System and procedure for controlling the steering of a vehicle

Abstract

Vehicle steering control system (100), comprising: a road wheel actuator (125) with a road wheel angle sensor (178) configured to detect a road wheel angle and a steering motor (176) configured to control the road wheel angle in response to a steering control signal; a steering wheel actuator (120) with a steering angle sensor (174) configured to detect a steering wheel angle, and a steering feedback motor (180) configured to rotate a steering wheel (170) in response to the road wheel angle, and configured to generate a steering torque value in response to a physical rotation of the steering wheel (170) by a driver; an inertial measurement unit (186) configured to detect lateral acceleration of the vehicle; an electronic control unit (172) configured to receive the road wheel angle and the steering torque value, to estimate the steering wheel angle in response to a failure of a steering angle sensor (174) as a function of the steering torque value, and to generate the steering control signal corresponding to the estimated steering wheel angle in response to a difference between the road wheel angle and the estimated steering wheel angle being less than a threshold value; and configured to perform a torque vector steering control function to calculate a required torque vectoring command in response to the lateral acceleration, and wherein the steering control signal is determined in response to the required torque vectoring command to steer the vehicle in a direction-dependent manner; and A steering control unit that is configured to control the steering of the vehicle in response to the steering control signal.

Description

[0001] The present disclosure relates generally to the programming of control systems for motor vehicles. More specifically, aspects of this disclosure relate to systems, methods, and devices for estimating a steering wheel angle in order to control a steer-by-wire steering system in response to a detection of a road wheel angle and an output torque of a steering feedback motor.

[0002] The connection between the steering system of a conventional motor vehicle and the front wheels is traditionally made via direct mechanical links between a device and the vehicle's front wheels. In a rack and pinion steering system, for example, turning a steering wheel rotates a pinion that engages with corresponding notches or teeth in a rack section of the steering system. Tie rods connect the rack section to the wheels, so that every rotation of the steering wheel ultimately turns the wheels by a resulting steering angle, which can vary depending on the steering ratio provided by the steering system. Instead of a rack and pinion, other steering linkages can also be used, such as worm gears in a recirculating ball steering system. In both examples, however, all steering linkages are purely mechanical.

[0003] In contrast, a steer-by-wire steering system uses an electronically controlled steering actuator located on or near the front drive axle and one or more transducers and / or other sensors to measure or detect the steering request or input to a device, typically a circular steering wheel. The sensors can be configured to measure the steering angle at the steering wheel. The electronic input signals representing these measured or detected values ​​are then transmitted electrically to a steering actuator, which executes a steering maneuver in response to the electronic input signals.

[0004] In steer-by-wire systems, where there is no physical connection between the steering wheel and the wheels, redundant steering angle sensors are crucial. This ensures that the system continues to function even if one sensor fails. By comparing data from multiple sensors, the system can detect deviations and maintain control, preventing loss of directional stability and potential accidents. This redundancy is critical for safety-critical systems like steering. Because steering angle sensors are critical for determining a vehicle's trajectory, vehicles must have redundant steering angle detection to operate safely. However, if one steering angle sensor is detected as faulty, this redundancy is lost.Accordingly, it would be desirable to provide systems and methods for real-time steering angle detection and validation in response to the failure of one or more steering wheel angle sensors. Furthermore, other desirable features and characteristics of the present description will become apparent from the following detailed description and the attached claims in conjunction with the attached drawings and the preceding technical field and background.

[0005] DE 11 2019 006 345 T5 describes a device and a method for controlling a steering assist motor, the device comprising a receiving unit for receiving steering angle information and driver steering torque information; a determining unit for the maximum steering angle; and a determining unit for a limit torque of the motor.

[0006] DE 10 2019 212 712 A1 describes a steer-by-wire system and a control method for it. A driver's steering intention can be accurately determined by estimating several state variables and a driver torque if the torque sensor or the steering angle sensor is not provided or is not functioning correctly.

[0007] DE 10 2018 114 988 A1 describes a steer-by-wire steering system for motor vehicles, comprising a steering actuator, a feedback actuator which transmits feedback from the road to a steering wheel, a first steering angle sensor and a second steering angle sensor which is independent of the feedback actuator.

