Control method for eps assisted u-turn

Abstract

The application discloses an EPS auxiliary control method for U-turn, comprising the following steps: step S1, receiving a request signal and obtaining sensor data; the request signal comprises a request activation signal, a request angle signal and a request angular velocity signal; the sensor data comprises a hand torque, a motor torque, a vehicle speed, a steering wheel rotation angle and a steering wheel rotation speed; step S2, judging a current U-turn state according to the request signal and the sensor data, and setting a U-turn state flag bit; step S3, calculating an auxiliary torque and outputting the auxiliary torque according to the U-turn state flag bit, the request signal and the sensor data; and step S4, controlling an EPS motor to assist the U-turn according to the auxiliary torque. The application prevents the vehicle from rotating inaccurately or unstably due to the driver intervention or the change of the wheel angle during the rapid rotation of the vehicle body during the U-turn, and effectively improves the rotation stability and the driving safety by providing a suitable motor torque through the EPS.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to a control method for EPS-assisted U-turns on the spot. Background Technology

[0002] When a vehicle is stationary, the static friction between the tires and the ground is much greater than the sliding friction when the tires slip. When the vehicle's U-turn function is activated, it is very easy to overcome the initial static friction and turn the vehicle quickly. However, during this rapid rotation, changes in wheel angle or driver intervention with the steering wheel can affect the accuracy and stability of the vehicle's rotation, significantly increasing the difficulty of the U-turn and posing a driving risk. Therefore, how to enable the EPS (Electric Power Steering) to monitor and judge conditions such as driver's hand force, steering wheel angle angular velocity, and vehicle speed in real time, and provide appropriate motor torque to assist the vehicle in making a U-turn, thereby improving vehicle stability and driving safety, is a current technical challenge. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides an EPS-assisted U-turn control method, comprising the following steps:

[0004] Step S1: Receive request signals and acquire sensor data; the request signals include request activation signals, request angle signals, and request angular velocity signals; the sensor data includes hand torque, motor torque, vehicle speed, steering wheel angle, and steering wheel speed.

[0005] Step S2: Determine the current U-turn status based on the request signal and sensor data, and set the U-turn status flag.

[0006] Step S3: Calculate and output the auxiliary torque based on the stationary U-turn status flag, request signal, and sensor data;

[0007] Step S4: Control the EPS motor to assist in turning around in place according to the auxiliary torque.

[0008] Preferably, in step S2, the in-place turning state includes an inactive in-place turning state, a pending in-place turning state, an activated in-place turning state, and a malfunctioning in-place turning state.

[0009] Preferably, the in-place turn status flag includes 0, 1, 2 and 3, where 0 indicates that the in-place turn is not activated, 1 indicates that the in-place turn is pending activation, 2 indicates that the in-place turn is activated, and 3 indicates that the in-place turn is faulty.

[0010] Preferably, in step S3, when the in-place turn status flag is 0, 1, or 3, the auxiliary torque is 0; when the in-place turn status flag is 2, the auxiliary torque is calculated by the PID controller based on the difference between the requested angle signal and the actual angle signal.

[0011] Preferably, the method for calculating the auxiliary torque based on the difference between the requested angle signal and the actual angle signal using a PID controller is as follows: Step S31, obtaining the desired angular velocity by passing the difference between the requested angle signal and the actual angle signal through a PID controller; Step S32, limiting the amplitude and gradient of the desired angular velocity to obtain the limited desired angular velocity; Step S33, obtaining the desired auxiliary torque by passing the difference between the limited desired angular velocity and the actual angular velocity through a PID controller.

[0012] Preferably, step S3 further includes verifying the calculated auxiliary torque. If the verification fails, the auxiliary torque is directly reduced to 0 Nm. If the verification succeeds, the auxiliary torque is output.

[0013] The beneficial effects of this invention are as follows:

[0014] When making a U-turn on the spot, the EPS (Electric Power Supply) provides appropriate motor torque to prevent inaccurate or unstable vehicle rotation caused by driver intervention or changes in wheel angle during rapid vehicle rotation, effectively improving rotational stability and driving safety. Attached Figure Description

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0016] Figure 1 A schematic diagram illustrating the components of an auxiliary system for turning around in place;

[0017] Figure 2 A flowchart illustrating the control method for EPS-assisted in-situ U-turns. Detailed Implementation

[0018] 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.

