Fault-tolerant reconstruction method for steer-by-wire device

Abstract

The application discloses a kind of steer-by-wire device fault-tolerant reconstruction methods, steer-by-wire device includes steering road feel executor, steer-by-wire executor and corresponding fault-tolerant reconstruction controller, corresponding fault-tolerant reconstruction controller includes steering monitoring unit, fault diagnosis unit and fault-tolerant reconstruction unit, steering monitoring unit is used to monitor the working parameter of steering execution motor in steer-by-wire device, fault diagnosis unit is used to determine the fault state of steer-by-wire device according to working parameter and identifies fault type, fault-tolerant reconstruction unit is used to when the fault of steer-by-wire device occurs, the working state of steering execution motor is switched to fault maintenance mode, to maintain the steering function of steer-by-wire device. According to working parameter, identify the fault type, when failure occurs, single three-phase motor limp control, position sensor reconstruction control and current sensor reconstruction control are carried out to steering execution motor, to ensure that steer-by-wire device still has certain steering control function under certain fault.

Description

Technical Field

[0001] This application relates to the field of automotive steering system technology, specifically to a fault-tolerant reconfiguration method for a steer-by-wire device. Background Technology

[0002] The automotive steer-by-wire system consists of three main parts: the steering wheel assembly, the steering actuator assembly, and the main controller (ECU), as well as auxiliary systems such as a fault diagnosis system and a power supply. The steering wheel assembly includes the steering wheel, a steering wheel angle sensor, a torque sensor, and a steering wheel return torque motor. Its main function is to convert the driver's steering intention (by measuring the steering wheel angle) into a digital signal and transmit it to the main controller; simultaneously, it generates steering wheel return torque based on the torque signal received from the main controller, providing the driver with corresponding road feel information. The steering actuator assembly includes front wheel angle sensors, a steering actuator motor, a steering motor controller, and front wheel steering components. Its function is to receive commands from the main controller and, through the steering motor controller, control the rotation of the steering wheels to achieve the driver's steering intention. The main controller analyzes and processes the collected signals, determines the vehicle's motion state, and sends instructions to the steering wheel return motor and steering motor controller to control the operation of the two drive motors, ensuring ideal vehicle response under various operating conditions. This reduces the driver's workload by compensating for changes in steering characteristics with vehicle speed. At present, steer-by-wire systems only use redundancy to ensure their reliability and safety. However, redundancy can only reduce the probability of malfunctions. When a malfunction occurs, the vehicle cannot continue to drive due to safety requirements and must be stopped for maintenance and repair. Summary of the Invention

[0003] The main technical problem addressed in this application is how to improve the safety and reliability of steer-by-wire devices.

[0004] According to the first aspect, one embodiment provides a fault-tolerant reconfiguration method for a steer-by-wire device, the steer-by-wire device including a steering road feel actuator, a steer-by-wire actuator and a corresponding fault-tolerant reconfiguration controller, the corresponding fault-tolerant reconfiguration controller including a steering monitoring unit, a fault diagnosis unit and a fault-tolerant reconfiguration unit;

[0005] The steering monitoring unit is used to monitor the operating parameters of the steering actuator motor in the steer-by-wire device; the steering actuator motor includes the actuator motor of the steering road feel actuator and the actuator motor of the steer-by-wire actuator, the steering actuator motor is used to provide steering driving force to achieve steering control, and the motor angle of the steering actuator motor is positively correlated with the vehicle's steering angle; the steering actuator motor includes a dual three-phase permanent magnet synchronous motor, and the operating parameters of the steering actuator motor include angle parameters and drive current parameters; the steering monitoring unit includes a position sensor and a current sensor, the position sensor is used to monitor the angle parameters, and the current sensor is used to monitor the drive current parameters;

[0006] The fault diagnosis unit is used to determine the fault status of the steer-by-wire device based on the operating parameters, and to identify the fault type of the steer-by-wire device when a fault occurs; the fault type includes motor fault, position sensor fault and / or current sensor fault;

[0007] The fault-tolerant reconfiguration unit is used to switch the working state of the steering actuator motor to fault maintenance mode when the steer-by-wire device malfunctions, so as to maintain the steering function of the steer-by-wire device.

[0008] The fault-tolerant reconfiguration method for the steer-by-wire device includes:

[0009] The operating parameters of the steering actuator motor are acquired in real time.

[0010] The fault type of the steer-by-wire device is identified based on the operating parameters.

[0011] When the steer-by-wire device malfunctions, the operating state of the steering actuator motor is switched to the fault maintenance mode. The fault maintenance mode includes single-phase three-phase motor limp control, position sensor reconfiguration control, and / or current sensor reconfiguration control. The single-phase three-phase motor limp control includes switching the dual three-phase permanent magnet synchronous motor synchronous drive steering control of the steering actuator motor to single-phase three-phase permanent magnet synchronous motor drive steering control. The position sensor reconfiguration control includes initializing and resetting the position sensor based on the monitored steering angle parameter value. The current sensor reconfiguration control includes initializing and resetting the current sensor based on the monitored drive current parameter value.

