Electric power steering system, steering wheel angle determination method and apparatus

Abstract

The application discloses an electric power steering system, a steering wheel angle determination method and equipment, and relates to the technical field of vehicles. By utilizing an existing torque angle sensor and a motor position sensor in an electric power steering system, combining a preset transmission ratio between an electric motor and a steering column, utilizing a vernier algorithm to convert a signal of the motor position sensor into an equivalent angle of the steering column and fusing the signal with a signal of the torque angle sensor, the measurable range of the absolute angle of the steering wheel is extended to be greater than the angle period of the output signal of the torque angle sensor without additionally increasing mechanical gear sets and independent Hall chips. The scheme reduces the hardware cost, simplifies the sensor structure, avoids wear and gap errors caused by gear meshing, and improves the operation reliability and angle measurement accuracy of the electric power steering system.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to an electric power steering system, a method for determining the steering wheel angle, and a device. Background Technology

[0002] With the development of electric power steering systems in automobiles, the demand for measuring large absolute steering wheel angles is constantly increasing. Most existing torque angle sensors on the steering column have an output signal period of no more than 360°, which cannot meet the detection requirements for steering wheel angles of ±720° and larger.

[0003] Currently, mainstream range extension solutions require the addition of mechanical gear sets and independent Hall chips, which not only increases hardware costs and complicates the sensor structure, but also makes the gear meshing prone to wear and clearance errors, affecting the operational reliability of the steering system. Summary of the Invention

[0004] This application provides an electric power steering system, a method for determining the steering wheel angle, and a device to solve the problems mentioned in the background art.

[0005] In a first aspect, this application provides an electric power steering system, comprising:

[0006] The system comprises a sensor system, an electronic control unit (ECU), and a power steering mechanism; both the sensor system and the power steering mechanism are electrically connected to the ECU; the power steering mechanism includes an electric motor; the sensor system includes a torque angle sensor mounted on the steering column and a motor position sensor mounted at the rotor position of the electric motor; the torque angle sensor is configured to output a first angle signal with a first angle period, and the motor position sensor is configured to output a second angle signal with a second angle period.

[0007] The electronic control unit is used for:

[0008] Acquire the first angle signal and the second angle signal;

[0009] Based on the preset transmission ratio between the motor and the steering column, the angle corresponding to the second angle signal is converted into the equivalent angle of the steering column;

[0010] Based on the equivalent angle of the steering column and the angle corresponding to the first angle signal, the absolute angle of the steering wheel is determined using a vernier algorithm; wherein the measurable range of the absolute angle of the steering wheel is greater than the first angle period.

[0011] In one possible design, the electronic control unit, when determining the absolute angle of the steering wheel using a vernier algorithm, is specifically used for:

[0012] The angle corresponding to the first angle signal is used as the main scale reference value, and the equivalent angle of the steering column is used as the secondary scale reference value.

[0013] The absolute angle of the steering wheel is determined by identifying the overlapping position of the waveforms of the main scale reference value and the secondary scale reference value.

[0014] In one possible design, the electronic control unit is further configured to:

[0015] When the vehicle starts, the absolute zero position of the steering wheel is determined based on the calculation results of the vernier algorithm;

[0016] During vehicle operation, the absolute angle of the steering wheel is updated according to a preset cycle.

[0017] In one possible design, the torque angle sensor comprises two rotors with a non-integer ratio of blade numbers, wherein the first angle period is the least common multiple of the two rotor output signal periods.

[0018] In one possible design, the measurable range of the absolute angle of the steering wheel is the least common multiple of the period corresponding to the first angle period and the period corresponding to the equivalent angle of the steering column; the measurement accuracy of the absolute angle of the steering wheel is the greatest common divisor of the period corresponding to the first angle period and the period corresponding to the equivalent angle of the steering column.

[0019] In one possible design, the motor position sensor uses a magnetoresistive chip or a Hall effect chip, and a magnet that cooperates with the motor position sensor is mounted on the rotor of the motor.

[0020] Secondly, this application provides a method for determining a steering wheel angle, applied to an electronic control unit in the electric power steering system described in any of the first aspects, the method comprising:

[0021] Acquire the first angle signal output by the torque angle sensor and the second angle signal output by the motor position sensor;

[0022] Based on the preset transmission ratio between the motor and the steering column, the angle corresponding to the second angle signal is converted into the equivalent angle of the steering column;

[0023] Based on the equivalent angle of the steering column and the angle corresponding to the first angle signal, the absolute angle of the steering wheel is determined using a vernier algorithm; wherein the measurable range of the absolute angle of the steering wheel is greater than the first angle period; wherein the first angle period is the signal period of the first angle signal.

[0024] In one possible design, determining the absolute angle of the steering wheel using a vernier algorithm includes:

[0025] The angle corresponding to the first angle signal is used as the main scale reference value, and the equivalent angle of the steering column is used as the secondary scale reference value.

[0026] The absolute angle of the steering wheel is determined by identifying the overlapping position of the waveforms of the main scale reference value and the secondary scale reference value.

