Parallel axis electronic power steering system steering stick detection and early warning method

Abstract

The application discloses a parallel axis type electronic power steering system steering jam detection and early warning method, which comprises the following steps: after a vehicle is started, a steering system controller performs power-on self-checking; an initial value of a power-assisted motor rotor position is acquired; when the vehicle meets preset activation conditions, a jam detection function is activated; according to the size and positive and negative of a steering wheel hand torque, a corresponding type of motor torque waveform mode is output; according to the steering wheel hand torque, a basic power-assisted curve is obtained by table lookup, and a basic power-assisted torque is obtained, and the output target motor torque is superimposed to serve as a final requested torque of the power-assisted motor. The application does not need to install additional sensors, acquires necessary input signals by receiving electronic power steering system and vehicle CAN communication nodes, actively detects the steering jam function, and saves cost.

Description

Technical Field

[0001] This invention relates to the field of automotive steering system technology, specifically to a method for detecting and warning of steering sticking in a parallel-axis electronic power steering system. Background Technology

[0002] Ball screw pairs are widely used in parallel-axis electronic power steering systems due to their advantages of high precision, reversibility, and high efficiency. However, in some extreme low-temperature environments, the rotational torque of the ball screw pair increases, leading to uneven rotation, affecting the driver's feel, and in severe cases, even causing the screw to seize up, endangering the driving safety of the entire vehicle.

[0003] Therefore, actively detecting and promptly alerting the driver to abnormal situations such as increased frictional torque in ball screw pairs under extreme low-temperature environments caused by temperature changes, and preventing vehicle deviation due to steering sticking to ensure driving safety, is a current technical challenge. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for detecting and warning of steering sticking in a parallel-axis electronic power steering system, comprising the following steps:

[0005] Step S1: After the vehicle is started, the steering system controller performs a power-on self-test.

[0006] Step S2: Obtain the initial value of the rotor position of the boost motor after power-on, and calculate the relative change value of the current rotor position of the boost motor;

[0007] Step S3: When the vehicle meets the preset activation conditions, activate the jam detection function and proceed to step S4; when the vehicle does not meet the preset activation conditions, end all steps.

[0008] Step S4: Based on the magnitude and sign of the steering wheel torque, output the corresponding type of motor torque waveform mode;

[0009] Step S5: Output the target motor torque based on the motor torque waveform pattern output in step S4;

[0010] Step S6: Based on the steering wheel hand torque, look up the basic power assist curve in the table to obtain the basic power assist torque, and add the target motor torque output in step S5 as the final requested torque of the power assist motor.

[0011] Step S7: When it is detected that condition four is not met, exit the jam detection function and set the target motor torque to zero.

[0012] The aforementioned satisfying the preset activation conditions specifically means satisfying all of the following conditions:

[0013] Condition 1: The steering system status, steering wheel torque, steering angle sensor status, and power steering motor rotor position are all valid.

[0014] Condition 2: The absolute value of the steering wheel angle does not exceed the maximum steering angle setting value;

[0015] Condition 3: The temperature of the steering controller does not exceed the maximum temperature setting.

[0016] Condition 4: The relative change in the rotor position of the assist motor does not exceed the maximum position setting value;

[0017] Condition 5: The vehicle speed is not lower than the minimum speed setting value;

[0018] Condition 6: Steering jam detection function is enabled.

[0019] Preferably, in step S1, after the vehicle is started by ignition, the steering system controller reads the steering sticking count value of the previous ignition cycle stored in the non-volatile random access memory.

[0020] Preferably, in step S3, the steering jam detection function is implemented through a steering jam detection state machine module. The steering jam detection state machine has 5 states, namely jam detection initialization state, jam detection activation state, jam detection exit state, jam detection torque output state, and jam detection fault confirmation state.

[0021] Preferably, in step S4, the specific method for outputting the corresponding type of motor torque waveform mode according to the magnitude and sign of the steering wheel torque is as follows:

[0022] When the absolute value of the steering wheel torque is less than the set maximum dead zone value and the steering wheel torque is non-negative, the motor torque waveform mode enters the positive symmetrical sawtooth wave mode.

[0023] When the absolute value of the steering wheel torque is less than the set maximum dead zone value and the steering wheel torque is negative, the motor torque waveform mode enters the reverse symmetrical sawtooth wave mode.

[0024] When the absolute value of the steering wheel torque is greater than the set maximum dead zone value, and the steering wheel torque is non-negative, the motor torque waveform mode enters the positive synchronous sawtooth wave mode.