[0012] In one embodiment, identifying the fault type of the steer-by-wire device based on the operating parameters includes:

[0013] The fault diagnosis unit includes a terminal sliding mode observer, which is used to monitor the motor operating angle of the steering actuator motor based on the angle parameters; the terminal sliding mode observer is also used to obtain the fault factors of each three phase of the dual three-phase permanent magnet synchronous motor.

[0014] The fault status of the two three-phase permanent magnet synchronous motors is determined based on the fault factors, and the faulty three-phase permanent magnet synchronous motor is identified.

[0015] In one embodiment, identifying the fault type of the steer-by-wire device based on the operating parameters further includes:

[0016] The dynamic differential equation of the steering actuator motor is:

[0017] T m1 =J m1 m1 +B m1 m1 +T α1 ;

[0018] T m2 =J m2 m2 +B m2 m2 +T α2 ;

[0019] T α =K m (θ m -i m θ c );

[0020] T m1 =K t1 i α1 ;

[0021] T m2 =K t2 i α2 ;

[0022] Among them, T m1 and T m2 These are the respective electromagnetic torques, K, of the two three-phase permanent magnet synchronous motors. t1 and K t2 These are the electromagnetic torque coefficients of the two three-phase permanent magnet synchronous motors, i α1 and i α2 These are the operating currents of the two three-phase permanent magnet synchronous motors, J. m1 and J m2These are the moments of inertia of the two three-phase permanent magnet synchronous motors, B. m1 and B m2 These are the damping coefficients, T, of the two three-phase permanent magnet synchronous motors, respectively. α1 and T α2 The output torques of the two three-phase permanent magnet synchronous motors, K, are respectively. m θ represents the torsional stiffness of the shaft of a three-phase permanent magnet synchronous motor. m θ is the operating angle of a three-phase permanent magnet synchronous motor. c The input angle of the reducer in the steer-by-wire device;

[0023] The dynamic differential equation of the steering actuator motor is:

[0024] J mi mi +B mi mi =K ti i αi -K mi (θ mi -i m θ c );

[0025] mi =(K ti i αi -B mi mi -T αi ) / J mi ;

[0026] set up:

[0027] α i =K ti / J mi ;

[0028] β i =B mi / J mi ;

[0029] γ i =K mi / J mi ;

[0030] Where the subscript i represents each of the three phases in the dual three-phase configuration, i.e., i=1 or 2. For simplicity, this method is used throughout the document. The terminal sliding mode observer is then described as follows:

[0031] mi =α i fi (t)i αi -β i mi -γ i (θ mi -i m θ c )+w(t)

[0032] =α i f i (t)i αi -β i mi -γ i (θ mi -i m θ c )+lS i +ρ×sigmoid(S i );

[0033] Among them, S i It is the terminal sliding surface, and has S i =e i + |e i | q sign(e i );

[0034] e i = mi - miw This is the observation error;

[0035] w(t) is the unmatched uncertainty term of the steer-by-wire device, and |w(t)| < ρ;

[0036] mi yes mi The observed value, f i (t) is the fault factor of the three-phase permanent magnet synchronous motor;

[0037] l (t) is an estimated value of the failure factor. l (t) is the fault factor estimation error;

[0038] l (t)= f i (t)- l (t);

[0039] q is the sliding mode surface parameter, and 0 < q < 1 is the terminal attractor exponent;

[0040] l and ρ are the gain coefficients of the sliding mode observer, and sigmoid(S i ) is the continuous switching function.

[0041] In one embodiment, identifying the fault type of the steer-by-wire steering device according to the working parameters further includes: <00,00506>

[0042] The acquisition formula of the fault factor is:

[0043] l (t) = -r i α i i αi S i ;

[0044] where r i is the gain coefficient;

[0045] When f i (t) < 1, it is determined that a fault has occurred in the three-phase permanent magnet synchronous motor.

[0046] In one embodiment, identifying the fault type of the steer-by-wire steering device according to the working parameters includes:

[0047] The steering monitoring unit monitors the three-phase currents of each three-phase permanent magnet synchronous motor, and each phase current corresponds to one current sensor;

[0048] The fault state of the current sensor monitoring the phase current is determined according to the respective error values calculated from the target current values and the corresponding target current amounts of the d-axis and the q-axis of the phase current in different coordinate systems. [[ID=4,7]]

[0049] In one embodiment, identifying the fault type of the steer-by-wire steering device according to the working parameters includes:

[0050] The steering monitoring unit monitors the angular position parameters of each three-phase permanent magnet synchronous motor through two position sensors;

[0051] The fault state of the position sensor is determined according to whether the difference between the two obtained angular position parameters is greater than a preset angular position threshold.

[0052] In one embodiment, identifying the fault type of the steer-by-wire steering device according to the working parameters further includes:

[0053] The fault diagnosis unit also includes a position observer, which is used to obtain the motor rotation angle model parameters of the three-phase permanent magnet synchronous motor based on the stator parameter acquisition equation of the three-phase permanent magnet synchronous motor.

[0054] The fault status of the two position sensors is determined based on the motor rotation angle model parameters and the rotation angle parameters of the two three-phase permanent magnet synchronous motors.

