An EPS steering angle zero-point driving automatic calibration system

Abstract

The application discloses an EPS steering angle zero-point driving automatic calibration system, which comprises a vehicle speed acquisition circuit, a steering wheel input torque acquisition circuit, a torque threshold comparison circuit, a vehicle speed threshold comparison circuit, a timer, an angle zero-point calibration state latch and a main control MCU; the signal output end of the vehicle speed acquisition circuit is electrically connected with the vehicle speed signal input end of the main control MCU and the first input end of the vehicle speed threshold comparison circuit; the second input end of the vehicle speed threshold comparison circuit is connected with a preset vehicle speed threshold voltage; and the output end of the vehicle speed threshold comparison circuit is electrically connected with the first trigger input end of the main control MCU. The application realizes multi-condition combination determination through a hardware circuit, and can automatically complete angle zero-point calibration in a driving process without a special diagnostic device; and the calibration state is locked through a latch, so that false triggering is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of automotive electric power steering systems, specifically to an EPS steering angle zero-point automatic calibration system for driving. Background Technology

[0002] Electric power steering (EPS) systems are widely used in advanced driver assistance functions such as active return-to-center, automatic parking, lane keeping, and autonomous driving. The precise operation of these functions highly depends on the accuracy of the angle signal provided by the steering angle sensor. When the zero-point reference of the angle sensor is deviated, it will directly cause abnormalities in various advanced control functions of the EPS, affecting the vehicle's driving safety and handling stability.

[0003] During vehicle assembly, due to the accumulation of assembly tolerances among various steering system components, misalignment inevitably occurs between the mechanical zero point of the angle sensor and the geometric zero point of the steering wheel in the vehicle coordinate system. Therefore, the angle zero point must be calibrated before the EPS (Electric Power Steering) system is put into use to ensure the accurate operation of the steering control logic. However, existing zero-point calibration methods have significant limitations. One method relies on the mechanical ignition key triggering calibration according to specific switching logic, but with the widespread adoption of keyless start vehicles, vehicles without mechanical keys cannot adapt to this calibration logic, severely limiting compatibility. Another method requires calibration using specialized diagnostic equipment. This not only requires repair shops to purchase expensive professional diagnostic equipment, but also prevents vehicle owners from performing calibration themselves during daily use. If a zero-point misalignment occurs, the owner must visit a repair shop equipped with specialized equipment, significantly increasing the time and financial costs of after-sales maintenance.

[0004] There is an urgent need for a technical solution that can autonomously calibrate the zero angle without requiring specialized diagnostic equipment or relying on key shifting, and can be performed under normal vehicle operating conditions. Summary of the Invention

[0005] To address the problems existing in current technologies, this invention provides an EPS steering angle zero-point automatic calibration system, comprising: a vehicle speed acquisition circuit, a steering wheel input torque acquisition circuit, a torque threshold comparison circuit, a vehicle speed threshold comparison circuit, a timer, an angle zero-point calibration state latch, and a main control MCU; the signal output terminal of the vehicle speed acquisition circuit is electrically connected to the vehicle speed signal input terminal of the main control MCU and the first input terminal of the vehicle speed threshold comparison circuit, respectively; the second input terminal of the vehicle speed threshold comparison circuit is connected to a preset vehicle speed threshold voltage; and the output terminal of the vehicle speed threshold comparison circuit is electrically connected to the first trigger input terminal of the main control MCU; the signal output of the steering wheel input torque acquisition circuit... The first input terminal of the torque threshold comparison circuit is electrically connected to the torque signal input terminal of the main control MCU and the first input terminal of the torque threshold comparison circuit, respectively. The second input terminal of the torque threshold comparison circuit is connected to a preset torque threshold voltage. The output terminal of the torque threshold comparison circuit is electrically connected to the second trigger input terminal of the main control MCU. The output terminal of the timer is electrically connected to the timing signal input terminal of the main control MCU. The angle zero-point calibration state latch is bidirectionally electrically connected to the main control MCU. The latching state output terminal of the angle zero-point calibration state latch is electrically connected to the calibration enable control terminal of the main control MCU. The calibration execution signal output terminal of the main control MCU is electrically connected to the zero-point calibration enable input terminal of the EPS system.