[0025] When the absolute value of the steering wheel torque is greater than the set maximum dead zone value and the steering wheel torque is negative, the motor torque waveform mode enters the reverse synchronous sawtooth wave mode.

[0026] Preferably, when the motor torque waveform mode is in the positive synchronous sawtooth wave mode, at time t0 within the jam detection cycle, when the steering wheel torque changes from greater than the set maximum dead zone value to less than the opposite of the set maximum dead zone value, the motor torque waveform mode migrates to the reverse synchronous sawtooth wave mode.

[0027] Preferably, when the motor torque waveform mode is in the reverse synchronous sawtooth wave mode, at time t0 within the jam detection cycle, when the steering wheel hand torque changes from the opposite number of the value less than the set maximum dead zone value to the value greater than the set maximum dead zone value, the motor torque waveform mode migrates to the forward synchronous sawtooth wave mode.

[0028] Preferably, the amplitude of the output target motor torque is calibrated, and the specific calibration steps are as follows:

[0029] Step A: Install the parallel shaft type electronic power steering sticking fault component on the vehicle. Place the vehicle on a flat, low-friction surface with the steering wheel in the center position and in a free state without human intervention.

[0030] Step B: Inject a preset sawtooth wave motor torque and observe whether the steering wheel angle changes. If the steering wheel rotates, gradually decrease the injected torque according to the preset torque gradient; if the steering wheel does not rotate, gradually increase the amplitude of the injected sawtooth wave torque according to the preset torque gradient.

[0031] Step C: Repeat step B above until the critical value of the injected sawtooth wave torque is obtained, which makes the steering wheel vibrate slightly and the change value of the observed motor rotor position signal is less than the set angle. The amplitude of the currently injected sawtooth wave torque is taken as the amplitude of the target motor torque.

[0032] Preferably, in step S7, when the jamming detection function exits the active state, or the set activation condition detection cycle is reached, the target motor torque is set to 0.

[0033] Preferably, in step S7, when the steering jamming detection state machine module is in the jamming detection fault confirmation state, the steering jamming count value is incremented by one.

[0034] Preferably, in step S5, a safety limit is applied to the output target motor torque. The specific safety limit method is as follows:

[0035] When the relative change in the rotor position of the assist motor does not exceed the maximum position setting value, the torque of the target motor is limited to the maximum torque setting value;

[0036] When the relative change in the rotor position of the assist motor exceeds the maximum position setting value, and the target motor torque is not 0, the target motor torque is limited to 0.

[0037] Preferably, the method for detecting and warning of steering lag in the parallel-axis electronic power steering system further includes step S8, whereby when the steering lag detection status machine module is in a lag detection fault confirmation state, the steering fault indicator light on the instrument panel is illuminated through a diagnostic message.

[0038] Compared with the prior art, the present invention provides a method for detecting and warning of steering sticking in a parallel shaft electronic power steering system. It can identify and provide early warning of abnormal situations where the friction torque of the ball screw pair increases due to temperature changes in extreme low-temperature environments, thereby improving the driver's driving safety.

[0039] This invention performs steering jam detection after the driver starts the engine and powers on the vehicle. The active detection has no impact on the driver's experience, and the vehicle's driving safety is controllable after the jam detection is activated.

[0040] This invention eliminates the need for additional sensors. It obtains the necessary input signals from the electronic power steering system and the vehicle's CAN communication node to achieve the active detection of steering lag, thus saving costs. Attached Figure Description

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0042] Figure 1 A schematic diagram of a vehicle power steering system structure for implementing a method to detect and warn of steering sticking in a parallel-axis electronic power steering system.

[0043] Figure 2 This is a schematic diagram of the state changes of the steering jam detection state machine module in Example 1;

[0044] Figure 3 This is a schematic diagram of the motor torque waveform pattern in Example 1;

[0045] Figure 4 This is a schematic diagram illustrating the migration of the motor torque waveform pattern in Example 1;

[0046] Figure 5 This is a schematic diagram of the method for safely limiting the output target motor torque in Example 2. Detailed Implementation

[0047] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can fully understand other advantages and technical effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific embodiments, and the details in this specification can also be applied based on different viewpoints, with various modifications or changes made without departing from the overall design concept of the invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. The following exemplary embodiments of the present invention can be implemented in many different forms and should not be construed as being limited to the specific embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete, and to fully convey the technical solutions of these exemplary embodiments to those skilled in the art.

