touch screen display, 12 enabling an operator to enter parameters relating to the predetermined criterion. Theinterface may also comprise a software interface, where software may be entered into thevehicle unit 150, e.g. stored in said memory, wherein the software is arranged to determine the predetermined criterion.
Determination of the distance between the work vehicle 110 and the wireless remotecontrol unit 130 can be based on either a local coordinate system or a global coordinatesystem. Furthermore, signals carrying data necessary for determining the distance can bereceived by the vehicle unit 150 either via a pull-operation or a push-operation. Figures 2and 3 below will illustrate safety systems based on local coordinate systems and globalcoordinate systems, as well as using pull-operations vs using push-operations fortransmitting signals carrying information relevant for positioning of a wireless remote control unit to a vehicle unit.
Figure 2 illustrates a safety system 200 for a remotely operated work vehicle 210, where thedistance determination is based on a local coordinate system and a vehicle unit 250comprising a transceiver is arranged to receive a signal by using a pull-operation, whereinthe signal carries information relevant for positioning of a wireless remote control unit 230.The illustrated safety system 200 is based on two way ranging time of flight, ToF, todetermine a distance between the work vehicle 210 and the wireless remote control unit230. A signal is transmitted from the transceiver at the vehicle unit 250 and a first time stamp is generated. The time stamp could e.g. be a local clock starting to run.
An operator unit at the wireless remote control unit 230 receives the signal and, after ashort duration associated with processing the signal, transmits a signal back to thetransceiver at the vehicle unit 250. The transceiver at the vehicle unit 250 receives the signaltransmitted from the operator unit and a second time stamp is generated, e.g. by stoppingsaid local clock. The time of flight is then determined by first determining the total durationfor the round trip and adjusting the roundtrip time by subtracting the duration it takes forthe operator unit to process the received signal and transmit a signal in response. Thedistance between the work vehicle and the wireless remote control unit may then bedetermined by dividing the adjusted roundtrip time by 2 and multiply by the speed for a radio wave through air. The signals to and from the operator unit comprises an ID that is 13 unique to the transceiver at the vehicle unit 250. That way the vehicle unit 250 may ensurethat the signals received by the transceiver are based on signals having originated from thetransceiver of the vehicle unit 250. ln other words, the ID is information relevant for positioning of the wireless remote control unit 230.
The determined distance is then used by the vehicle unit 250 of the safety system 200 toprovide at least one second control signal to the work vehicle 210 ifthe determined distance falls within a predetermined safety distance interval.
Since the position 260a of the transceiver with respect to the work vehicle is known, it maybe used as an origin of the local coordinate system. Obtaining information relevant forpositioning of the work vehicle is thus straight-forward; since the position of the transceiveris predetermined to be an origin of the local coordinate system, the position of the workvehicle is taken to be the position of the transceiver in the local coordinate system. ln other words, the position ofthe work vehicle is at a distance measure of zero from the origin.
The transceiver 250 is arranged to provide a first time stamp when transmitting a signal tobe received by an operator unit 255 arranged at the wireless remote control unit 230. Theoperator unit comprises a second transceiver arranged to receive the signal transmittedfrom the vehicle unit 250 and, in response to receiving said signal, transmit a time stampedsignal back to the transceiver of the vehicle unit 250. When the vehicle unit receives thetime stamped signal, the time stamp of the time stamped signal is compared to the first timestamp. By assuming a speed at which the signal travels, e.g. the speed of light for a radiosignal, the distance between the work vehicle 210 and the wireless remote control unit 230is determined. ln other words, the time stamped signal received by the transceiver of thevehicle unit 250 corresponds to a signal carrying information relevant for positioning of thewireless remote control unit 230. The time stamp corresponds to the information relevantfor positioning of the wireless remote control unit 230, since it corresponds to a time offlight, determined by a time difference of arrival. The vehicle unit 250 is further arranged tocontrol a drive operation 290 of the work vehicle 210 by providing second control signals tothe drive operation 290 if the determined distance falls within a predetermined safetydistance interval. By periodically transmitting signals from the vehicle unit 250, via its transceiver, the distance between the work vehicle 210 and the wireless remote control unit 14 230 is always known and the safety system 200 may stop or slow down the work vehicle 210if it gets too close or too far away from the wireless remote control unit 230, depending onhow the safety system 200 is arranged. ln other words, the vehicle unit 250 is arranged toprovide a second control signal to the work vehicle 210, wherein the second control signal isarranged to control the drive operation 290 of the work vehicle 210 based on the periodic comparison.
Figure 3 illustrates a safety system 300 for a remotely operated work vehicle 310, whereinthe distance determination is based on a global coordinate system provided by a globalnavigational satellite system, GNSS, 375. A vehicle unit 350 is arranged at the work vehicleand is further arranged to receive a signal 320 that is periodically transmitted from anoperator unit 355 arranged at a wireless remote control unit 330. ln other words, a push-operation is used to transfer information relevant for positioning of the wireless remotecontrol unit 330 from the wireless remote control unit 330 to the vehicle unit 350. Thus, theoperator unit 355 is arranged to transmit at least one signal 320 carrying informationX'Y'Z'remote contrm relevant for positioning of the wireless remote control unit 330 to thevehicle unit 350. The vehicle unit 350 further comprises a receiver arranged to receive atleast one signal from the GNSS 375 carrying information relevant for positioning of thereceiver in the global coordinate system. The information may be a set of coordinatesrelating to the global coordinate system. Since the receiver is arranged at the work vehicle310, the position of the receiver corresponds to a position of the work vehicle. Thecoordinates received from the GNSS 375 are preferably corrected based on informationprovided by stationary references of the GNSS 375. For instance, the GNSS could be adifferential global positioning system, DGPS, where global coordinates XYZworkvehide, XYZremotemmm provided by the satellites of the DGPS are corrected using information AXYZWOrk Vehide, AXYZremotecontro| from stationary references of the DGPS having known global coordinates.