[0006] Preferably, the torque threshold comparison circuit includes a comparator, a first voltage divider resistor, and a second voltage divider resistor; the non-inverting input of the comparator is connected to the signal output of the steering wheel input torque acquisition circuit via the first voltage divider resistor, the inverting input of the comparator is connected to the preset torque threshold voltage via the second voltage divider resistor, and the output of the comparator is electrically connected to the second trigger input of the main control MCU.

[0007] More preferably, the preset torque threshold voltage is the voltage value corresponding to a steering wheel input torque of 1 Newton-meter, and the preset vehicle speed threshold voltage is the voltage value corresponding to a vehicle speed of 20 kilometers per hour.

[0008] More preferably, the angle zero-point calibration state latch is a latch chip, the data input terminal of the latch chip is electrically connected to the flag bit write terminal of the main control MCU, the clock input terminal of the latch chip is electrically connected to the flag bit latch control terminal of the main control MCU, and the data output terminal of the latch chip is electrically connected to the flag bit read terminal and the calibration enable control terminal of the main control MCU, respectively.

[0009] More preferably, the angle zero-point calibration state latch is an electrically erasable programmable read-only memory, and the chip select pin, clock pin, and data input / output pin of the electrically erasable programmable read-only memory are electrically connected to the corresponding general-purpose input / output ports of the main control MCU.

[0010] More preferably, when the main control MCU outputs a vehicle speed compliance signal at the output terminal of the vehicle speed threshold comparison circuit, outputs a torque compliance signal at the output terminal of the torque threshold comparison circuit, and the timing duration output by the timer reaches 5 seconds, it outputs a zero-point calibration execution signal to the EPS system through the calibration execution signal output terminal.

[0011] Further preferably, it also includes a zero-point clearing trigger signal input terminal, which is electrically connected to the clearing trigger input port of the main control MCU; the main control MCU outputs a zero-point calibration execution signal to the EPS system through the calibration execution signal output terminal, and writes a zero-point flag clear signal through the angle zero-point calibration status latch.

[0012] More preferably, the zero-point clear trigger signal input terminal receives a valid clear trigger signal when the steering wheel is turned to the left full limit position for 5 seconds and then to the right full limit position for 5 seconds, the vehicle speed is greater than 20 kilometers per hour, and the power-on duration is within 30 seconds; when the timing duration output by the timer reaches 30 seconds and the clear trigger signal is valid, the main control MCU writes a zero-point flag clear signal to the angle zero-point calibration state latch through the flag bit writing terminal.

[0013] More preferably, when the flag bit output by the zero-point calibration state latch is 1, the main control MCU blocks the signal output of the calibration execution signal output terminal.

[0014] Technical effects: This invention achieves real-time determination of vehicle speed and steering wheel torque conditions in pure hardware by setting up vehicle speed threshold comparison circuits and torque threshold comparison circuits. It can accurately identify whether the vehicle is in a suitable straight-line driving condition without relying on software algorithms. By setting up an angle zero-point calibration state latch, the calibration state is persistently stored in hardware latching mode. When the flag bit is 1, the main control MCU blocks the calibration execution signal output, eliminating miscalibration during driving from the hardware level. By connecting the output terminals of the vehicle speed threshold comparison circuit, torque threshold comparison circuit, and timer to different trigger input terminals of the main control MCU, the main control MCU will only output the calibration execution signal when the three hardware conditions are met simultaneously. This fundamentally solves the problems of traditional calibration methods relying on dedicated diagnostic equipment, being unable to adapt to one-button start vehicles, and being prone to accidental tampering of the zero point due to mis-triggering. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This invention relates to an EPS steering angle zero-point automatic vehicle calibration system. Figure 2 Design a vehicle speed acquisition circuit for this invention. Figure 3 A steering wheel input torque acquisition circuit was designed for this invention. Detailed Implementation

