Method for operating a motor vehicle with an electric assisted steering system

Abstract

The present invention provides a method for operating a motor vehicle (2) having an electric power steering system (4), the method comprising the following steps: - determining the steering angular velocity (LWG) of the motor vehicle (2); - determining the driver's hand torque variation (FMA) applied by the driver of the motor vehicle (2); - evaluating at least the steering angular velocity (LWG) and the driver's hand torque variation (FMA) to determine whether the driver's hand torque variation (FMA) and the steering angular velocity (LWG) are uncorrelated; and - outputting an error signal (FS) when the driver's hand torque variation (FMA) and the steering angular velocity (LWG) are uncorrelated.

Description

Technical Field

[0001] This invention relates to a method for operating a motor vehicle with an electric power steering system. Furthermore, the invention includes a computer program product and controller for performing this method, an electric power steering system having such a controller, and a motor vehicle having such an electric power steering system. Background Technology

[0002] Modern motor vehicles (such as passenger cars) have multiple driver assistance systems. Advanced Driver Assistance Systems (FAS in German; ADAS in English) are electronic aids in motor vehicles designed to assist the driver in specific driving situations. Here, there is often a focus on safety and improved driving comfort. These driver assistance systems involve partially or autonomously controlling the vehicle's drive (e.g., gas, braking), control (e.g., parking steering assist), or signaling devices.

[0003] Electric power steering (EPS) systems are electric-assisted steering systems that typically operate when the driver applies steering torque. A significant advantage of the electric drive in EPS is that the steering can be adaptively designed and is also carried out by driver assistance systems. The steering system can also be used as an actuator for further driver assistance tasks (such as automatic steering intervention in Electronic Stability Program II, parking and lane-keeping assist, etc.).

[0004] In operation, electric power steering assists the driver by measuring the torque applied by the driver and amplifying it via an actuator (e.g., a motor such as a servo motor). This motor, as an example of all possible forms of assistance, provides enhanced comfort on the one hand, and on the other hand, it is used to achieve additional functions such as lane-keeping assist. In any case, the torque requirement of the motor directly affects the steering behavior of the motor vehicle and thus the driver. The conventional assistance of this electric power steering system can be understood in a broader sense as a driver assistance function. Therefore, the invention described herein is also effective for assisting the driver's steering torque.

[0005] Because driver assistance systems rely on sensor data and correct execution, errors cannot be completely eliminated. For safety reasons, the torque requirements for the motor may be limited if necessary. This can be done, for example, by limiting each function individually or by limiting all functions overall.

[0006] However, these solutions may also incorrectly limit torque even when there are no errors and therefore no need for limitation, thus adversely affecting the "normal" or "good" functions of the driver assistance system. In these cases, the limiting function misjudges the driving situation.

[0007] Known limiting functions restrict the magnitude and / or rate of steering torque required by driver assistance systems to small values. However, this severely limits the authority of these driver assistance systems. DE 102014201107 A1 discloses a method in which the current steering angular velocity is compared with the permissible range of driver hand torque to prevent undesirable driver assistance requests. In particular, a high steering angular velocity can also be applied by pre-introducing energy into the system. This results in a high steering angular velocity in the direction of the center position of the steering wheel due to tire restoring force, especially under conditions of increased vehicle speed and dynamic maneuvering, while maintaining a low driver hand torque. Known solutions detect violations in this case or must be parameterized so that violations of these specific maneuvers no longer occur; however, this may result in the actual safety functions no longer being adequately guaranteed.

[0008] Therefore, the object of the present invention is to show a method in which the errors of the above conditions can be avoided. Summary of the Invention

[0009] The object of this invention is achieved by a method for operating a motor vehicle with an electric power steering system, the steps of which are as follows:

[0010] - Determine the steering angular velocity of the motor vehicle;

[0011] - Determine the change in driver's manual torque applied by the driver of the motor vehicle;

[0012] - Evaluate at least the steering angular velocity and driver hand torque changes to determine whether the driver hand torque changes and steering angular velocity are uncorrelated; and

[0013] - An error signal is output when the driver's manual torque changes and the steering angular velocity are unrelated.

