A steering wheel angle estimation method without angle sensor

Abstract

The present application relates to the technical field of vehicle steering control, and discloses a steering wheel angle estimation method without angle sensor, comprising: acquiring a motor position signal collected by a motor position sensor, and calculating a motor angular displacement amount; taking the motor angular displacement amount as input, controlling the motor to perform forward and reverse mid-position addressing respectively, determining a steering wheel target mid-position value according to a limit angular displacement amount recorded by the addressing, and driving the steering wheel to rotate to the target mid-position value to complete mid-position calibration; according to a difference between the target mid-position value and a real-time motor angular displacement amount, performing conversion by using a mechanical transmission ratio, calculating and outputting an actual steering wheel angle value. The present application uses a motor position sensor to replace a steering wheel angle sensor, effectively solves the installation problem caused by limited sensor range and compact structure space, realizes automatic and accurate calibration of the steering wheel mid-position, and reduces the vehicle development and layout cost.

Description

Technical Field

[0001] This invention relates to the field of vehicle steering control technology, and in particular to a method for estimating steering wheel angle without an angle sensor. Background Technology

[0002] As an important component of the vehicle system, the steering wheel angle sensor is used to detect the steering wheel rotation angle signal and transmit it to the ECU of the vehicle steering system in real time. This enables the vehicle steering system to coordinate the torque of the power steering motor in real time, allowing the car to steer according to the driver's intention and complete the functional interaction between the driver and the vehicle.

[0003] As one of the main development directions in the current automotive industry, autonomous driving eliminates human operation, with the entire process being autonomously controlled by the vehicle. It does not require "human intention" as an input signal. Therefore, the steering wheel torque angle sensor, a key component for human-machine interaction, is being replaced by a motor position sensor that can also detect angles. Furthermore, with the current vehicle structure layout becoming more compact and highly integrated, some models are looking to eliminate the steering wheel angle sensor altogether.

[0004] Current technology uses traditional automotive steering control, employing a steering wheel angle sensor as the input signal for autonomous driving to collect the steering wheel angle and complete the steering. However, in autonomous driving, the motor position sensor, which also detects angle signals, performs the same function as the steering wheel angle sensor. Furthermore, the steering wheel angle sensor has angle limitations, requiring matching based on the mechanical limits of different vehicles. If the sensor's range is exceeded, a larger angle range sensor or an angle extension algorithm is needed to meet practical requirements, making it difficult to support future "360° tire steering." This results in low versatility and increases controller development costs. Therefore, a method based on a motor position sensor to extend the steering wheel angle is urgently needed. Summary of the Invention

[0005] This invention provides a sensorless steering wheel angle estimation method. It uses a motor position sensor to extend the steering wheel angle, replacing the redundant steering wheel angle sensor, optimizing the steering gear structure, and solving the problem that some vehicle models cannot install a steering wheel angle sensor due to their compact structure. The invention uses the RPS center position self-learning function to complete the automatic calibration of the steering wheel center position. Compared with the traditional manual calibration, it solves the problems of low accuracy and cumbersome steps in steering wheel center position calibration. Furthermore, the motor position sensor does not have an angle limit, which solves the problem of needing to adapt to different vehicle models due to angle limitations.

[0006] This invention provides a sensorless steering wheel angle estimation method, comprising:

[0007] Acquire the motor position signal collected by the motor position sensor, and calculate the motor angular displacement based on the motor position signal;

[0008] Using the motor angular displacement as an input signal, the motor is controlled to perform forward centering addressing and reverse centering addressing respectively. The target centering value of the steering wheel is determined based on the limit motor angular displacement recorded during the addressing process, and the steering wheel is controlled to rotate to the target centering value of the steering wheel to complete the steering wheel centering calibration.

[0009] Based on the difference between the target center value of the steering wheel and the angular displacement of the motor, the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel is used for conversion, and the actual angle value of the steering wheel is calculated and output.

[0010] Furthermore, the step of acquiring the motor position signal collected by the motor position sensor and calculating the motor angular displacement based on the motor position signal specifically includes:

[0011] The mechanical angle of the motor is obtained discretely at each sampling time according to a fixed sampling period;

[0012] Calculate the original difference in rotation angle between the current sampling time and the previous sampling time for the mechanical angle of the motor;

[0013] The original difference in the rotation angle is corrected by circumferential folding to eliminate the boundary jump at the zero point and obtain the true rotation angle displacement of the motor within the corresponding sampling period;

[0014] The actual rotational angular displacements at each discrete moment are recursively accumulated to output the final cumulative angular displacement of the motor.