[0017] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0018] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0019] The existing EPS steering angle zero-point calibration system has the following main technical problems: the mechanical zero point of the angle sensor is misaligned with the geometric zero point of the steering wheel due to the assembly error. Zero-point calibration must be completed to ensure the accurate operation of the steering control logic. However, the traditional key gear calibration method cannot be adapted to one-button start models. The diagnostic equipment calibration method requires special equipment and is expensive. Car owners cannot complete the calibration themselves in daily use.

[0020] Based on this, please refer to Figures 1-3This embodiment provides an EPS steering angle zero-point automatic calibration system, including a vehicle speed acquisition circuit, a steering wheel input torque acquisition circuit, a torque threshold comparison circuit, a vehicle speed threshold comparison circuit, a timer, an angle zero-point calibration state latch, and a main control MCU. The signal output terminal of the vehicle speed acquisition circuit is electrically connected to the vehicle speed signal input terminal of the main control MCU and the first input terminal of the vehicle speed threshold comparison circuit, respectively. The vehicle speed acquisition circuit is used to acquire the real-time vehicle speed signal during vehicle operation. This real-time vehicle speed signal is represented as a voltage in the circuit. The signal output terminal of the vehicle speed acquisition circuit simultaneously transmits the aforementioned voltage signal representing the vehicle speed to the vehicle speed signal input terminal of the main control MCU and the first input terminal of the vehicle speed threshold comparison circuit. The second input terminal of the vehicle speed threshold comparison circuit is connected to a preset vehicle speed threshold voltage, which is a pre-set fixed voltage reference value that corresponds one-to-one with the preset vehicle speed threshold. The vehicle speed threshold comparison circuit internally compares the voltage value representing the real-time vehicle speed received at the first input terminal with the preset vehicle speed threshold voltage connected to the second input terminal. When the voltage value representing the real-time vehicle speed reaches or exceeds the preset vehicle speed threshold voltage, the output terminal of the vehicle speed threshold comparison circuit outputs a vehicle speed compliance signal to the first trigger input terminal of the main control MCU. This vehicle speed compliance signal is a high-level active signal. When the voltage value representing the real-time vehicle speed is lower than the preset vehicle speed threshold voltage, the output terminal of the vehicle speed threshold comparison circuit does not output a vehicle speed compliance signal, i.e., it remains in a low-level state. The signal output terminal of the steering wheel input torque acquisition circuit is electrically connected to the torque signal input terminal of the main control MCU and the first input terminal of the torque threshold comparison circuit, respectively. This steering wheel input torque acquisition circuit is used to acquire the real-time torque signal applied to the steering wheel when the driver operates the steering wheel. This real-time torque signal is represented in voltage form in the circuit. The signal output terminal of the steering wheel input torque acquisition circuit simultaneously transmits the aforementioned voltage signal representing the torque to the torque signal input terminal of the main control MCU and the first input terminal of the torque threshold comparison circuit. The second input terminal of the torque threshold comparison circuit is connected to a preset torque threshold voltage, which is a pre-set fixed voltage reference value that corresponds one-to-one with the preset torque threshold. Internally, the torque threshold comparison circuit compares the voltage value representing the real-time torque received at the first input terminal with the preset torque threshold voltage connected to the second input terminal. When the voltage value representing the real-time torque is less than the preset torque threshold voltage, the output terminal of the torque threshold comparison circuit outputs a torque compliance signal to the second trigger input terminal of the main control MCU. This torque compliance signal is a high-level valid signal, corresponding to the driver having released both hands from the steering wheel or only lightly holding the steering wheel without applying sufficient torque for active steering. When the voltage value representing the real-time torque is greater than or equal to the preset torque threshold voltage, the output terminal of the torque threshold comparison circuit does not output a torque compliance signal, i.e., it remains in a low-level state.The timer's output is electrically connected to the timing signal input of the main control MCU. The timer has timing start, timing reset, and timing duration output functions. It responds to control commands issued by the main control MCU to start timing or reset to zero, and transmits the accumulated timing duration to the main control MCU in real time. The angle zero-point calibration status latch is bidirectionally electrically connected to the main control MCU. The latch status output of the angle zero-point calibration status latch is electrically connected to the calibration enable control terminal of the main control MCU. This angle zero-point calibration status latch stores the angle zero-point flag bit, which is a single binary status information bit, with a value of 0 or 1. A value of 0 indicates that the angle zero-point calibration has not yet been completed, and a value of 1 indicates that the angle zero-point calibration has been completed. Due to its hardware circuit characteristics, the angle zero-point calibration status latch can stably maintain its stored flag bit state during normal system power supply, and will not lose it due to software reset or program crashes of the main control MCU. The calibration execution signal output terminal of the main control MCU is electrically connected to the zero-point calibration enable input terminal of the EPS system. The main control MCU monitors the output status of the vehicle speed threshold comparison circuit through the first trigger input terminal, the output status of the torque threshold comparison circuit through the second trigger input terminal, and the timing duration output by the timer through the timing signal input terminal. When the first trigger input terminal of the main control MCU receives the vehicle speed compliance signal, the second trigger input terminal simultaneously receives the torque compliance signal, and the timing duration output by the timer reaches the preset duration threshold, the main control MCU determines that the vehicle is currently in a stable straight-line driving condition that meets the calibration requirements. Then, it outputs a zero-point calibration execution signal to the zero-point calibration enable input terminal of the EPS system through the calibration execution signal output terminal, triggering the EPS system to automatically calibrate the zero point of the angle. The technical effects achieved by the above technical solution include: real-time and accurate determination of vehicle speed and steering wheel torque conditions through hardware comparison of vehicle speed threshold comparison circuit and torque threshold comparison circuit, without relying on software algorithm for threshold judgment, with fast response speed and high reliability; and hardware latching of the angle zero-point calibration state latch to ensure that the calibration state is stably maintained and not lost during system power supply, avoiding repeated calibration of calibrated vehicles.