[0055] In one embodiment, when the steer-by-wire device malfunctions, switching the operating state of the steering actuator motor to the fault sustainment mode includes:

[0056] The limp control of the single-phase three-phase motor is to disconnect the single-phase three-phase of the faulty dual-phase three-phase permanent magnet synchronous motor, and the other single-phase three-phase of the non-faulty dual-phase three-phase permanent magnet synchronous motor provides the full steering drive force.

[0057] The current sensor reconfiguration control replaces the original faulty phase current value with the faulty phase current value calculated using Kirchhoff's current law.

[0058] The position sensor reconfiguration control replaces the angle parameters monitored by the faulty position sensor with motor angle model parameters calculated by the position observer.

[0059] According to a second aspect, one embodiment provides a computer-readable storage medium storing a program that can be executed by a processor to implement the fault-tolerant reconfiguration method for steering-by-wire as described in the first aspect.

[0060] According to a third aspect, one embodiment provides a computer program product including a computer program and / or instructions, which, when executed by a processor, implement the fault-tolerant reconfiguration method for the steering-by-wire device as described in the first aspect.

[0061] According to the fault-tolerant reconfiguration method of the steer-by-wire device in the above embodiment, the fault type is first identified based on the working parameters. When a fault occurs, single-phase and three-phase motor limp control, position sensor reconfiguration control, and current sensor reconfiguration control are performed on the steering actuator motor to ensure that the steer-by-wire device still has a certain steering function under specific fault conditions, thereby improving the safety and reliability of the steer-by-wire device. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the steer-by-wire device in one embodiment;

[0063] Figure 2 This is a schematic diagram of the functional units of the steer-by-wire device in one embodiment;

[0064] Figure 3 This is a flowchart illustrating a fault-tolerant reconfiguration method for a steer-by-wire device in one embodiment.

[0065] Figure 4 This is a schematic diagram of the current coordinate transformation of three-phase current in one embodiment. Detailed Implementation

[0066] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0067] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0068] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0069] In this application embodiment, a relatively complete fault diagnosis and fault-tolerant reconstruction system is innovatively proposed for the steering actuator motor and various sensors of the steer-by-wire device. This system can quickly and accurately locate the fault location and adopt corresponding fault-tolerant strategies according to different fault degrees, so that the dual three-phase permanent magnet synchronous motor system can still provide sufficient steering resistance torque under specific fault conditions.

[0070] Example 1:

[0071] Please refer to Figure 1This is a schematic diagram of the steer-by-wire device in one embodiment. This application discloses a fully redundant steer-by-wire system for advanced autonomous driving. The system consists of a Handwheel actuator (HWA), a Roadwheel actuator (RWA), and a redundant power supply system. A high-voltage battery powers two independent low-voltage batteries via a DC / DC module, forming Powerpackage1 and Powerpackage2 dual-circuit redundant power supplies. One power supply powers part of the control units of the HWA and RWA, while the other powers the backup control unit of the RWA, preventing the loss of steering function due to a single power supply failure. The Handwheel actuator (HWA) integrates a steering wheel, torque and angle sensor, worm gear reduction mechanism, and travel limit device. It has built-in Powerpackage1 / 2 and Powerpackage2 / 2 dual independent control units to drive the dual three-phase permanent magnet synchronous motors of the HWA. The torque and angle sensor... The TAS (Traction Actuator) acquires driver steering commands via SENT signals and feeds them back to the HWA (Hardware Assisted Vehicle) controller. Road sense control commands are transmitted to the VCU (Vehicle Control Unit) via the CANFD bus. The RWA (Road steerable actuator) is equipped with redundant Steering Angle Sensors (SAS), a synchronous belt-ball screw reduction mechanism, and dual Powerpackage control units. The dual Powerpackage control units drive the dual three-phase permanent magnet synchronous motors of the RWA. The SAS sensor acquires the actual position of the rack and pinions and feeds it back to the RWA controller via SENT signals. The RWA receives the target steering commands sent by the VCU via the four-channel CANFD bus and drives the dual three-phase permanent magnet synchronous motors to achieve wheel steering. The VCU, as the core of the system, achieves bidirectional interaction with the HWA and RWA through the CANFD1~4 multi-channel redundant communication links. At the same time, it works with terminating resistors to ensure the integrity of bus signals. In the event of a single point of failure in any power supply, control unit, or communication link, the system can seamlessly switch through the redundant architecture to maintain ≥50% steering output capability, meet ASIL-D level functional safety requirements, and provide a reliable steerable actuator solution for advanced autonomous driving.

[0072] Please refer to Figure 2This is a schematic diagram of the functional units of a steer-by-wire device in one embodiment. The steer-by-wire device includes a steering road feel actuator, a steer-by-wire actuator, and a corresponding fault-tolerant reconfiguration controller. The corresponding fault-tolerant reconfiguration controller includes a steering monitoring unit 10, a fault diagnosis unit 20, and a fault-tolerant reconfiguration unit 30. The steering monitoring unit 10 monitors the operating parameters of the steering actuator motor in the steer-by-wire device. The steering actuator motor includes the actuator motor of the steering road feel actuator and the actuator motor of the steer-by-wire actuator. The steering actuator motor provides steering driving force to achieve steering control, and the motor angle of the steering actuator motor is positively correlated with the vehicle's steering angle. The steering actuator motor includes a dual three-phase permanent magnet synchronous motor, and its operating parameters include angle parameters and drive current parameters. The steering monitoring unit 10 includes a position sensor and a current sensor. The position sensor monitors the angle parameters, and the current sensor monitors the drive current parameters. The fault diagnosis unit 20 determines the fault state of the steer-by-wire device based on the operating parameters and identifies the fault type when a fault occurs. The fault types include motor fault, position sensor fault, and / or current sensor fault. The fault-tolerant reconfiguration unit 30 is used to switch the working state of the steering actuator motor to fault maintenance mode when the steer-by-wire device malfunctions, so as to maintain the steering function of the steer-by-wire device.