[0014] Assume that every desired, important vehicle response is initiated by the driver.

[0015] Various measures can be taken in response to error signals. For example, if an error signal is set, the permissible absolute steering torque amplitude for driver assistance functions can be reduced in the zero direction. However, other measures can also be taken to maintain the effectiveness of safety functions. Furthermore, when the error signal no longer exists, the permissible absolute steering torque amplitude for driver assistance functions can be increased to a maximum value depending on the speed. Additionally, the steering torque required by driver assistance functions can be limited to the permissible steering torque amplitude.

[0016] The advantage of the method described here is that the limitations are primarily based on the driver's steering expectations. There is no need to pre-prepare and classify possible steering angular velocities related to the driver's hand torque. The focus is solely on whether the driver intends to steer in a direction different from the current steering wheel movement. Therefore, the number of erroneous violation detections is significantly reduced during rapid steering movements initiated by the driver or caused by the restoring force of the tires. The availability of potential functions is significantly increased, and driver assistance systems can operate more effectively. Furthermore, compared to the method described in DE 102014201107A1, the simplified calibration by reducing the number of parameters results in cost savings.

[0017] At the same time, drivers expect the detection not to compromise safety in the event of an error. Inactivity detection also ensures that the maximum permissible steering angular velocity is reduced to a certain level in the event of driver inattention, thus providing the driver with sufficient reaction time in error situations.

[0018] Finally, a correlation test is performed between the driver's hand torque change and the steering angular velocity. Therefore, the driver's hand torque change and the steering angular velocity can be correlated and evaluated in a particularly simple way.

[0019] According to one embodiment, to determine whether the driver's torque change and steering angular velocity are uncorrelated, the direction of the driver's torque change and the direction of the steering angular velocity are determined and compared. When the directions of the driver's torque change and the steering angular velocity are not the same, it is inferred that the driver's torque change and steering angular velocity are uncorrelated. For example, the direction of the driver's torque change in a first direction can be represented by the value 1 of a variable, and in a second direction opposite to the first direction by the value -1 of a variable, while the direction of the steering angular velocity in the first direction is represented by the value 1 of a variable, and in the second direction opposite to the first direction by the value -1 of a variable. Therefore, whether the driver's torque change and steering angular velocity are correlated can be determined through a simple logical association of specific corresponding directions. If they point in different directions, an error signal is set.

[0020] According to another embodiment, in order to determine the driver's torque variation applied by the driver of the motor vehicle, only driver's torque variation values ​​greater than a threshold are used. Therefore, a dead zone can be easily formed, thereby ensuring that a predetermined range of driver's torque variation values ​​symmetrical around 0 is not considered and does not disrupt further analysis.

[0021] According to another embodiment, a value representing the driver's activity is detected, and when the value representing the driver's activity is less than a limit value, the threshold used for the dead zone of the driver's hand torque variation is changed. Therefore, an inactive driver, i.e., a driver who does not actively steer or release the steering wheel, can be considered in a particularly simple way.

[0022] According to another embodiment, the steering angular velocity of the motor vehicle is determined only using steering angular velocity values ​​greater than a threshold. Therefore, a dead zone can be formed in a simple manner, thereby ensuring that the limited range of steering angular velocity values ​​symmetrical around 0 remains unconsidered and does not disrupt further analysis.

[0023] According to another embodiment, a value representing the driver's activity is detected, and if the value representing the driver's activity is less than a limit value, the threshold for the dead zone used for the steering angular velocity is changed. Therefore, an inactive driver, i.e., a driver who is not steering or releasing the steering wheel, can be considered in a particularly simple way.

[0024] According to another embodiment, the permissible limit of steering torque required by the driver assistance function is reduced in the presence of an error signal. Therefore, steering intervention is reduced in the event of an error, thereby improving safety. According to another embodiment, the reduction of the maximum limit of steering torque required by the driver assistance function is based on a predetermined function. For example, a ramp function with various configurations can be used (e.g., constant, linearly increasing with time, quadratically increasing with time, or a function determined by vehicle dynamics). Furthermore, the ramp function can be formed from the maximum available torque or the current limit to a target value via a low-pass step function.

