Method and device for recognizing contact between hand and vehicle steering wheel

Abstract

The invention relates to a method for detecting a contact of a hand with a steering wheel (51) of a vehicle, in which method a test signal (14) is applied to the steering wheel (51) by means of an actuator (2), in which method a reaction (9) on the steering wheel (51) to the test signal (14) is detected by means of a sensor (3), and in which method the contact of the hand with the steering wheel (51) is detected by means of the sensor (3). A decision (6) is made as to whether at least one hand of the driver is in contact with the steering wheel (51) on the basis of the detected reaction (9), a test signal (14) is applied according to a predetermined torque curve (5), and the torque curve (5) rises to a predetermined minimum torque (16) at the beginning in a skipping manner, the minimum torque corresponds to a minimum friction (12) of a steering system (50) of the vehicle. The invention also relates to a device (1) for detecting a contact between a hand and a steering wheel (51) of a vehicle.

Description

[0001] This invention relates to a method and apparatus for identifying contact between a hand and a vehicle steering wheel.

[0002] In modern vehicles, sensors are used to monitor driver activity. For example, capacitive sensors on the steering wheel can be used to determine whether at least one of the driver's hands is on the steering wheel (also known as hand grip detection). Based on the sensor data recorded capacitively, multiple levels of states (e.g., no contact, slight left / right grip to strong grip on both sides, etc.) can be determined, and this state is transmitted to, for example, supporting functions such as longitudinal and / or lateral guidance assist systems. For instance, this state can be provided as input to adaptive cruise control (ACC), thereby activating the initiation process for following the vehicle ahead when at least one hand is detected in contact with the steering wheel. Furthermore, driver monitoring cameras are known to detect driver activity.

[0003] In addition, some methods utilize artificial intelligence or rule-based approaches to detect driver activity, particularly driver activity related to hand grip detection. For example, AI methods, particularly artificial neural networks, can be trained to perform hand grip detection based on detected torque, detected steering angle, and / or changes in these variables. On the other hand, rule-based methods passively evaluate steering signals (e.g., steering torque, steering speed, and / or steering angle) based on thresholds and / or signal curves, or actively operate through torque application, where a test signal is applied to the steering wheel via an actuator, representing a counter-torque generated by the hand placed on the steering wheel, which can be detected by sensors. Once such counter-torque is detected, it is assumed that at least one hand is on the steering wheel. This approach is known, for example, from DE 10 201 3209 459 A1.

[0004] The objective of this invention is to improve the method and apparatus for recognizing contact between a hand and a vehicle steering wheel.

[0005] According to the invention, this task is accomplished by a method having the features of claim 1 and an apparatus having the features of claim 10. Advantageous embodiments of the invention arise from the dependent claims.

[0006] Specifically, a method for identifying contact between a hand and a vehicle steering wheel is provided, wherein a test signal is applied to the steering wheel by an actuator, wherein the steering wheel’s response to the test signal is detected by means of a sensor, and wherein a decision is made on whether at least one of the driver’s hands is in contact with the steering wheel based on the detected response, wherein the test signal is applied according to a predetermined torque curve, and wherein the torque curve abruptly increases to a predetermined minimum torque at the beginning, the minimum torque corresponding to the minimum friction of the vehicle steering system.

[0007] In addition, a device for identifying hand contact with a vehicle steering wheel has been specifically created, comprising an actuator configured to apply a test signal to the steering wheel, a sensor configured to detect the response to the test signal on the steering wheel, and a control device configured to initiate the application of the test signal, evaluate the detected response, and make a decision on whether at least one of the driver's hands is in contact with the steering wheel based on the detected response, wherein the test signal is applied according to a predetermined torque curve, and wherein the torque curve initially increases abruptly to a predetermined minimum torque, which corresponds to the minimum friction of the vehicle steering system.

[0008] This method and apparatus enable the overcoming of system-related friction in the steering system in the shortest possible time, allowing for near-zero-delay detection of the reaction to an applied test signal without the driver's hands on the steering wheel perceiving the test signal as an interference. This is achieved by only jumping to a specified minimum torque, but then increasing the torque only slowly thereafter. This is based on the idea that the driver cannot perceive the test signal until the minimum friction is overcome, meaning that care must be taken not to design the test signal to interfere with the driver only after the minimum friction is overcome. Furthermore, each steering system has individual friction forces. However, for a steering system installed in a vehicle, a tolerance band can be defined that includes a large number of minimum and maximum possible frictions of similar steering systems. Based on this, the minimum possible friction of the tolerance band is specified as the minimum friction of this method and apparatus. This allows this system-related minimum friction to be overcome immediately by a sudden increase when the test signal is applied, resulting in a faster system response and allowing the detection of the hand-induced reaction on the steering wheel in the shortest possible time.