[0073] Please refer to Figure 3 This is a flowchart illustrating a fault-tolerant reconfiguration method for a steer-by-wire device in one embodiment. Another embodiment of this application discloses a fault-tolerant reconfiguration method for a steer-by-wire device, comprising:

[0074] Step 101: Obtain working parameters.

[0075] The operating parameters of the steering actuator motor are acquired in real time. In one embodiment, the operating parameters (steering angle parameters and drive current parameters) of the steering actuator motor are monitored by the position sensor and current sensor of the steering monitoring unit.

[0076] Step 102: Determine the fault type.

[0077] The fault type of the steer-by-wire device is identified based on its operating parameters. In one embodiment, the fault diagnosis unit includes a terminal sliding mode observer. The terminal sliding mode observer monitors the operating angle of the steering actuator motor based on the angle parameters. It also acquires the fault factors for each of the three phases of the dual three-phase permanent magnet synchronous motor, determines the fault state of the dual three-phase permanent magnet synchronous motor based on the fault factors, and identifies the three-phase permanent magnet synchronous motor that has experienced a fault. The dual three-phase permanent magnet synchronous motor can be considered as two three-phase permanent magnet synchronous motors connected in parallel. The calculation method for the fault factors of the dual three-phase permanent magnet synchronous motor includes:

[0078] The dynamic differential equation of the dual three-phase permanent magnet synchronous motor is:

[0079] T m1 =J m1 m1 +B m1 m1 +T α1 ;

[0080] T m2 =J m2 m2 +B m2 m2 +T α2 ;

[0081] T α =K m (θ m -i m θ c );

[0082] T m1 =K t1 i α1 ;

[0083] T m2 =K t2 i α2 ;

[0084] Among them, T m1 and T m2 These are the respective electromagnetic torques, K, of the two three-phase permanent magnet synchronous motors. t1 and K t2 These are the electromagnetic torque coefficients of the two three-phase permanent magnet synchronous motors, i α1 and i α2 These are the operating currents of the two three-phase permanent magnet synchronous motors, J. m1 and J m2 These are the moments of inertia of the two three-phase permanent magnet synchronous motors, B. m1 and B m2 These are the damping coefficients, T, of the two three-phase permanent magnet synchronous motors, respectively. α1 and T α2 The output torques of the two three-phase permanent magnet synchronous motors, K, are respectively. m θ represents the torsional stiffness of the shaft of a dual three-phase permanent magnet synchronous motor. m θ is the operating angle of a dual three-phase permanent magnet synchronous motor. c The input angle of the reducer in the steer-by-wire device;

[0085] The dynamic differential equation of the steering actuator motor is:

[0086] J mi mi +B mi mi =K ti i αi -K mi (θ mi -i m θ c );

[0087] mi =(K ti i αi -B mi mi -T αi ) / J mi ;

[0088] set up:

[0089] α i =K ti / J mi ;

[0090] β i =B mi / J mi ;

[0091] γ i =K mi / J mi ;

[0092] Where the subscript i represents each of the three phases in the dual three-phase configuration, i.e., i=1 or 2. For simplicity, this method is used throughout the document. The terminal sliding mode observer is then described as follows:

[0093] mi =α i f i (t)i αi -β i mi -γ i (θ mi -i m θ c )+w(t)

[0094] =α i f i (t)i αi -β i mi -γ i(θ mi - i m θ c ) + lS i + ρ × sigmoid(S i );

[0095] Where S i is the terminal sliding surface, and S i = e i + |e i | q sign(e i );

[0096] e i = mi - miw is the observation error;

[0097] w(t) is the unmatched uncertainty of the steer - by - wire system, and |w(t)| < ρ;

[0098] <00002​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​i ;

[0105] Where, r i This is the gain coefficient. It is set by... , , The magnitude of f allows the observation error of the terminal sliding mode observer to converge asymptotically, and the fault factor value of the motor can be calculated. When f i When f(t)=1, it indicates that the motor is fault-free; when f i When (t)<1, it is determined that the dual three-phase permanent magnet synchronous motor has a fault, and the corresponding fault flag is set. At this time, it is necessary to further determine the fault location.