[0025] According to another embodiment, when no error signal is set, the permissible limit of steering torque required by the driver assistance function increases to a maximum value according to a predetermined function. For example, ramp functions with various configurations can also be used (e.g., constant, linearly increasing with time, quadratically increasing with time, or functions formed depending on vehicle dynamics). Furthermore, the ramp function can be formed from the maximum available torque or the current limit to the target value via a low-pass step function.

[0026] According to another embodiment, the maximum allowable limit is represented by a settable value for the vehicle. In an advantageous embodiment, this value can vary depending on the vehicle speed.

[0027] According to another embodiment, a value representing the driver's activity is detected, and if the value representing the driver's activity is less than a threshold and the vehicle's steering angular velocity is greater than a limit value, it is inferred to be an error condition. Therefore, situations in which the driver is not paying attention and at least does not actively apply rotational or steering torque to the steering wheel are particularly considered. In other words, these situations are considered error conditions where a sudden steering deflection occurs without driver steering wheel operation.

[0028] Furthermore, the present invention includes a computer program product and controller for performing this method, an electric power steering system having such a controller, and a motor vehicle having such an electric power steering system. Attached Figure Description

[0029] The invention will now be explained with reference to the accompanying drawings. In the drawings:

[0030] Figure 1 A schematic diagram of an electric power steering system for motor vehicles is shown.

[0031] Figure 2 It shows according to Figure 1 A schematic diagram of the operation method flow of the electric power steering system according to the first exemplary embodiment shown.

[0032] Figure 3 It shows according to Figure 1 A schematic diagram of the operation method flow of the electric power steering system according to the second exemplary embodiment shown.

[0033] Figure 4 It shows Figure 2 and 3 The diagram shows a further step in the method flow for further error handling. Detailed Implementation

[0034] First refer to Figure 1 .

[0035] The diagram shows an electric power steering system 4 for a motor vehicle 2 (e.g., a passenger car), which has wheels 10a and 10b. In this embodiment, the steerable left and right front wheels can be loaded with a steering angle δ. The electric power steering system 4 is an electric power steering system that is effective when steering motion occurs.

[0036] In this exemplary embodiment, the electric power steering system 4 includes a steering torque sensor 8, an electric motor 12, and a controller 14.

[0037] In this embodiment, the electric motor 12 (program-controlled electric servo motor) assists and bears the steering torque of the driver by rotating the steering wheel 6.

[0038] The driver's hand moment (FHM) can be detected using the steering torque sensor 8. The driver's hand moment (FHM) is the torque applied and implemented by the driver of the motor vehicle 2 to the steering wheel 6.

[0039] In this exemplary embodiment, the controller 14 is designed to determine a target value for the auxiliary torque while analyzing the actual value of the driver's torque, and to provide a servo torque from the target value for actuating the electric motor 12. Furthermore, the controller 14 is designed to receive steering torque requirements for at least one driver assistance function, or to calculate and accordingly modify the control of the electric motor 12 based on the input signal.

[0040] The electric power steering system 4 can be designed as an EPS or EPAS (EPS: Electric Power Steering, EPAS: Electric Power Assisted Steering) system, in which the electric motor 12 assists and carries the driver's steering torque.

[0041] During the operation of motor vehicle 2, a high steering angular velocity can also be applied by pre-introducing energy into the system. Therefore, the restoring force of tires 10a and 10b, especially with the increase in vehicle speed and dynamic handling, results in a high steering angular velocity LWG (Lenkwinkelgeschwindigkeit) in the direction of the steering wheel center position, and simultaneously a low driver hand torque FHM.

[0042] This can be interpreted as an error by controller 14, resulting in the safety function being disabled and therefore unavailable.