According to some aspects, the vehicle unit 350 further comprises a processing element,wherein the processing element is communicatively connected to the drive operation 390and wherein the processing element is arranged to control the drive operation 390 of thework vehicle 310 by providing the second control signal. The processing element may bearranged to receive information relating to roll, pitch heading or a temperature of the work vehicle, e.g. from corresponding sensors in the work vehicle 310, and base the provided second control signal on this information as well. ln other words, the processing elementmay serve as an engine control unit where work vehicle system information and the spatialrelationship between the work vehicle and the wireless remote control unit is processed together to provide the second control signal.
Additional features that provide enhanced functionality of a safety system according to thepresent disclosure will be discussed below. The features will provide the safety system withadditional information on which the safety system may base the generation of control signals. lt may be desirable in some cases to determine if an operator has his back to the workvehicle during operational use. Therefore, according to some aspects, the vehicle unit andthe wireless remote control unit each comprises direction detection means arranged todetermine a direction of the work vehicle and the wireless remote control unit, respectively.The vehicle unit is further arranged to determine a relative direction between thedetermined directions of the work vehicle and the wireless remote control unit. The vehicleunit is also arranged to stop the work vehicle based on a predetermined relative directioncriterion. For example, the vehicle unit and the wireless remote control unit may eachcomprise a pair of compasses. The direction indicated by the compass arranged at thewireless remote control unit is transmitted to the vehicle unit. The vehicle unit is furtherarranged to determine a relative direction between the determined directions of the workvehicle and the wireless remote control unit. By having a predetermined forward directionof the wireless remote control, the relative direction can then be used to determine if theforward direction is facing towards or away from the work vehicle. lf the wireless remotecontrol unit, and assumingly also the operator, is determined to be facing away from thework vehicle, a control signal is transmitted to the work vehicle. According to some aspects,the work vehicle is arranged to stop when the relative direction indicates that the wirelessremote control unit is facing away from the work vehicle. ln other words, the vehicle unit is arranged to stop the work vehicle based on a predetermined relative direction criterion.
The predetermined relative direction criterion may also be arranged to detect if an operatoris at risk of losing focus of the task of operating the work vehicle. lf, for instance, something happening behind the operator, e.g. a sudden loud sound, grabs the attention of the 16 operator, the operator might start to turn around to face to object of his or her attention,and also start to face away from the work vehicle in doing so. The predetermined relativedirection criterion may thus be arranged to control the drive operation of the work vehicle,e.g. stop or slow down the work vehicle, based on the operator rotating around his verticalaxis faster than a predetermined speed and greater than a predetermined angle. Forinstance, predetermined relative direction criterion may be a 180 degree turn within two seconds.
One particular danger is that of the operator falling and becoming separated from thewireless remote control unit or falling in such a way that the operator quickly ends up infront of a moving work vehicle. An example of the latter could be an operator operating atrench compactor at the edge of a trench. The operator may be well outside apredetermined minimum safety distance, but a sudden slip could cause the operator to fallinto the trench and land in front of the trench compactor. The safety system is preferablyarranged to respond quickly in order to meet the associated rapid change of the operating situation.
Thus, according to some aspects the operator unit comprises a first orientation sensor,wherein the first orientation sensor is arranged to determine an acceleration and/or achange in orientation of the wireless remote control unit. The first orientation sensor maycomprise an accelerometer to determine acceleration and a gyroscope to determinechanges in orientation. ln the example of the trench compactor, a quick change inacceleration may be interpreted as falling straight down in the trench. A sudden verticalacceleration may be used to indicate a dropped wireless remote control unit. A suddenhorizontal acceleration may be used to indicate that wireless remote control unit has beensuddenly separated from the operator. For instance, the wireless remote control unit mayhave been knocked away from the operator by accident. The change in orientation may beused to indicate that the operator is also rotating fast, i.e. the operator is falling. Any of theindications, singly or in combination, may constitute a basis for a predetermined criterion onwhich to stop the work vehicle. Thus, the vehicle unit is arranged to stop the work vehiclebased on the determined acceleration and/or change in orientation meeting at least onepredetermined criterion. According to some aspects, the operator unit is arranged to transmit signals comprising information relating to determined acceleration and/or change 17 in orientation to the vehicle unit. The vehicle unit is preferably arranged to transmit acontrol signal arranged to stop the work vehicle based on the determined acceleration and/or change in orientation meeting at least one predetermined criterion.
Many work vehicles work are intended to be operated under harsh conditions, e.g. varyingterrain and hot temperatures. Depending on the nature of said harsh conditions, the workvehicle may be adversely affected to pose a danger to the operator or the functionality of the safety system might risk getting compromised.
The automatic safety system of US 8 672 582 B2 may be used to illustrate an automaticsafety system not arranged to consider varying terrain. An operator of a work vehicle movingin a forward direction may walk close by as long as the operator is close to the rear of thework vehicle. The safety system detects that the work vehicle is moving away from theoperator and allows continued operational use even though the operator is within theprotective field of the rear detector. lf the work vehicle tilts to the point where it falls over inthe direction of the operator, there is no functionality in the automatic safety system to prevent the resulting accident.
Thus, according to some aspects of the present disclosure the vehicle unit comprises asecond orientation sensor arranged to provide the vehicle unit with information relating toroll, pitch and heading of the work vehicle. The vehicle unit is further arranged to stop thework vehicle based on the information relating to roll, pitch and heading of the work vehiclemeeting at least one predetermined criterion. According to some further aspects, thepredetermined criterion is a maximally allowed roll and pitch, respectively. The maximallyallowed roll and pitch may be further based on the heading of the work vehicle. The headingofthe work vehicle may be used in conjunction with a determination of operator position toapply more a conservative predetermined criterion of the operator is or risk getting too close to a tilting work vehicle.