[0019] The purpose of this invention is to provide a control method for EPS-assisted U-turns in place, which can solve the problem of vehicle stability and driving safety when driver intervention or changes in wheel angle affect vehicle rotation when the U-turn function is activated.

[0020] The components of an auxiliary U-turn control system are as follows: Figure 1 As shown, it includes a communication module, a vehicle speed sensor, a steering wheel angle and angular velocity sensor (or a motor RPS sensor), a steering wheel hand force sensor, a motor torque sensor, a stationary turn status recognition module, an auxiliary stationary turn torque control module, a safety verification module, and an EPS motor.

[0021] When a vehicle makes a U-turn, the steering precision may be reduced due to driver intervention or changes in wheel angle, which can affect the stability of the U-turn and reduce driving safety.

[0022] This invention provides a control method for EPS-assisted U-turns in place, comprising the following steps:

[0023] Step S1: Receive request signals and acquire sensor data; the request signals include request activation signals, request angle signals, and request angular velocity signals; the sensor data includes hand torque, motor torque, vehicle speed, steering wheel angle, and steering wheel speed.

[0024] Step S2: Determine the current U-turn status based on the request signal and sensor data, and set the U-turn status flag.

[0025] Step S3: Calculate and output the auxiliary torque based on the stationary U-turn status flag, request signal, and sensor data;

[0026] Step S4: Control the EPS motor to assist in turning around in place according to the auxiliary torque.

[0027] The specific control method for achieving EPS-assisted U-turn in conjunction with the vehicle control system is as follows:

[0028] In step S1, the communication module receives a request activation signal (s) from the host computer. req ), request angle signal (w) req ), requesting angular velocity signal (v req The data acquisition module obtains sensor data, such as hand force torque (m). tbt Motor torque (m) mot ), vehicle speed (v) veh Steering wheel angle (w) str ) and steering wheel speed (v str (or motor RPS rotation angle w) rps and rotational speed v rps )information.

[0029] In step S2, the U-turn status identification module determines the current U-turn status based on the obtained request signal and sensor data and sets the U-turn status flag: 0 indicates that the U-turn is not activated, 1 indicates that the U-turn is pending activation, 2 indicates that the U-turn is activated, and 3 indicates that the U-turn is in a fault state.

[0030] The logic for determining the status of a U-turn is as follows: if the activation request signal is not activated, the hand torque is less than the preset maximum hand torque, the motor torque is less than the preset maximum motor torque, the steering wheel angle is less than the preset maximum angle, and the steering wheel speed is less than the preset maximum speed, the U-turn status flag is set to 1; otherwise, it is set to 0.

[0031] That is, when the activation signal s is requested req =s no_request m tbt <m max_tbt (e.g., 1.0 Nm), hand torque m mot <m max_mot (e.g., 8Nm), motor torque w str_abs <w max_str (e.g., 60°), steering wheel angle v str_abs <v max_str (e.g., 60° / s) or motor RPS rotation angle w rps_abs <w max_rps (e.g., 1200°), motor RPS speed v rps_abs <v max_rps (e.g., 1200° / s) If all the above conditions are met, the in-place turn status flag will be set to 1; otherwise, it will be set to 0.

[0032] When the U-turn status flag is in position 1, if the activation request signal is active, the vehicle speed is less than the preset maximum U-turn speed, and the absolute value of the difference between the request angle signal and the steering wheel angle is less than the preset angle difference, the U-turn status flag will be set to position 2.

[0033] That is, when the in-place U-turn status flag is set to 1, and the activation signal s is requested. req =s request Vehicle speed v veh <v max_veh (e.g., 1 km / h), request the absolute value of the difference between the angle signal and the steering wheel angle (|w req -w str_abs |)<Δw diff When the angle is 10°, the position of the "turn around in place" status marker will be set to 2.