[0015] Furthermore, the formula for calculating the original difference in the angle is as follows:

[0016]

[0017] Where k is the discrete sampling time number, Let be the mechanical angle of the motor collected at time k, and satisfy . , This represents the original difference in the angle at time k.

[0018] The circumferential folding correction satisfies the following piecewise function:

[0019]

[0020] in, This represents the actual angular displacement of the motor during the kth sampling period;

[0021] The recursive accumulation satisfies the following recursive formula:

[0022]

[0023] Where S[k] is the total cumulative angular displacement of the motor at time k, and the initial condition set by the system is S[0]=0.

[0024] Further, the step of using the motor angular displacement as an input signal to control the motor to perform forward and reverse center position addressing respectively, determining the target center position value of the steering wheel based on the limit motor angular displacement recorded during the addressing process, and controlling the steering wheel to rotate to the target center position value to complete the steering wheel center position calibration includes:

[0025] The motor is controlled to enter the speed control mode, and a constant speed request is issued to initiate forward and reverse mid-position addressing.

[0026] During the addressing process, the operating status parameters of the motor are monitored in real time. When it is determined that the operating status parameters meet the preset limit arrival conditions, the motor is determined to have reached the mechanical limit of the vehicle, and the motor angular displacement at this time is recorded as the limit motor angular displacement. The limit motor angular displacement includes the right limit displacement and the left limit displacement.

[0027] Calculate the arithmetic mean of the right limit displacement and the left limit displacement, and determine the arithmetic mean as the target center value of the steering wheel;

[0028] Switch the motor to position control mode, and drive the mechanical transmission mechanism to rotate the steering wheel with the target center value of the steering wheel as the target request, until the target center value of the steering wheel is reached to complete the steering wheel center calibration.

[0029] Furthermore, the operating status parameters of the motor include the actual motor speed and the motor feedback current; the determination that the operating status parameters meet the preset limit arrival conditions includes:

[0030] The absolute value of the current actual speed of the motor is less than or equal to a preset speed threshold, and the absolute value of the current feedback current of the motor is greater than or equal to a preset current threshold.

[0031] When the above conditions are met continuously for a preset time, it is determined that the motor has reached the mechanical limit of the vehicle.

[0032] Furthermore, in the step of controlling the motor to enter the speed control mode and issuing a constant speed request to initiate forward and reverse mid-position addressing, the torque output of the motor speed loop is controlled using PI regulation logic, specifically including:

[0033] Calculate the speed deviation: ;

[0034] Calculate the update of the integral term: ;

[0035] Calculate the total torque output: ;

[0036] Where n[k] is the preset constant speed request value, This refers to the actual speed of the motor. Let Ts be the rotational speed deviation at time k, and Ts be the sampling period. Let k be the integral term at time k. For speed proportional gain, Let Te[k] be the integral gain of the rotational speed, and Te[k] be the total torque output at time k.

[0037] Furthermore, in the step of driving the mechanical transmission mechanism to rotate the steering wheel by using the target center value of the steering wheel as the target request, the following logic control motor position loop is used:

[0038] Calculate positional deviation: ;

[0039] Convert position deviation into speed ring commands: ;

[0040] in, Let S[k] be the target median value of the steering wheel, and S[k] be the angular displacement of the motor at time k. Let $k$ be the position deviation at time $k$. For position scaling gain, This is the command request value for the speed ring;

[0041] When the position deviation is determined to satisfy At that time, it is determined that the steering wheel center position calibration is complete, among which This is the preset calibration success threshold.

[0042] Furthermore, the step of calculating and outputting the actual steering wheel angle value based on the difference between the target center value of the steering wheel and the angular displacement of the motor, using the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel, specifically includes:

[0043] The motor angular displacement is calculated in real time and the steering wheel target center value is determined by calibration. The motor angular displacement is subtracted from the steering wheel target center value to calculate the angular difference between the motor and the physical center.

[0044] The angle difference is divided by the mechanical transmission ratio of the mechanical transmission mechanism for proportional conversion, and the conversion result is output as the actual angle value of the steering wheel.