[0106] In one embodiment, the steering monitoring unit monitors the three-phase current of each three-phase permanent magnet synchronous motor, with each phase current corresponding to a current sensor. The fault state of the current sensor monitoring that phase current is determined based on the error values ​​calculated from the target current values ​​on the d-axis and q-axis in different coordinate systems and their corresponding target current quantities. To improve the accuracy and effectiveness of fault diagnosis, multiple verifications should be performed within a short period when determining the fault factor and fault flag. Taking the fault diagnosis of the current sensor as an example, if the calculated fault factor of the current sensor exceeds the threshold, the value of the fault counter is incremented by one and delayed by 5ms. When the value of the fault counter reaches 3, the fault flag Fault_i is set to 1. The three-phase current sensor uses a coordinate transformation-based fault diagnosis method, which can quickly locate the fault location. After a fault occurs, the faulty phase current sensor is quickly isolated, and the accurate faulty phase current is obtained using a current reconstruction method based on Kirchhoff's current law for subsequent fault-tolerant control.

[0107] In one embodiment, the process of diagnosing faults in a current sensor includes:

[0108] For each of the three phases of a dual three-phase permanent magnet synchronous motor, the current is:

[0109] i a +i b +i c =0;

[0110] Among them, i a i b , and i c These are the three-phase currents of the single-phase and three-phase permanent magnet synchronous motors, respectively.

[0111] Please refer to Figure 4 This is a schematic diagram of the current coordinate transformation of three-phase current in one embodiment. In different coordinate systems, the phase a current can be expressed as:

[0112] ;

[0113] ;

[0114] Among them, i d_cmd and i q_cmd In synchronous rotating coordinate system shaft and The target current value of the shaft.

[0115] i (a) α_cmd and i (a) β_cmd These are the target quantities of phase a current in the rotating coordinate system, i and i. (a) and i (a) These are the target quantities of phase a current in the stationary coordinate system. The error e in both coordinate systems is determined by... (a) = i (a) α_cmd - i (a) α Whether the current sensor in phase a is faulty can be determined by whether it is within a certain threshold range Δi. Similarly, the faults in phases b and c can be determined.

[0116] In one embodiment, the steering monitoring unit monitors the rotation angle parameters of each three-phase permanent magnet synchronous motor using two position sensors. The fault status of the position sensors is determined based on whether the difference between the two acquired rotation angle parameters is greater than a preset rotation angle threshold. In one embodiment, since each of the dual three-phase permanent magnet synchronous motors has one position sensor, the fault is determined by comparing the two position signals and determining whether their error is within a certain threshold range. If the error threshold exceeds the defined range, the position sensor is determined to be faulty. Further, the two position signals are compared with the position signal observed by the observer, and the position signal with the larger difference from the observed signal is determined to be the fault signal. In one embodiment, the fault diagnosis unit also includes a position observer, which is used to obtain the motor rotation angle model parameters of each three-phase permanent magnet synchronous motor based on the stator parameter acquisition equation, and then determine the fault status of the two position sensors based on the motor rotation angle model parameters and the rotation angle parameters of the dual three-phase permanent magnet synchronous motors. Based on the unscented Kalman filtering method, the position signal observer is designed as follows:

[0117] For surface-mounted permanent magnet synchronous motors, there is L d =L q Establish the stator voltage equation in the dq axis, i.e., the synchronous rotating coordinate system:

[0118] ;

[0119] Among them, u d for Axis voltage, uq for Shaft voltage, R is stator resistance, i d and i q They are respectively shaft and Axis current, ψ d and ψ q They are respectively shaft and axial permanent magnet flux linkage coefficient, ω e ω is the electric angular velocity.

[0120] The stator flux linkage equation is:

[0121] ;

[0122] Where, ψ f Let be the flux linkage constant of the permanent magnet. Then the stator voltage equation can be:

[0123] ;

[0124] Where p is the number of magnetic pole pairs.

[0125] The stator voltage equation in the stationary coordinate system obtained by the inverse Park transformation is:

[0126] ;

[0127] Among them, E α and E β To extend the back electromotive force.

[0128] Define the extended back electromotive force as:

[0129] ;

[0130] Where, θ e Let be the electrical angle. Then the spatial state equation for the current can be rewritten as:

[0131] ;

[0132] ;

[0133] The nonlinear state equation of the steering actuator motor is expressed as:

[0134] x(t) = f[x(t)] + Bu(t);

[0135] y(t) = Cx(t);

[0136] Where x(t)=[ i α i β w w θe ] T These are the state variables of the motor position observation system;

[0137] u(t) = [u α u β ] T This is the control variable for the motor position observation system;

[0138] y(t) = [i α i β ] T This is the output of the motor position observation system;

[0139] f(x) is a function of the motor position observation system, which is:

[0140] ;

[0141] ;

[0142] ;

[0143] The mathematical model for discretizing a continuous-time system is then:

[0144] x k =f(x k-1 )+B k-1 u k-1 +V k-1 ;

[0145] y k =Cx k +W k ;

[0146] Among them, subscript k represents the current moment, and k-1 represents the previous moment. For system noise, For measuring noise.

[0147] The unscented Kalman filter algorithm is used to initialize, update time, update measurements, and estimate the state of a discretized mathematical model, thereby calculating the observed motor position. The unscented Kalman filter employs unscented transform to handle nonlinear systems and accurately captures the statistical characteristics of the system state through Sigma point sampling.

[0148] For an n-dimensional state vector, generate 2n+1 Sigma points:

[0149] X （0） k-1 =x k-1 ;

[0150] X （i） k-1=x k-1 +( ) i , i=1,…,n;

[0151] X （i） k-1 =x k-2 +( ) i-n , i = n+1, ..., 2n;

[0152] Where λ is the scaling parameter.