[0021] Existing torque threshold comparison schemes mostly employ software analog-to-digital conversion followed by comparison, which suffers from response delays and susceptibility to software interference. Therefore, this torque threshold comparison circuit includes a comparator, a first voltage divider resistor, and a second voltage divider resistor. The non-inverting input of the comparator is connected to the signal output of the steering wheel input torque acquisition circuit via the first voltage divider resistor. This non-inverting input receives the voltage signal representing the real-time torque from the steering wheel input torque acquisition circuit. The inverting input of the comparator is connected to a preset torque threshold voltage via the second voltage divider resistor. This preset torque threshold voltage is pre-set based on the voltage division relationship between the second voltage divider resistor and a reference voltage source, and its voltage value precisely corresponds to a specific torque threshold. The output of the comparator is electrically connected to the second trigger input of the main control MCU. When the voltage signal representing the real-time torque received at the non-inverting input is less than the preset torque threshold voltage connected to the inverting input, the comparator outputs a high-level signal to the second trigger input of the main control MCU. This high-level signal serves as the torque compliance signal. When the voltage signal representing the real-time torque received at the non-inverting input is greater than or equal to the preset torque threshold voltage connected to the inverting input, the comparator output remains low and does not output a torque compliance signal. Through the comparator's pure hardware comparison method, the real-time torque signal directly completes the threshold comparison and outputs the judgment result on the transmission path, without the need for analog-to-digital conversion or software algorithm judgment. The technical effects achieved by the above solution include: using a comparator in conjunction with voltage divider resistors to achieve hardware comparison of the torque threshold, the response time is in the microsecond range, far superior to the millisecond response of the software comparison method; it does not occupy the analog-to-digital conversion resources and software computing resources of the main control MCU, reducing the computational burden and program complexity of the main control MCU.

