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  • 专利说明
  • 权利要求
  • 类似技术
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    • 专利摘要:
    18 Abstract A steering wheel torque evaluation module (2) for evaluating torque applied by adriver to a steering wheel (4) of a vehicle (6) to indicate a hands-off steering wheelsituation, the module is configured to receive a steering wheel torque signal (8)including torque values Tqdriver continuously obtained by a torque sensor device(10) arranged to measure torque at a steering wheel shaft (12) coupled to thesteering wheel. The evaluation module comprises a first calculation unit (14), asecond calculation unit (16), a comparison unit (18) and a timer (20) structured tomeasure time related to the steering wheel torque signal (8), the module isconfigured to receive a torque reference value Tqref, a loose torque referencevalue Tqrefloose, and preferably also an abort torque reference value Tqabortrepresenting a predetermined threshold level determined such that torque valuesgreater than Tqabort represent a hand steering situation, and that Tqref Wmax the comparison unit is configured to generate an indication signal (22). (Figure 2)
    公开号:SE1650200A1
    申请号:SE1650200
    申请日:2016-02-16
    公开日:2017-08-17
    发明作者:Bredberg Linus；Andersson Jonny
    申请人:Scania Cv Ab；
    IPC主号:
    专利说明:

    A steering wheel torque evaluation module Technical field The present disclosure relates to a steering wheel torque evaluation module forevaluating torque applied by a driver to a steering wheel of a vehicle to indicate ahands-off steering wheel situation, and a method in relation to the evaluation module.
    Backgroundln vehicles, e.g. cars and trucks, of today intelligent driver assistance systems are becoming frequently used. Even though advanced driver assistance systembecomes more intelligent and takes more and more load off the driver, the driveris still responsible for driving the vehicle. When introducing systems that assist inkeeping the vehicle within the lane, sometimes called Lane Keeping Assist (LKA)systems, there are legal requirements that stipulate that the driver should havethe control of the operation of the vehicle. This may be ascertained by detectingthe driver's steering wheel activity. The detection may be performed by providinga so-called “hands on wheel-detection”. This is often performed by observing thedriver torque on the steering column, and may be done either passively (by justobserving with respect to a reference torque) or with active stimuli in form of aweak induced torque from which a response from the driver is expected.
    Using actively induced torque in a truck may be difficult since the driver must notbe disturbed by the added torque in question and it is difficult to determine asuitable torque reference value that fits different wheel combinations as thesystem may then interpret internal friction/inertia as a driver response.
    Using only passive torque observations and setting a reference level works fine aslong as the driver holds the wheel quite firmly. lt is however difficult to detect whenthe driver holds the steering wheel very loosely. The present invention relates to a module and a method applying passive torque observations. 2 Below some patent documents will be discussed that disclose various systems ofdetermining steering wheel torque.
    US20120041645 relates to a steering control apparatus for vehicle and a steeringcontrol method. The steering wheel torque value is determined and a timederivative value of the detected steering wheel torque is determined. A hands-offsituation may be determined based upon those values.
    EP1645454 relates to an equipment for detecting the action of a driver on thesteering wheel of the steering system of a motor vehicle provided with a drivingassistant system. An alarm signal is generated if the torque applied by the driverto the steering wheel and its derivative both remain simultaneously below therespective lower thresholds for at least a predetermined reference time duration.
    US20130158771 discloses a control system to determine if a hands on steeringwheel condition is provided. A sensor is arranged to measure an amount ofapplied torque exerted upon the hand wheel. The measured signal is processedand it is determined if a hands on steering wheel condition exists based upon the processed signal.
    And finally, EP2093093 relates to a method and device for detecting an absenceof driver activity at the steering wheel. The steering wheel torque is measured anddetermined, and the derivative of the torque is also determined. These values arecompared to threshold values, and an alarm signal is generated if certainconditions are fulfilled in order to indicate absence of driving activity at the steering wheel.