[0027] In one possible design, the method also includes:

[0028] When the vehicle starts, the absolute zero position of the steering wheel is determined based on the calculation results of the vernier algorithm;

[0029] During vehicle operation, the absolute angle of the steering wheel is updated according to a preset cycle.

[0030] Thirdly, this application provides an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0031] The memory stores computer-executed instructions;

[0032] The processor executes computer execution instructions stored in the memory to implement the method as described in any of the second aspects.

[0033] The electric power steering system, steering wheel angle determination method, and device provided in this application utilize existing torque angle sensors and motor position sensors within the electric power steering system. Combined with a preset transmission ratio between the motor and steering column, a vernier algorithm is used to convert the motor position sensor signal into an equivalent steering column angle, which is then fused with the torque angle sensor signal. This expands the measurable range of the steering wheel's absolute angle to a value greater than the angle period of the torque angle sensor's output signal without requiring additional mechanical gear sets or independent Hall effect chips. This solution reduces hardware costs, simplifies sensor structure, avoids wear and clearance errors caused by gear meshing, improves the operational reliability and angle measurement accuracy of the electric power steering system, and fully utilizes existing sensor resources within the system, demonstrating excellent engineering practicality and integration advantages. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0035] Figure 1 This is a schematic diagram of the structure of an electric power steering system provided in an embodiment of this application;

[0036] Figure 2 A waveform diagram of a cursor algorithm provided in an embodiment of this application;

[0037] Figure 3 A flowchart illustrating a method for determining the steering wheel angle according to an embodiment of this application;

[0038] Figure 4 This is a structural example diagram of an electronic device provided in an embodiment of this application.

[0039] Figure label:

[0040] 11-Electric control unit; 12-Motor; 13-Torque angle sensor; 14-Motor position sensor; 15-Steering column; 16-Steering wheel; 17-Reduction mechanism; 18-Steering gear; 19-Wheel.

[0041] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0042] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application.

[0043] To clearly understand the technical solution of this application, the solutions of the prior art will be described in detail first.

[0044] Electric power steering (EPS) is a core control system in modern automotive chassis. It uses an electric motor to output auxiliary torque, reducing the driver's steering effort and improving the vehicle's steering ease, stability, and handling. The absolute steering angle, as an input parameter of the EPS, directly determines the control precision of functions such as steering assist, return-to-center control, and active safety interventions. With the increasing prevalence of driver assistance functions such as intelligent driving, automatic parking, and lane keeping, the industry's requirements for the detection range, accuracy, and system reliability of the large-angle absolute steering angle are continuously rising.

[0045] In existing electric power steering systems, the torque angle sensor standardly equipped in the steering column is an integrated core detection device that can simultaneously collect steering torque and steering angle signals. However, limited by the sensor chip architecture, sampling principle, and packaging structure, the angle signal period output by existing torque angle sensors generally does not exceed 360°, and can only achieve accurate detection of the steering angle within a single turn of the steering wheel. In actual driving, parking, and stationary turning conditions, the steering wheel generally involves multiple turns of steering with angles of ±720° or even larger. Existing single-cycle angle sensors cannot complete the absolute angle positioning within a large angle range, resulting in a measurement range limitation and failing to meet the functional requirements of advanced driver assistance systems.

[0046] To address the insufficient range of torque angle sensors, current mainstream range expansion solutions rely on hardware modifications. The core approach involves adding a mechanical gear set to the steering column transmission structure, coupled with a dedicated Hall effect sensor chip. This solution leverages the mechanical principle of gear transmission to amplify the sensor's detection range, enabling multi-turn angle detection. However, this hardware expansion solution has several inherent drawbacks: First, it requires additional hardware such as gear sets, dedicated Hall effect chips, and mounting brackets, increasing the material and assembly costs of the sensor and steering system. Second, the additional mechanical gear set alters the original sensor's integrated structure, complicating the steering column sensor module and occupying more space within the vehicle. Third, during long-term gear meshing, mechanical wear, meshing clearance, and transmission jamming are prone to occur, introducing clearance and transmission errors, reducing angle detection accuracy, increasing the mechanical failure rate of the steering system, and severely impacting the operational stability and reliability of the electric power steering system.

[0047] In summary, existing technologies suffer from problems such as small angle detection range, high hardware modification costs, complex structure, large mechanical errors, and poor system reliability.

[0048] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0049] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or modules, and may be electrical, mechanical, or other forms.

[0050] Figure 1 This is a schematic diagram of the structure of an electric power steering system provided in an embodiment of this application; as shown Figure 1 As shown, this application provides an electric power steering system, including:

[0051] The system includes a sensor system, an electronic control unit 11, and a power steering mechanism. Both the sensor system and the power steering mechanism are electrically connected to the electronic control unit 11. The power steering mechanism includes a motor 12. The sensor system includes a torque angle sensor 13 mounted on the steering column 15 and a motor position sensor 14 mounted at the rotor position of the motor 12. The torque angle sensor 13 is configured to output a first angle signal with a first angle period, and the motor position sensor 14 is configured to output a second angle signal with a second angle period.