[0009] The advantage of this method and device is that it can detect reactions more quickly (i.e., especially counter-torque on the steering wheel caused by at least one hand). This also allows for a faster decision on whether the driver's at least one hand is in contact with the steering wheel. Consequently, the appropriate signals can be provided to driver assistance functions more quickly, which improves driving comfort.

[0010] Another advantage is that this method and device eliminate the need for capacitive sensors, such as those on the steering wheel, because reliable hand grip detection can be performed even without capacitive sensors. This saves on consumables, costs, and installation space.

[0011] Actuators, particularly those in steering systems, such as the motor of the steering system. Sensors, particularly those in steering systems, such as torque sensors and / or steering angle sensors on steering assist units. In principle, multiple actuators and / or multiple sensors can also be provided.

[0012] Components of the device, particularly control devices, can be designed individually or in combination as a combination of hardware and software, such as program code designed to execute on a microcontroller or microprocessor. Alternatively, components can be specified individually or in combination as application-specific integrated circuits (ASICs) and / or field-programmable gate arrays (FPGAs).

[0013] In one embodiment, the method is specified to be performed only if it cannot be reliably determined otherwise that at least one hand is on the steering wheel. This allows the process to be initiated as needed. In particular, the application of a test signal can be omitted if it has already been reliably determined using another sensor (e.g., a capacitive sensor or a driver's camera) or another method (e.g., using artificial intelligence and / or rule-based methods).

[0014] In one embodiment, after reaching minimum torque, the torque curve increases to a predetermined value with a predetermined first slope. This ensures that the test signal on the steering wheel will not be disturbing to the driver with their hands on the steering wheel, but will still elicit a response in the shortest possible time. For example, a series of empirical tests can be used to determine the first slope.

[0015] In one embodiment, the torque curve is specified to decrease with a second slope after a predetermined time period, at least until a predetermined minimum torque is reached. This allows the applied test signal to return to zero slowly. This return can also be designed to avoid bothering the driver. For example, the second slope can be determined using a series of empirical tests. The second slope can also correspond to a first slope with the opposite sign.

[0016] In one embodiment, when counter-torque is detected, the torque curve decreases with a third slope at least until a predetermined minimum torque is reached. This allows for different handling of situations where no reaction is triggered and detected, and situations where counter-torque is detected as a reaction. Particular care must be taken in the case of detected counter-torque to design the (third) slope so that changes in torque on the steering wheel are not perceived as disturbances.

[0017] In a further embodiment, the third slope is specified to be numerically smaller than the second slope. As a result, when counter-torque is detected, the test signal can return to zero more slowly than if no counter-torque is detected.

[0018] In one implementation, based on the decision made, an enable signal for at least one assistance system is generated and provided, which is enabled when at least one of the driver's hands is in contact with the steering wheel. This enables the control assistance system.

[0019] In particular, in one embodiment, an enable signal may be specified to enable the (re)start process of adaptive cruise control (ACC).

[0020] In one implementation, the method is specified to be executed only if at least one assistance system sends a ready signal. This allows the process to be initiated as needed. For example, adaptive cruise control (ACC) can send such a ready signal if the vehicle in front starts moving again from a standstill and can be followed. In a further development, the method can also be specified to begin only if a ready signal has already been sent and it cannot be reliably determined whether at least one hand is on the steering wheel.

[0021] Further features for designing this device are derived from the description of embodiments of the method. The advantages of this device are the same as those of embodiments of the method.

[0022] The invention will now be explained in more detail using preferred exemplary embodiments with reference to the accompanying drawings. Herein lies:

[0023] Figure 1 A schematic diagram illustrating an embodiment of a device for recognizing hand contact with a vehicle steering wheel;

[0024] Figure 2a A schematic diagram showing the variation of a conventional test signal over time (existing technology);

[0025] Figure 2b A schematic diagram illustrating the change of the test signal over time according to the present invention is shown;

[0026] Figure 3 A schematic diagram illustrating another embodiment of the method and apparatus is shown.

[0027] Figure 1 A schematic diagram of an embodiment of a device 1 for recognizing contact between a hand and a vehicle steering wheel 51 is shown. Device 1 is specifically part of a vehicle steering system 50. In addition to the steering wheel 51, the steering system 50 includes a steering lever 52, a steering support unit 53, and a rack 54. Device 1 is specifically configured to perform the methods described in this disclosure, which will be explained in more detail using device 1.