    As the use of driver assistance systems increase also the requirements of thesteering wheel detection system increase and therefore there is a generaldemand to achieve an improved detection in relation to hands off steering wheeldetection. 5 3 Therefore, the object of the present invention is to achieve an improved moduleand method configured to detect various driver behaviors in order to generatereliable hands off steering wheel indication signals.
    SummaryThe above-mentioned object is achieved by the present invention according to the independent claims.
    Preferred embodiments are set forth in the dependent claims.
    The major advantage of the solution implemented by the steering wheel torqueevaluation module is that a robust hands-on-wheel detection is achieved that iseasily tunable and that also may handle various driver behaviors, e.g. drivers thatlike to hold very loosely on the steering wheel, which is the case for many haulagedrivers, and drivers that apply a low steering wheel torque. By implementing theevaluation module the risk for false alarms is highly reduced. Another advantageis that no actively induced steering torque needs to be applied.
    More particularly, the implemented solution consists of two parts: one fordetecting continuously low steering wheel torque and one advantageous embodiment for detecting a loosely held steering wheel.
    Low steering wheel torque is detected by determining an accumulated energymeasure W based upon the detected Tqdriver in relation to Tqref and the time.Preferably, the energy measure W is reset if Tqdriver is larger than a referencevalue Tqabort.
    Loosely held steering wheel is determined by providing a further torque threshold,Tqloose, between Tqref and Tqabort, and to calculate a counter value C independence of the relationship between Tqref and Tqloose, that in turn is used forresetting the accumulated energy W if certain conditions are fulfilled. 4 An evaluation module is provided with a first calculation unit and a secondcalculation unit being configured to determine an indication signal by taking twodifferent parts of a driver's steering wheel activity behavior into account, both thatthe driver essentially does not hold the steering wheel, and that the driver onlyapplies a very low torque to the steering wheel.
    The detection is based upon determining how a detected steering wheel torqueTqdriver is related to a reference torque, Tqref. ln a simplified example if the detected steering wheel torque is close to 0, i.e. thedifference A between and Tqref is approximately Tqref, during a predeterminedtime period, the driver is considered to have his hands off the steering wheel andan alarm should be generated.
    Brief description of the drawinqs Figure 1 shows a truck provided with the evaluation module according to thepresent invention.
    Figure 2 is a schematic diagram illustrating the evaluation module according tothe present invention.
    Figures 3A-3D shows diagrams illustrating various aspects of the presentinvenfion.
    Figure 4 is a flow diagram illustrating the method according to the present invenfion.
    Detailed descriptionThe evaluation module and the method will now be described in detail with references to the appended figures. Throughout the figures the same, or similar,items have the same reference signs. Moreover, the items and the figures are notnecessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
    First with references to the block diagram shown in figure 2, the present inventionrelates to a steering wheel torque evaluation module 2 for evaluating torque 5 applied by a driver to a steering wheel 4 of a vehicle 6 (see figure 1). The purposeof the module is to indicate a hands-off steering wheel situation.
    The evaluation module is configured to determine if the driver is considered tofulfil the set requirements for having active control of the steering of the vehicle.The evaluation module is configured to generate at least one indication signalbeing indicative of the steering activity performed by the driver.
    More in detail, the evaluation module 2 is configured to receive a steering wheeltorque signal 8 including torque values Tqdriver continuously obtained by a torquesensor device 10 arranged to measure torque at a steering wheel shaft 12coupled to the steering wheel.
    The torque value of the steering wheel is measured by a conventional torquesensor device 10 that is arranged e.g. at the steering wheel shaft. Thus, themeasured torque value represents the torque applied to the steering wheel by thedriver and is denoted Tqdriver.
    When a driver assistance system (not shown) is used automated steering may beapplied, e.g. when a lane keeping assist system is used, the steering wheelmoves in accordance with the steering applied by the automated steering system.This movement is also detected by the torque measurement system, but themeasurement values are very small and are related to the inertia of the steeringwheel, provided that the driver does not touch the steering wheel. Thus, Tqdriver is essentially a measure of the torque the driver supplies to the steering wheel.