[0045] Furthermore, the actual steering wheel angle value:

[0046]

[0047] in, This represents the actual steering wheel angle value output at time k. Let be the angular displacement of the motor at time k; is the target median value of the steering wheel; i is the mechanical transmission ratio.

[0048] The present invention also provides a sensorless steering wheel angle estimation device, based on the sensorless steering wheel angle estimation method described above, the device comprising:

[0049] The acquisition module is used to acquire the motor position signal collected by the motor position sensor and calculate the motor angular displacement based on the motor position signal;

[0050] The addressing module is used to control the motor to perform forward centering addressing and reverse centering addressing respectively, using the motor angular displacement as the input signal. Based on the limit motor angular displacement recorded during the addressing process, the target centering value of the steering wheel is determined, and the steering wheel is controlled to rotate to the target centering value of the steering wheel to complete the steering wheel centering calibration.

[0051] The output module is used to calculate and output the actual steering wheel angle value based on the difference between the target center value of the steering wheel and the angular displacement of the motor, using the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel.

[0052] The beneficial effects of this invention are as follows:

[0053] 1. The motor position sensor of this invention can replace the steering wheel angle sensor, reduce the complexity of the control algorithm, optimize development costs, reduce the wiring layout of the whole vehicle, and save the space of the whole vehicle.

[0054] 2. This invention can automatically calibrate the center position of the steering wheel, making the center position calibration value more accurate and the steps simpler, greatly reducing the workload of calibrating the center position of the steering wheel of the whole vehicle.

[0055] 3. Steering wheel angle sensors have angle limitations, while motor position sensors extend the steering wheel angle without range limitations. The steering wheel angle limit depends on the mechanical limit of the entire vehicle, making it more applicable. Attached Figure Description

[0056] Figure 1 This is a block diagram of the steering system control logic according to an embodiment of the present invention.

[0057] Figure 2 This is a flowchart of the state machine execution of a steering system according to an embodiment of the present invention.

[0058] Figure 3 This is a block diagram of the logic structure of a motor angular displacement algorithm according to an embodiment of the present invention.

[0059] Figure 4 This is a block diagram of forward and reverse midpoint addressing control according to an embodiment of the present invention.

[0060] Figure 5 This is a block diagram of the steering wheel center position calibration control according to an embodiment of the present invention.

[0061] Figure 6 This is a block diagram of a steering wheel angle simulation algorithm according to an embodiment of the present invention.

[0062] Figure 7 This is a discrete simulation diagram of a motor angular displacement algorithm according to an embodiment of the present invention.

[0063] Figure 8 This is a waveform diagram illustrating a specific implementation example of an embodiment of the present invention.

[0064] Figure 9 This is a schematic diagram of the device structure according to an embodiment of the present invention.

[0065] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0066] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0067] like Figure 1 , Figure 2 The present invention provides a sensorless steering wheel angle estimation method, comprising the following: (The diagram shows the steering system control logic block diagram and the steering system state machine execution flowchart.)

[0068] S1. Obtain the motor position signal collected by the motor position sensor, and calculate the motor angular displacement based on the motor position signal.

[0069] In a specific embodiment of the present invention, in order to calculate the motor angular displacement, it is first necessary to calculate the motor speed (i.e., the actual rotational angular displacement) within a unit sampling period. Since the motor position signal is a sawtooth wave signal with a range of 0° to 360°, the boundary transition problem at the zero-crossing point must be addressed during the calculation process. The logical structure block diagram and discrete simulation implementation diagram of the motor angular displacement algorithm are shown below. Figure 3 and Figure 7 As shown. Specifically, step S1 includes the following sub-steps:

[0070] S101. According to a fixed sampling period, the mechanical angle of the motor at each sampling moment is discretely acquired. Specifically,

[0071] The sampling time sequence is set to k (where k = 1, 2, 3, ...), and the sampling period is fixed at Ts (unit: s). At time k, the mechanical angle of the motor collected by the motor position sensor is obtained and denoted as . Its measuring range satisfies: .

[0072] S102. Calculate the original difference in rotation angle between the current moment and the previous moment.

[0073] The mechanical angle of the motor at time k. Subtract its value from the previous time step, i.e., the (k-1)th time step. The original difference value of the corner is obtained. The calculation formula is as follows:

[0074]

[0075] There is a 0° / 360° boundary jump problem here. For example, if the motor mechanical angle changes from 358° to 2° across zero, the calculated original difference is -356°, but the actual rotation angle of the motor is only 4°. Therefore, angle jump compensation must be performed on this original difference.