[0153] (1) The state variables and covariance matrix are initialized as follows.

[0154] ;

[0155] Where X0 is the initial state variable of the motor position observation system. 0 represents the predicted value of the initial state of the motor position observation system, and P0 represents the covariance matrix of the initial state.

[0156] (2) Time update.

[0157] ① Calculate the Sigma point weights:

[0158] W m (0) =λ / (n+λ);

[0159] W c (0) =λ / (n+λ)+(1-α 2 +β);

[0160] W m (i) =W c (i) =1 / [2(n+λ)], i=1,…,2n;

[0161] Where β is a parameter used to combine information from higher-order terms.

[0162] ② Propagate the Sigma point through the state equation:

[0163] X (i) k | k-1 = f(X) （i） k-1 )+B k-1 u k-1 , i=0,…,2n;

[0164] ③ Calculate the predicted state value:

[0165] x k |k-1 = Σ i=0 2n W m （i） X (i) k | k-1 ;

[0166] ④ Calculate the prediction error covariance matrix:

[0167] P k | k-1 =Σ i=0 2n W c （i） [X （i） k | k-1 -x k | k-1 ][X （i） k | k-1 -x k | k-1 ] T + Q k ;

[0168] Among them, Q k Let be the process noise covariance matrix.

[0169] (3) Measurement update.

[0170] ① Propagate the Sigma point through the measurement equation:

[0171] Y （i） k | k-1 =CX （i） k | k-1 , i=0,…,2n;

[0172] ② Calculate the predicted measurement value:

[0173] y k | k-1 =Σ i=0 2n W m （i） Y （i） k | k-1 ;

[0174] ③ Calculate the measurement prediction covariance matrix:

[0175] P γγ =Σ i=0 2n W c （i）[Y （i） k | k-1 -y k | k-1 ][Y （i） k | k-1 -y k | k-1 ] ᵀ +R k ;

[0176] Among them, R k To measure the noise covariance matrix.

[0177] ④ Calculate the cross-covariance matrix of state and measurement:

[0178] P xγ =Σ i=0 2n W c （i） [X （i） k | k-1 -x k | k-1 ][Y （i） k | k-1 -y k | k-1 ] T ;

[0179] (4) State estimation.

[0180] ① Calculate the Kalman gain:

[0181] K k =P xγ P γγ -1 ;

[0182] Among them, K k This is the Kalman gain matrix.

[0183] ② Update the state estimate:

[0184] x k =x k | k-1 +K k (y k -y k | k-1 );

[0185] Where, x k y is the estimated value of the state variable at time k in the motor position observation system. k This is the measurement value at time k.

[0186] ③ Update the covariance matrix:

[0187] P k =P k | k-1 -K k P γγ K k T ;

[0188] Among them, P k This is the estimated value of the state covariance matrix at time k. The observation of the motor position is now complete.

[0189] Step 103: Switch working status.

[0190] When the steer-by-wire system malfunctions, the operating state of the steering actuator motor is switched to a fault sustaining mode. This fault sustaining mode includes single-phase / three-phase motor limp control, position sensor reconfiguration control, and / or current sensor reconfiguration control. Single-phase / three-phase motor limp control involves switching the steering actuator motor's dual-phase / three-phase permanent magnet synchronous motor synchronous drive steering control to single-phase / three-phase permanent magnet synchronous motor drive steering control. Position sensor reconfiguration control involves initializing and resetting the position sensor based on monitored angle parameter values. Current sensor reconfiguration control involves initializing and resetting the current sensor based on monitored drive current parameter values. In one embodiment, single-phase / three-phase motor limp control disconnects the faulty single-phase / three-phase of the dual-phase / three-phase permanent magnet synchronous motor, and the remaining single-phase / three-phase of the motor that is not faulty provides all steering drive force. Current sensor reconfiguration control replaces the original faulty phase current value with the faulty phase current value calculated using Kirchhoff's current law. Position sensor reconfiguration control replaces the angle parameters monitored by the faulty position sensor with motor angle model parameters calculated by the position observer.

[0191] Based on the calculation results of the motor fault factors, the fault diagnosis results of the current sensor, and the fault diagnosis results of the position sensor, corresponding fault flag bits are set. When there are no faults in the motor and sensors, all fault flag bits are 0, and the steering system works normally. When the motor fails, Fault_m is set to 1 to issue a fault warning to the driver. At this time, it is necessary to further determine the location of the fault. If the current sensor fails, Fault_i is set to 1, and the system enters the current sensor fault reconstruction mode, replacing the original fault phase current value with the fault phase current observation value calculated using Kirchhoff's current law. If the position sensor fails, Fault_t is set to 1, and the system enters the position sensor fault reconstruction mode, replacing the original fault position signal with the position signal observation value calculated by the position observer. If neither the current nor the position sensor fails, it is determined to be a motor mechanical fault. At this time, Fault_i and Fault_t are both 0, and the system enters the single-phase three-phase motor limp-out working mode, temporarily providing all steering torque within the rated torque range of the single-phase three-phase motor; and providing rated torque outside the rated torque range of the single-phase three-phase motor. In one embodiment, since the probability of the current sensor and the position sensor failing simultaneously is low, and the probability of the multi-phase current in the current sensor failing simultaneously is also low, the above two failure scenarios are not considered, and no separate operating mode is set.