[0048] The methods for detecting and warning of steering sticking in parallel-axis electronic power steering systems in Examples 1 and 2 below can be adopted as follows: Figure 1 The software and hardware architecture of the vehicle power steering system shown is implemented.

[0049] The vehicle power steering system includes an external communication input module, a complex drive module, a system state machine module, an ADC acquisition module, a non-volatile storage module, a steering sticking detection state machine module, a sticking detection torque calculation module, a safety limiting module, a basic power steering module, a communication diagnostic module, and a motor control module.

[0050] The external communication input module receives vehicle speed signals from the vehicle communication node and connects to the input of the steering sticking detection state machine module.

[0051] The complex drive module receives and calculates the rotor position information of the power steering motor and connects to input terminal two of the steering sticking detection state machine module. The system state machine module calculates the system state and connects to input terminal three of the steering sticking detection state machine module.

[0052] The ADC acquisition module collects steering wheel torque, steering wheel angle, steering controller temperature, and steering angle sensor status, and connects to input terminal four of the steering sticking detection state machine module, input terminal two of the steering sticking detection torque calculation module, and input terminal one of the basic power assist module.

[0053] The non-volatile memory module is used to read and store the steering sticking count value and is connected to input terminal five of the steering sticking detection state machine module. The steering sticking detection state machine module calculates the sticking detection state in real time based on the input signal and is connected to input terminal one of the communication diagnostic output module and input terminal one of the steering sticking detection torque calculation module.

[0054] The steering sticking detection torque calculation module calculates the target motor torque required for detection and connects to the input of the safety limiting module. The safety limiting module imposes torque boundary restrictions on the target motor torque and adds it to the basic assist torque output by the basic assist module to obtain the final requested torque for the assist motor.

[0055] Example 1

[0056] This embodiment provides a method for detecting and warning of steering sticking in a parallel-axis electronic power steering system, including the following steps:

[0057] Step S1: After the vehicle is started, the steering system controller performs a power-on self-test and reads the steering sticking count value of the previous ignition cycle stored in the non-volatile random access memory.

[0058] Step S2: Obtain the initial value of the rotor position of the boost motor after power-on, and calculate the relative change value of the current rotor position of the boost motor;

[0059] Step S3: When the vehicle meets the preset activation conditions, activate the jam detection function and proceed to step S4; when the vehicle does not meet the preset activation conditions, end all steps.

[0060] Step S4: Based on the magnitude and sign of the steering wheel torque, output the corresponding type of motor torque waveform mode;

[0061] Step S5: Output the target motor torque based on the motor torque waveform pattern output in step S4;

[0062] Step S6: Based on the steering wheel hand torque, look up the basic power assist curve in the table to obtain the basic power assist torque, and add the target motor torque output in step S5 as the final requested torque of the power assist motor.

[0063] Step S7: When it is detected that condition four is not met, exit the jamming detection function and set the target motor torque to zero.

[0064] Meeting the preset activation conditions specifically means meeting all of the following conditions:

[0065] Condition 1: The steering system status, steering wheel torque, steering angle sensor status, and power steering motor rotor position are all valid.

[0066] Condition 2: The absolute value of the steering wheel angle does not exceed the maximum steering angle setting (e.g., 180°);

[0067] Condition 3: The temperature of the steering controller does not exceed the maximum temperature setting (e.g., 4°C);

[0068] Condition 4: The relative change in the rotor position of the assist motor does not exceed the maximum position setting value (e.g., 3°);

[0069] Condition 5: The vehicle speed is not lower than the minimum speed setting (e.g., 5 kph);

[0070] Condition 6: Steering jam detection function is enabled.

[0071] Preferably, the sticking detection function is implemented through a steering sticking detection state machine module, specifically as follows: Figure 2 As shown: The steering jamming detection status machine has 5 states, namely jamming detection initialization state, jamming detection activation state, jamming detection exit state, jamming detection torque output state, and jamming detection fault confirmation state.

[0072] It acquires the current steering system status, steering system controller temperature, steering wheel torque, steering angle sensor status, steering wheel angle, power steering motor rotor position, and vehicle speed.