[0028] Device 1 includes actuator 2, sensor 3, and control device 4. Actuator 2 may be an actuator of steering assist unit 53, such as an electric motor. Actuator 2 is configured to apply test signal 14 to steering wheel 51. Test signal 14 is specifically the torque applied to steering wheel 51. Sensor 3 is configured to detect the response 9 to test signal 14 on steering wheel 51. Sensor 3 may be, for example, a torque sensor on steering assist unit 53 of steering system 50.

[0029] The control device 4 includes, for example, a computing device 4-1 (e.g., a microcontroller or microprocessor) and a memory 4-2. The control device 4 is configured to cause a test signal 14 to be applied. For this purpose, the control device 4 controls the actuator 2 accordingly. Furthermore, the control device 4 is configured to evaluate the detected reaction 9 and make a decision 6 based on the detected reaction 9 regarding whether at least one of the driver's hands is in contact with the steering wheel 51.

[0030] Here, a test signal 14 is applied according to a predetermined torque curve 5, which is stored, for example, in the memory 4-2 of the control device 4. The torque curve 5 is implemented by the actuator 2. The torque curve 5 initially increases abruptly to a predetermined minimum torque, which corresponds to the minimum friction of the vehicle's steering system 50.

[0031] Figure 2a A schematic diagram illustrating the conventional test signal 10 used in the prior art over time (time axis t) is shown. Test signal 10 corresponds to torque curve 5. This conventional test signal 10 includes a slope in which the applied torque 11 increases linearly from zero to a predetermined value, remains there for a predetermined time period, and then decreases linearly to zero. A minimum friction 12 associated with the system must be overcome. Compared to the conventional test signal 10, the system response 13 of the steering system is delayed.

[0032] Figure 2b A schematic diagram illustrating the test signal 14 according to the invention over time (time axis t) is shown. The test signal 14 corresponds to the torque curve 5. The test signal 14 according to the invention has a jump 15 at the beginning, where it jumps to a predetermined minimum torque 16, which corresponds to the minimum friction 12 of the vehicle steering system. Furthermore, for clarity, the maximum friction force 17 and the average friction force 18 of the steering system are also shown; these values ​​are statistically determined and particularly relevant to a large number of identically designed steering systems.

[0033] Because, in addition to the test signal 14 according to the invention, Figure 2b The conventional test signal 10 is also shown, thus revealing the advantage of faster detection of the steering wheel response. Therefore, the system response 19 under the application of the test signal 14 according to the invention occurs earlier by time Δt than the system response 13 under the application of the conventional test signal 10, because the jump 15 overcomes the minimum friction 12 more quickly.

[0034] It can be stipulated that the method is only performed when it is impossible to reliably determine by other means whether at least one hand is on the steering wheel 51. For this purpose, the control device 4 receives, for example, signal 58 ( Figure 1In order to initiate the method, or if, for example, an artificial intelligence method or a rule-based method can also be executed on the control device 4, the control device 4 itself generates a signal 58 that cannot reliably determine whether the hand is in contact with the steering wheel 51 based on sensor data obtained from sensor 3 (and / or other sensors).

[0035] It can be stipulated that after reaching the minimum torque of 16, the torque curve 5 will have a predetermined first slope of 20 ( Figure 2b Increase to the predetermined (maximum) value of 21.

[0036] It can be stipulated that the torque curve 5, after a predetermined time period, has a second slope of 22 ( Figure 2b It will drop to at least the predetermined minimum torque of 16.

[0037] The first slope 20, the predetermined value 21, and the second slope 22 can be determined, for example, based on a series of empirical tests, in which in particular it is determined that at which slopes 20 and 22 the change in torque on the steering wheel has not been perceived or disturbed.

[0038] Figure 3 A schematic diagram illustrating another embodiment of the method and apparatus is shown. In this embodiment, when a counter-torque 23 is detected, the torque curve 5 decreases at least to a predetermined minimum torque 16 with a third slope 24. Essentially, the process of the test signal 14 according to the invention, or the torque curve 5 in this embodiment, is similar in other respects to... Figure 2b The process is shown in the figures. The same reference numerals denote the same terms and features. As an example, for clarity, two different curves with counter-torque 23 are shown, which may occur when the driver places one or both hands on the steering wheel. Counter-torque 23 is detected specifically when it exceeds (or falls below) the tolerance range 25 around the system response 19. This schematically illustrates the time points t1 and t2 of two exemplary curves for counter-torque 23. After counter-torque 23 is detected, the torque curve 5 is then adjusted such that it decreases at least to a predetermined minimum torque 16 with a third slope 24, as... Figure 3 As shown in the example, the third slope 24 can have the same value as the second slope 22.

[0039] It can also be specified that the third slope 24 is numerically smaller than the second slope 22. This allows the test signal 14 to decrease even more gently.