[0043] To avoid false detections under the aforementioned conditions, in this embodiment, the controller 14 is designed to determine the steering angular velocity LWG of the vehicle 2 and the change in driver's manual torque FMA applied by the driver of the vehicle 2. The change in driver's manual torque corresponds to the derivative of the driver's manual torque FHM. To perform the tasks described below, controller 14 may include hardware and / or software components.

[0044] In order to set an error signal FS when an error occurs, controller 14 checks whether the driver's manual torque change FMA and steering angular velocity LWG are related or unrelated in direction.

[0045] Assume that every important vehicle response is initiated by the driver.

[0046] Controller 14 is designed to determine and compare the direction of the driver's hand torque change FMA and the direction of the steering angular velocity LWG. When the direction of the driver's hand torque change FMA and the direction of the steering angular velocity LWG are not the same, it is inferred that the driver's hand torque change FMA and the steering angular velocity LWG are unrelated.

[0047] When a logic value of 1 is assigned to the first direction and a logic value of -1 is assigned to the second direction opposite to the first direction, if the direction of the change in steering angle and the direction of the change in driver's torque have the same logic value, then the change in steering angle (i.e., the sign of the steering angular velocity LWG) is related to the rate of change of driver's torque FHM (i.e., the change in driver's torque FMA). When neither the steering angle nor the driver's torque changes, i.e., the change in steering angular velocity or driver's torque is 0, a logic value of 0 is also assigned to the corresponding direction.

[0048] An error does exist when the following conditions are met:

[0049] When sgn(dδ / dt)*sgn(dFHM / dt)=-1.

[0050] In this exemplary embodiment, to increase robustness and eliminate error detection, the controller 14 is designed to filter the steering angular velocity LWG and the driver's hand torque FHM, for example, using a first-order low-pass filter.

[0051] To further improve robustness, controller 14 is designed to use a dead zone. This excludes the range of driver hand torque FHM and steering angular velocity LWG that are symmetrical around 0 from further evaluation.

[0052] For example, it is possible to consider only the rate of change of the driver's hand torque (FHM) and steering angular velocity (LWG) when they are higher than a settable or fixed threshold.

[0053] For this purpose, in this exemplary embodiment, the controller 14 is designed to determine the driver's torque change FMA applied by the driver of the motor vehicle 2 using only the driver's torque change value and to determine the steering angular velocity LWG of the motor vehicle 2 using only steering angular velocity values ​​greater than the corresponding threshold, so as to exclude values ​​within a predetermined range from the evaluation.

[0054] Furthermore, the controller 14 in this embodiment has a function for detecting driver inactivity. The driver inactivity detection function detects whether the driver has not made any significant steering intervention within a predetermined time period, or whether the manual torque introduced by the driver into the system is lower than a predetermined limit value within a specific time period.

[0055] In an alternative embodiment, the controller 14 is also designed to infer an error condition when the driver is detected to be inactive (FIA=1) and the steering angular velocity LWG has exceeded a predetermined limit value GW (Grenzwert). This limit value GW can be determined based on the speed of the vehicle 2 or other vehicle state-related variables.

[0056] FIA = 1 &dδ / dt > GW > FS = 1

[0057] The function for detecting driver inactivity can be designed to evaluate the curve of the driver's hand torque FHM over a specific settable time period to infer driver inactivity.

[0058] If the controller 14 detects an error, it then reduces the torque (current limit) of the currently available driver assistance function from a predetermined maximum value (maximum limit) in each execution step, for example, by a predetermined ramp function in the 0 direction. The maximum available torque (maximum limit) can be determined primarily by speed v and possibly other variables to describe the vehicle condition of the motor vehicle 2. However, unlike this embodiment, other measures may be performed in response to the presence of an error.

[0059] Ramp functions with various constructions can be used (e.g., constant, linearly increasing with time, quadratically increasing with time, or functions formed depending on vehicle dynamics). Furthermore, ramp functions can be formed from the maximum available torque or current limit to a target value via a low-pass step function.

[0060] Furthermore, the initial value of the ramp function can be advanced from the available torque or the maximum limit to the currently required torque. In an advantageous embodiment, the minimum absolute value from the current limit and the required torque is used as the initial value of the ramp function.