[0192] The fault-tolerant reconfiguration method for a steer-by-wire device disclosed in this application includes a steering road feel actuator, a steer-by-wire actuator, and a corresponding fault-tolerant reconfiguration controller. The corresponding fault-tolerant reconfiguration controller includes a steering monitoring unit, a fault diagnosis unit, and a fault-tolerant reconfiguration unit. The steering monitoring unit monitors the operating parameters of the steering actuator motor in the steer-by-wire device, which includes the actuator motor of the steering road feel actuator and the actuator motor of the steer-by-wire actuator. The fault diagnosis unit determines the fault state of the steer-by-wire device based on the operating parameters and identifies the fault type. The fault-tolerant reconfiguration unit switches the operating state of the steering actuator motor to a fault-maintaining mode when a fault occurs in the steer-by-wire device, thereby maintaining the steering function of the steer-by-wire device. Based on the operating parameters, the fault type is identified. When a fault occurs, single-phase and three-phase motor limp control, position sensor reconfiguration control, and current sensor reconfiguration control are performed on the steering actuator motor to ensure that the steer-by-wire device still has a certain steering control function under specific fault conditions, thereby improving the safety and reliability of the steer-by-wire device.

[0193] Those skilled in the art will understand that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, which may include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to achieve the above functions. For example, the program can be stored in the memory of a device, and when the program in the memory is executed by the processor, all or part of the above functions can be achieved. In addition, when all or part of the functions in the above embodiments are implemented by computer programs, the program can also be stored in a server, another computer, disk, optical disk, flash drive, or external hard drive, etc., and can be downloaded or copied to the memory of a local device, or the system of the local device can be updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be achieved.

[0194] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A fault-tolerant reconfiguration method for a steer-by-wire device, characterized in that, The steer-by-wire device includes a steering road feel actuator, a steer-by-wire actuator, and a corresponding fault-tolerant reconfiguration controller. The corresponding fault-tolerant reconfiguration controller includes a steering monitoring unit, a fault diagnosis unit, and a fault-tolerant reconfiguration unit. The steering monitoring unit is used to monitor the operating parameters of the steering actuator motor in the steer-by-wire device. The steering actuator motor includes the actuator motor of the steering road feel actuator and the actuator motor of the steer-by-wire actuator. The steering actuator motor is used to provide steering driving force to achieve steering control. The motor rotation angle of the steering actuator motor is positively correlated with the vehicle's steering angle. The steering actuator motor includes a dual three-phase permanent magnet synchronous motor, and the operating parameters of the steering actuator motor include steering angle parameters and drive current parameters; the steering monitoring unit includes a position sensor and a current sensor, the position sensor is used to monitor the steering angle parameters, and the current sensor is used to monitor the drive current parameters; The fault diagnosis unit is used to determine the fault status of the steer-by-wire device based on the operating parameters, and to identify the fault type of the steer-by-wire device when a fault occurs; the fault type includes motor fault, position sensor fault and / or current sensor fault; The fault-tolerant reconfiguration unit is used to switch the working state of the steering actuator motor to fault maintenance mode when the steer-by-wire device malfunctions, so as to maintain the steering function of the steer-by-wire device. The fault-tolerant reconfiguration method for the steer-by-wire device includes: The operating parameters of the steering actuator motor are acquired in real time. The fault type of the steer-by-wire device is identified based on the operating parameters. When the steer-by-wire device malfunctions, the operating state of the steering actuator motor is switched to the fault maintenance mode. The fault maintenance mode includes single-phase three-phase motor limp control, position sensor reconfiguration control, and / or current sensor reconfiguration control. The single-phase three-phase motor limp control includes switching the dual three-phase permanent magnet synchronous motor synchronous drive steering control of the steering actuator motor to single-phase three-phase permanent magnet synchronous motor drive steering control. The position sensor reconfiguration control includes initializing and resetting the position sensor based on the monitored steering angle parameter value. The current sensor reconfiguration control includes initializing and resetting the current sensor based on the monitored drive current parameter value.

2. The fault-tolerant reconfiguration method for the steer-by-wire device as described in claim 1, characterized in that, The fault type of the steer-by-wire device is identified based on the operating parameters, including: The fault diagnosis unit includes a terminal sliding mode observer, which is used to monitor the motor operating angle of the steering actuator motor based on the angle parameters; the terminal sliding mode observer is also used to obtain the fault factors of each three phase of the dual three-phase permanent magnet synchronous motor. The fault status of the two three-phase permanent magnet synchronous motors is determined based on the fault factors, and the faulty three-phase permanent magnet synchronous motor is identified.