Another issue is the build-up of heat within a work vehicle during operational use. The workvehicle may generate a lot of heat itself and when operating in a hot environment, the build-up of heat may adversely affect electronics arranged at the work vehicle. ln particular, anycomponents of the safety system that are arranged at the work vehicle might run the risk of impaired functionality if the temperature gets too high. Therefore, according to some 18 aspects, the vehicle unit comprises a temperature sensor, wherein the temperature sensor isarranged to provide the vehicle unit with information relating to a temperature of the workvehicle. The vehicle unit is further arranged to provide at least one second control signalbased on the information relating to said temperature of the work vehicle meeting apredetermined criterion. The predetermined criterion may be a maximally allowable temperature of the work vehicle.
Figure 4 illustrates preferred aspects of the safety system 400 for a remotely operated workvehicle 410. The work vehicle 410 is arranged to receive a first control signal (not shown)from a wireless remote control unit 430. The first control signal is arranged to control a driveoperation 490 of the work vehicle 410. The safety system 400 comprises a vehicle unit 450arranged at the work vehicle 410 and an operator unit 455 arranged at the wireless remotecontrol unit 430. The vehicle unit 450 comprises a first and a second transceiver arranged ata first and a second transceiver position 460a, 460c, respectively. The operator unit 455comprises a third transceiver arranged at a third transceiver position 460b. The first andsecond transceivers are arranged to communicate with the third receiver. The vehicle unit450 further comprises a processing element, wherein the processing element iscommunicatively connected to the first transceiver and to the drive operation 490. Theprocessing element is further arranged to control the drive operation 490 of the workvehicle 410 by providing a second control signal. By communicatively connecting the firsttransceiver to the drive operation via the processing element, a master node comprising thefirst transceiver may be defined. According to some aspects, the master node is furtherarranged to regulate the communication between the second and third transceivers and themaster node. The safety system is arranged to direct all communication between thetransceivers that is directly or indirect addressed to controlling the drive operation 490 to pass via the master node.
According to a first aspect, the safety system 400 is based on using two way time of flightranging to determine a first and a second distance between the third transceiver position460b at the wireless remote control unit 430 and the first and second transceiver positions460a, 460c at the vehicle unit 450 and send control signals to the drive operation 490 via the master node based on the determined first and second distances. 19 The first and second transceivers are preferably ultra-wideband, UWB, transceivers arrangedto transmit and receive a signal comprising a unique ID. The unique ID enables the UWBtransceivers to correlate received signals with a specific origin. The third transceiver ispreferably also an UWB transceiver of the same type as the first and second transceivers.The unique IDs then enable first and third transceivers to determine if a signal from thesecond transceiver was generated in response to a signal originating from the first or thethird transceiver. In other words, the ID comprises information relevant for positioning ofthe wireless remote control unit. Ultra-wideband is a technology for wirelessly transmittingsignals across a wide frequency spectrum. The wider the bandwidth, the more ”squarewave"-like the signal can be made, which correlates with a shorter rise time. The shorter risetime may be used to make it easier to determine if a ”zero” or ”one” is transmitted, which inturn may be used in synchronization of received and transmitted signals. In other words, themore ”square wave"-like signal enables more precise time synchronization. The moreprecise time synchronization in turn leads to improved accuracy when measuring distancesusing a time of flight, ToF, approach. According to some aspects, the accuracy of time offlight distance measurements is around 10 cm. This is much more accurate than, e.g.distance measurements based on radio signal strength indicator, RSSI, using RFIDtechnology, with a typical precision of about 20 cm. According to some aspects, the UWBtransceivers are arrange to provide a maximum bandwidth of 500 MHz. According to someaspects, the UWB transceivers are arranged to operate in the GHZ frequency range. A UWBradio signal is far wider than typical radio signals in use today. The UWB aspect makes thecorresponding UWB radio signals very robust against interference. The UWB transceivers arepreferably arranged for coherent reception for maximum range and accuracy. According tosome aspects, all UWB transceivers are arranged to transmit on the same frequency. Thetransceivers are further arranged to only communicate with units carrying IDs correspondingto IDs of a predetermined white list. The white list may be determined at initiation of thesafety system by linking the first and third transceivers of the vehicle unit 450 to the second transceiver of the operator unit 430.
The first and third transceivers are each arranged to periodically transmit signals to the thirdtransceiver. A first time stamp representing an initial time of the two-way ranging is generated at the same time a signal is transmitted to the (UWB) transceiver at the operator unit 455. The UWB transceiver at the operator unit 455 is arranged to transmit a signal 420a,420b carrying a unique ID back to the first and third (UWB) transceivers when a signal fromone of the first and second transceivers is received. When the signal 420a, 420b carrying theunique ID is received by the first and third transceivers, the ID is used to determine which ofthe first and third transceiver was used to trigger the transmission of the signal 420a, 420b.A second time stamp representing a finishing time of the two-way ranging is generatedwhen the signal 420a, 420b is received. By comparing the first and second time stamps andassuming that the radio signal travels at the speed of light, the first and second distances can be determined by the vehicle unit 450.
When a radio signal passes a human body, it experiences a slight change in index ofrefraction, which affects the determined distance slightly. By determining distances withrespect to two separate points at the vehicle unit 450, the likelihood that all determineddistances are affected by human blocking is reduced. Additional UWB transceivers alsoprovides redundancy if one transceiver should experience problems. According to someaspects, a third transceiver is arranged at the vehicle unit 450. Three transceivers at thework vehicle 410 enables the vehicle unit 450 to determine an exact position of the wireless remote control unit 430 based on triangulation.