[0022] The lack of a unified hardware reference standard for setting threshold parameters in existing technologies leads to inconsistencies in thresholds across different vehicles or batches of calibration systems, affecting the accuracy and consistency of calibration triggering. Therefore, the preset torque threshold voltage is set to the voltage value corresponding to 1 Newton-meter of steering wheel input torque, and the preset vehicle speed threshold voltage is set to the voltage value corresponding to a vehicle speed of 20 kilometers per hour. The steering wheel input torque acquisition circuit converts the acquired mechanical torque signal into a voltage signal, with a linear correspondence; that is, each unit of torque corresponds to a specific voltage value. Therefore, the preset torque threshold voltage is set to the voltage value corresponding to 1 Newton-meter of torque. When the torque applied to the steering wheel by the driver is less than 1 Newton-meter, the torque threshold comparison circuit determines that the threshold is met. This condition corresponds to the driver releasing both hands from the steering wheel or only lightly holding the steering wheel without actively applying steering torque. The vehicle speed acquisition circuit converts the acquired vehicle speed signal into a voltage signal, and the conversion relationship is also linear. A preset vehicle speed threshold voltage is set to the voltage value corresponding to a vehicle speed of 20 km / h. When the vehicle speed reaches or exceeds 20 km / h, the vehicle speed threshold comparison circuit determines that the standard has been met. This condition corresponds to the vehicle being at a normal driving speed, not in a low-speed maneuvering or stationary state. By establishing a definite correspondence between the two specific physical quantities, 1 Newton-meter and 20 km / h, and the voltage threshold, the triggering conditions of each calibration system are traceable to a unified physical quantity reference standard. The technical effects achieved by the above solution include: by quantifying the torque threshold and vehicle speed threshold into voltage values ​​corresponding to 1 Newton-meter and 20 km / h respectively, the calibration triggering conditions have clear physical meaning and a unified hardware reference standard, eliminating threshold dispersion caused by batch differences in components and ensuring the consistency of calibration triggering conditions between different vehicles.

[0023] In existing technologies, calibration state storage often employs software-based writing to memory, which carries risks of unreliable write timing and loss of state due to power fluctuations. Therefore, the angle zero-point calibration state latch is a latch chip. The latch chip's data input is electrically connected to the flag bit write terminal of the main control MCU. The main control MCU writes the value of the angle zero-point flag bit (0 or 1) to the latch chip through this data input. The latch chip's clock input is electrically connected to the flag bit latch control terminal of the main control MCU. When the main control MCU applies a latch pulse signal to the clock input, the latch chip latches the current level state of the data input and holds it at its data output. The latched flag bit value does not change with subsequent changes in the data input level until the next latch pulse arrives. The data output terminal of the latch chip is electrically connected to both the flag bit read terminal and the calibration enable control terminal of the main control MCU. On one hand, the data output terminal sends the current flag bit value to the flag bit read terminal of the main control MCU for the MCU to read and determine whether calibration is complete. On the other hand, it directly sends the flag bit status to the calibration enable control terminal of the main control MCU. When the flag bit is 1, the calibration enable control terminal of the main control MCU, upon receiving this high-level signal, disables the output of the calibration execution signal at the hardware level. The latch chip is a sequential logic circuit, and its latched state remains stable during normal power supply, independent of periodic software refresh or write-back. The technical effects achieved by the above solution include: hardware latching of the flag bit is achieved through the latch chip, the state is maintained without software intervention, and it has strong resistance to power fluctuations and electromagnetic interference; the data output terminal is connected to both the flag bit read terminal and the calibration enable control terminal of the main control MCU, realizing real-time hardware-level feedback of the flag bit status, allowing direct control of calibration enable without software query.

