Steering system, vehicle comprising the steering system and method for operating the steering system

Abstract

Steering system (102), vehicle (100) comprising the steering system (102), and method for operating a steering system (102) of a vehicle (100), wherein the steering system (102) comprises a steering angle actuator (104) for detecting a steering command and a steering actuator (106) for moving steered wheels (108) of the vehicle (100), wherein in the event of a failure of the steering actuator (106), lateral guidance of the vehicle (100) is carried out by a brake (110) and / or a drive (112) and / or a rear-axle steering (114) of the vehicle (100), in particular based on sensor information that describes a driving dynamics of the vehicle, preferably based on a yaw rate and / or lateral acceleration, wherein a deviation between the steering command and a steering movement achieved by the lateral guidance is detected, and wherein the deviation is reported back to a driver via the steering angle actuator (104).

Description

State of the art

[0001] The invention is based on a steering system, a vehicle comprising the steering system and a method for operating the steering system.

[0002] In a steering system with a steering angle actuator for detecting a steering request and a steering actuator for moving steered wheels of the vehicle, it is possible to influence the steering feel of a driver of the vehicle. Disclosure of the invention

[0003] By means of the steering system and the method for operating the steering system of a vehicle according to the independent claims, a steering feeling of a driver of the vehicle is meaningfully influenced in the event of a failure of a steering actuator.

[0004] The steering system comprises a steering angle actuator for detecting a steering command and a steering actuator for moving steered wheels of the vehicle. The method provides that, in the event of a steering actuator failure, lateral guidance of the vehicle is performed by a brake and / or a drive and / or rear-axle steering of the vehicle, in particular based on sensor information describing the vehicle's driving dynamics, preferably based on a yaw rate and / or lateral acceleration. A deviation between the steering command and a steering movement achieved by the lateral guidance is detected, and the deviation is reported back to a driver via the steering angle actuator.

[0005] It can be provided that the steering angle actuator is movable up to an end stop, which is reported back to the driver with an end stop torque set via the steering angle actuator, wherein the end stop torque is adjusted depending on the deviation.

[0006] It can be provided that the deviation between a target yaw rate of the vehicle defined by the steering request and a yaw rate achieved by the lateral guidance and / or between a target lateral acceleration of the vehicle defined by the steering request and a lateral acceleration achieved by the lateral guidance is determined.

[0007] It can be provided that the end stop torque is determined with a first order of magnitude if the deviation is greater in magnitude than a first threshold value, wherein the end stop torque is determined with a second order of magnitude if the deviation is greater in magnitude than a second threshold value, wherein the first threshold value is smaller than the second threshold value, wherein the second order of magnitude is greater than the first order of magnitude.

[0008] It can be provided that the deviation is reported back by means of an artificial excitation, in particular a vibration, of the steering angle actuator.

[0009] It can be provided that the steering actuator comprises a rack for moving the steered wheels, wherein a steering movement provided by the steering actuator is fed back by an artificial excitation of the steering angle actuator, which is determined as a function of a size of a rack force or a rack torque provided by the steering actuator, wherein in the event of failure of the steering actuator, a substitute size for the size is determined as a function of sensor information describing the driving dynamics of the vehicle, preferably based on the yaw rate and / or the lateral acceleration, and the artificial excitation is determined as a function of the substitute size.

[0010] The steering system for the vehicle comprises a steering angle actuator for detecting a steering command and a steering actuator for moving steered wheels of the vehicle, wherein the steering system is designed, in the event of a failure of the steering actuator, to influence a lateral guidance of the vehicle by means of a brake and / or a drive and / or a rear axle steering of the vehicle, in particular based on sensor information that describes a driving dynamics of the vehicle, preferably based on a yaw rate and / or lateral acceleration, to detect a deviation between the steering command and a steering movement achieved by the lateral guidance, and to report the deviation back to a driver via the steering angle actuator.

[0011] It can be provided that the steering angle actuator is movable up to an end stop, wherein the steering system is designed to report the end stop to the driver with an end stop torque set via the steering angle actuator, and to adapt the end stop torque depending on the deviation.

[0012] It can be provided that the steering system is designed to determine the deviation between a target yaw rate of the vehicle defined by the steering request and a yaw rate achieved by the lateral guidance and / or between a target lateral acceleration of the vehicle defined by the steering request and a lateral acceleration achieved by the lateral guidance.

[0013] It can be provided that the steering system is designed to determine the end stop torque with a first order of magnitude if the deviation is greater in magnitude than a first threshold value, and to determine the end stop torque with a second order of magnitude if the deviation is greater in magnitude than a second threshold value, wherein the first threshold value is smaller than the second threshold value, wherein the second order of magnitude is greater than the first order of magnitude.