[0008] DE 10 2022 214 324 A1 describes a steering control device and a steering control method of a vehicle, the steering control device comprising a receiver configured to receive absolute steering angle information, relative steering angle information and rack position information of the vehicle, a determination unit configured to determine estimated information of the absolute steering angle based on the rack position information and the relative steering angle information if there is an anomaly in the absolute steering angle information, and a control unit configured to perform position adjustment control.

[0009] It can be considered an objective to provide an alternative system and an alternative method for controlling the steering of a vehicle, thereby increasing the reliability of a steer-by-wire steering system. This objective is achieved by the subject matter of claim 1 and claim 10.

[0010] This document presents vehicle control systems and methods, the associated control logic for providing vehicle control systems, methods for manufacturing and operating such systems, and motor vehicles equipped with steer-by-wire steering control systems. By way of example and without limitation, various embodiments of systems for providing a steering wheel angle sensor estimation and validation system in a motor vehicle equipped with a steer-by-wire steering control system are presented and disclosed herein.

[0011] According to one embodiment, a vehicle steering control system comprises a road wheel angle sensor configured to detect a road wheel angle, a steering feedback motor configured to rotate a steering wheel in response to the road wheel angle and generate a steering torque value in response to a physical rotation of the steering wheel by a vehicle driver, a processor configured to receive the road wheel angle and the steering torque value in order to estimate a steering wheel angle in response to the steering torque value and to generate a validated steering angle in response to a difference between the road wheel angle and the steering wheel angle being less than a threshold, and a steering controller configured to control the steering of a vehicle in response to the validated steering angle.

[0012] According to one embodiment, the road wheel angle is detected in response to a failure of a steering angle sensor.

[0013] According to one embodiment, the steering torque value is determined using a Kalman filter in response to a requested electric motor command, a torque sensor output, and input noise.

[0014] According to one embodiment, the steering control is configured to perform a dynamic backup steering control function in response to the validated steering angle.

[0015] According to one embodiment, the processor is further configured to perform a diagnostic and corrective action when the difference between the road wheel angle and the steering wheel angle exceeds the threshold.

[0016] According to one embodiment, the vehicle steering control system further comprises a steering angle sensor, wherein the road wheel angle is detected in response to a fault in the steering angle sensor.

[0017] According to one embodiment, the steering control is configured to perform a TVSC in response to the validated steering angle.

[0018] According to one embodiment, the threshold is determined in response to a speed of the host vehicle, a duration, and an amount of an estimated angular error.

[0019] According to one embodiment, the steering control further comprises a steering motor for adjusting the road wheel angle in response to the validated steering angle.

[0020] The inventive method for controlling the steering of a vehicle comprises detecting a road wheel angle by a road wheel angle sensor of a road wheel actuator, detecting a lateral acceleration of the vehicle by an inertial measurement unit, calculating a required torque vectoring command in response to the lateral acceleration, detecting by a processor a steering torque value from a steering feedback motor in response to a physical rotation of a steering wheel by a driver, determining a steering wheel angle in response to the steering torque value, generating a validated steering angle by the processor in response to a difference between the road wheel angle and the steering wheel angle being less than a threshold value, and controlling a vehicle steering direction by a steering controller in response to the validated steering angle.

[0021] According to one embodiment, the road wheel actuator comprises a road wheel angle sensor for detecting the road wheel angle and a steering motor for controlling the road wheel angle in response to a steering control signal generated by the steering control system.

[0022] According to one embodiment, a failure of a steering wheel angle sensor is also detected, wherein the road wheel angle is detected in response to the failure of the steering wheel angle sensor.

[0023] According to one embodiment, the validated steering angle is refined using a Kalman filter in response to the steering torque value, the road wheel angle, and input noise.

[0024] According to one embodiment, the threshold value is determined in response to the steering wheel angle and a steering angle change rate.

[0025] According to one embodiment, the steering feedback motor is mechanically coupled to the vehicle's steering wheel.

[0026] According to one embodiment, the validated steering angle is used to perform at least one of a dynamic backup steering control function and a torque vector steering control function.

[0027] According to one embodiment, the road wheel actuator comprises a first road wheel angle sensor and a second road wheel angle sensor, wherein the road wheel angle is determined in response to a mathematical combination of a first output of the first road wheel angle sensor and a second output of the second road wheel angle sensor.