[0076] S103. Perform circumferential folding correction on the original difference of the rotation angle to obtain the true rotation angle displacement within the sampling period.

[0077] If the position signal does not cross zero, the original difference is the actual rotational angular displacement of the current cycle; if the position signal crosses zero, the original difference is adjusted by adding or subtracting 360° to perform a circumferential folding correction, ensuring that the actual rotational angle range of the output motor is limited to within a certain range. Within the range.

[0078] Specifically, the actual angular displacement of the motor during the kth sampling period The circumferential folding correction logic satisfies the following piecewise function:

[0079]

[0080] S104. Accumulate the actual rotational angular displacement at each discrete moment and output the final cumulative angular displacement of the motor.

[0081] The recursive formula for calculating the cumulative angular displacement output of the motor by summing the actual rotational angular displacements of each cycle after the above-mentioned circumferential folding correction is as follows:

[0082]

[0083] In the formula, The total angular displacement at time k is expressed in degrees (°). At the initial moment of the system, the initial condition is set to S[0]=0, and S[k] is used as the input signal for subsequent mid-position self-learning address calibration.

[0084] S2. Using the motor angular displacement as an input signal, control the motor to perform forward centering addressing and reverse centering addressing respectively. Determine the target centering value of the steering wheel based on the limit motor angular displacement recorded during the addressing process, and control the steering wheel to rotate to the target centering value of the steering wheel to complete the steering wheel centering calibration.

[0085] In a specific embodiment of the present invention, the automatic addressing and calibration of the steering wheel center position is completed based on the center position self-learning function of the RPS (Rotary Position Sensor). The cumulative angular displacement S[k] of the motor calculated in the above steps is used as the input signal, and the physical position is detected and zeroed by switching between speed mode and position mode. The control block diagrams for forward and reverse center position addressing and steering wheel center position calibration, as well as the detection waveform diagrams for specific implementation examples, are shown below. Figure 4 , Figure 5 and Figure 8 As shown. Specifically, step S2 includes the following sub-steps:

[0086] S201. Control the motor to enter the speed control mode and issue a constant speed request to initiate forward and reverse mid-position addressing. Specifically,

[0087] Send a constant speed request to the motor controller, setting the given motor speed to be [value missing]. (in, The preset center addressing speed (positive and negative signs represent forward and reverse directions, respectively) is used. The motor responds to the requested speed by rotating to locate the vehicle's mechanical and physical limits.

[0088] Under the above speed control mode, the control logic of the motor speed loop is as follows:

[0089] First, calculate the speed deviation: (in, This refers to the actual rotational speed of the motor, i.e., the rate of change of the actual rotational angular displacement obtained in the preceding steps.

[0090] Secondly, the torque output of the motor speed loop is calculated using a PI control method, specifically as follows:

[0091] Points system update:

[0092] Total torque output:

[0093] In the formula, For speed proportional gain, is the integral gain of rotational speed, and Ts is the sampling period.

[0094] S202. During the addressing process, the operating status parameters of the motor are monitored in real time to determine whether the mechanical limit of the vehicle has been reached, and the limit motor angular displacement when the limit is reached is recorded.

[0095] During the forward and reverse rotation of the motor, the current cumulative angular displacement S[k] of the motor is continuously recorded, and the current actual speed of the motor is monitored simultaneously. and the motor feedback current (i.e., Q-axis current). The trigger condition for determining whether the motor has reached the vehicle's left or right mechanical limit requires that both of the following conditions be met simultaneously:

[0096] Condition 1: The absolute value of the current actual motor speed is less than or equal to the preset speed threshold (e.g., the absolute value of the current motor speed is ≤10 Rpm).

[0097] Condition 2: The absolute value of the current Q-axis current fed back by the motor is greater than or equal to the preset current threshold (e.g., the current Q-axis current is 40A or -40A).

[0098] When the above conditions are met continuously for a preset time (e.g., for 1 second), the motor is determined to be in a limit switch condition. At this time, an addressing flag (either a forward addressing flag or a reverse addressing flag) is output, and the motor angular displacement at this time is recorded as the right limit displacement. and left limit displacement .