[0061] On the other hand, if there are no error conditions and the current limit is below the maximum limit, the return rate is determined using a ramp function, and the current limit is returned to the maximum limit using this return rate. The same method as for error conditions can be applied to determine the return rate.

[0062] Finally, controller 14 is designed to symmetrically limit the torque required by the driver assistance function to the limits currently calculated.

[0063] refer to Figure 2 The following will now be explained according to the first exemplary embodiment. Figure 1 The method flow for operating the electric power steering system 4 is shown in the figure.

[0064] In the first step S1000, the method is started. The method can be started cyclically at a predetermined, fixed, or configurable sampling rate.

[0065] In a further step S1010, the controller 14 reads the measured values. Additionally, measured values ​​representing information about the vehicle's state can be read, such as its speed v, longitudinal and lateral acceleration and / or yaw rate, and internal steering measurements (e.g., steering angle δ, steering speed, and / or driver's hand torque FHM). In this exemplary embodiment, the controller 14 reads measured values ​​representing the speed v, steering angular velocity LWG, and driver's hand torque FHM of the motor vehicle 2.

[0066] In a further step S1020, the presence of the driver's hand torque change FMA is checked. If the derivative of the driver's hand torque FHM, i.e., the driver's hand torque change FMA, is not read by the controller 14, steps S1030 and S1040 are executed, thereby determining the driver's hand torque change FMA after filtering the driver's hand torque FHM using a first-order low-pass filter (in step S1030) and, for example, through numerical differentiation (in step S1040). Otherwise, the method proceeds to step S1050.

[0067] In this exemplary embodiment, further signal refinement using an additional filter is provided in a further step S1050. However, this step may be omitted if there is a corresponding signal quality.

[0068] Furthermore, in this embodiment, in a further step S1060, driver activity is determined. For this purpose, existing measurements are evaluated, particularly the driver's hand torque FHM and / or the driver's hand torque change FMA, to determine whether the driver actively influences vehicle events or whether he is relatively inactive.

[0069] The driver inactivity detection function uses the FIA ​​(Factory Inactivity Detection) signal to detect inactive drivers. The -flag) provides a logic 1, and the active driver provides a logic 0 for the signal FIA. In another advantageous embodiment of the method, the signal FIA may also take a value between 0 and 1 to ensure a smooth transition of parameters selected for subsequent steps.

[0070] In a further step S1070, parameters for subsequent testing are specifically selected using the signal FIA. In a further step S1080, the range of measured values ​​(e.g., driver's hand torque change FMA and steering angular velocity LWG) is excluded from further evaluation. For this purpose, a dead zone is used in this embodiment to exclude regions symmetrically near 0.

[0071] In a further step S1090, the directions of the driver's manual torque change FMA and the steering angular velocity LWG are determined respectively, and the corresponding symbols are assigned as already explained.

[0072] In a further step S1100, the assigned symbols are analyzed, that is, the symbols or directions are checked to see if they are the same or different.

[0073] If the check display symbol or direction in step S1100 is different, the evaluation criterion is violated, and in a further step S1110, the error signal (e.g., in the form of an error flag FS) is set to logic 1. On the other hand, if the evaluation criterion is not violated, the error signal (e.g., in the form of an error flag FS) is set to logic 0 in step S1120.

[0074] In a further step S1130, a transition to an error handling method is performed, which will be referred to later. Figure 4 Please provide an explanation.

[0075] Deviating from this embodiment, the order of steps S1000 to S1130 may be different. For example, the individual steps, step groups, or values ​​may be reversed. In addition, it is also possible to provide that individual or multiple steps are performed at the same time, i.e., simultaneously.

[0076] refer to Figure 3 The following will now be described according to the second exemplary embodiment. Figure 1 Further method flow for operating the electric power steering system 4 shown.

[0077] Steps S2000 to S2060 and steps S2080 to S2130 correspond to steps S1000 to S1060 and S1080 to S1030 in the method flow of the first embodiment.

[0078] In other words, the method according to the second embodiment differs from the method according to the first embodiment in that step S2070 and further steps S2140 to S2160 are included.