[0028] According to one embodiment, the steering control is further capable of generating a steering control signal in response to the validated steering angle, and wherein the steering control signal is coupled to a steering motor within the road wheel actuator.

[0029] The vehicle steering control system according to the invention comprises a road wheel actuator with a road wheel angle sensor configured to detect a road wheel angle and a steering motor configured to control the road wheel angle in response to a steering control signal, a steering wheel actuator with a steering angle sensor configured to detect a steering wheel angle and a steering feedback motor configured to rotate a steering wheel in response to the road wheel angle and configured to generate a steering torque value in response to a physical rotation of the steering wheel by a driver, and an electronic control unit configured to receive the road wheel angle and the steering torque value.The system estimates the steering wheel angle in response to a steering angle sensor failure, depending on the steering torque value, and generates the steering control signal corresponding to the estimated steering wheel angle in response to a difference between the road wheel angle and the estimated steering wheel angle being less than a threshold value, with the steering of the host vehicle being controlled in response to the steering control signal.

[0030] The vehicle steering control system according to the invention further comprises an inertial measurement unit configured to detect a lateral acceleration of the host vehicle, wherein the electronic control unit is further configured to perform a torque vector steering control function to calculate a required torque vectoring command in response to the lateral acceleration, and wherein the steering control signal is determined in response to the required torque vector command to control the host vehicle in a direction-dependent manner.

[0031] The present description is further described below in conjunction with the following drawings, where identical reference numerals denote identical elements, and where: Fig. 1 a functional block diagram of a vehicle comprising a steer-by-wire steering system with a steering wheel angle sensor estimation and validation system according to the embodiments of the present disclosure; Fig. 2 shows a block diagram of an exemplary implementation of a system for implementing a steering wheel angle sensor estimation and validation system in a motor vehicle according to an exemplary embodiment of the present disclosure; Fig. 3 shows an exemplary implementation of a handwheel actuator for performing steering wheel angle sensor estimation and validation in accordance with embodiments of the present disclosure; Fig. 4 shows a flowchart illustrating an exemplary implementation of a Kalman filter for estimating and validating the steering wheel angle sensor according to the embodiments of the present disclosure; and Fig. Figure 5 shows a flowchart illustrating an exemplary implementation of a method for performing steering wheel angle sensor estimation and validation in accordance with embodiments of the present disclosure.

[0032] Achieving a reliable control system is a continuous improvement process, especially in the case of a safety-critical mechanism. A framework for capturing measurement inaccuracies in real time, an algorithmic procedure for systematically detecting errors, and the validation of information used by control units play a crucial role in the reliability and robustness of control systems. Since the steering angle is a critical measurement, three independent sets of measurements are available, derived from primary, secondary, and tertiary steering angle sensors (SAS). Validating steering angle information can prove challenging if the handwheel actuator (HWA) fails, resulting in the loss of primary and secondary SAS data.The systems and methods disclosed herein implement an algorithmic solution for estimating the handwheel steering angle based on torque measurements / estimates and mathematical models, for validating the tertiary SAS output, for detecting potential failures, for determining the state of steering deterioration, and for carrying out related corrective actions.

[0033] Fig. Figure 1 shows a steer-by-wire steering system 100 with a steering wheel angle sensor estimation and validation system according to the embodiments of the present disclosure. An exemplary vehicle comprises a steering system 100, a handwheel actuator (HWA) 120, a road wheel actuator (RWA) 125, and an electronic control unit (ECU) 172. The HWA 120 comprises a steering wheel 170, a steering angle sensor (SAS) 174, and a steering feedback motor 180. The SAS 174 detects the movement of the steering wheel 170 and transmits this command to the steer-by-wire ECU 172, which then forwards the command to the RWA 125. The RWA 125 includes the steering motor 176, which controls a rack and pinion drive 126, and road wheel angle sensors 178, which provide feedback signals about the movement of the wheels 134 to the ECU 172.The ECU 172 then transmits these feedback signals to the steering feedback motor 180, which then moves the steering wheel 170 to provide feedback to the driver, similar to the feedback provided by the wheels in a vehicle with manual steering. The tie rods 132 connect a rack 130 to the wheels 134 and convert the movement of the rack 130 into a rotation of the wheels 134.