In other words, we have continuous, bi-directional communication between UWBtransceivers at the vehicle unit 450 and the UWB transceiver at the operator unit 455.Operational use of the work vehicle 410 is allowed to continue as long as at least one of thedistances is within a predetermined zone, e.g. greater than a certain distance, or in betweena minimum distance and a maximum distance. Control circuitry of UWB master node isarranged to alert control circuitry of the work vehicle 410 upon leaving the predeterminedzone. According to some aspects, the vehicle unit 450 is arranged to work with multiplezones. For instance, vehicle unit 450 is arranged to stop the work vehicle if the distance tothe wireless remote control unit is within a first interval, slow down the work vehicle in asecond distance interval and emit a warning signal within a third distance interval. Accordingto some aspects, the wireless remote control unit 130 is arranged to emit a vibration, a visual signal and/or a sound if the distance between the work vehicle 110 and the wireless remote control unit 130 falls within the third distance interval. 21 The transceivers at the vehicle unit 450 together with the transceiver at the operator unit455 form a communication link. The vehicle unit 450 is arranged to compare the timestamps of the signals passing over the communication link with a present time anddetermine if the received information is reliable based on the comparison. ln other words,the time stamps are used as a link check to ensure reliability of the data and hence also thereliability of the determined first and second distances. The vehicle unit 450 is furtherarranged to provide message quality check, cyclic redundancy check and automaticacknowledgement of messages. ln other words, the link itself is checked on every messagebut the safety system 400 also gets error codes from work vehicle positioning elements, e.g. transceivers or sensors of the vehicle unit 450, if something is wrong.
The distance between the transceivers at the vehicle unit 450 is known and may be used toprovide additional system checks. The determined first and second distances, representede.g. as vectors, should only differ by a vector corresponding to the distance between thetransceivers at the vehicle unit 450. lf the difference exceeds a predetermined threshold, itmay be used as an indication that there is something wrong with at least one of the determined first and second distances.
The vehicle unit 450 is further arranged to report an error if any of the first and second distances are outside of the allowable interval.
The vehicle unit 450 preferably comprises a second orientation sensor arranged to providethe vehicle unit 450 with information relating to roll, pitch and heading of the work vehicle410. The vehicle unit 450 is further arranged to stop the work vehicle 410 based on theinformation relating to roll, pitch and heading of the work vehicle meeting at least one predetermined criterion.
The vehicle unit preferably also comprises a temperature sensor, wherein the temperaturesensor is arranged to provide the vehicle unit 450 with information relating to a temperatureof the work vehicle. The vehicle unit 450 is further arranged to provide at least one secondcontrol signal based on the information relating to said temperature of the work vehicle exceeding a maximally allowable temperature. 22 According to some aspects, the UWB transceivers are Bluetooth compliant. This enables thetransceivers at the vehicle unit to be paired with the transceiver at the operator unit 455.The pairing may be performed in different ways. The basic idea is to listen to the Bluetoothparing sequence and use Bluetooth to send a unique ID from the transceivers arranged atthe vehicle unit to the transceiver arranged at the operator unit 455, which are paired onboth ends of the UWB link. According to some aspects, the third transceiver is arranged totransmit its unique ID through the Bluetooth link. The master node is arranged receive theunique ID and transmit it to the slave node(s) arranged at the vehicle unit 450. Ifthe first andthird transceivers are within range of the second transceiver and have correct IDs they willbe allowed to establish a link. According to some aspects, the vehicle unit 450 is arranged topair the transceivers upon start up, wherein the two transceivers arranged at the vehicleunit 450 that are closest to the third transceiver are paired. By making sure that the first and second transceivers are closest during start up, they will be paired with the third transceiver.
The handling of several work vehicles in the same area is troublesome when we are at thesame frequency. According to some aspects, if the safety system 400 detects another safetysystem, the one with the lowest unique ID will become master. The master then will sendthe ”speech order” so that every safety system gets a timeslot. The master sends a synchsignal and everyone knows when it's their time to transmit. The number of systems is limited by the update frequency and needed transmit time.
If the frequency by which signals are transmitted and received is much smaller than thefrequency of empty time slots, it may not be necessary to implement a speech order. Thelikelihood of a collision, where two signals attempt to use the same time slot, may be sosmall that it is more efficient to simply assume that the signaling works, and try to retransmitif it is determined that a collision did occur. Thus, according to some aspects, signaling isperformed without a predetermined speech order. According to some further aspects, thesafety system 400 is arranged to detect a collision and retransmit a signal based on the detection of the collision.
According to some aspects, each transmitted signal comprises a checksum and the safetysystem 400 is arranged to perform a cyclic redundancy check after each transmission based on the checksum, the safety system 400 further being arranged to detect a collision based 23 on the cyclic redundancy check. According to some further aspects, the safety system 400 isarranged to retransmit a signal based on detection of a collision after a predeterminedduration. According to some further aspects, the predetermined duration is a few micro- seconds.
According to a second aspect, the safety system 400 is based on coordinates from adifferential global navigational satellite system, DGNSS, e.g. differential GPS, to determinethe first and a second distances. The vehicle unit 450 comprises a first and a second GPSreceiver arranged to receive a first and a second vehicle coordinate signal comprising theGPS coordinates of first and second positions 460a, 460c of the vehicle unit 450. Theoperator unit 455 comprises a third receiver arranged to receive an operator coordinatesignal comprising the GPS coordinates of the position 460b of the wireless remote controlunit 430. GPS coordinates are typically accurate to within a few meters, which might beinadequate precision to ensure safe operation of the work vehicle. Thus, according to somefurther aspects the first, second and third receivers are further arranged to receivecorrective information, the corrective information being based on predetermined GPScoordinates of at least one reference point. The at least one reference point may begeostationary reference points and/or reference points arranged at the work vehicle 410.The vehicle unit 450 is further arranged to improve the accuracy of the GPS coordinates ofthe positions of the work vehicle and the wireless remote control unit based on thecorrective information. ln other words, differential GPS is used to improve the accuracy down to decimeter accuracy.
The signaling to control the drive operation 490 may then be performed analogous to thatof the aspects implementing a solution based on relative coordinates, as described above using time of flight.
Figure 5 illustrates method steps of a method 500 performed in a safety system for aremotely operated work vehicle. The work vehicle is arranged to receive a first control signalfrom a wireless remote control unit, the first control signal being arranged to control a driveoperation of the work vehicle. The safety system comprises a vehicle unit arranged at the work vehicle and an operator unit arranged at the wireless remote control unit. 24 The method 500 performs the steps corresponding to the way the functional units havebeen disclosed in Figures 1-4. ln other words, the method 500 carries out actions performed by the safety systems of any of Figures 1-4.