[0024] Latch chips cannot retain their stored state after a system power failure, requiring the flag bits to be rewritten each time power is restored, which is inconvenient in some applications. Therefore, the angle zero-point calibration state latch is an electrically erasable programmable read-only memory (EEPROM). The EEPROM's chip select pin, clock pin, and data input / output pins are electrically connected to the corresponding general-purpose input / output ports of the main control MCU. The main control MCU selects the memory chip by outputting a chip select signal through the chip select pin, outputs a synchronous clock signal through the clock pin to control the data exchange cycle, and uses the data input / output pins to write and read the flag bit data. The EEPROM has non-volatile storage characteristics, ensuring that the data stored within it remains intact even after the chip is completely powered off. When the system is powered back on, the main control MCU directly reads the previously written flag bit state from the memory through the data input / output pins, without needing to re-execute the calibration process. This memory exchanges data with the main control MCU via a serial communication protocol, requiring only three pins: chip select, clock, and data input / output. The technical effects achieved by the above technical solution include: the non-volatile characteristics of electrically erasable programmable read-only memory enable the persistent storage of flag bits after the system is powered off, and no recalibration is required after power is restored; the serial interface connection method has fewer pins, which helps to simplify the layout of printed circuit boards and reduce the size of the system.

[0025] Existing technologies lack a clear hardware timing mechanism for multi-condition combination judgments, as the timing of each condition's fulfillment differs, making it difficult to accurately determine when all conditions are simultaneously satisfied. Therefore, when the main control MCU outputs a vehicle speed compliance signal at the output of the vehicle speed threshold comparison circuit, a torque compliance signal at the output of the torque threshold comparison circuit, and the timer's timing duration reaches 5 seconds, it outputs a zero-point calibration execution signal to the EPS system through the calibration execution signal output. When the vehicle speed threshold comparison circuit detects a vehicle speed of 20 km / h or higher, its output continuously outputs a high-level vehicle speed compliance signal; when the torque threshold comparison circuit detects a steering wheel input torque less than 1 Nm, its output continuously outputs a high-level torque compliance signal. The main control MCU continuously monitors the level states of the first and second trigger inputs. When both are high, the main control MCU sends a start-time command to the timer, and the timer starts counting from zero. During the timing process, the main control MCU continuously monitors whether the vehicle speed and torque achievement signals remain at a high level. If either signal goes low during the timing process, i.e., the vehicle speed drops below 20 km / h or the torque rises above 1 Nm, the main control MCU immediately sends a reset command to the timer to zero and waits for both conditions to be met simultaneously again before restarting the timing. Only when the vehicle speed and torque achievement signals remain continuously at a high level for 5 seconds does the timer output a timing completion signal to the main control MCU. The main control MCU confirms that the vehicle has been continuously in a stable straight-line driving state, and then outputs a zero-point calibration execution signal to the EPS system through the calibration execution signal output terminal. The technical effects achieved by the above solution include: by using a 5-second duration threshold, the instantaneous noise and accidental fluctuations of the vehicle speed and torque signals are effectively filtered out, ensuring that the calibration operation is triggered only under stable straight-line driving conditions. This avoids accidental calibration due to instantaneous signal changes caused by road bumps or occasional minor driver operations, thus improving the accuracy and reliability of the calibration.