[0099] S203. Calculate and determine the target center value of the steering wheel based on the recorded right limit displacement and left limit displacement.

[0100] After both forward and reverse addressing are completed and the extreme displacements (i.e., the maximum and minimum values ​​of the motor angular displacement) are recorded, the arithmetic mean of the two values ​​is calculated as the median reference benchmark, i.e., the requested median angular displacement value of the steering wheel target. The calculation formula is:

[0101]

[0102] S204. Switch to motor position control mode, and use the target center value of the steering wheel as the target request to drive the mechanical assembly to complete the synchronous calibration.

[0103] Determine the target median value Then, using this value as the input request value for motor position control, the steering wheel center position calibration process begins. At this point, the motor position loop control logic is as follows:

[0104] Calculate positional deviation: This converts the positional deviation into a speed ring command. (in, (This refers to the position proportional gain). The motor is controlled to rotate until the position deviation is minimal, i.e., when the following condition is met: ( When the preset calibration success threshold is reached, the mechanical assembly is determined to have reached the target center position. At this point, the steering wheel is rotated to the target center value, the calibration process is complete, and the center value is recorded and output. For use in subsequent angle simulation calculations.

[0105] S3. Based on the difference between the target center value of the steering wheel and the angular displacement of the motor, the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel is used for conversion, and the actual angle value of the steering wheel is calculated and output.

[0106] In a specific embodiment of the present invention, step S3 is implemented using a steering wheel angle simulation algorithm. Since the motor and steering wheel are connected via a mechanical structure such as a worm gear reduction mechanism, a fixed transmission ratio exists between the steering wheel rotation angle and the motor angle. After the target midpoint value of the steering wheel is calibrated, data mapping and conversion are performed between the real-time calculated motor angular displacement and the calibrated midpoint value. The algorithm structure diagram for steering wheel angle simulation is as follows: Figure 6 As shown. Specifically, step S3 includes the following sub-steps:

[0107] S301. Obtain the real-time calculated motor angular displacement and the calibrated target median value of the steering wheel. Specifically, obtain the real-time calculated cumulative total motor angular displacement S[k] at the current discrete sampling time k, and the target median value of the steering wheel calibrated and recorded in the aforementioned steps. As the input signal for the angle simulation algorithm.

[0108] S302. Calculate the angle difference between the real-time motor angular displacement and the target center value of the steering wheel. In the internal control program, subtract the target center value of the steering wheel from the current motor angular displacement S[k]. This eliminates the offset caused by the zero-position calibration and obtains the relative angular displacement of the motor relative to the physical center position.

[0109] S303. Utilize the mechanical transmission ratio of the mechanical transmission mechanism to perform a proportional conversion on the angle difference.

[0110] The equation is scaled and converted based on the mechanical transmission ratio i between the motor and the steering wheel. In this embodiment, the mechanical transmission mechanism is specifically a worm gear reduction mechanism, and its corresponding preset mechanical transmission ratio i is 20. The angle difference calculated in step S302 is divided by the mechanical transmission ratio 20 to map the relative angular displacement at the motor end to the actual rotation angle at the steering wheel end.

[0111] S304. Calculate and output the final actual steering wheel angle value. The complete mathematical formula for the steering wheel angle simulation algorithm is as follows:

[0112]

[0113] in, The actual steering wheel angle value output at time k (i.e., the simulated steering wheel angle); This represents the total cumulative angular displacement of the motor at time k. The target center value of the steering wheel is recorded for calibration; i is the mechanical transmission ratio of the mechanical transmission mechanism, which is 20 in this embodiment.

[0114] The above formula is continuously cyclically calculated, and the corresponding actual steering wheel angle value is output to the ECU and other underlying controllers of the car steering system in real time. Thus, the extended estimation of the steering wheel angle by the motor position sensor is completed without relying on an independent steering wheel angle sensor.

[0115] In a preferred embodiment of the present invention, to better apply the above method to the underlying controller of a real vehicle steering system, the sensorless steering wheel angle estimation method further includes the system's underlying state machine transition logic before and during the execution of the core algorithm. Specifically, the complete system control logic execution flow is as follows:

[0116] After the vehicle system is powered on, it first completes system initialization, self-test and related pre-processing logic, and then the system enters the operation preparation state, waiting to receive the open wave command (i.e. the system enable command).