[0073] Where T0 represents power-on self-test; T1 represents the status of the steering system, steering wheel torque, angle sensor status, and power steering motor rotor position (meeting condition one), and the absolute value of the steering wheel angle does not exceed the maximum angle setting of 180° (meeting condition two), the steering controller temperature does not exceed the maximum temperature setting of 4℃ (meeting condition three), the relative change value of the power steering motor rotor position does not exceed the maximum position setting of 3° (meeting condition four), the vehicle speed is not lower than the minimum speed setting of 5kph (meeting condition five), and the steering sticking detection function is enabled (meeting condition six); T2 The following conditions must be met: the absolute value of the steering wheel angle exceeds the maximum steering angle setting by 180° (condition two is not met); the relative change in the position of the power steering motor rotor exceeds the maximum position setting by 3° (condition four is not met); the steering controller temperature exceeds the maximum temperature setting by 4° (condition three is not met); the vehicle speed is not lower than the minimum speed setting by 5 kph when the steering wheel hand torque is invalid (condition one is not met); the vehicle speed is not lower than the minimum speed setting by 5 kph when the power steering motor rotor position is invalid (condition one is not met); or the vehicle speed is not lower than the minimum speed setting by 5 kph when the steering angle sensor is invalid. A value of 5 kph (not meeting condition one), or the steering jamming function is not enabled (not meeting condition six); T3 represents the relative change in the position of the power steering motor rotor exceeding the maximum position setting value by 3° (not meeting condition four); T4 represents the relative change in the position of the power steering motor rotor not exceeding the maximum position setting value by 3° (meeting condition four); T5 represents the relative change in the position of the power steering motor rotor not less than the maximum position setting value by 3° (not meeting condition four), or the absolute value of the steering wheel angle exceeds the maximum angle setting value by 180° (not meeting condition two), or the angle sensor is invalid (not meeting condition six). Condition 1); T6 represents the vehicle speed being less than the minimum speed setting value of 5 kph (condition 5 is not met), and T7 represents the relative change value of the assist motor rotor position not exceeding the maximum position setting value of 3° within the set 6s detection time (condition 4 is met); when T0 is met, the system enters the jam detection initialization state. At this time, if T2 is not met and T1 is met, the system enters the jam detection activation state. Then, if T3 is not met and T4 is met, the system enters the jam detection torque output state. Finally, if T5 and T6 are not met and T7 is met, the system enters the jam detection fault confirmation state.

[0074] Step S4: Based on the magnitude and sign of the steering wheel torque, output the corresponding type of motor torque waveform mode; such as... Figure 3 As shown, the specific motor torque waveform pattern is as follows:

[0075] 1. When the absolute value of the steering wheel torque is less than the set maximum dead zone value and the steering wheel torque is non-negative, the motor torque waveform mode enters the positive symmetrical sawtooth wave mode (a).

[0076] 2. When the absolute value of the steering wheel torque is less than the set maximum dead zone value and the steering wheel torque is negative, the motor torque waveform mode enters the reverse symmetrical sawtooth wave mode (b).

[0077] 3. When the absolute value of the steering wheel torque is greater than the set maximum dead zone value, and the steering wheel torque is non-negative, the motor torque waveform mode enters the positive synchronous sawtooth wave mode (c).

[0078] 4. When the absolute value of the steering wheel torque is greater than the set maximum dead zone value and the steering wheel torque is negative, the motor torque waveform mode enters the reverse synchronous sawtooth wave mode (d).

[0079] In some modes, when the steering wheel torque changes, a corresponding mode transition is required. The transition of the motor torque waveform mode is as follows: Figure 4 As shown:

[0080] When the motor torque waveform mode is in the positive synchronous sawtooth wave mode (a), at time t0 within the jam detection cycle, when the steering wheel hand torque changes from greater than the set maximum dead zone value to less than the opposite number of the set maximum dead zone value, the motor torque waveform mode needs to be switched to the reverse synchronous sawtooth wave mode. That is, after time t0, the motor torque waveform changes from the solid line in Figure (a) to the dashed line output.

[0081] When the motor torque waveform mode is in the reverse synchronous sawtooth wave mode (b), at time t0 within the jam detection cycle, when the steering wheel torque changes from the opposite number of the maximum dead zone value less than the set value to the value greater than the set value, the motor torque waveform mode needs to be switched to the forward synchronous sawtooth wave mode. That is, after time t0, the motor torque waveform changes from the solid line in Figure (b) to the dashed line output.

[0082] Preferably, the amplitude of the target motor torque output in step S5 is calibrated. The specific calibration steps are as follows:

[0083] Step A: Install the parallel shaft type electronic power steering sticking fault component on the vehicle. Place the vehicle on a flat, low-friction surface with the steering wheel in the center position and in a free state without human intervention.