3. The fault-tolerant reconfiguration method for the steer-by-wire device as described in claim 2, characterized in that, Identifying the fault type of the steer-by-wire device based on the operating parameters also includes: The dynamic differential equation of the steering actuator motor is: T m1 =J m1 m1 +B m1 m1 +T α1 ; T m2 =J m2 m2 +B m2 m2 +T α2 ; T α =K m (i m -i m i c ); T m1 =K t1 i α1 ; T m2 =K t2 i α2 ; Among them, T m1 and T m2 These are the respective electromagnetic torques, K, of the two three-phase permanent magnet synchronous motors. t1 and K t2 These are the electromagnetic torque coefficients of the two three-phase permanent magnet synchronous motors, i α1 and i α2 These are the operating currents of the two three-phase permanent magnet synchronous motors, J. m1 and J m2 These are the moments of inertia of the two three-phase permanent magnet synchronous motors, B. m1 and B m2 These are the damping coefficients, T, of the two three-phase permanent magnet synchronous motors, respectively. α1 and T α2 The output torques of the two three-phase permanent magnet synchronous motors, K, are respectively. m θ represents the torsional stiffness of the shaft of a three-phase permanent magnet synchronous motor. m θ is the operating angle of a three-phase permanent magnet synchronous motor. c The input angle of the reducer in the steer-by-wire device; The dynamic differential equation of the steering actuator motor is: J mi mi +B mi mi =K ti i αi -K mi (θ mi -i m θ c ); mi =(K ti i αi -B mi mi -T αi ) / J mi ; set up: a i =K ti / J mi ; b i =B mi / J mi ; c i =K mi / J mi ; Where the subscript i represents each of the three phases in the dual three-phase configuration, i.e., i=1 or 2. For simplicity, this method is used throughout the document. The terminal sliding mode observer is then described as follows: mi =a i f i (t)i αi -b i mi -c i (i mi -i m i c )+w(t) =a i f i (t)i αi -b i mi -c i (i mi -i m i c )+lS i +ρ×sigmoid(S i ); Among them, S i It is the terminal sliding surface, and has S i =e i + |e i | q sign(e i ); e i = mi - miw This is the observation error; w(t) is the unmatched uncertainty term of the steer-by-wire device, and |w(t)| < ρ; mi yes mi The observed value, f i (t) is the fault factor of the three-phase permanent magnet synchronous motor; l (t) is an estimated value of the failure factor. l (t) is the fault factor estimation error; l (t)= f i (t)- l (t); where \(q\) is the sliding surface parameter and \(0 < q < 1\) is the terminal attractor exponent; l and ρ are the gain coefficients of the sliding mode observer, sigmoid(S i ) is a continuous switching function.

4. The fault-tolerant reconfiguration method for the steer-by-wire device as described in claim 3, characterized in that, Identifying the fault type of the steer-by-wire device based on the operating parameters also includes: The formula for obtaining the fault factor is: l (t)=-r i α i i αi S i ; Where, r i This is the gain coefficient; When f i When (t) < 1, the three-phase permanent magnet synchronous motor is determined to have a fault.

5. The fault-tolerant reconfiguration method for the steer-by-wire device as described in claim 1, characterized in that, The fault type of the steer-by-wire device is identified based on the operating parameters, including: The steering monitoring unit monitors the three-phase current of each of the three-phase permanent magnet synchronous motors, and each phase current corresponds to a current sensor; The fault status of the current sensor monitoring the phase current is determined based on the error values ​​calculated from the target current values ​​of the d-axis and q-axis and their corresponding target current quantities in different coordinate systems for any of the phase currents.

6. The fault-tolerant reconfiguration method for the steer-by-wire device as described in claim 1, characterized in that, The fault type of the steer-by-wire device is identified based on the operating parameters, including: The steering monitoring unit monitors the rotation angle parameters of each of the three-phase permanent magnet synchronous motors through two position sensors; The fault status of the position sensor is determined based on whether the difference between the two obtained angle parameters is greater than a preset angle threshold.

7. The fault-tolerant reconfiguration method for the steer-by-wire device as described in claim 6, characterized in that, Identifying the fault type of the steer-by-wire device based on the operating parameters also includes: The fault diagnosis unit also includes a position observer, which is used to obtain the motor rotation angle model parameters of the three-phase permanent magnet synchronous motor based on the stator parameter acquisition equation of the three-phase permanent magnet synchronous motor. The fault status of the two position sensors is determined based on the motor rotation angle model parameters and the rotation angle parameters of the two three-phase permanent magnet synchronous motors.

8. The fault-tolerant reconfiguration method for the steer-by-wire device as described in claim 7, characterized in that, When the steer-by-wire device malfunctions, the operating state of the steering actuator motor is switched to the fault maintenance mode, including: The single-phase three-phase motor limp control disconnects the faulty single-phase three-phase of the dual-phase three-phase permanent magnet synchronous motor, and the other single-phase three-phase permanent magnet synchronous motor that has not failed provides all steering drive force. The current sensor reconfiguration control replaces the original faulty phase current value with the faulty phase current value calculated using Kirchhoff's current law. The position sensor reconfiguration control replaces the angle parameters monitored by the faulty position sensor with motor angle model parameters calculated by the position observer.

9. A computer-readable storage medium, characterized in that, The medium stores a program that can be executed by a processor to implement the fault-tolerant reconfiguration method for the steering-by-wire device as described in any one of claims 1 to 8.

10. A computer program product comprising a computer program and / or instructions, characterized in that, When the computer program and / or instructions are executed by the processor, they implement the fault-tolerant reconfiguration method for the steering-by-wire device as described in any one of claims 1 to 8.

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