[0034] The steering system 100 is configured to measure the steering wheel angle (SWA). The SWA is the angle by which the steering wheel deviates either to the left or right from an unturned position. The unturned position of the steering wheel corresponds to a straight-ahead driving configuration, with the vehicle traveling straight ahead or in reverse. The driver can move the steering wheel from the unturned position to, for example, make the vehicle turn. In doing so, the driver can initiate an SWA. The SWA can be measured by the SAS 174, which is connected to the vehicle's steering column. The SAS 174 can be operationally coupled to the ECU 172, either via a direct electronic connection or via a connection through another computer or processing system of the vehicle. The ECU 172 uses the SWA measurement in the methods and systems described in this disclosure.

[0035] In some exemplary embodiments, the vehicle may be configured to measure a yaw component of the vehicle motion. The yaw component can be used to calculate an estimated lateral acceleration of the vehicle. For example, a vehicle traveling straight ahead (or directly backward) experiences no yaw or lateral acceleration (Ay). However, if the vehicle initiates a turn while traveling forward (or backward), the vehicle occupants will feel a slight pull to the left or right as the vehicle turns left or right, respectively. The lateral acceleration can be measured relative to the acceleration due to gravity. The yaw component can be measured in the vehicle using an accelerometer or similar device, such as an inertial measurement unit (IMU) 186.The IMU 186 can be operationally coupled to the ECU 172, either via a direct electronic connection or via a connection through another computer or processing system of the vehicle. The ECU 172 uses yaw measurement in the methods and systems of this disclosure.

[0036] The steering system 100 determines the direction and magnitude of a steering command from the driver and adjusts the steering wheel to the wheels. The SAS 174 sensors housed in the HWA 120 always have more than one sensor, which are combined in a single unit for redundancy, accuracy, and reliability. In some exemplary embodiments, the steering system 100 can include a tertiary SAS in addition to the primary and secondary rotation sensors within the SAS 174. Tertiary SAS is a third set of SAS measurement information available in the absence or failure of the primary and secondary rotation sensors in the SAS 174. The tertiary SAS measures a desired steering angle commanded by the driver and transmits this information to the ECU 172. In the event of an HWA failure, for example, a dynamic backup steering control function (DSBC function) can be activated.Dynamic Backup Steering Control calculates the steering angle command based on vehicle speed and other important parameters for execution by the RWA 125. In the event of a simultaneous failure of both the HWA 120 and the RWA 125, a Torque Vector Steering Control (TVSC) function can be used to calculate the necessary torque vectoring commands, such as the yaw moment, to steer the vehicle.

[0037] Now, referring to Fig. Figure 2 shows a block diagram illustrating an exemplary implementation of a system 200 for implementing a steering wheel angle sensor estimation and validation system in a motor vehicle. The exemplary system 200 may include a handwheel actuator (HWA) 210, a road wheel actuator (RWA) 220, an electronic control unit (ECU) 230, and a tertiary sensor validation unit 240.

[0038] The HWA 210 can comprise a primary HWA 211, which includes a primary angle sensor 212 and a primary torque sensor 213, and a secondary HWA 215, which includes a secondary angle sensor 216 and a secondary torque sensor 217. The RWA 220 comprises a secondary RWA-A sensor 221 and a secondary RWA-B sensor 222 for detecting a wheel position angle of the RWA 220. In some exemplary embodiments, the wheel position angle can be determined in response to the secondary RWA sensors 221, 222 mounted on the steering column or directly on the RWA 220 itself. The secondary RWA sensors 221, 222 can measure the rotational movement and convert it into an electrical signal representing the steering angle. Alternatively, the road wheel angle can be determined using linear position sensors that can track the movement of components within the steering mechanism to determine the resulting wheel angle.A tertiary steering angle can be determined in response to the outputs of the secondary RWA sensors 221, 222.