[0084] Step B: Inject a preset sawtooth wave motor torque (e.g., 0.5Hz 1Nm), and observe whether the steering wheel angle changes. If the steering wheel rotates, gradually decrease the injected torque according to the preset torque gradient (e.g., 0.1Nm); if the steering wheel does not rotate, gradually increase the amplitude of the injected sawtooth wave torque according to the torque gradient of 0.1Nm.

[0085] Step C: Repeat step B above until the critical value of injected sawtooth wave torque of 3° is obtained, which makes the steering wheel vibrate slightly and the change value of the observed motor rotor position signal is less than the set angle. The amplitude of the currently injected sawtooth wave torque is taken as the amplitude of the target motor torque.

[0086] Preferably, in step S7, when the jamming detection function exits the active state, or reaches the set activation condition detection cycle (e.g., 6s), the target motor torque is set to 0.

[0087] Preferably, in step S7, when the steering jamming detection state machine module is in the jamming detection fault confirmation state, the steering jamming count value is incremented by one.

[0088] Example 2

[0089] Based on Example 1, the parallel shaft electronic power steering system steering jam detection and early warning method provided in this example further limits the output target motor torque in step S5.

[0090] The principles of specific security restriction methods are as follows: Figure 5 As shown:

[0091] When the relative change in the rotor position of the assist motor does not exceed the maximum position setting value (e.g., 3°), the target motor torque is limited to the maximum torque setting value (e.g., 1 Nm).

[0092] When the relative change in the rotor position of the assist motor exceeds the maximum position setting value (e.g., 3°) and the target motor torque is not 0, the target motor torque is limited to 0.

[0093] Example 3

[0094] Based on Example 1, the method for detecting and warning of steering lag in a parallel-axis electronic power steering system provided in this example further adds step S8. When the steering lag detection state machine module is in the lag detection fault confirmation state, the steering malfunction indicator light on the instrument panel is illuminated through a diagnostic message. The fault can only be cleared and the malfunction indicator light will turn off when a vehicle diagnostic service command is received to clear the fault.

[0095] Under normal circumstances, it is necessary to determine in real time whether the jam detection function is enabled. If the jam detection function is not enabled, the jam detection function should be turned off and the fault light should be illuminated. When the jam detection function is enabled, but the jam detection status machine does not detect the jam confirmed state, the steering fault indicator light on the instrument panel should be turned off.

[0096] At the same time, the steering jamming fault count value obtained in step 7 needs to be stored in non-volatile random access memory when the steering system is powered off and in sleep mode, for reading in the next ignition cycle.

[0097] The present invention has been described in detail above through specific embodiments and examples, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for detecting and warning of steering sticking in a parallel-axis electronic power steering system, characterized in that, Includes the following steps: Step S1: After the vehicle is started, the steering system controller performs a power-on self-test. Step S2: Obtain the initial value of the rotor position of the boost motor after power-on, and calculate the relative change value of the current rotor position of the boost motor; Step S3: When the vehicle meets the preset activation conditions, activate the jam detection function and proceed to step S4; when the vehicle does not meet the preset activation conditions, end all steps. Step S4: Based on the magnitude and sign of the steering wheel torque, output the corresponding type of motor torque waveform mode; calibrate the amplitude of the output target motor torque. The specific calibration steps are as follows: Step A: Install the parallel shaft type electronic power steering sticking fault component on the vehicle. Place the vehicle on a flat, low-friction surface with the steering wheel in the center position and in a free state without human intervention. Step B: Inject a preset sawtooth wave motor torque and observe whether the steering wheel angle changes. If the steering wheel rotates, gradually decrease the injected torque according to the preset torque gradient; if the steering wheel does not rotate, gradually increase the amplitude of the injected sawtooth wave torque according to the preset torque gradient. Step C: Repeat step B above until the critical value of the injected sawtooth wave torque is obtained, which makes the steering wheel vibrate slightly and the change value of the observed motor rotor position signal is less than the set angle. The amplitude of the currently injected sawtooth wave torque is taken as the amplitude of the target motor torque. Step S5: Based on the motor torque waveform pattern output in step S4, output the target motor torque; apply a safety limit to the output target motor torque, specifically as follows: when the relative change in the position of the assist motor rotor does not exceed the maximum position setting value, the target motor torque is limited to within the maximum torque setting value; when the relative change in the position of the assist motor rotor exceeds the maximum position setting value, and the target motor torque is not 0, the target motor torque is limited to 0. Step S6: Based on the steering wheel hand torque, look up the basic power assist curve in the table to obtain the basic power assist torque, and add the target motor torque output in step S5 as the final requested torque of the power assist motor. Step S7: When it is detected that condition four is not met, exit the jam detection function and set the target motor torque to zero. The aforementioned satisfying the preset activation conditions specifically means satisfying all of the following conditions: Condition 1: The steering system status, steering wheel torque, steering angle sensor status, and power steering motor rotor position are all valid. Condition 2: The absolute value of the steering wheel angle does not exceed the maximum steering angle setting value; Condition 3: The temperature of the steering controller does not exceed the maximum temperature setting. Condition 4: The relative change in the rotor position of the assist motor does not exceed the maximum position setting value; Condition 5: The vehicle speed is not lower than the minimum speed setting value; Condition 6: Steering jam detection function is enabled; The power steering system includes an external communication input module, a complex drive module, a system state machine module, an ADC acquisition module, a non-volatile storage module, a steering lag detection state machine module, a lag detection torque calculation module, a safety limiting module, a basic power steering module, a communication diagnostic module, and a motor control module. The external communication input module receives vehicle speed signals from the vehicle communication node and is connected to input terminal one of the steering lag detection state machine module. The complex drive module receives and calculates the power steering motor rotor position information and is connected to input terminal two of the steering lag detection state machine module. The system state machine module calculates the system state and connects to the input terminals of the steering jam detection state machine module. The ADC acquisition module collects steering wheel torque, steering wheel angle, steering controller temperature, and steering angle sensor status, and connects to input terminal four of the steering sticking detection state machine module, input terminal two of the steering sticking detection torque calculation module, and input terminal one of the basic power assist module.

2. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 1, characterized in that, In step S1, after the vehicle is started by ignition, the steering system controller reads the steering sticking count value of the previous ignition cycle stored in the non-volatile random access memory.

3. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 1, characterized in that, In step S3, the steering jam detection function is implemented through the steering jam detection state machine module. The steering jam detection state machine has 5 states, namely jam detection initialization state, jam detection activation state, jam detection exit state, jam detection torque output state, and jam detection fault confirmation state.

4. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 1, characterized in that, In step S4, the specific method for outputting the corresponding type of motor torque waveform mode based on the magnitude and sign of the steering wheel torque is as follows: When the absolute value of the steering wheel torque is less than the set maximum dead zone value and the steering wheel torque is non-negative, the motor torque waveform mode enters the positive symmetrical sawtooth wave mode. When the absolute value of the steering wheel torque is less than the set maximum dead zone value and the steering wheel torque is negative, the motor torque waveform mode enters the reverse symmetrical sawtooth wave mode. When the absolute value of the steering wheel torque is greater than the set maximum dead zone value, and the steering wheel torque is non-negative, the motor torque waveform mode enters the positive synchronous sawtooth wave mode. When the absolute value of the steering wheel torque is greater than the set maximum dead zone value and the steering wheel torque is negative, the motor torque waveform mode enters the reverse synchronous sawtooth wave mode.

5. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 4, characterized in that, When the motor torque waveform mode is in the positive synchronous sawtooth wave mode, at time t0 within the jam detection cycle, when the steering wheel torque changes from greater than the set maximum dead zone value to less than the opposite of the set maximum dead zone value, the motor torque waveform mode will switch to the reverse synchronous sawtooth wave mode.

6. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 4, characterized in that, When the motor torque waveform mode is in the reverse synchronous sawtooth wave mode, at time t0 within the jam detection cycle, when the steering wheel torque changes from the opposite number of the value less than the set maximum dead zone value to the value greater than the set maximum dead zone value, the motor torque waveform mode will switch to the forward synchronous sawtooth wave mode.

7. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 1, characterized in that, In step S7, when the jamming detection function exits the active state, or the set activation condition detection cycle is reached, the target motor torque is set to 0.

8. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 3, characterized in that, In step S7, when the steering jamming detection state machine module is in the jamming detection fault confirmation state, the steering jamming count value is incremented by one.

9. The method for detecting and warning of steering sticking in a parallel-axis electronic power steering system according to claim 3, characterized in that, The method for detecting and warning of steering lag in the parallel-axis electronic power steering system further includes step S8, whereby when the steering lag detection status machine module is in a lag detection fault confirmation state, the steering fault indicator light on the instrument panel is illuminated through a diagnostic message.

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