[0052] The sensor system and the assist mechanism are both connected to the electronic control unit 11 by electrical signals. The electronic control unit 11 is the control center of the system and can collect sensor signals in real time, process the angle data, and control the assist mechanism to output assist torque.

[0053] The power steering mechanism includes an electric motor 12 for outputting steering assistance power. The electric motor 12 is the power output component of the electric power steering system, and it establishes a mechanical transmission connection with the vehicle's steering column 15 through a reduction gear transmission mechanism. The working principle is as follows: the electronic control unit 11 determines the driver's steering needs based on signals such as steering wheel angle, vehicle speed, and steering torque, and controls the electric motor 12 to output an auxiliary torque of corresponding magnitude and direction. This torque is transmitted to the steering column 15 through the mechanical transmission structure, offsetting road resistance and steering mechanical resistance, thus achieving the steering assistance function and reducing the driver's operating load. Furthermore, the rotation angle of the electric motor 12 rotor and the rotation angle of the steering column 15 have a fixed and precise transmission ratio. This transmission ratio is a factory-calibrated parameter for the vehicle, with no deviation or fluctuation.

[0054] Specifically, the sensor system includes a torque angle sensor 13 fixedly mounted on the steering column 15, and a motor position sensor 14 mounted at the rotor position of the motor 12.

[0055] The torque angle sensor 13 is a standard detection device, integrated into the middle section of the steering column 15, and rotates synchronously with the steering column 15. Its working principle is as follows: through magnetoelectric induction or Hall effect detection, it detects the torsional torque and rotation angle of the steering column 15 in real time, outputting a continuous first angle signal. The inherent detection characteristic of the torque angle sensor 13 is that the angle signal period does not exceed 360°, meaning it can only accurately detect changes in steering angle within a single revolution. It can provide real-time feedback on the precise angular position and steering effort of the steering wheel in a single revolution, offering advantages such as high detection accuracy and fast response speed. However, it has a limited range and cannot identify the absolute position of multiple revolutions of the steering wheel. The torque angle sensor 13 requires no modification or replacement, completely reusing the existing hardware structure.

[0056] The motor position sensor 14 is an integrated sensor built into the motor 12, fixedly mounted at the end of the motor 12 rotor, and rotates synchronously with the rotor to detect the rotational position and angle of the motor 12 rotor in real time. Its working principle is as follows: it acquires the continuous rotational angle of the motor rotor in real time and outputs a second angle signal with a second angle period. Because the motor 12 and steering column 15 have a reduction gearing relationship, the number of rotations and the angle range of the motor rotor are much greater than those of the steering column 15. Therefore, the second angle period has a period difference with the first angle period of the torque angle sensor 13, and the angle signal is continuous without interruption or mechanical lag. The motor position sensor 14 is a standard component already installed in the vehicle and does not require additional installation, thus not increasing any hardware cost or mechanical structure.

[0057] Specifically, the electronic control unit 11 is used to: acquire a first angle signal and a second angle signal; convert the angle corresponding to the second angle signal into an equivalent angle of the steering column according to the preset transmission ratio between the motor 12 and the steering column 15; and determine the absolute angle of the steering wheel using a vernier algorithm based on the equivalent angle of the steering column and the angle corresponding to the first angle signal; wherein the measurable range of the absolute angle of the steering wheel is greater than the first angle period.

[0058] Specifically, the electronic control unit 11 (ECU) is the calculation and control center of the system, and has built-in preset transmission ratio parameters, vernier algorithm program and data calibration parameters.

[0059] Optionally, the electronic control unit 11 collects the first angle signal (measured single-turn angle of the steering column 15) output by the torque angle sensor 13 and the second angle signal (real-time angle of the motor rotor) output by the motor position sensor 14 in real time and synchronously through the vehicle signal line, ensuring that the timing of the two signals is synchronized and without delay, providing accurate raw data for subsequent calculations.

[0060] Optionally, based on a fixed preset transmission ratio (reduction ratio) between the motor 12 and the steering column 15, the real-time angle of the motor rotor is reverse-calculated to accurately convert the large-stroke rotation angle of the motor rotor into the corresponding equivalent rotation angle of the steering column 15. This calculation process is based on inherent mechanical parameters, has no mechanical error, and can accurately restore the theoretical rotation angle range of the steering column 15.

[0061] The vernier algorithm works by using two angle signals with different periods to form an angle difference feature. The first angle signal ensures the accuracy of the angle in a single turn, and the equivalent angle of the steering column identifies the number of turns of the steering wheel. By combining the angle matching relationship of the two signals, the period range limitation of a single sensor is eliminated, and the absolute angle position after multiple turns of the steering wheel is calculated. Ultimately, a large angle detection range far exceeding 360° is achieved, which can fully cover the detection needs of steering wheel ±720° and larger turning angles.

[0062] Specifically, such as Figure 1 As shown, the electric power steering system also includes: a steering wheel 16, wheels 19, a steering column 15, a reduction gear 17, and a steering unit 18.