[0040] It can be stipulated that, based on the decision 6 made (Figure 6), an enable signal 7 for at least one assistance system 56 is generated and provided, which is activated when at least one of the driver's hands is in contact with the steering wheel 51. The enable signal 7 can then be transmitted to the assistance system 56.

[0041] In further improvements, it can be specified that enable signal 7 enables the (re)start process of adaptive speed control 57.

[0042] It can be specified that the method is executed only if at least one auxiliary system 56 sends a ready signal 8. Alternatively, it can be specified that signals 8 and 58 are logically linked, and the method is executed only when both signals are present.

[0043] The torque curve 5 shown according to the invention is selected only as an example to illustrate the disclosed method, and in principle it can be designed differently, particularly with respect to slopes 20, 22, 24 and predetermined value 21.

[0044] List of reference numerals

[0045] 1 device

[0046] 2 Actuators

[0047] 3 Sensors

[0048] 4 Control Unit

[0049] 4-1 Computing Equipment

[0050] 4-2 Memory

[0051] 5. Torque Curve

[0052] 6. Decision

[0053] 7 Enable signal

[0054] 8. Ready signal

[0055] 10 Traditional test signals

[0056] 11 Torque

[0057] 12 Minimum Friction

[0058] 13 System Response (Traditional Test Signals)

[0059] 14. Test signal according to the present invention

[0060] 15 Jumps

[0061] 16 Minimum Torque

[0062] 17. Maximum friction force

[0063] 18. Average value (friction)

[0064] 19 System Response (based on the test signal according to the invention)

[0065] 20 First slope

[0066] 21. Pre-set (maximum) value

[0067] 22 Second slope

[0068] 23. Counter torque

[0069] 24 Third slope

[0070] 25 Tolerance range

[0071] 50 Steering System

[0072] 51 Steering Wheel

[0073] 52. Steering rod

[0074] 53 Steering Assist Unit

[0075] 54 racks

[0076] 56. Auxiliary Systems

[0077] 57. Adaptive Cruise Control (ACC)

[0078] 58 signal

[0079] t time

[0080] t1 and t2 time points

Claims

1. A method for recognizing contact between a hand and a vehicle steering wheel (51), in, The test signal (14) is applied to the steering wheel (51) by means of the actuator (2). The reaction (9) of the test signal (14) on the steering wheel (51) is detected by means of sensor (3), and Among them, a decision (6) is made on whether at least one of the driver's hands is in contact with the steering wheel (51) based on the detected reaction (9). Among them, a test signal (14) is applied according to a predetermined torque curve (5), and, The torque curve (5) initially jumps to a predetermined minimum torque (16), which corresponds to the minimum friction (12) of the vehicle's steering system (50).

2. The method according to claim 1, characterized in that, The method is performed only when it is impossible to determine in any other way whether at least one hand is on the steering wheel (51).

3. The method according to claim 1 or 2, characterized in that, After reaching the minimum torque (16), the torque curve (5) increases to a predetermined value (21) with a predetermined first slope (20).

4. The method according to any one of the preceding claims, characterized in that, After a predetermined time period, the torque curve (5) drops at least to the predetermined minimum torque (16) with a second slope (22).

5. The method according to any one of the preceding claims, characterized in that, When the counter-torque (23) is detected, the torque curve (5) drops to at least the predetermined minimum torque (16) with a third slope (24).

6. The method according to claim 5, characterized in that, The third slope (24) is smaller in value than the second slope (22).

7. The method according to any one of the preceding claims, characterized in that, Based on the decision made (6), an enable signal (7) is generated and provided for at least one auxiliary system (56), which is enabled when at least one of the driver's hands is in contact with the steering wheel (51).

8. The method according to claim 7, characterized in that, The enable signal (7) enables the (re)start process for adaptive speed control (57).

9. The method according to any one of the preceding claims, characterized in that, This method is performed only when at least one auxiliary system (56) sends a ready signal (8).

10. A device (1) for recognizing contact between a hand and a steering wheel (51) of a vehicle, the device comprising: Actuator (2), which is configured to apply test signal (14) to steering wheel (51), Sensor (3), which is configured to detect the response (9) to the test signal (14) on the steering wheel (51), and Control device (4). The control device (4) is configured to, The application of the test signal (14) is triggered. The response to the test was evaluated (9), and Based on the detected reaction (9), a decision (6) is made regarding whether at least one of the driver's hands is in contact with the steering wheel (51). Among them, a test signal (14) is applied according to a predetermined torque curve (5), and The torque curve (5) initially jumps to a predetermined minimum torque (16), which corresponds to the minimum friction (17) of the vehicle's steering system (50).

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