[0079] In the next step S2070, it is checked whether the driver is inactive. If it has been determined that the driver is active (FIA=0), the method continues. Figure 2 The steps have already been explained. Otherwise (FIA=1), the method proceeds to step S2140.

[0080] If the driver is not active (FIA=1), the steering angular velocity LWG is checked in step S2140.

[0081] In a further step S2150, the steering angular velocity LWG is compared with the limit value GW, that is, it is checked whether the steering angular velocity LWG is higher than the limit value GW.

[0082] When the absolute steering angular velocity LWG is lower than the limit value GW, in the further step S2160, the error signal (e.g., in the form of an error flag FS) is set to logic 0; otherwise, in step S2110, the error signal (e.g., in the form of an error flag) is set to logic 1.

[0083] In a further step S2130, a transition to a method for error handling is performed, which will be referred to later. Figure 4 Please provide an explanation.

[0084] Deviating from this embodiment, the order of steps S2000 to S2160 may be different. For example, the individual steps, step groups, or values ​​may be reversed. In addition, it is also possible to provide that individual or multiple steps are performed at the same time, i.e., simultaneously.

[0085] Now for reference Figure 4 .

[0086] In the first step S3000, the method is started. The method can be started cyclically at a predetermined, fixed, or configurable sampling rate. However, typically, it is started at each call. Figure 2 or Figure 3 After the method is executed, that method is executed.

[0087] In a further step S3010, an error condition is checked, specifically whether the error signal FS (Fehlersignal) is set to logic 1. If an error condition exists, the method proceeds to steps S3020 and S3030. Otherwise, the method proceeds to step S3040 and subsequent steps.

[0088] If an error condition exists, in a further step S3020, the torque authority is determined at what rate R or linear slope the ramp function decreases. The rate R may be a constant value, or the rate R may be determined based on the time since the error condition occurred, the speed v of the vehicle 2, the steering angular velocity LWG, the driver's hand torque rate, the yaw rate, the lateral acceleration, or a combination of these values.

[0089] In a further step S3030, the current torque limit DML (Drehmomentlimit) begins to decrease from the current torque limit DML by the parameter (i.e., rate R) of the ramp function specified in step S3020.

[0090] On the other hand, if there are no errors, the maximum limit ML is determined in the further step S3040 based on the speed v of the motor vehicle 2. Possible further measurements of the vehicle's condition may be considered.

[0091] In a further step S3050, it is checked whether the current torque limit DML is lower than the previously determined maximum limit ML. If so, the method proceeds to step S3060; otherwise, it proceeds to step S3080.

[0092] In step S3060, a rate R is determined to return the maximum value. The rate R may have a constant value, or the rate R may be determined based on the time since the error condition ceased to exist, the speed v of the vehicle 2, the steering angular velocity LWG, the driver's hand torque rate, the yaw rate, the lateral acceleration, or a combination of these values.

[0093] In a further step S3070, the value of the ramp function defined in step S3080, namely the rate R, is increased from the current torque limit DML, but never exceeds the maximum limit ML.

[0094] On the other hand, if the current torque limit DML is greater than or equal to the maximum limit ML, then in a further step S3080, the current torque limit DML is set to the value of the maximum limit ML. In all the described branches, the method ends at step S3090.

[0095] Deviating from this embodiment, the order of steps S3000 to S3090 may be different. For example, the individual steps, step groups, or values ​​may be reversed. In addition, it is also possible to provide that individual or multiple steps are performed at the same time, i.e., simultaneously.

[0096] In a further step not shown here, the steering torque required by the driver assistance function is limited in amount of the current torque limit DML, but not in direction, or its sign may be changed.

[0097] The advantage of the method described here is that the limitations are primarily based on the driver's steering expectations. There is no need to pre-prepare and classify possible steering angular velocities related to the driver's hand torque (FHM). The focus is solely on whether the driver intends to steer in a direction different from the current steering wheel movement. Therefore, the rate of erroneous violation detection during rapid steering movements initiated by the driver is significantly reduced. Consequently, the availability of potential functions is significantly increased, and driver assistance systems can operate more effectively. Furthermore, cost savings are achieved by simplifying calibration through a reduction in the number of parameters.