[0063] The steering wheel 16 is a manually operated component for the driver, fixedly locked to the top of the steering column 15 and rotating synchronously with the steering column 15 on the same axis. The driver inputs the steering torque and steering angle by rotating the steering wheel 16. The forward and reverse rotation and the number of rotations of the steering wheel 16 directly correspond to the vehicle's steering direction and steering amplitude, providing the system with the original steering operation input.

[0064] The steering column 15 is a hollow rigid transmission column, serving as the transmission carrier between the steering wheel 16 and the lower steering actuator. Its upper end is rigidly connected to the steering wheel 16, and its lower end is connected in series with the reduction gear 17 and the steering unit 18. The steering column 15 possesses high-precision rigid transmission characteristics, enabling lossless transmission of the steering wheel 16's rotation angle and torsional torque. Simultaneously, it supports the integrated installation of the torque angle sensor 13, ensuring absolute synchronous rotation between the sensor and the steering column 15, with no relative slippage or transmission backlash, providing a stable mechanical mounting reference for angle and torque detection.

[0065] The reduction mechanism 17 is a fixed transmission matching structure between the electric motor 12 and the steering column 15. It can be a worm gear reduction structure and is fixedly mounted between the steering column 15 and the output shaft of the electric motor 12, with a fixed reduction ratio. The reduction mechanism 17 is used to realize the conversion from high speed and low torque of the motor to low speed and high assist torque, establish a unique correspondence between the rotation angle of the rotor of the electric motor 12 and the rotation angle of the steering column 15, and form a precise and fixed mechanical transmission ratio.

[0066] The steering gear 18 adopts a rack and pinion structure and serves as the steering actuator. Its input end connects to the reduction mechanism 17 and the motor power output end, while its output end connects to the wheels 19 on both sides. The steering gear 18 converts the rotational motion transmitted by the steering column 15 into the linear reciprocating motion of the rack, thereby driving the wheels 19 to deflect and enabling the vehicle to turn left or right. The wheels 19 are the final actuators, following the movements of the steering gear 18 to complete the steering posture adjustment, and are the final execution carriers of the steering function.

[0067] The electric power steering system provided in this application utilizes the existing torque angle sensor 13 and motor position sensor 14 within the electric power steering system. Combined with the preset transmission ratio between the motor 12 and the steering column 15, a vernier algorithm is used to convert the signal from the motor position sensor 14 into an equivalent steering column angle, which is then fused with the signal from the torque angle sensor 13. This expands the measurable range of the steering wheel's absolute angle to a value greater than the angle period of the torque angle sensor 13's output signal without adding additional mechanical gear sets or independent Hall effect chips. This solution reduces hardware costs, simplifies the sensor structure, avoids wear and clearance errors caused by gear meshing, improves the operational reliability and angle measurement accuracy of the electric power steering system, and fully utilizes existing sensor resources within the system, demonstrating good engineering practicality and integration advantages.

[0068] As an optional implementation, based on any of the above embodiments, the electronic control unit 11, when determining the absolute angle of the steering wheel using a vernier algorithm, is specifically used for:

[0069] The angle corresponding to the first angle signal is used as the main scale reference value, and the equivalent angle of the steering column is used as the secondary scale reference value.

[0070] The main scale reference value is the measured angle of the steering column 15 corresponding to the first angle signal. The main scale reference value originates from the real-time detection signal of the original torque angle sensor 13 of the steering column 15. Optionally, the torque angle sensor 13 includes two rotors with a non-integer ratio of blade numbers, where the first angle period is the least common multiple of the output signal periods of the two rotors. For example, using a combination of 4-blade and 5-blade rotors, corresponding to outputting 90° and 72° basic period signals, respectively, the two basic period signals are coupled to form a first angle period signal with a least common multiple of 360°.

[0071] It should be noted that this first angle signal directly corresponds to the actual rotation angle of the steering column 15, featuring high detection accuracy, strong real-time performance, and no conversion error. It can accurately reflect subtle angle changes within a single turn of the steering wheel, serving as a high-precision angle reference for the vernier algorithm and ensuring the detailed accuracy of the final absolute angle. However, its inherent limitation is a limited cycle time, making it unable to independently identify the absolute number of turns and large-scale positions of multiple steering wheel rotations.

[0072] The auxiliary reference value is the equivalent angle of the steering column after conversion. The auxiliary reference value is obtained by combining the motor rotor angle collected by the motor position sensor 14 with the vehicle's preset fixed reduction gear ratio. The motor position sensor 14 can output a 360° full-cycle continuous rotor angle signal in real time. Since the electric power steering system's motor 12 and steering column 15 are a reduction gear transmission structure, and the transmission ratio i is a fixed calibration value greater than 1 (selected as 15.2 in this embodiment), for every multiple rotations of the motor rotor, the steering column 15 rotates one revolution.

[0073] Optionally, the formula for calculating the equivalent angle of the steering column is: Equivalent angle of steering column = Motor rotor angle ÷ Transmission ratio i. This calculation formula yields a secondary scale angle signal with a period less than the 360° period of the main scale, such as a converted period of 360° / 15.2. This secondary scale reference has a smaller period and a higher waveform change frequency, accurately capturing the large-range rotation of the steering column 15, compensating for the insufficient range of the main scale signal, and serving as a reference for vernier algorithm rotation counting and large-range distance measurement.