The method comprises obtaining S501 information relating to a first position of the workvehicle. The method further comprises transmitting S502 at least one signal carryinginformation relevant for positioning of the wireless remote control unit to the vehicle unit.As has been discussed above in relation to e.g. Figures 2 and 3, the information may beobtained by receiving coordinates from a global navigational satellite system, GNSS, or bededuced based on time stamps relating to when the signals have been transmitted and received.
The method 500 further comprises determining S503 a spatial relationship, e.g. a distance,between the work vehicle and the wireless remote control unit based on the informationrelating to a first position of the work vehicle and the information relevant for positioning ofthe wireless remote control unit. The method 500 also comprises periodically determiningS504 if the spatial relationship meets a predetermined criterion and providing S505 a secondcontrol signal to the work vehicle, the second control signal being arranged to control the drive operation ofthe work vehicle based on the periodic determination.
According to some aspects, e.g. those disclosed in relation to Fig. 4, determining S503 thespatial relationship may further comprise the optional step of determining S506 a first and asecond distance between the work vehicle and the wireless remote control unit. The step ofperiodically determining S504 if the spatial relationship meets a predetermined criterionmay further comprise the optional step of, for each of the first and second distances,determining S507 if at least one of the first and second distances falls within apredetermined distance interval. The step of providing S505 a second control signal to thework vehicle may further comprise the optional step of arranging S508 the at least onesecond control signal to stop the work vehicle if at least one ofthe first and second distancesfall within the predetermined distance interval and fall within a second predetermineddistance interval. The determination of the two different distances provides redundancy and enables greater flexibility in how the safety system can respond to different situations. The second predetermined distance interval may be arranged to function as a sanity check, which will be elaborated further in relation to Figs. 6 and 7 below.
The method advantageously takes into account information relating to the current drivestatus of the work vehicle. Thus, according to some aspects the method 500 furthercomprises obtaining S509 information relating to roll, pitch and heading of the work vehicle,and arranging S510 the at least one second control signal to stop the work vehicle if at least one of the roll, pitch and heading meets a predetermined criterion.
Figure 6 illustrates a flow diagram according to some aspects of the present disclosure. Tooease the explanation, system units and their arrangements are referenced to those of thepreferred aspects illustrated in relation to figure 4. However the flow diagram is not limitedto the preferred aspects of Fig. 4. For instance, the distance determination and its evaluationdescribed below is not limited to determining a two distances; the flow diagram applies to spatial relationships comprising any number of distances.
At some point after starting the work vehicle 410, the third transceiver at the operator unit455 is paired with the first and second transceivers at the vehicle unit 410. The pairing maybe performed immediately at start up or at a later stage during operational use using theBluetooth compliant communication link, as described in relation to Fig. 4. During thepairing, unique |Ds used to identify signal origins are determined. According to someaspects, a white list comprising a set of unique |Ds which are associated with the safetysystem is also determined. Distances between the third transceiver at the operator unit 455and the transceivers at the vehicle unit 410 are periodically determined and evaluated. Theevaluation comprises determining if either distance is within a predetermined safety zone.The evaluation may also comprise a sanity check, which may be used to detect problemswith determining the first and second distances. Examples further illustrating this part willbe given below in relation to Fig. 7. lf it is determined that the wireless remote control unit430, and hence the operator using the same, is at an appropriate distance the method isarranged to proceed to examine additional parameters relating to the current operationalconditions, and if the wireless remote control unit 430 is too close or too far away withrespect to the work vehicle 410, a stop signal is transmitted to the drive operation of the work vehicle 410. lf the current operational conditions, e.g. roll, pitch and heading of the 26 work vehicle 410, are considered to be safe, the work vehicle 410 is allowed to proceed, anda stop signal arranged to stop the work vehicle 410 is transmitted if not. As long as themethod does not find a need to intervene with the operational use of the work vehicle 410,the method proceeds with the periodic determination and evaluation of the first and second distances.
Figure 7 illustrates a flow diagram relating to evaluation of determined distances. The flowdiagram is illustrated for two distances, such as the first and second distance described inrelation to Figs. 4 and 6 above, but the principles apply to any number of distances greaterthan two as well. The flow diagram of Fig. 7 is an example of what may take place in thesteps of ”Determine distance" and evaluate if the safety system got ”Reasonable results " inFig. 6. The first and second distance are obtained e.g. as described with reference to Fig. 4.They are each compared to a first safety distance interval. For example, the first and seconddistances are checked to see if either of them are within 0 m and 2 m. ln other words, thesystem tries to determine if the wireless remote control unit is within 2 m of the workvehicle 410. Since the work vehicle 410 usually has a front and a rear end, the first andsecond distances may measure the distance of the wireless remote control unit 430 to thefront and the rear end, respectively. lf the wireless remote control unit 430 is found to befurther than 2 m away from both ends of the work vehicle, both vehicle positioningelements transmit a respective GO signal, wherein the GO signal is arranged to allowcontinued operational use of the work vehicle 410 without any intervening actions taken by the safety system 400.
Now, turning to the evaluation of the first distance (the left side of Fig. 7; the correspondingsteps are taken with regards to the evaluation of the second distance). lf the first distance isfound to be less than 2 m, it needs to be determined if this is reliable or not. The methodperforms a check ifthe vehicle positioning element has sent a real value or an error. ln Fig. 7,the error is represented by a distance of 0 m, but could in principle take on any value. The value is preferably selected such that is practically impossible to misinterpret.