[0039] The primary HWA 211 and the secondary HWA 215 are configured to couple SWA values ​​to a primary master controller 231 of the ECU 230. The RWA wheel position value is coupled by the RWA 220 to the secondary master controller 232 of the ECU 230. Due to the safety-critical function of the steering, a real-time coherence check is performed between the primary angle sensor 212, the secondary angle sensor 216, and the tertiary steering angle from the secondary RWA sensors 221 and 222 to ensure the accuracy and validity of the sensor information. The primary master controller 231 can detect a match between the first SWA from the primary HWA 211 and the secondary SWA from the secondary HWA 215.If the two SWA values ​​are within a threshold deviation indicating that neither the primary angle sensor 212 nor the secondary angle sensor 216 has failed, and both display the same SWA value, the operation of the control system 200 would be normal and no validation using the tertiary steering angle is required. If the two SWA values ​​are not within a threshold deviation, indicating a failure of the primary angle sensor 212 and / or the secondary angle sensor 216, validation using the tertiary steering angle is required.

[0040] A problem arises if, due to the lack of functionality of the primary angle sensor 212 and the secondary angle sensor 216, the tertiary steering angle cannot be validated by the secondary smoke and heat exhaust ventilation (SHEV) sensors 221 and 222, and no further physical sensor duplication is available to reconstruct a substitute signal in the event of a fault detection for validation purposes and to determine appropriate corrective actions. If it is determined that both the primary angle sensor 212 and the secondary angle sensor 216 of the SHEV 210 have failed, the steering control system 200 would be limited to DSBC and TVSC (depending on the SHEV failure condition), and the tertiary steering angle would become the crucial source of angle measurement and would have to be validated for safety reasons.An algorithm 240 for validating the tertiary sensor can be used to estimate the SWA 245 based on torque measurements / estimates from the primary torque sensor 213 and the secondary torque sensor 217 using a mathematical model to validate the output of the tertiary SAS, detect potential failures, determine the state of steering degradation, and implement appropriate corrective actions. If the estimated SWA 245 correlates with the tertiary steering angle from the secondary RWA sensors 221 and 222, the tertiary steering angle 241 is confirmed at 243 and coupled with the DSBC 225 and the TVSC 233. If the tertiary steering angle 241 deviates from the estimated SWA 245 by an amount greater than a threshold, the system is configured to determine a diagnostic and corrective action 246.

[0041] In some exemplary embodiments, a mitigation strategy can be developed for cases where the angle output of the tertiary sensor is invalid. In the event of a primary / secondary SAS failure, the tertiary SAS can be used to control the steering via DSBC and TVSC. If DSBC takes over steering, a fixed steering ratio can be set, allowing the driver to travel further during the button cycle than with TVSC. If the tertiary angle sensor has failed and cannot be validated, a range of recommended mitigation measures for different degrees of sensor degradation can be considered. In some exemplary embodiments, the calibration parameters for DSBC and TVSC can differ, as the severity of the fault may have a greater impact when indirect steering control functions are activated.

[0042] Now, referring to Fig. Figure 3 shows a diagram illustrating an exemplary implementation of a handwheel actuator 300 for performing steering wheel angle sensor estimation and validation in accordance with embodiments of the present disclosure. The algorithm 240 for validating the tertiary sensor from Fig. Algorithm 2 can be used to validate the accuracy of the tertiary angle sensor measurement and for potential fault detection in the event of a loss of the primary and secondary HWA steering angle sensors. Algorithm 240 for validating the tertiary sensor of Fig. 2. Furthermore, it can be used to set internal diagnostics in the event of the tertiary sensor unit's validity, to transmit the driver's steering input to the DSBC to generate the necessary steering command for the road when the HWA has failed, and to set internal diagnostics in the event of the tertiary sensor unit's validity, to transmit the driver's steering input to the TVSC to generate the yaw moment for directional control of the vehicle command when both the HWA and RWA have failed. In addition, the algorithm can be configured to set an internal diagnostic and decide on corrective actions, such as a message to a driver information center, when the tertiary sensor output is invalid.

[0043] The algorithm for validating the tertiary sensor performs several steps to protect against tertiary sensor failures and implements corrective actions to ensure system accuracy. To estimate the steering wheel angle, some sensor information and a handwheel actuator model are used. An observer is designed that uses a state-space model and the necessary sensor information to estimate the steering wheel angle independently of the steering angle measurement unit. Subsequently, a comparison is performed between the estimated and measured steering angles, and appropriate diagnostic countermeasures are determined based on the results of the validity study.