[0074] Specifically, the absolute angle of the steering wheel is determined by identifying the overlapping position of the waveforms of the main scale reference and the secondary scale reference.

[0075] The core logic of the vernier algorithm is to utilize the difference between the large period and high precision of the main scale and the small period and high resolution of the vernier scale, and eliminate the angular ambiguity of the single-cycle signal by identifying the unique overlapping feature point of the two signal waveforms, thereby calculating the absolute angle of the steering wheel over a very large range.

[0076] To more intuitively illustrate the changing patterns, periodic characteristics, and implementation principles of the vernier algorithm for the two angle signals, this embodiment provides a visual explanation accompanied by waveform diagrams of the vernier algorithm. Figure 2 A waveform diagram of a cursor algorithm provided in an embodiment of this application is shown below. Figure 2 As shown, the horizontal axis represents the steering wheel angle, in degrees, with a range of 0° to 1800°, representing the overall rotation angle range of the steering wheel; the vertical axis represents the sensor output angle value, in degrees, with a range of 0° to 360°, corresponding to the angle output range of a single-cycle sensor.

[0077] The first curve represents the first angle period signal (γ), which is the original angle signal output by the torque angle sensor 13. The fixed period is 360°, and it serves as the main reference value for the vernier algorithm. The second curve represents the theoretical angle at the end of the steering column (β÷i), which is the equivalent angle signal of the steering column obtained by converting the original signal of the motor position sensor 14 to the transmission ratio. The converted period is 360° / 15.2, and it serves as the secondary reference value for the vernier algorithm.

[0078] from Figure 3The waveforms clearly show that the main scale signal has a standard 360° period, with a smooth waveform change rhythm and a large period span; the equivalent angle signal period of the vernier scale is much smaller than that of the main scale, and the waveform changes more frequently. Because the main scale period (360°) and the vernier scale's converted period (360° / 15.2) are not integer multiples, the two waveforms will not overlap across the entire range, but will only produce a unique and precise overlap point at a specific absolute angle position. This characteristic is also the core basis for the vernier algorithm to achieve absolute angle positioning.

[0079] Optionally, the electronic control unit 11 synchronously acquires the main scale angle waveform and the secondary scale angle waveform in real time, and the two waveforms change continuously and synchronously with the rotation of the steering wheel. Since the conversion period of the main scale and the secondary scale is a non-integer multiple relationship, the two waveforms only have a unique precise overlap point at a specific absolute angle position of the steering column 15, and there is a fixed angle difference at other positions. Optionally, the electronic control unit 11 has a built-in waveform comparison program that scans and identifies the waveform amplitude and phase overlap position of the two signals in real time, and each precise overlap of the waveforms is an absolute angle reference point.

[0080] Based on this absolute angle reference point, and combined with the least common multiple of the two signal cycles, the maximum measurable range of the steering wheel's absolute angle can be determined. For example, the main scale cycle is 360°, the vernier scale's converted cycle is 360° / 15.2, and the least common multiple of the two signal cycles can reach 1800°, fully covering the vehicle's steering wheel's conventional limit steering range of ±720°, while reserving sufficient range redundancy. Furthermore, the greatest common divisor of the two signals determines the angle measurement error range, keeping the overall measurement error within a very small range, balancing a large measurement range with high precision.

[0081] The electric power steering system provided in this application embodiment uses the first angle signal output by the torque angle sensor 13 as the main reference value and the equivalent steering column angle calculated by the motor position sensor 14 as the secondary reference value. The absolute angle of the steering wheel is determined by identifying the overlap position of the main and secondary waveforms. By utilizing the phase overlap point between two signals with different cycles to achieve angle resolution, the measurable range of the absolute angle is effectively expanded without increasing the resolution of a single sensor. Furthermore, the determination of the waveform overlap position has a natural filtering characteristic for signal noise, and the mutual verification of the main and secondary signals can suppress the drift and error of a single sensor. Thus, while ensuring measurement accuracy, the robustness and reliability of the absolute angle determination are enhanced.

[0082] As an optional implementation, based on any of the above embodiments, the electronic control unit 11 is further configured to:

[0083] When the vehicle starts, the absolute zero position of the steering wheel is determined based on the calculation results of the vernier algorithm; during vehicle operation, the absolute angle of the steering wheel is updated according to a preset cycle.

[0084] It should be noted that the vehicle ignition and power-on, and system initialization phases are the core stages for establishing the steering angle detection reference. Existing multi-turn angle detection solutions generally suffer from the problem of not being able to autonomously identify the zero point upon power-on, requiring manual calibration, external reference signals, or data stored from the previous power-off, which is prone to problems such as reference offset, memory failure, and angle jumps. In this embodiment, after the electronic control unit 11 completes power-on initialization, it automatically triggers the vernier algorithm reference calibration logic, without any manual intervention or external calibration equipment.