[0014] It can be provided that the steering system is designed to report the deviation by means of an artificial excitation, in particular a vibration, of the steering angle actuator.

[0015] It can be provided that the steering actuator comprises a rack for moving the steered wheels, wherein the steering system is designed to report back a steering movement provided by the steering actuator by an artificial excitation of the steering angle actuator, which is determined as a function of a size of a rack force or a rack torque provided by the steering actuator, and in the event of failure of the steering actuator, to determine a substitute size for the size depending on sensor information describing the driving dynamics of the vehicle, preferably based on the yaw rate and / or the lateral acceleration, and to determine the artificial excitation as a function of the substitute size.

[0016] A vehicle that includes the steering system has corresponding advantages.

[0017] Further advantageous embodiments can be found in the following description and the drawing. The drawing shows: Fig. 1 a schematic representation of a vehicle with a steering system, Fig. 2 a flowchart with steps of a method for operating the steering system.

[0018] In Fig. 1 schematically shows a vehicle 100 with a steering system 102. The steering system 102 is, for example, a steer-by-wire steering system.

[0019] The steering system 102 includes a steering angle actuator 104 and a steering actuator.

[0020] The steering angle actuator 104 is designed to detect a steering request from a driver of the vehicle 100.

[0021] The steering angle actuator 104 is designed to output feedback to the driver regarding the steering behavior of the vehicle 100.

[0022] The steering angle actuator 104 includes, for example, a steering wheel or a joystick.

[0023] It may be provided that the steering angle actuator 104 is movable up to an end stop. In one example, the steering system 102 is configured to report the end stop to the driver using an end stop torque set via the steering angle actuator 104.

[0024] The steering actuator 106 is designed to move steered wheels 108 of the vehicle 100.

[0025] In the example, the steering actuator 106 comprises a rack that is moved by the steering actuator with a rack force or a rack torque.

[0026] If the steering actuator 106 fails, direct control of the steered wheels 108 with the steering actuator 106 is impossible. In the example, the steering angle actuator 104 functions independently of the steering actuator 106.

[0027] The steering system 102 is designed to influence a lateral guidance of the vehicle 100 by means of a brake 110 and / or a drive 112 and / or a rear axle steering 114 of the vehicle 100 in the event of a failure of the steering actuator 106.

[0028] The steering system 102 is configured to influence the lateral guidance based on sensor information describing the driving dynamics of the vehicle 100. The sensor information is, for example, a yaw rate and / or lateral acceleration of the vehicle 100. In the example, the vehicle 100 includes a sensor 116 configured to detect the sensor information, e.g., the yaw rate and / or lateral acceleration.

[0029] The steering system 102 is designed to detect a deviation between the steering request and a steering movement achieved by the lateral guidance.

[0030] The steering system 102 is configured to report the deviation to a driver via the steering angle actuator 104. The steering system 102 is configured, for example, to report the deviation by means of an artificial excitation, in particular a vibration, of the steering angle actuator 104.

[0031] The steering system 102 is designed, for example, to report back a steering movement provided by the steering actuator 106 by an artificial excitation of the steering angle actuator 104, which is determined as a function of a size of a rack force or a rack torque provided by the steering actuator 106.

[0032] For example, in the event of a failure of the steering actuator 106, the steering system 102 is configured to determine a substitute variable for the variable based on sensor information describing the driving dynamics of the vehicle 100, and to determine the artificial excitation based on the substitute variable. The steering system 102 is configured, for example, to determine the substitute variable based on the yaw rate and / or the lateral acceleration.

[0033] It can be provided that the steering system 102 is designed to adapt the end stop torque depending on the deviation.

[0034] In one example, the steering system 102 is configured to determine the deviation between a desired yaw rate of the vehicle defined by the steering command and a yaw rate achieved by the lateral guidance.

[0035] In one example, the steering system 102 is configured to determine the deviation between a desired lateral acceleration of the vehicle defined by the steering command and a lateral acceleration achieved by the lateral guidance.

[0036] In one example, the steering system 102 is designed to determine the deviation as a function of a particularly weighted sum of the deviation between the desired yaw rate of the vehicle defined by the steering command and the yaw rate achieved by the lateral guidance and the deviation between the desired lateral acceleration of the vehicle defined by the steering command and the lateral acceleration achieved by the lateral guidance.

[0037] The steering system 102 may be configured to determine the end stop torque with a first magnitude if the deviation is greater in magnitude than a first threshold value.

[0038] The steering system 102 may be configured to determine the end stop torque with a second magnitude if the deviation is greater in magnitude than a second threshold value.