A value greater than 0 m, but still less than 2 m would thus indicate a successful measurement telling the safety system 400 that the wireless remote control unit 430 is too 27 close, less than 2 m from the work vehicle 410. The method comprises transmitting a NoGO signal, the NoGO signal being arranged to stop the work vehicle 410. lf instead an error value was received, indicating that the determination of the first distancewas unsuccessful or otherwise unreliable, the second distance might still be used as aredundancy. The minimum safety distance of 2 m assumes a certain precision associatedwith both the first and the second distance being determined properly. Thus, if one distancedetermination fails, it may be necessary to increase the minimum safety distance. Accordingto some aspects, an approximate length of the work vehicle 410 is added to the minimumsafety distance when one of the first or second distances failed to be determined. Fig. 7illustrates the second distance being evaluated against a minimum safety distance of 3 m.The value of 3 m is only for illustrative purposes and could in principle be any numberresulting in an increase of the minimum safety distance. lf the second distance passes thewider safety distance interval, the method transmits a GO signal; otherwise a NoGO signal istransmitted. Thus, for each distance to be determined, a corresponding GO or NoGO signal isprovided. The two (or more) resulting GO/NoGO signals are then evaluated by an ANDfunction and passed on to downstream functions. That is, only if two GO signals are providedis the work vehicle 410 allowed to proceed, otherwise a NoGO signal is provided and the work vehicle 410 is stopped.
Figure 8 illustrates control signaling according to some aspects. The control signals areGO/NoGO signals as discussed in relation to Fig. 7 and ”Forward, Reverse, Left, Right” refersto possible directions of movement of a work vehicle. The example is provided for a workvehicle having four drum drive with two different speeds and two directions, controlled viatwo hydraulic valves; one for speed selection and the other for direction. The signalingillustrated in Fig. 8a uses four AND gates where the GO/NoGO signals are arranged on onepin of a respective AND gate and the desired direction of movement on another. Fig. 8billustrates an example where the work vehicle is receives first control signals from thewireless remote control unit indicating a desired movement forward combined with a rightturn. However, only movement forward and left turns are allowed based on the Go/NoGOsignals. Depending on the safety system, the work vehicle may be allowed to move forward, which is the only desired direction given a GO signal, or the work vehicle is stopped because 28 the system requires all desired directions of movement to be allowed via respective GO signals.
Figure 9 illustrates a flow diagram according to some aspects of the present disclosure. Theflow diagram is meant to illustrate how the work vehicle 410 of Fig. 4 takes into accountinformation from an orientation sensor and a heat sensor in addition to the two distances itis arranged to determine. The lower left loop starting with ”measure distance" correspondsto ”determine distance" and ”reasonable results” of Fig. 6, which has been further illustratedin different aspects in Figs. 7 and 8. The loops starting with ”read orientation sensor” and”read temperature sensor” receives measurements from respective sensors and checks ifthe measurements are reasonable. Analogous to the distance measurement, the orientationsensor data and the temperature data may comprise orientation and temperature valuesthat are unreasonable to indicate that an error in the measurement process has occurred.The vehicle unit 450 may be based on a CAN bus system, where measurement data is storedin the different nodes and requested periodically by the master node for evaluation. Theoptional steps ”store result” is meant to illustrate that the nodes of the work vehicle 410may comprise memory arranged to store the measurement data until it is either overwritten or retrieved by the master node.
Figure 10 illustrates a flow diagram according to some aspects of the present disclosure. Theflow diagram is meant to illustrate distance determination for a vehicle unit 450, such as theone of the work vehicle 410 in Fig. 4, wherein the vehicle unit comprises a plurality of nodes,each arranged to determine a distance between the work vehicle 410 and the wirelessremote control unit 430. The figure illustrates N processes, wherein each processcorresponds to a process such as the ones illustrated in Fig.7. |nstead of only two distancesbeing determined, we here have N distances that are being determined. The step”predetermined error signal free measurement” looks for error messages in the signals, suchas the ”zero distance" of Fig. 7. lf no error is reported, the vehicle unit 450 proceeds to checkif the distance is within a predetermined interval. Depending on the outcome of distancedetermination of other nodes, as will be described below, the safety system 400 may bearranged such that the work vehicle 410 is slowed down or stopped if the determinedistance is below the lower bound of the predetermined interval and arranged such that the wireless remote control unit 430 emits a warning signal, e.g. a vibration, sound or visual 29 signal, if the determined distance is greater than the upper bound of the predetermined interval. lf the determined distance falls outside the predetermined interval, the outcomes of thedistances determined by the other nodes are also considered. The safety system 400 willissue a Go or NoGO signal depending on the other determined distances. For instance, anoperator may be allowed to walk behind a work vehicle 410 moving in a forward direction, even if the operator is considered to be too close to a rear position of the work vehicle.
The disclosure also relates to a computer program comprising computer program codewhich, when executed, causes a safety system according to the present disclosure to carry out an aspect according to the disclosed method.
The safety system is also applicable to situations where two or more work vehicles areoperating autonomously. Consider, for illustrative purposes, two work vehicles that arearrange to operate autonomously, i.e. without the need from an operator. The vehicle unitmay then be arranged in one of the work vehicles and the operator unit in the other vehicle.The safety system is arranged analogous to the principles of geo-fencing, with the workvehicle having the operator unit being ”fenced in” by the (one or more) work vehicle(s)having vehicle units arranged to communicate with the operator unit. The work vehiclehaving the operator unit may be arranged to transmit warning signals to other work vehiclesentering a predetermined distance interval from the work vehicle having the operator unit.According to some aspects, the wireless remote control unit further comprises an externalcontrol unit. The external control unit is a unit that is not arranged at a work vehicle andserves as a central control node arranged to transmit first control signals to the two (or more) work vehicles. ln addition to protecting the operator, the safety system may also be arranged to protectother people. For instance, the safety system may comprise a plurality of personnel unitshaving functionality arranged to enable determining a spatial relationship between thepersonnel unit and the work vehicle, the functionality being similar to that of the operatorunit of a wireless remote control. The personnel units may then be worn by people otherthan the operator and the vehicle unit of the work vehicle may determine if a person other than the operator of the work vehicle has a spatial relationship to the work vehicle meeting a predetermined criterion, e.g. the person other than the operator being within a predetermined distance from the work vehicle. ln the context of the present disclosure, the term work vehicle is used to denote vehiclesdesigned for road construction work, e.g. compactors. The safety system is also applicablefor other types of remotely operated heavy vehicles dedicated for specific work tasks, e.g. for remotely operated industrial trucks and vehicles used in mining operations. 31