[0034] When the U-turn status flag is 0 or 1, the U-turn status flag will be set to 3 if any of the following conditions are met:

[0035] Condition 1: The hand force torque is greater than the preset first minimum torque, and the duration is greater than the first threshold; that is, m tbt >m min_tbt (e.g., 1.0 Nm) and the duration is greater than the first threshold (e.g., 300 ms);

[0036] Condition 2: The steering wheel angle is greater than the preset minimum steering angle, and the duration is greater than the second threshold; that is, w str_abs >w min_str (e.g., 60°) and the duration is greater than the second threshold (e.g., 30ms);

[0037] Condition 3: The steering wheel speed is greater than the preset minimum speed, and the duration is greater than the third threshold; that is, v str_abs >v min_str (e.g., 60° / s) and the duration is greater than the third threshold (e.g., 40ms).

[0038] Condition 4: The vehicle speed is greater than the preset minimum speed; that is, v veh >v min_veh (e.g., 100km / h).

[0039] Alternatively, conditions could be added regarding the motor's RPS angle and speed, i.e., w rps_abs >w min_rps (e.g., 1200°) and the duration is greater than the threshold (e.g., 40ms), v rps_abs >v min_rps (e.g., 1200° / s) and the duration is greater than the threshold (e.g., 30ms).

[0040] When the U-turn status indicator is at position 2, the U-turn status indicator will be changed to position 3 if any of the following conditions are met:

[0041] Condition 11: The hand torque is greater than the preset second minimum torque, and the duration is greater than the fourth threshold; that is, m tbt >m min_tbt2 (e.g., 3.0 Nm) and the duration is greater than the fourth threshold (e.g., 50 ms);

[0042] Condition 12: The steering wheel angle is greater than the preset minimum steering angle, and the duration is greater than the second threshold; that is, w str_abs >w min_str (e.g., 60°) and the duration is greater than the second threshold (e.g., 30ms);

[0043] Condition 13: The steering wheel speed is greater than the preset minimum speed, and the duration is greater than the third threshold; that is, v str_abs >v min_str (e.g., 60° / s) and the duration is greater than the third threshold (e.g., 40ms);

[0044] Condition 14: The requested angle signal is greater than the preset angle signal, and the duration is greater than the fifth threshold; that is, w req >w min_req (e.g., 60°) and the duration is greater than the fifth threshold (e.g., 40ms);

[0045] Condition 15: The requested angular velocity signal is greater than the preset angular velocity signal, and the duration is greater than the sixth threshold; that is, v str_abs >v min_str (e.g., 60° / s) and the duration is greater than the sixth threshold (e.g., 40ms);

[0046] Condition 16: The absolute value of the difference between the requested angle signal and the steering wheel angle is greater than the preset angle difference, and the duration is greater than the seventh threshold; that is, |w req -w str_abs |)>Δw diff (e.g., 60°) and the duration is greater than the threshold (e.g., 30ms);

[0047] Condition 17: The vehicle speed is greater than the preset minimum speed; that is, v veh >v min_veh1 (e.g., 200 km / h).

[0048] In step S3, the auxiliary U-turn torque control module calculates the auxiliary torque based on the status flags output by the U-turn status recognition module, the requested angle and angular velocity, vehicle speed, steering wheel angle and angular velocity, and hand force. When the U-turn status flag is 0, 1, or 3, the auxiliary torque is 0; when the U-turn status flag is 2, the auxiliary torque is calculated by the PID controller based on the difference between the requested angle signal and the actual angle signal.

[0049] More specifically, the method for calculating the auxiliary torque using a PID controller based on the difference between the requested angle signal and the actual angle signal is as follows:

[0050] Step S31: The desired angular velocity is obtained by passing the difference between the requested angle signal and the actual angle signal through a PID controller.

[0051] Step S32: Limit the amplitude and gradient of the desired angular velocity to obtain the desired angular velocity after the limit;

[0052] In step S33, the difference between the limited desired angular velocity and the actual angular velocity is processed by a PID controller to obtain the desired auxiliary torque.