[0098] At the same time, drivers expect the detection not to compromise safety in the event of an error. Inactivity detection can simultaneously ensure that the maximum permissible steering angle (LWG) drops to a certain level in the event of driver inattention, thus providing the driver with sufficient reaction time in error situations.

[0099] According to Figure 2 and Figure 3 In a further advantageous embodiment of the method, steps S1100 and S2100 additionally check whether the steering torque required by the driver assistance function points in the same direction as the preprocessed steering angular velocity signal, and only in these cases is the error signal (e.g., in the form of an error flag FS) set to logic 1.

[0100] List of reference numerals in the attached diagram:

[0101] 2 Motor vehicles

[0102] 4. Electric power steering system

[0103] 6. Steering wheel

[0104] 8. Steering torque sensor

[0105] 10a Wheel

[0106] 10b Wheel

[0107] 12 Electric motors

[0108] 14 Controller

[0109] δ steering angle

[0110] DML Current Torque Limit

[0111] FIA Driver Inactivity Sign

[0112] FS error signal

[0113] FHM Driver's Hand Torque

[0114] FMA Driver's Hand Torque Variation

[0115] GW limit

[0116] LWG steering angular velocity

[0117] ML maximum limit

[0118] R rate

[0119] v speed

[0120] S1000-S1300 Steps

[0121] S2000-S2160 Steps

[0122] S3000-S3090 Steps

Claims

1. A method for operating a motor vehicle (2) having an electric power steering system (4), the method comprising the following steps: - Determine the steering angular velocity of the motor vehicle (2); - Determine the change in driver's manual torque applied by the driver of the motor vehicle (2); - Evaluate at least the steering angular velocity and the driver's hand torque variation to determine whether the driver's hand torque variation and the steering angular velocity are uncorrelated; and - An error signal is output when the driver's manual torque change and the steering angular velocity are unrelated; In order to determine whether the change in driver's hand torque and the steering angular velocity are unrelated, the direction of the change in driver's hand torque and the direction of the steering angular velocity are determined and compared. If the direction of the change in driver's hand torque and the direction of the steering angular velocity are not the same, it is inferred that the change in driver's hand torque and the steering angular velocity are unrelated. In order to determine the driver's torque variation applied by the driver of the motor vehicle (2), only the driver's torque variation value that is greater than the threshold value is used.

2. The method according to claim 1, wherein, The threshold is changed when the value representing the driver's activity is less than a limit value.

3. The method according to claim 2, wherein, To determine the steering angular velocity of the motor vehicle, a steering angular velocity value greater than a second threshold is used.

4. The method according to claim 3, wherein, The value representing the driver's activity is detected, and when the value representing the driver's activity is less than a limit value, the second threshold is changed.

5. The method according to claim 1, wherein, When the aforementioned error signal is present, the steering torque required by the driver assistance function is reduced to the torque limit.

6. The method according to claim 5, wherein, When the error signal is not set, the permissible limit of the steering torque required by the driver assistance function is increased to the maximum value according to a predetermined function.

7. The method according to claim 6, wherein, The maximum value of the permissible limit is represented by a settable value for the motor vehicle (2).

8. The method according to claim 5, wherein, The torque limit of the steering torque requested by the driver assistance function is increased according to a predetermined function.

9. The method according to any one of claims 1 to 8, wherein, The value representing the driver's activity is detected, and when the value representing the driver's activity is less than a threshold and the steering angular velocity of the motor vehicle (2) is greater than a limit value, it is inferred to be an error condition.

10. A computer program product for performing the method according to any one of claims 1 to 9.

11. A controller (14) designed to perform the method according to any one of claims 1 to 9.

12. An electric assisted steering system (4) for a motor vehicle (2) having a controller (14) according to claim 11.

13. A motor vehicle (2) having an electric assisted steering system (4) according to claim 12.

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