    The evaluation module comprises a first calculation unit 14, a second calculationunit 16, a comparison unit 18 and a timer 20 structured to measure time related tothe steering wheel torque signal 8. The module is configured to receive a torquereference value Tqref representing a predetermined threshold level determinedsuch that torque values below Tqref represent a possible hands-off steeringsituation. The value Tqref is set to a value being such that it is likely that the driverdoes not hold the steering wheel. This value is set in advance and is empirically determined. 6 The module is configured to receive a loose torque reference value Tqreflooserepresenting a predetermined threshold level determined such that torque valuesbetween Tqref and Tqrefloose represent a loose hand steering situation. ln oneembodiment Tqrefloose is 10-30% larger than Tqref, and preferably Tqrefloose =1.2 * Tqref. Thus, Tqref < Tqrefloose. ln one embodiment the module is further configured to receive an abort torquereference value Tqabort representing a predetermined threshold level determinedsuch that torque values greater than Tqabort represent a hand steering situation.Advantageously, Tqabort is 150-300% larger than Tqref, and preferably Tqabort =2 * Tqref.
    Preferably, the following relationship between the reference values exists: Tqref ln general, when Tqdriver is below Tqref it is considered that the driver does nothave his hands on the steering wheel. One additional parameter to take intoaccount is the magnitude of the difference between the reference value and themeasured torque value. Provided that Tqdriver is below Tqref, a hands-off alarmshould be generated after a shorter time period if the magnitude of the differenceis larger in comparison if the magnitude is smaller. ln other word, if the magnitude of the difference is small the measured torque isclose to the reference value, i.e. it is more likely that the driver has his hands onthe steering wheel.
    The first calculation unit 14 is configured to continuously determine a differencevalue A between the absolute value of Tqdriver, and Tqref. Then, the firstcalculation unit 14 is configured to calculate an accumulated energy measure Wbased upon A and a time t related to the measurements of Tqdriver and Tqref in accordance to a set of calculation rules. 7 The thus determined energy measure W is applied to the comparison unit 18 thatis configured to compare W with a threshold value Wmax. lf W > Wmax thecomparison unit is configured to generate at least one indication signal 22.
    The at least one indication signal may e.g. be a tactile or audible hands-off alarmsignal generated to make the driver aware of that he/she must take active part inthe steering of the vehicle. The indication signal may also include a control signalto be applied to the driver assistance system, e.g. for turning it off.
    Thereafter W is reset, i.e. W = 0. W may also be reset if Tqdriver is greater thanTqabort.
    According to one embodiment the evaluation module works by accumulating, inthe first calculation unit, the energy W in the differential between the absolutevalue of the measured driving torque and the reference torque according to: W = I (mwwflxrqæf ~ lTqdn-W. f) The energy Wmax required for a hands-off alarm, may be calculated according to: Wmax I Tqrefz * tref tref is an appropriately determined time period being in the interval of 1-3seconds. lf appropriate, Wcould also be accumulated in other manners, e.g. linearly or witha similar function. lf Wreaches W the driver is considered to have his hands off the wheel.