[0117] Upon receiving the open wave command, the system uses the motor position signal collected by the motor position sensor as the input signal to trigger the motor angular displacement algorithm (i.e., execute the aforementioned step S1) to calculate and update the motor angular displacement in real time.

[0118] Subsequently, the system receives the RPS center-position self-learning instruction, using the real-time acquired motor angular displacement, center-position speed request value, and actual motor speed as input signals to control the motor to perform forward or reverse center-position addressing; after one side of the addressing is completed, the system outputs a forward or reverse reversal flag; upon receiving the reversal flag, the system records the maximum displacement of the motor during the forward or reverse addressing process; then it calculates the motor angular displacement center value (i.e., the steering wheel target center position), and uses this center value as the motor position control request value to enter the steering wheel center-position calibration process; after the motor position reaches the center value, it determines that the calibration is complete, and the system records and outputs the center value (i.e., executes the aforementioned step S2).

[0119] After calibration, the system uses the recorded target center value of the steering wheel and the real-time calculated motor angular displacement as input signals to trigger the steering wheel angle simulation algorithm, calculate and continuously output the simulated steering wheel angle (i.e., execute the aforementioned step S3).

[0120] like Figure 9 As shown, the present invention also provides a sensorless steering wheel angle estimation device, based on the sensorless steering wheel angle estimation method described above, the device comprising:

[0121] Acquisition module 1 is used to acquire the motor position signal collected by the motor position sensor and calculate the motor angular displacement based on the motor position signal;

[0122] Addressing module 2 is used to control the motor to perform forward centering addressing and reverse centering addressing respectively, using the motor angular displacement as the input signal. It determines the target centering value of the steering wheel based on the limit motor angular displacement recorded during the addressing process, and controls the steering wheel to rotate to the target centering value of the steering wheel to complete the steering wheel centering calibration.

[0123] Output module 3 is used to calculate and output the actual angle value of the steering wheel based on the difference between the target center value of the steering wheel and the angular displacement of the motor, using the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel.

[0124] Each of the above modules is used to perform the respective steps in the sensorless steering wheel angle estimation method described above. The specific implementation method is as described in the above method embodiment, and will not be repeated here.

[0125] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0126] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for estimating steering wheel angle without an angle sensor, characterized in that, include: Acquire the motor position signal collected by the motor position sensor, and calculate the motor angular displacement based on the motor position signal; Using the motor angular displacement as an input signal, the motor is controlled to perform forward centering addressing and reverse centering addressing respectively. The target centering value of the steering wheel is determined based on the limit motor angular displacement recorded during the addressing process, and the steering wheel is controlled to rotate to the target centering value of the steering wheel to complete the steering wheel centering calibration. Based on the difference between the target center value of the steering wheel and the angular displacement of the motor, the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel is used for conversion, and the actual angle value of the steering wheel is calculated and output.

2. The sensorless steering wheel angle estimation method according to claim 1, characterized in that, The step of acquiring the motor position signal collected by the motor position sensor and calculating the motor angular displacement based on the motor position signal specifically includes: The mechanical angle of the motor is obtained discretely at each sampling time according to a fixed sampling period; Calculate the original difference in rotation angle between the current sampling time and the previous sampling time for the mechanical angle of the motor; The original difference in the rotation angle is corrected by circumferential folding to eliminate the boundary jump at the zero point and obtain the true rotation angle displacement of the motor within the corresponding sampling period; The actual rotational angular displacements at each discrete moment are recursively accumulated to output the final cumulative angular displacement of the motor.

3. The sensorless steering wheel angle estimation method according to claim 2, characterized in that, The formula for calculating the original difference of the turning angle is: Where k is the discrete sampling time number, Let be the mechanical angle of the motor collected at time k, and satisfy . , This represents the original difference in the angle at time k. The circumferential folding correction satisfies the following piecewise function: in, This represents the actual angular displacement of the motor during the kth sampling period; The recursive accumulation satisfies the following recursive formula: Where S[k] is the total cumulative angular displacement of the motor at time k, and the initial condition set by the system is S[0]=0.