[0044] An exemplary HWA model is used to explain the relationship between various sensory / non-sensory information and physical parameters of the HWA 300. Since the torsional stiffness of the torque sensor is relatively low, the HWA 300 can be divided into two parts: the handwheel assembly 310 and the steering column assembly 320. The handwheel assembly 310 consists of the handwheel and part of the column that connects the handwheel 310 to the torque sensor. The steering column assembly 320 consists of the remaining part of the steering column, the road feedback motor 330, and its reduction gear. Each of the two assemblies has one rotational degree of freedom: the angle of the steering wheel and the angle of the steering column. The dynamic 2DOF (degree of freedom) model of the handwheel steering assembly can be written as follows: Jhθ¨h=−khθh−chθ˙h+Th−Ttb Ttb=ktb(θc−θh)+ctb(θ˙c−θ˙h) Jmθ¨c=−kmθc−cmθ˙c+Ttb−Tm

[0045] Let us consider a dynamic model with 1 DOF for a road feedback motor 330 with a time constant τ m for torque evolution and the distinction between requested and delivered engine torque: τmT˙m+Tm=Tm,req where θ_h and θ_c are the steering wheel and column angles, respectively. k_h, k_m, and k_tb are the stiffnesses of the steering wheel, motor, and torsion bar, respectively. T_h is the torque input from the driver, and T_tb is the torque measured by the torque sensor. J_h and J_m are the equivalent moments of inertia of the steering wheel and motor, respectively. c_h, c_m, and c_tb are the equivalent damping coefficients of the steering wheel, motor, and torsion bar, respectively. T_m and T_(m,req) represent the delivered and requested motor torque, respectively, and τ_m is the corresponding motor time constant.

[0046] In this step, an observer is designed to estimate the steering handwheel angle based on the available state-space model, parameters, and inputs. A Kalman filter-based method can be used to estimate the steering handwheel angle using the following state-space model: A=[01000−ktb+khJs−ctb+chJsktbJsctbJs000010ktbJmctbJm−ktb+kmJm−ctb+cmJm−1Jm0000−1τm],B=[0001Jh00001τm0]Cplant model= [ktbctb−ktb−ctb01000000001],Cobserver=[ktbctb−ktb−ctb000001],D=[0]3×2 x˙=Ax+Bu+W y=Cx+Du+V where W is the process noise and V is the sensor noise, the state variables, input and output vectors can be defined as follows: x'={θhθ˙hθmθ˙mTm},u'={Tm,reqTd},yplant model'={TtbθhTm},yobserver'={TtbTm}

[0047] Fig. Figure 4 shows a flowchart illustrating an exemplary implementation of Method 400 for providing a Kalman filter for estimating and validating the steering wheel angle sensor according to the embodiments of the present disclosure. Method 400 is first operational to initiate the filter at 410. Method 400 then predicts the values ​​for X, P, and Z at 420. Method 400 then corrects the predicted values ​​at 430 based on the initial and predicted values. x: State vector representing the true state of the system. P: State covariance matrix, which represents the uncertainty or error in the state estimation. A: State transition matrix that describes how the state evolves over time. B: Control input matrix (if applicable) showing the effect of external control inputs on the state. u: Control input vector, if applicable, representing the control inputs applied to the system. F: Covariance matrix of the process noise, representing the uncertainty or error in the process model. H: Measurement matrix that relates the state to the measurements. Z: Measurement vector representing the observed measurements. R: Covariance matrix of the measurement noise, which represents the uncertainty or error in the measurements. K: Kalman gain matrix, which is used to incorporate measurements into state estimation.

[0048] In Fig.Figure 5 is a flowchart illustrating an exemplary implementation of a method 500 for performing steering wheel angle sensor estimation and validation in accordance with embodiments of the present disclosure. The method 500 is first operational to receive primary and secondary torque sensor outputs and the requested electric motor command. These output values ​​may include the steering wheel angle, the steering column angle, and the supplied motor torque. In response to the primary and secondary torque sensor outputs and the requested electric motor command, the method 500 is next configured to determine, at Figure 520, the steering wheel angle, the column torque value, and the actual motor torque using a factory standard model.