权利要求:
Claims (9)
[1] 1. CLAll/IS 1.
[2] 2. A safety system (100, 200, 300, 400) for a remotely operated work vehicle (110, 210,310, 410), the work vehicle (110, 210, 310, 410) being arranged to receive a firstcontrol signal (170) from a wireless remote control unit (130, 230, 330, 430), the firstcontrol signal (170) being arranged to control a drive operation (190, 290, 390, 490)of the work vehicle (110, 210, 310, 410), wherein the safety system (100, 200, 300,400) comprises a vehicle unit (150, 250, 350, 450) arranged at the work vehicle (110,210, 310, 410) and an operator unit (155, 255, 355, 455) arranged at the wirelessremote control unit (130, 230, 330, 430), characterized in that the operator unit(155, 255, 355, 455) is arranged to transmit at least one signal (120, 220, 320, 420a,420b) carrying information relevant for positioning of the wireless remote controlunit (130, 230, 330, 430) to the vehicle unit (150, 250, 350, 450) and that the vehicle unit (150, 250, 350, 450) is arranged to obtain information relating toa first position (160a, 460a) of the work vehicle (110, 210, 310, 410), to determine a spatial relationship between the work vehicle (110, 210, 310, 410)and the wireless remote control unit (130, 230, 330, 430) based on the informationrelating to a first position (160a, 460a) of the work vehicle (110, 210, 310, 410) andthe information relevant for positioning of the wireless remote control unit (130,230, 330, 430), to periodically determine if the spatial relationship meets apredetermined criterion, and to provide a second control signal (180) to the workvehicle (110, 210, 310, 410), the second control signal (180) being arranged tocontrol the drive operation (190, 290, 390, 490) of the work vehicle (110, 210, 310, 410) based on the periodic determination. The safety system (100, 200, 300, 400) according to claim 1, characterized in that thevehicle unit (150, 250, 350, 450) further comprises a processing element, wherein theprocessing element is communicatively connected to the drive operation (190, 290,390, 490), and wherein the processing element is arranged to control the driveoperation (190, 290, 390, 490) of the work vehicle (110, 210, 310, 410) by providing the second control signal (180). 32 The safety system (100, 200, 300, 400) according to claim 1 or 2, characterized inthat the processing element further comprises processing circuitry arranged toreceive the information relating to a first position (160a, 460a) of the work vehicle(110, 210, 310, 410) and the information relevant for positioning of the wirelessremote control unit (130, 230, 330, 430), and in that the processing circuitry isfurther arranged to determine said spatial relationship and generate the secondsignal based on whether the spatial relationship the spatial relationship meets the predetermined criterion. The safety system (100, 200, 300, 400) according to any of the preceding claims,characterized in that the spatial relationship relates to a first distance between thework vehicle (110, 210, 310, 410) and the wireless remote control unit (130, 230,330, 430) and in that the predetermined criterion comprises the first distance falling within a predetermined distance interval. The safety system (100, 200, 300, 400) according to claim 4, characterized in that thesecond control signal (180) is arranged to stop the work vehicle (110, 210, 310, 410) if the work vehicle (110, 210, 310, 410) enters the predetermined distance interval. The safety system (100, 200, 300, 400) according to claim 4 or 5, characterized inthat the vehicle unit (150, 250, 350, 450) is arranged to determine the first distanceusing two-way ranging time of flight based on a time stamp based on the informationrelating to a position (160a, 460a) of the work vehicle (110, 210, 310, 410) that istime stamped at an initial time of the two-way ranging and a time stamp based on a received signal that is time stamped at a finishing time of the two-way ranging. The safety system (100, 200, 300, 400) according to claim 6, characterized in that thevehicle unit (150, 250, 350, 450) comprises a first transceiver and the operator unit(130, 230, 330, 430) comprises a second transceiver, wherein the first transceiver isarranged to transmit an initiation signal at said initial time to the second transceiver, and wherein second transceiver is arranged to receive the initiation signal and 33 10. 11. transmit a response signal to the first transceiver, the response signal comprising said time stamp for the finishing time. The safety system (100, 200, 300, 400) according to any of c|aims 1-5, characterizedin that the information relevant for positioning (160a, 460a) of the work vehicle (110,210, 310, 410) and information relevant for positioning of the wireless remotecontrol unit (130, 230, 330, 430) comprise respective global navigational satellite system, GNSS, coordinates obtained from a global navigational satellite system. The safety system (100, 200, 300, 400) according to claim 8, characterized in that thevehicle unit (150, 250, 350, 450) comprises a first receiver arranged to receive avehicle coordinate signal comprising the GNSS coordinates (XYZWOrk Vehide) of theposition (160a, 460a) of the work vehicle, and in that the operator unit (155, 255,355, 455) comprises a second receiver arranged to receive an operator coordinatesignal comprising the GNSS coordinates (XYZremote contrm) of the position of the wireless remote control unit (130, 230, 330, 430). The safety system (100, 200, 300, 400) according to claim 8, characterized in that thefirst and second receivers are further arranged to receive corrective information(AXYZWOrk Vehide, AXYZremote contrm), the corrective information being based onpredetermined GNSS coordinates of at least one reference point, wherein the vehicleunit (150, 250, 350, 450) is further arranged to improve the accuracy of the GNSScoordinates of the positions of the work vehicle and the wireless remote control unit based on the corrective information. The safety system according to any ofthe preceding c|aims, characterized in that theinformation relevant for positioning (160a, 460a) of the work vehicle (110, 210, 310,410) comprises information relating to a second position ofthe work vehicle, that thespatial relationship further relates to a second distance between the work vehicle(110, 210, 310, 410) and the wireless remote control unit (130, 230, 330, 430) basedon the second position, and in that the predetermined criterion comprises the second distance falling within a second predetermined distance interval. 34 12. The safety system (100, 200, 300, 400) according to any of the preceding claims, 1
[3] 3. 1
[4] 4. 1