[0026] When replacing the steering gear assembly or discovering a deviation in the original calibration zero point, it is necessary to clear the old zero-point calibration data and re-perform calibration. Existing technology lacks a dedicated clearing trigger mechanism. Therefore, a zero-point clearing trigger signal input terminal is also included, electrically connected to the clearing trigger input port of the main control MCU. This zero-point clearing trigger signal input terminal receives clearing trigger signals generated by external operations, including combinations of steering wheel extreme position operations. The main control MCU outputs a zero-point calibration execution signal to the EPS system through the calibration execution signal output terminal to trigger calibration, and writes a zero-point flag clear signal to the angle zero-point calibration status latch to clear the old calibration state. When the main control MCU detects a valid clear trigger signal at its clear trigger input port, it first outputs a clear command to the EPS system through the calibration execution signal output terminal, notifying the EPS system to clear its internally stored old zero-point data. Then, the main control MCU writes a 0 value to the angle zero-point calibration status latch through its flag bit write terminal. This 0 value is the zero-point flag clear signal, changing the flag bit stored in the latch from 1 to 0, indicating that the angle zero point has not yet been calibrated. After completing these two steps, the system returns to the uncalibrated state and can execute the angle zero-point calibration process again. This clear trigger mechanism and calibration trigger mechanism are independent of each other; receiving the clear trigger signal will not trigger the output of the calibration execution signal, and meeting the calibration trigger conditions will not trigger the clear operation. The technical effects achieved by the above solution include: by setting an independent zero-point clear trigger signal input terminal, a dedicated hardware clear channel is provided for recalibration after replacing the steering gear assembly or zero-point offset; the clear operation and calibration operation are independent of each other and do not interfere with each other, avoiding logical conflicts between the two operations during execution.

[0027] Generating a clear trigger signal requires a specific combination of operations to prevent false triggering, but existing technology lacks timing constraints for the clear trigger operation. Therefore, the zero-point clear trigger signal input terminal receives a valid clear trigger signal when the steering wheel is turned to its left full limit for 5 seconds, then to its right full limit for 5 seconds, the vehicle speed is greater than 20 km / h, and the power-on time is within 30 seconds. The left full limit of the steering wheel refers to the steering wheel being turned to its mechanical steering limit, determined by the steering gear's mechanical limiting structure; once the steering wheel reaches this position, it cannot be turned further to the left. The right full limit of the steering wheel refers to the steering wheel being turned to its mechanical steering limit, once the steering wheel reaches this position, it cannot be turned further to the right. The generation of the clear trigger signal requires the simultaneous fulfillment of four conditions: the steering wheel must first be turned to the left to its mechanical limit position and held in that position for 5 seconds; after holding the left limit for 5 seconds, the steering wheel must be turned to the right to its mechanical limit position and held in that position for 5 seconds; the vehicle speed must be greater than 20 km / h, a condition monitored in real time by the vehicle speed acquisition circuit and the vehicle speed threshold comparison circuit; and the power-on duration must be within 30 seconds, meaning the clear trigger signal must be received within a 30-second time window from the moment the vehicle is first powered on. All four conditions must be met simultaneously for the zero-point clear trigger signal input terminal to receive a valid clear trigger signal; failure to meet any condition renders the clear trigger signal invalid. The technical effects achieved by this solution include: through the specific mechanical limit position operation combination of holding the left and right limits for 5 seconds, and the strict timing constraint of the 30-second power-on time window, the clear trigger requires the driver to perform a series of specific, non-routine driving operations, thus ensuring the high reliability of the clear trigger from both operational and timing perspectives, effectively preventing accidental clearing during normal driving.

[0028] Unless otherwise specified, the equipment components involved in the above embodiments are all conventional equipment components, and the connection methods and control methods involved are all conventional connection methods and control methods unless otherwise specified.

[0029] The present invention has been described in detail above with reference to the embodiments. However, those skilled in the art will understand that, without departing from the spirit of the present invention, various specific parameters in the above embodiments can be changed to form multiple specific embodiments, all of which are common variations of the present invention, and will not be described in detail here.