[0049] The state observer 530 is configured to receive the steering wheel angle, column torque value, actual engine torque, primary and secondary torque sensor output, requested electric motor command, and input noise, and to determine a corrected steering wheel angle, steering column angle, and delivered engine torque. Next, the method determines whether a difference between the estimated steering angle and the corrected steering wheel angle exceeds a threshold. Furthermore, the method at 540 determines whether the magnitude of a difference between the estimated steering angle rate and the actual steering angle rate exceeds a threshold. In some exemplary embodiments, the threshold at 535 can be determined based on the vehicle speed and the error duration above the predefined calibration angle value.If the thresholds are not exceeded, procedure 500 activates the DSBC or TVSC at 545 without further remediation. Procedure 500 then returns to executing the standard HWA model. If the thresholds are exceeded, procedure 500 determines a control and degradation state and specifies a required remediation action. Depending on the degradation state, procedure 500 may then return to executing the standard HWA model.

Claims

[1] Vehicle steering control system (100), comprising: a road wheel actuator (125) with a road wheel angle sensor (178) configured to detect a road wheel angle and a steering motor (176) configured to control the road wheel angle in response to a steering control signal; a steering wheel actuator (120) with a steering angle sensor (174) configured to detect a steering wheel angle, and a steering feedback motor (180) configured to rotate a steering wheel (170) in response to the road wheel angle, and configured to generate a steering torque value in response to a physical rotation of the steering wheel (170) by a driver; an inertial measurement unit (186) configured to detect lateral acceleration of the vehicle; an electronic control unit (172) configured to receive the road wheel angle and the steering torque value, to estimate the steering wheel angle in response to a failure of a steering angle sensor (174) as a function of the steering torque value, and to generate the steering control signal corresponding to the estimated steering wheel angle in response to a difference between the road wheel angle and the estimated steering wheel angle being less than a threshold value; and configured to perform a torque vector steering control function to calculate a required torque vectoring command in response to the lateral acceleration, and wherein the steering control signal is determined in response to the required torque vectoring command to steer the vehicle in a direction-dependent manner; and A steering control unit that is configured to control the steering of the vehicle in response to the steering control signal. [2] Vehicle steering control system (100) according to claim 1, further comprising a processor configured to generate a validated steering angle in response to a difference between the road wheel angle and the steering wheel angle being less than a threshold value. [3] Vehicle steering control system (100) according to claim 1, wherein the road wheel angle is detected in response to a failure of a steering angle sensor (174). [4] Vehicle steering control system (100) according to claim 1, wherein the steering torque value is determined using a Kalman filter in response to a requested electric motor command, a torque sensor output and an input noise. [5] Vehicle steering control system (100) according to claim 2, wherein the steering control is configured to perform a dynamic backup steering control function in response to the validated steering angle. [6] Vehicle steering control system (100) according to claim 2, wherein the processor is further configured to perform a diagnostic and corrective action when the difference between the road wheel angle and the steering wheel angle exceeds the threshold. [7] Vehicle steering control system (100) according to claim 2, wherein the steering control is configured to perform a TVSC in response to the validated steering angle. [8] Vehicle steering control system (100) according to claim 1, wherein the threshold is determined in response to a speed of the vehicle, a time duration, and an amount of an estimated angular error. [9] Vehicle steering control system (100) according to claim 2, wherein the steering control further comprises a steering motor (176) for adjusting the road wheel angle in response to the validated steering angle. [10] Method for controlling the steering of a vehicle, comprising: Detect, by means of a road wheel angle sensor (178) of a road wheel actuator (125), a road wheel angle; Detect, by means of an inertial measurement unit (186), a lateral acceleration of the vehicle; Calculating a required torque vectoring command in response to the lateral acceleration; Detect, by a processor, a steering torque value from a steering feedback motor (180) in response to a physical rotation of a steering wheel (170) by a vehicle driver; Determining a steering wheel angle in response to the steering torque value; Generating, by the processor, a validated steering angle in response to a difference between the road wheel angle and the steering wheel angle being less than a threshold; and Steering, by means of a steering control, a vehicle steering direction in response to the validated steering angle.

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