[0085] Optionally, when the vehicle is stationary and starting, the steering wheel is in a fixed initial position. The torque angle sensor 13 of the steering column 15 outputs a steady-state first angle signal, and the motor position sensor 14 simultaneously outputs a steady-state second angle signal. After conversion by the transmission ratio, the steady-state equivalent angle of the steering column is obtained. The electronic control unit 11 scans the unique overlapping position of the waveforms of the two steady-state signals in real time, defines the absolute angle value corresponding to the overlapping position as the absolute zero point of the steering wheel, and fixes it as the angle reference origin for this vehicle power-on cycle.

[0086] This zero-point calibration method relies on the inherent periodic characteristics of dual sensors and the unique matching relationship of the vernier waveform. It can generate a unique and accurate absolute zero point every time it is powered on, avoiding the reference deviation problem caused by the existing solution relying on power failure memory. It is also suitable for the reference reset requirements of special scenarios such as vehicle maintenance, battery power failure, and system restart, ensuring that the corner detection reference is accurate and reliable after each power-on.

[0087] Specifically, under all operating conditions such as vehicle driving, turning on the spot, and parking, the electronic control unit 11 has a built-in preset angle update cycle (which can be calibrated according to the vehicle model and can be selected as a short cycle in milliseconds) to continuously and cyclically execute the signal acquisition, angle conversion, and vernier algorithm calculation process, and periodically refresh the absolute angle data of the steering wheel.

[0088] Optionally, the electronic control unit 11 synchronously acquires the real-time changing first angle signal and the corresponding signal of the steering column equivalent angle according to a fixed preset cycle, dynamically identifies the waveform overlap position of the two signals, and, combined with the absolute zero point reference calibrated upon power-on, iteratively corrects the absolute angle value of the steering wheel in real time. Compared with the traditional angle update method of single calculation and cumulative counting, the periodic update mechanism can offset the cumulative errors caused by low-speed drift, minor signal interference, and mechanical micro-backlashes in real time, realizing dynamic calibration and real-time refresh of angle data. In addition, the short-cycle iterative update adapts to the working conditions of high-speed reciprocating rotation and large-angle continuous rotation of the steering wheel, ensuring that the angle output has no lag, no jump, and no cumulative deviation.

[0089] The electric power steering system provided in this application utilizes a vernier algorithm to determine the absolute zero-point position of the steering wheel upon vehicle startup, eliminating the need for the driver to manually straighten the steering wheel or perform additional zero-point calibration. This achieves rapid initialization with precise absolute angles upon power-on. During vehicle operation, the absolute angle is continuously updated at preset intervals, effectively suppressing the cumulative drift that may occur from long-term operation of a single sensor. This ensures that the steering system maintains accurate absolute steering wheel angles throughout its entire lifespan, improving user convenience and guaranteeing the angle perception accuracy and control safety of the electric power steering system under various operating conditions.

[0090] As an optional implementation, based on any of the above embodiments, the measurable range of the absolute angle of the steering wheel is the least common multiple of the corresponding period of the first angle period and the equivalent angle period of the steering column; the measurement accuracy of the absolute angle of the steering wheel is the greatest common divisor of the corresponding period of the first angle period and the equivalent angle period of the steering column.

[0091] The first angle period, namely the inherent period γ of the output signal of the torque angle sensor 13, is fixed at 360° in this embodiment and is the actual angle detection period of the steering column 15. The equivalent angle corresponding period of the steering column is the theoretical angle period β of the original angle signal of the motor position sensor 14 after being converted by the transmission ratio and mapped to the steering column 15. Its value is 360° / i, where i is the fixed reduction transmission ratio between the motor 12 and the steering column 15 (15.2 is selected in this embodiment).

[0092] The maximum effective measurable range of the steering wheel absolute angle is determined by the least common multiple of the first angle period γ and the equivalent angle period β of the steering column. This principle originates from the waveform uniqueness matching mechanism of the vernier algorithm. Since the difference between the main scale period γ and the secondary scale conversion period β is a non-integer multiple, the waveforms of the two periodic signals only have a unique, periodic, and precise overlap within the angle range corresponding to the least common multiple. Within this range, each steering wheel absolute angle corresponds to a unique combination of main scale and secondary scale angle values, with no angular ambiguity or data overlap, accurately distinguishing each absolute turning angle position. When the angle range exceeds the least common multiple, the waveform combination of the two signals will exhibit repetitive characteristics, causing the absolute angle determination to fail.

[0093] Optionally, the electronic control unit 11 has a built-in mathematical calculation model that can calculate the least common multiple of the two cycles in real time based on the transmission ratio parameters calibrated by the whole vehicle, and use this as the upper limit of the range for the absolute angle detection of the steering wheel.

[0094] The inherent measurement accuracy of the steering wheel absolute angle is determined by the greatest common divisor of the first angle period γ and the equivalent angle period β of the steering column, which is the underlying constraint threshold for the detection accuracy of this algorithm. The greatest common divisor represents the minimum angular resolution at which the two periodic signals can achieve precise matching, that is, the minimum steering wheel angle change that the electronic control unit 11 can recognize.