[0039] In the example, the first threshold is smaller than the second threshold. In the example, the second magnitude is larger than the first magnitude.

[0040] In Fig. Figure 2 shows a flowchart with steps of a method for operating the steering system 102. The steering system 102 includes, for example, a computing device configured to execute the method.

[0041] The method includes a step 202.

[0042] In step 202, a steering request is detected by the steering angle actuator 104 and the steering actuator 106 moves the rack to move the steered wheels 108 in accordance with the steering request.

[0043] The steering movement provided by the steering actuator 106 is fed back, for example, by the artificial excitation of the steering angle actuator 104, which is determined depending on the magnitude of the rack force or the rack torque provided by the steering actuator 106.

[0044] In step 202, a check is performed to determine whether or not the steering actuator 106 is failing. If the steering actuator 106 is failing, step 204 is executed. Otherwise, step 202 is executed.

[0045] In step 204, the lateral guidance of the vehicle 100 is influenced by the brake 110 and / or the drive 112 and / or the rear axle steering 114 of the vehicle 100.

[0046] The lateral guidance is influenced, for example, based on sensor information that describes the driving dynamics of the vehicle 100.

[0047] In the example, lateral guidance is based on the yaw rate and / or lateral acceleration.

[0048] For example, a steering angle detected at the steering angle actuator 104 with a particularly variable steering ratio is converted into a target yaw rate φ̇ nom calculated and compared with a measured actual yaw rate φ̇ ist controlled by remaining actuators, e.g. brake 110, drive 112, rear axle steering 114.

[0049] For example, a steering angle detected at the steering angle actuator 104 with a particularly variable steering ratio is converted into a target lateral acceleration anonymous calculated and compared with a measured actual lateral acceleration ayist regulated by the remaining actuators.

[0050] The method includes a step 206.

[0051] In step 206, the deviation between the steering request and the steering movement achieved by the lateral guidance is recorded.

[0052] It may be provided that the end stop torque is adjusted depending on the deviation.

[0053] The method includes a step 208.

[0054] In step 208, the deviation is reported back to the driver via the steering angle actuator 104. The deviation is reported back, for example, by means of artificial excitation, in particular vibration, of the steering angle actuator 104.

[0055] The artificial excitation of the steering angle actuator 104 is determined in the event of failure of the steering actuator 106, for example, depending on sensor information that describes the driving dynamics of the vehicle 100.

[0056] The artificial excitation is determined, for example, based on the surrogate size for the size.

[0057] The substitute variable is determined, for example, based on the yaw rate. The substitute variable is determined, for example, based on the lateral acceleration. The substitute variable is determined, for example, based on the yaw rate and the lateral acceleration.

[0058] It can be provided that the substitute variable depends on a deviation of the target yaw rate ̇̇̇φ̇ nom from the actual yaw rate φ̇ ist is determined:

[0059] It can be provided that the substitute value depends on a deviation of the target lateral acceleration anonymous from the actual lateral acceleration ayist is determined.

[0060] For the size of the rack force F Z For example, the replacement size FZe the rack force is determined, for example, as follows: FZe=Kφ˙(vx)(φ˙nom−φ˙ist)+Kay(vx)(aynom−ayist) where K φ̇ (v x ) and K ay (v x ) each with an optional longitudinal speed v x of the vehicle 100 dependent weighting factor.

[0061] It can be provided that the end stop is reported back to the driver via the end stop torque set with the steering angle actuator 104.

[0062] The end stop torque is determined, for example, with the first magnitude if the deviation is greater than the first threshold value.

[0063] The end stop torque is determined, for example, with the second order of magnitude if the deviation is greater than the second threshold value.

[0064] The end stop is applied, for example, at the point where a large and sharply increasing yaw rate deviation, or a comparable driving dynamics variable, indicates that a limit of the lateral guidance potential has been reached via the remaining actuators.

[0065] Due to the first threshold value, Threshold_1, the applied end-stop torque in the example assumes the first magnitude. For the yaw rate, for example: |(φ˙nom−φ˙ist)|≥Threshold_1

[0066] In this example, the second threshold, Threshold_2, sets a maximum end-stop torque. For the yaw rate, for example: |(φ˙nom−φ˙ist)|≥Threshold_2

[0067] This gives the driver a sensible steering feel even at this fallback level.

[0068] Step 202 is then executed.