4. The sensorless steering wheel angle estimation method according to claim 1, characterized in that, The steps of using the motor angular displacement as an input signal to control the motor to perform forward and reverse center position addressing, determining the target center position value of the steering wheel based on the limit motor angular displacement recorded during the addressing process, and controlling the steering wheel to rotate to the target center position value to complete the steering wheel center position calibration include: The motor is controlled to enter the speed control mode, and a constant speed request is issued to initiate forward and reverse mid-position addressing. During the addressing process, the operating status parameters of the motor are monitored in real time. When it is determined that the operating status parameters meet the preset limit arrival conditions, the motor is determined to have reached the mechanical limit of the vehicle, and the motor angular displacement at this time is recorded as the limit motor angular displacement. The limit motor angular displacement includes the right limit displacement and the left limit displacement. Calculate the arithmetic mean of the right limit displacement and the left limit displacement, and determine the arithmetic mean as the target center value of the steering wheel; Switch the motor to position control mode, and drive the mechanical transmission mechanism to rotate the steering wheel with the target center value of the steering wheel as the target request, until the target center value of the steering wheel is reached to complete the steering wheel center calibration.

5. The sensorless steering wheel angle estimation method according to claim 4, characterized in that, The motor's operating status parameters include the motor's actual speed and the motor's feedback current; determining whether the operating status parameters meet the preset limit arrival conditions includes: The absolute value of the current actual speed of the motor is less than or equal to a preset speed threshold, and the absolute value of the current feedback current of the motor is greater than or equal to a preset current threshold. When the above conditions are met continuously for a preset time, it is determined that the motor has reached the mechanical limit of the vehicle.

6. The sensorless steering wheel angle estimation method according to claim 4, characterized in that, In the step of controlling the motor to enter the speed control mode and issuing a constant speed request to initiate forward and reverse mid-position addressing, the torque output of the motor speed loop is controlled using PI regulation logic, specifically including: Calculate the speed deviation: ; Calculate the update of the integral term: ; Calculate the total torque output: ; Where n[k] is the preset constant speed request value, This is the actual speed of the motor. Let Ts be the rotational speed deviation at time k, and Ts be the sampling period. Let k be the integral term at time k. For speed proportional gain, Let Te[k] be the integral gain of the rotational speed, and Te[k] be the total torque output at time k.

7. The sensorless steering wheel angle estimation method according to claim 4, characterized in that, In the step of driving the mechanical transmission mechanism to rotate the steering wheel by using the target center value of the steering wheel as the target request, the following logic control motor position loop is used: Calculate positional deviation: ; Convert position deviation into speed ring commands: ; in, Let S[k] be the target median value of the steering wheel, and S[k] be the angular displacement of the motor at time k. Let $k$ be the position deviation at time $k$. For position scaling gain, This is the command request value for the speed ring; When the position deviation is determined to satisfy At that time, it is determined that the steering wheel center position calibration is complete, among which This is the preset calibration success threshold.

8. The sensorless steering wheel angle estimation method according to claim 1, characterized in that, The step of calculating and outputting the actual steering wheel angle value based on the difference between the target center value of the steering wheel and the angular displacement of the motor, using the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel, specifically includes: The motor angular displacement is calculated in real time and the steering wheel target center value is determined by calibration. The motor angular displacement is subtracted from the steering wheel target center value to calculate the angular difference between the motor and the physical center. The angle difference is divided by the mechanical transmission ratio of the mechanical transmission mechanism for proportional conversion, and the conversion result is output as the actual angle value of the steering wheel.

9. The sensorless steering wheel angle estimation method according to claim 8, characterized in that, The actual steering wheel angle value: in, This represents the actual steering wheel angle value output at time k. Let be the angular displacement of the motor at time k; is the target median value of the steering wheel; i is the mechanical transmission ratio.

10. A sensorless steering wheel angle estimation device, based on the sensorless steering wheel angle estimation method according to any one of claims 1 to 9, characterized in that, The device includes: The acquisition module is used to acquire the motor position signal collected by the motor position sensor and calculate the motor angular displacement based on the motor position signal; The addressing module is used to control the motor to perform forward centering addressing and reverse centering addressing respectively, using the motor angular displacement as the input signal. Based on the limit motor angular displacement recorded during the addressing process, the target centering value of the steering wheel is determined, and the steering wheel is controlled to rotate to the target centering value of the steering wheel to complete the steering wheel centering calibration. The output module is used to calculate and output the actual steering wheel angle value based on the difference between the target center value of the steering wheel and the angular displacement of the motor, using the mechanical transmission ratio of the mechanical transmission mechanism between the motor and the steering wheel.

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