[5] 5. characterized in that the vehicle unit (150, 250, 350, 450) and the wireless remotecontrol unit (130, 230, 330, 430) each comprises direction detection means arrangedto determine a direction of the work vehicle (110, 210, 310, 410) and the wirelessremote control unit (130, 230, 330, 430), respectively, wherein the vehicle unit (150,250, 350, 450) is further arranged to determine a relative direction between thedetermined directions of the work vehicle (110, 210, 310, 410) and the wirelessremote control unit (130, 230, 330, 430), and in that the vehicle unit (150, 250, 350,450) is arranged to stop the work vehicle (110, 210, 310, 410) based on a predetermined relative direction criterion. The safety system (100, 200, 300, 400) according to any of the preceding claims,characterized in that the operator unit (155, 255, 355, 455) comprises a firstorientation sensor, wherein the first orientation sensor is arranged to determine anacceleration and/or a change in orientation of the wireless remote control unit (130,230, 330, 430), and wherein the vehicle unit (150, 250, 350, 450) is arranged to stopthe work vehicle (110, 210, 310, 410) based on the determined acceleration and/or change in orientation meeting at least one predetermined criterion. The safety system (100, 200, 300, 400) according to any of the preceding claims,characterized in that the vehicle unit (150, 250, 350, 450) comprises a secondorientation sensor arranged to provide the vehicle unit (150, 250, 350, 450) withinformation relating to roll, pitch and heading of the work vehicle (110, 210, 310,410), wherein the vehicle unit (150, 250, 350, 450) is further arranged to stop thework vehicle (110, 210, 310, 410) based on the information relating to roll, pitch andheading of the work vehicle (110, 210, 310, 410) meeting at least one predetermined criterion. The safety system (100, 200, 300, 400) according to any of the preceding claims,characterized in that the vehicle unit (150, 250, 350, 450) comprises a temperature sensor, wherein the temperature sensor is arranged to provide the vehicle unit (150, 1
[6] 6. 1
[7] 7. 250, 350, 450) with information relating to a temperature of the work vehicle (110,210, 310, 410), wherein the vehicle unit (150, 250, 350, 450) is further arranged toprovide at least one second control signal (180) based on the information relating tosaid temperature of the work vehicle (110, 210, 310, 410) meeting a predetermined criterion. A method (500) performed in a safety system for a remotely operated work vehicle,the work vehicle being arranged to receive a first control signal from a wirelessremote control unit, the first control signal being arranged to control a driveoperation of the work vehicle, wherein the safety system comprises a vehicle unitarranged at the work vehicle and an operator unit arranged at the wireless remote control unit, characterized in that the method (500) comprises the steps of: obtaining (S501) information relating to a first position ofthe work vehicle; - transmitting (S502) at least one signal carrying information relevant forpositioning of the wireless remote control unit to the vehicle unit; - determining (S503) a spatial relationship between the work vehicle and thewireless remote control unit based on the information relating to a first positionof the work vehicle and the information relevant for positioning of the wirelessremote control unit; - periodically determining (S504) if the spatial relationship meets a predeterminedcriterion; and - providing (S505) a second control signal to the work vehicle, the second control signal being arranged to control the drive operation of the work vehicle based on the periodic determination. The method (500) according to claim 16, characterized in that determining (S503) the spatial relationship further comprises - determining (S506) a first and a second distance between the work vehicle andthe wireless remote control unit; in that periodically determining (S504) if thespatial relationship meets a predetermined criterion further comprises - for each of the first and second distances, determining (S507) if at least one of the first and second distances falls within a predetermined distance interval; and 36 in that providing (S505) a second control signal to the work vehicle furthercomprises - arranging (S508) the at least one second control signal to stop the work vehicle ifat least one of the first and second distances fall within the predetermined distance interval and fall within a second predetermined distance interval. 1
[8] 8. The method (500) according to claim 16 or 17, characterized in that the method (500)further comprises the steps of:- obtaining (S509) information relating to roll, pitch and heading of the workvehicle; and- arranging (S510) the at least one second control signal to stop the work vehicle if at least one ofthe roll, pitch and heading meets a predetermined criterion.1
[9] 9. A computer program comprising computer program code which, when executed, causes a safety system according to any of claims 1-15 to carry out the method according to any of claims 16-18. 37

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公开号 | 公开日

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AU2017254352B2|2021-07-08|

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EP3446189A1|2019-02-27|

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WO2017184068A1|2017-10-26|

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SE539699C2|2017-10-31|

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法律状态:

优先权:

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申请号 | 申请日 | 专利标题

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SE1650538A|SE539699C2|2016-04-21|2016-04-21|Safety system, method and computer program for remotely controlled work vehicles|SE1650538A| SE539699C2|2016-04-21|2016-04-21|Safety system, method and computer program for remotely controlled work vehicles|

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PCT/SE2017/050388| WO2017184068A1|2016-04-21|2017-04-20|Safety system, method and computer program for remotely controlled work vehicles|

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US16/095,034| US10976735B2|2016-04-21|2017-04-20|Safety system, method and computer program for remotely controlled work vehicles|

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CA3022137A| CA3022137A1|2016-04-21|2017-04-20|Safety system, method and computer program for remotely controlled work vehicles|

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AU2017254352A| AU2017254352B2|2016-04-21|2017-04-20|Safety system, method and computer program for remotely controlled work vehicles|

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EP17786254.7A| EP3446189A4|2016-04-21|2017-04-20|Safety system, method and computer program for remotely controlled work vehicles|