    InaX 7 The time it takes for this to happens depends on the actual steering wheel input, i.e. if the Tqdme, is close to 0 it is much more certain than if Tqdme, is close to Tqref.This also reduces the risk for false alarms. lf the torque is between Tqïef < Tqdriver decreased with a suitable speed, e.g. 5 times faster than it is normally decreased according to: W = W - 5 * (Tqmf - |Tqdme, )2 The indication or warning itself may consist of two or more gradually increasingindication steps. The first one could be a discrete tell-tale or similar. After a pre-set time duration, e.g. in the interval of 3-5 seconds, and provided that no steeringtorque is detected, an escalated warning could be generated. This could also bein combination of generating and applying a control signal to the drivingassistance system, e.g. the cruise control or similar, for switching it offjust to get the driver's attention. ln order to detect smaller driver torques a second part is applied in addition to thefirst part which has been described above. ln order to apply this second part the evaluation module comprises a secondcalculation unit. This second part applies an event-based method and is basedupon on the assumption that the driver frequently makes very small corrections,each not strong enough to trigger a reset of the hands off energy accumulator, which will occur when Tqdriver > Tqabort. ln accordance to this second part a third reference level, Tqmflme is used whereTqref < Tqrefloose
    权利要求:
    Claims (18)
    [1] 1. A steering wheel torque evaluation module (2) for evaluating torqueapplied by a driver to a steering wheel (4) of a vehicle (6) to indicate a hands-offsteering wheel situation, the module is configured to receive a steering wheeltorque signal (8) including torque values Tqdriver continuously obtained by atorque sensor device (10) arranged to measure torque at a steering wheel shaft(12) coupled to the steering wheel, c h a r a c t e r i z e d in that evaluationmodule comprises a first calculation unit (14), a second calculation unit (16), acomparison unit (18) and a timer (20) structured to measure time related to thesteering wheel torque signal (8), the module is configured to receive a torquereference value Tqref representing a predetermined threshold level determinedsuch that torque values below Tqref represent a possible hands-off steeringsituation, a loose torque reference value Tqrefloose representing a predeterminedthreshold level determined such that torque values between Tqref and Tqreflooserepresent a loose hand steering situation, and that Tqref < Tqrefloose, wherein said first calculation unit (14) is configured to continuously determine adifference value A between the absolute value of Tqdriver, and Tqref, and tocalculate an accumulated energy measure W based upon A and a time t related tothe measurements of Tqdriver and Tqref in accordance to a set of calculationrules; and wherein the comparison unit (18) is configured to compare W with athreshold value Wmax, and ifW > Wmax the comparison unit is configured togenerate an indication signal (22).
    [2] 2. The evaluation module according to claim 1, wherein said secondcalculation unit is configured to calculate a counter value C in dependence of theresult of a comparison of Tqdriver and Tqrefloose in accordance with a set ofevent-based rules, such that C is increased if Tqdriver > Tqrefloose, and whereinthe comparison unit is configured to compare C to a value Cmax and if C > Cmax within a predefined time period tc, W is reset.
    [3] 3. The evaluation module according to claim 1 or 2, wherein the moduleis configured to receive an abort torque reference value Tqabort representing a predetermined threshold level determined such that torque values greater thanTqabort represent a hand steering situation, and that Tqref < Tqrefloose
    [4] 4. The evaluation module according to claim 3, wherein the comparisonunit is configured to compare Tqdriver to Tqabort and if Tqdriver > Tqabort W isreset.
    [5] 5. The evaluation module according to any of claims 1-4, wherein the set of calculation rules comprises determining W = l (mwwflxrqæf ~ lTqdn-W. f) _
    [6] 6. The evaluation module according to claim 2, wherein said set ofevent-based rules comprises decreasing the counter C if Tqdriver is continuouslybelow Tqloose during a predetermined time period.
    [7] 7. The evaluation module according to any of claims 1-6, whereinTqrefloose is 10-30% larger than Tqref, and preferably Tqrefloose = 1.2 * Tqref.
    [8] 8. The evaluation module according to claim 3 or 4, wherein Tqabort is150-300% larger than Tqref, and preferably Tqabort = 2 * Tqref.