Claims

[1] Method for operating a steering system (102) of a vehicle (100), characterized by in that the steering system (102) comprises a steering angle actuator (104) for detecting a steering command and a steering actuator (106) for moving steered wheels (108) of the vehicle (100), wherein in the event of a failure of the steering actuator (106), lateral guidance of the vehicle (100) is carried out by a brake (110) and / or a drive (112) and / or a rear-axle steering (114) of the vehicle (100), in particular based on sensor information which describes a driving dynamics of the vehicle, preferably based on a yaw rate and / or lateral acceleration (204), wherein a deviation between the steering command and a steering movement achieved by the lateral guidance is detected (206), and wherein the deviation is reported back to a driver via the steering angle actuator (104) (208). [2] Method according to claim 1, characterized bythat the steering angle actuator (104) is movable up to an end stop, which is reported back to the driver with an end stop torque set via the steering angle actuator (104) (208), wherein the end stop torque is adjusted depending on the deviation (206). [3] Method according to one of the preceding claims, characterized by that the deviation between a target yaw rate of the vehicle defined by the steering command and a yaw rate achieved by the lateral guidance and / or between a target lateral acceleration of the vehicle defined by the steering command and a lateral acceleration achieved by the lateral guidance is determined (206). [4] Method according to claim 3, characterized bythat the end stop torque is determined with a first order of magnitude (208) if the deviation is greater in magnitude than a first threshold value, wherein the end stop torque is determined with a second order of magnitude (208) if the deviation is greater in magnitude than a second threshold value, wherein the first threshold value is smaller than the second threshold value, wherein the second order of magnitude is greater than the first order of magnitude. [5] Method according to one of the preceding claims, characterized by that the deviation is reported back (208) by means of an artificial excitation, in particular a vibration, of the steering angle actuator (104). [6] Method according to claim 5, characterized byin that the steering actuator (106) comprises a rack for moving the steered wheels, wherein a steering movement provided by the steering actuator (106) is fed back by an artificial excitation of the steering angle actuator (104), which is determined (202) as a function of a size of a rack force or a rack torque provided by the steering actuator (106), wherein in the event of failure of the steering actuator (106), a substitute size for the size is determined as a function of sensor information describing the driving dynamics of the vehicle (100), preferably based on the yaw rate and / or the lateral acceleration, and the artificial excitation is determined as a function of the substitute size (208). [7] Steering system (102) for a vehicle (100), characterized byin that the steering system (102) comprises a steering angle actuator (104) for detecting a steering request and a steering actuator (106) for moving steered wheels (108) of the vehicle (100), wherein the steering system (102) is designed, in the event of a failure of the steering actuator (106), to influence a lateral guidance of the vehicle (100) by means of a brake (110) and / or a drive (112) and / or a rear-axle steering (114) of the vehicle (100), in particular based on sensor information which describes a driving dynamics of the vehicle, preferably based on a yaw rate and / or lateral acceleration, to detect a deviation between the steering request and a steering movement achieved by the lateral guidance, and to report the deviation back to a driver via the steering angle actuator (104). [8] Steering system (102) according to claim 7, characterized bythat the steering angle actuator (104) is movable up to an end stop, wherein the steering system (102) is designed to report the end stop to the driver with an end stop torque set via the steering angle actuator (104), and to adapt the end stop torque depending on the deviation. [9] Steering system (102) according to one of claims 7 or 8, characterized by that the steering system (102) is designed to determine the deviation between a desired yaw rate of the vehicle defined by the steering request and a yaw rate achieved by the lateral guidance and / or between a desired lateral acceleration of the vehicle defined by the steering request and a lateral acceleration achieved by the lateral guidance. [10] Steering system (102) according to claim 9, characterized bythat the steering system (102) is designed to determine the end stop torque with a first order of magnitude if the deviation is greater in magnitude than a first threshold value, and to determine the end stop torque with a second order of magnitude if the deviation is greater in magnitude than a second threshold value, wherein the first threshold value is smaller than the second threshold value, wherein the second order of magnitude is greater than the first order of magnitude. [11] Steering system (102) according to one of claims 7 to 10, characterized by that the steering system (102) is designed to report the deviation by means of an artificial excitation, in particular a vibration, of the steering angle actuator. [12] Steering system (102) according to claim 11, characterized byin that the steering actuator (106) comprises a rack for moving the steered wheels, wherein the steering system is designed to report back a steering movement provided by the steering actuator (106) by an artificial excitation of the steering angle actuator (104), which is determined as a function of a size of a rack force or a rack torque provided by the steering actuator (106), and in the event of failure of the steering actuator (106), to determine a substitute size for the size depending on sensor information describing the driving dynamics of the vehicle (100), preferably based on the yaw rate and / or the lateral acceleration, and to determine the artificial excitation as a function of the substitute size. [13] Vehicle (100), characterized by that the vehicle comprises the steering system (102) according to one of claims 7 to 12.

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