Claims

1. An EPS steering angle zero-point automatic calibration system, characterized in that, include: Vehicle speed acquisition circuit, steering wheel input torque acquisition circuit, torque threshold comparison circuit, vehicle speed threshold comparison circuit, timer, angle zero point calibration status latch, and main control MCU; The signal output terminal of the vehicle speed acquisition circuit is electrically connected to the vehicle speed signal input terminal of the main control MCU and the first input terminal of the vehicle speed threshold comparison circuit, respectively. The second input terminal of the vehicle speed threshold comparison circuit is connected to a preset vehicle speed threshold voltage, and the output terminal of the vehicle speed threshold comparison circuit is electrically connected to the first trigger input terminal of the main control MCU. The signal output terminal of the steering wheel input torque acquisition circuit is electrically connected to the torque signal input terminal of the main control MCU and the first input terminal of the torque threshold comparison circuit, respectively. The second input terminal of the torque threshold comparison circuit is connected to a preset torque threshold voltage, and the output terminal of the torque threshold comparison circuit is electrically connected to the second trigger input terminal of the main control MCU. The output terminal of the timer is electrically connected to the timing signal input terminal of the main control MCU. The angle zero-point calibration state latch is bidirectionally electrically connected to the main control MCU, and the latching state output terminal of the angle zero-point calibration state latch is electrically connected to the calibration enable control terminal of the main control MCU. The calibration execution signal output terminal of the main control MCU is electrically connected to the zero-point calibration enable input terminal of the EPS system.

2. The EPS steering angle zero-point automatic calibration system according to claim 1, characterized in that, The torque threshold comparison circuit includes a comparator, a first voltage divider resistor, and a second voltage divider resistor; the non-inverting input of the comparator is connected to the signal output of the steering wheel input torque acquisition circuit via the first voltage divider resistor, the inverting input of the comparator is connected to the preset torque threshold voltage via the second voltage divider resistor, and the output of the comparator is electrically connected to the second trigger input of the main control MCU.

3. The EPS steering angle zero-point automatic calibration system according to claim 1, characterized in that, The preset torque threshold voltage is the voltage value corresponding to a steering wheel input torque of 1 Newton-meter, and the preset vehicle speed threshold voltage is the voltage value corresponding to a vehicle speed of 20 kilometers per hour.

4. The EPS steering angle zero-point automatic driving calibration system according to claim 1, characterized in that, The zero-point calibration state latch is a latch chip. The data input terminal of the latch chip is electrically connected to the flag bit write terminal of the main control MCU. The clock input terminal of the latch chip is electrically connected to the flag bit latch control terminal of the main control MCU. The data output terminal of the latch chip is electrically connected to the flag bit read terminal and the calibration enable control terminal of the main control MCU, respectively.

5. The EPS steering angle zero-point automatic calibration system according to claim 1, characterized in that, The zero-point calibration state latch is an electrically erasable programmable read-only memory (EEPROM). The chip select pin, clock pin, and data input / output pin of the EEPROM are electrically connected to the corresponding general-purpose input / output ports of the main control MCU.

6. The EPS steering angle zero-point automatic driving calibration system according to claim 1, characterized in that, When the main control MCU outputs a vehicle speed compliance signal at the output terminal of the vehicle speed threshold comparison circuit, outputs a torque compliance signal at the output terminal of the torque threshold comparison circuit, and the timing duration output by the timer reaches 5 seconds, it outputs a zero-point calibration execution signal to the EPS system through the calibration execution signal output terminal.

7. The EPS steering angle zero-point automatic calibration system according to claim 1, characterized in that, It also includes a zero-point clear trigger signal input terminal, which is electrically connected to the clear trigger input port of the main control MCU; the main control MCU outputs a zero-point calibration execution signal to the EPS system through the calibration execution signal output terminal, and writes a zero-point flag clear signal through the angle zero-point calibration status latch.

8. The EPS steering angle zero-point automatic driving calibration system according to claim 7, characterized in that, The zero-point clearing trigger signal input terminal receives a valid clearing trigger signal when the steering wheel is turned to the left full limit position for 5 seconds and then to the right full limit position for 5 seconds, the vehicle speed is greater than 20 kilometers per hour, and the power-on duration is within 30 seconds; when the timing duration output by the timer reaches 30 seconds and the clearing trigger signal is valid, the main control MCU writes a zero-point flag clearing signal to the angle zero-point calibration status latch through the flag bit writing terminal.

9. The EPS steering angle zero-point automatic calibration system according to claim 1, characterized in that, When the flag bit output by the zero-point calibration state latch is 1, the main control MCU disables the signal output of the calibration execution signal output terminal.

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