[0095] It should be noted that the accuracy of the difference change between the two periodic signals is limited by their greatest common divisor. All waveform overlap deviations and angle calculation errors will not exceed this threshold range. This accuracy value is the inherent accuracy of the system and is not affected by the steering angle, steering speed, or changes in operating conditions, enabling equal accuracy detection across the entire measurement range.

[0096] Optionally, the electronic control unit 11 can also establish an error judgment mechanism based on the greatest common divisor accuracy threshold, and filter abnormal signals that exceed the accuracy range in real time, shielding invalid data caused by road bumps, electrical interference, and slight sensor vibrations, thereby further improving the stability and accuracy of angle detection.

[0097] As an alternative implementation, based on any of the above embodiments, the motor position sensor 14 adopts a magnetoresistive chip or a Hall chip, and a magnet that cooperates with the motor position sensor 14 is installed on the rotor of the motor 12.

[0098] Among them, the magnet is fixedly embedded or bonded to the center of the end of the rotor of the motor 12, and can rotate synchronously and coaxially with the motor rotor without relative displacement or transmission gap; the magnetoresistive chip or Hall chip, as the detection subject, is fixedly arranged inside the end cover of the motor housing, and maintains a preset uniform sensing gap with the rotor sensing magnet. The two have no mechanical contact, forming a closed non-contact detection structure with a compact overall structure and high integration.

[0099] Optionally, the magnet is a uniformly magnetized permanent magnet, which can form a stable, uniform, and fixed-direction spatial magnetic field within the chip's sensing area. When the rotor of motor 12 rotates with the steering system, the magnet rotates synchronously and coaxially with the rotor, causing the magnetic field direction and phase at the sensor detection position to change continuously and linearly with the rotor's rotation angle. This achieves a one-to-one correspondence between the mechanical rotation angle and the magnetic field phase, providing a continuous and stable magnetic field excitation source for the downstream chip detection. The permanent magnet has good magnetic field consistency, no attenuation, and no mechanical hysteresis, ensuring that the magnetic field changes without distortion under full speed conditions.

[0100] The Hall effect chip operates based on the Hall electromagnetic induction effect. It integrates a Hall sensor element to capture real-time changes in the magnetic field generated by the rotation of the rotor magnet. When the magnetic field phase changes with the rotor angle, the Hall element cuts the magnetic field lines and outputs an analog voltage signal linearly related to the magnetic field angle. This analog voltage signal, after internal conditioning, outputs a continuous periodic second angle signal, accurately reflecting the real-time rotation angle, direction, and speed of the motor rotor. The Hall effect chip features fast response, a wide dynamic range, and vibration resistance, making it suitable for high-speed, high-frequency reciprocating rotation conditions of motors.

[0101] Among them, the magnetoresistive chip can be anisotropic magnetoresistive, giant magnetoresistive, or tunnel magnetoresistive. The resistance value of the magnetoresistive element inside the chip changes linearly with the change of the direction of the external magnetic field. The change in resistance is converted into a voltage signal through a bridge circuit, and finally outputs a high-precision, low-noise rotor angle periodic signal. Compared with Hall effect chips, magnetoresistive chips have higher magnetic field sensing sensitivity, better signal linearity, less temperature drift, and superior static angle detection accuracy.

[0102] Figure 3 This is a flowchart illustrating a method for determining a steering wheel angle according to an embodiment of this application, as shown below. Figure 3 As shown, the execution entity in this embodiment is the electronic control unit in the electric power steering system.

[0103] S201. Obtain the first angle signal output by the torque angle sensor and the second angle signal output by the motor position sensor.

[0104] S202. Based on the preset transmission ratio between the motor and the steering column, the angle corresponding to the second angle signal is converted into the equivalent angle of the steering column.

[0105] S203. Based on the equivalent angle of the steering column and the angle corresponding to the first angle signal, the absolute angle of the steering wheel is determined using a vernier algorithm; wherein, the measurable range of the absolute angle of the steering wheel is greater than the first angle period; wherein, the first angle period is the signal period of the first angle signal.

[0106] Optionally, the absolute angle of the steering wheel is determined using a vernier algorithm, including: using the angle corresponding to the first angle signal as the main scale reference value and the equivalent angle of the steering column as the secondary scale reference value; and determining the absolute angle of the steering wheel by identifying the overlapping position of the waveforms of the main scale reference value and the secondary scale reference value.

[0107] Optionally, the method further includes: determining the absolute zero position of the steering wheel based on the calculation result of the vernier algorithm when the vehicle is started; and updating the absolute angle of the steering wheel according to a preset cycle during vehicle operation.

[0108] It should be noted that the technical effects of the steering wheel angle determination method in this embodiment have been described in detail in the above embodiments of the electric power steering system, and will not be repeated here.

[0109] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application, as shown below. Figure 4 As shown, the electronic device 30 provided in this embodiment includes a processor 31 and a memory 32 that is communicatively connected to the processor 31.

[0110] The memory 32 stores computer execution instructions; the processor 31 executes the computer execution instructions stored in the memory 32 to implement the method provided in any of the above embodiments.