    [9] 9. A method in relation to a steering wheel torque evaluation module forevaluating torque applied by a driver to a steering wheel of a vehicle to indicate ahands-off steering wheel situation, the method comprises: - receiving a steering wheel torque signal including torque values Tqdrivercontinuously obtained by a torque sensor device arranged to measure torque at asteering wheel shaft coupled to the steering wheel, c h a r a c t e r i z e d i n thatthe method further comprises: - receiving, by said evaluation module, a torque reference value Tqrefrepresenting a predetermined threshold level determined such that torque values 16 below Tqref represent a possible hands-off steering situation, a loose torquereference value Tqrefloose representing a predetermined threshold leveldetermined such that torque values between Tqref and Tqrefloose represent aloose hand steering situation, and that Tqref < Tqrefloose, - continuously determining, by a first calculation unit, a difference value A betweenthe absolute value of Tqdriver, and Tqref, and - calculating an accumulated energy measure W based upon A and a timetrelated to the measurements of Tqdriver and Tqref in accordance to a set ofcalculation rules; and - comparing, by a comparison unit, W with a threshold value Wmax, and ifW > Wmax generating an indication signal.
    [10] 10. The method according to claim 9, wherein said method comprises: - comparing, by a second calculation unit, Tqdriver and Tqrefloose in accordancewith a set of event-based rules, - calculating, by a second calculation unit, a counter value C in dependence of theresult of the comparison, such that C is increased if Tqdriver > Tqrefloose, and - comparing C to a value Cmax and if C > Cmax within a predefined time period tc, W is reset.
    [11] 11. The method according to claim 9 or 10, wherein the methodcomprises receiving, by said evaluation module, an abort torque reference valueTqabort representing a predetermined threshold level determined such that torquevalues greater than Tqabort represent a hand steering situation, and that Tqref < Tqrefloose < Tqabort.
    [12] 12. The method according to claim 11, wherein the method comprises comparing Tqdriver to Tqabort and if Tqdriver > Tqabort W is reset.
    [13] 13. The method according to any of claims 9-12, wherein the set of calculation rules comprises determining 17 W = I (mwwflxrqmf ~ lTqdfl-.W f)
    [14] 14. The method according to claim 10, wherein said set of event-based rules comprises decreasing the counter C if Tqdriver is continuously below Tqloose during a predetermined time period.
    [15] 15. The method according to any of claims 9-14, wherein Tqrefloose is10-30% larger than Tqref, and preferably Tqrefloose = 1.2 * Tqref.
    [16] 16. The method according to claim 10 or 11, wherein Tqabort is 150-300% larger than Tqref, and preferably Tqabort = 2 * Tqref.
    [17] 17. A computer program P, wherein said computer program P comprisesa computer program code to cause a control unit (30), or a computer connected tosaid control unit (30), to perform the method according to any of claims 9-16.
    [18] 18. A computer program product comprising a computer program codestored on a computer-readable medium to perform the method according to any ofthe claims 9-16, when said computer program code is executed by a control unit (30) or by a computer connected to said control unit (30).
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    同族专利:
    公开号 | 公开日
    DE102017001243B4|2021-05-27|
    DE102017001243A1|2017-08-17|
    SE539620C2|2017-10-17|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DE602004012105T2|2004-10-08|2009-03-12|C.R.F. Società Consortile per Azioni, Orbassano|Device for detecting the action of a driver on a steering wheel of a steering system of a motor vehicle|
    EP2093093B1|2008-02-25|2012-10-17|Volkswagen Aktiengesellschaft|Method and device for detecting an absence of driver activity at the steering wheel|
    DE102009028647A1|2009-08-19|2011-02-24|Zf Lenksysteme Gmbh|Method and device for detecting an operating state of a steering wheel in a vehicle|
    ES2401034T3|2010-08-11|2013-04-16|Thyssenkrupp Presta Ag|Steering control device for a vehicle and steering control method|
    US8548667B2|2011-12-15|2013-10-01|Steering Solutions Ip Holding Corporation|Hands on steering wheel detect in lane centering operation|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1650200A|SE539620C2|2016-02-16|2016-02-16|A steering wheel torque evaluation module|SE1650200A| SE539620C2|2016-02-16|2016-02-16|A steering wheel torque evaluation module|
    DE102017001243.1A| DE102017001243B4|2016-02-16|2017-02-09|Steering wheel torque evaluation module|
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