[0111] The program may include program code, which includes computer-executable instructions. Memory 32 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device.

[0112] In this embodiment, the memory 32 and the processor 31 are connected via a bus. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 4 The bus is represented by a single straight line, but this does not mean that there is only one bus or one type of bus.

[0113] This application also provides a computer-readable storage medium, including computer-executable instructions stored in the computer-readable storage medium, which, when executed by a processor, are used to implement the method provided in any of the above embodiments.

[0114] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method provided in any of the above embodiments.

[0115] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to implement the solution of this embodiment according to actual needs.

[0116] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The unit composed of the above modules can be implemented in hardware or in the form of hardware plus software functional units.

[0117] The integrated modules described above, implemented as software functional modules, can be stored in a computer-readable storage medium. These software functional modules, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods of the various embodiments of this application.

[0118] It should be understood that the aforementioned processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly manifested as execution by a hardware processor, or execution by a combination of hardware and software modules within the processor.

[0119] The memory may include high-speed RAM, and may also include non-volatile storage (NVM), such as at least one disk storage device, and may also be a USB flash drive, external hard drive, read-only memory, disk or optical disc, etc.

[0120] The aforementioned storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0121] An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be an integral part of the processor. The processor and storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and storage medium can exist as discrete components in an electronic control unit or main control device.

[0122] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An electric power steering system, characterized in that, include: The system comprises a sensor system, an electronic control unit (11), and a power steering mechanism; both the sensor system and the power steering mechanism are electrically connected to the electronic control unit (11); the power steering mechanism includes a motor (12); the sensor system includes a torque angle sensor (13) mounted on the steering column (15) and a motor position sensor (14) mounted at the rotor position of the motor (12); the torque angle sensor (13) is configured to output a first angle signal having a first angle period, and the motor position sensor (14) is configured to output a second angle signal having a second angle period; The electronic control unit (11) is used for: Acquire the first angle signal and the second angle signal; Based on the preset transmission ratio between the motor (12) and the steering column (15), the angle corresponding to the second angle signal is converted into the equivalent angle of the steering column; Based on the equivalent angle of the steering column and the angle corresponding to the first angle signal, the absolute angle of the steering wheel is determined using a vernier algorithm; wherein the measurable range of the absolute angle of the steering wheel is greater than the first angle period.

2. The system according to claim 1, characterized in that, The electronic control unit (11), when determining the absolute angle of the steering wheel using the vernier algorithm, is specifically used for: The angle corresponding to the first angle signal is used as the main scale reference value, and the equivalent angle of the steering column is used as the secondary scale reference value. The absolute angle of the steering wheel is determined by identifying the overlapping position of the waveforms of the main scale reference value and the secondary scale reference value.

3. The system according to claim 1, characterized in that, The electronic control unit (11) is also used for: When the vehicle starts, the absolute zero position of the steering wheel is determined based on the calculation results of the vernier algorithm; During vehicle operation, the absolute angle of the steering wheel is updated according to a preset cycle.

4. The system according to claim 1, characterized in that, The torque angle sensor (13) includes two rotors with a non-integer ratio of blade numbers, wherein the first angle period is the least common multiple of the two rotor output signal periods.

5. The system according to claim 1, characterized in that, The measurable range of the absolute angle of the steering wheel is the least common multiple of the period corresponding to the first angle period and the period corresponding to the equivalent angle of the steering column; the measurement accuracy of the absolute angle of the steering wheel is the greatest common divisor of the period corresponding to the first angle period and the period corresponding to the equivalent angle of the steering column.

6. The system according to any one of claims 1-5, characterized in that, The motor position sensor (14) uses a magnetoresistive chip or a Hall chip, and a magnet that cooperates with the motor position sensor (14) is installed on the rotor of the motor (12).

7. A method for determining the steering wheel angle, characterized in that, The method, applied to the electronic control unit in the electric power steering system according to any one of claims 1-6, comprises: Acquire the first angle signal output by the torque angle sensor and the second angle signal output by the motor position sensor; Based on the preset transmission ratio between the motor and the steering column, the angle corresponding to the second angle signal is converted into the equivalent angle of the steering column; Based on the equivalent angle of the steering column and the angle corresponding to the first angle signal, the absolute angle of the steering wheel is determined using a vernier algorithm; wherein the measurable range of the absolute angle of the steering wheel is greater than the first angle period; wherein the first angle period is the signal period of the first angle signal.

8. The method according to claim 7, characterized in that, The process of determining the absolute angle of the steering wheel using a vernier algorithm includes: The angle corresponding to the first angle signal is used as the main scale reference value, and the equivalent angle of the steering column is used as the secondary scale reference value. The absolute angle of the steering wheel is determined by identifying the overlapping position of the waveforms of the main scale reference value and the secondary scale reference value.

9. The method according to claim 7 or 8, characterized in that, Also includes: When the vehicle starts, the absolute zero position of the steering wheel is determined based on the calculation results of the vernier algorithm; During vehicle operation, the absolute angle of the steering wheel is updated according to a preset cycle.

10. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 7-9.

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