[0053] The aforementioned angle signal can also be replaced by rack-and-pinion related signals. For example, when the position of the "turning in place" status flag is 2, the expected rack speed is obtained by the PID controller based on the difference between the expected rack position and the actual rack position. The expected rack speed is then limited by the amplitude and gradient to obtain the limited expected rack speed. The difference between the limited expected rack speed and the actual rack position is then used by the PID controller to obtain the expected motor control torque. Finally, the dual closed-loop control system of the control module will output the calculated auxiliary torque.

[0054] Preferably, step S3 further includes verifying the calculated auxiliary torque. If the verification fails, the auxiliary torque is directly reduced to 0 Nm. If the verification succeeds, the auxiliary torque is output.

[0055] The EPS motor controls the in-situ turn to assist in turning around, based on the motor compensation torque input from the auxiliary in-situ turn torque control module. The flowchart of the entire auxiliary in-situ turn function is as follows: Figure 2 As shown.

[0056] 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 control method for EPS-assisted U-turn in place, characterized in that, Includes the following steps: Step S1: Receive request signals and acquire sensor data; the request signals include request activation signals, request angle signals, and request angular velocity signals; the sensor data includes hand torque, motor torque, vehicle speed, steering wheel angle, and steering wheel speed. Step S2: Determine the current U-turn status based on the request signal and sensor data, and set the U-turn status flag. Step S3: Calculate and output the auxiliary torque based on the stationary U-turn status flag, request signal, and sensor data; Step S4: Control the EPS motor to assist in turning around on the spot according to the auxiliary torque; In step S2, the in-place turning state includes the in-place turning not activated state, the in-place turning waiting to be activated state, the in-place turning activated state, and the in-place turning failure state. The flag for the U-turn status includes 0, 1, 2 and 3, where 0 indicates that the U-turn is not activated, 1 indicates that the U-turn is pending activation, 2 indicates that the U-turn is activated, and 3 indicates that the U-turn is faulty. When the U-turn status flag is 0 or 1, the U-turn status flag will be set to 3 if any of the following conditions are met: Condition 1: The hand force torque is greater than the preset first minimum torque, and the duration is greater than the first threshold. Condition 2: The steering wheel angle is greater than the preset minimum angle, and the duration is greater than the second threshold. Condition 3: The steering wheel speed is greater than the preset minimum speed, and the duration is greater than the third threshold. Condition 4: The vehicle speed is greater than the preset minimum speed.

2. The EPS-assisted in-situ turning control method according to claim 1, characterized in that, In step S3, when the in-place turn status flag is 0, 1, or 3, the auxiliary torque is 0; when the in-place turn status flag is 2, the auxiliary torque is calculated by the PID controller based on the difference between the requested angle signal and the actual angle signal.

3. The EPS-assisted in-situ turning control method according to claim 2, characterized in that, The method for calculating the auxiliary torque using a PID controller based on the difference between the requested angle signal and the actual angle signal is as follows: Step S31: The desired angular velocity is obtained by passing the difference between the requested angle signal and the actual angle signal through a PID controller. Step S32: Limit the amplitude and gradient of the desired angular velocity to obtain the desired angular velocity after the limit; In step S33, the difference between the limited desired angular velocity and the actual angular velocity is processed by a PID controller to obtain the desired auxiliary torque.

4. The EPS-assisted in-situ turning control method according to claim 1, characterized in that, Step S3 also includes verifying the calculated auxiliary torque. If the verification fails, the auxiliary torque is directly reduced to 0 Nm. If the verification succeeds, the auxiliary torque is output.

5. The EPS-assisted in-situ turning control method according to claim 1, characterized in that, If the activation request signal is not activated, the hand torque is less than the preset maximum hand torque, the motor torque is less than the preset maximum motor torque, the steering wheel angle is less than the preset maximum angle, and the steering wheel speed is less than the preset maximum speed, the stationary turn status flag will be set to 1; otherwise, it will be set to 0.

6. The EPS-assisted in-situ turning control method according to claim 1, characterized in that, When the U-turn status flag is in position 1, if the activation request signal is active, the vehicle speed is less than the preset maximum U-turn speed, and the absolute value of the difference between the request angle signal and the steering wheel angle is less than the preset angle difference, the U-turn status flag will be set to position 2.

7. The EPS-assisted in-situ turning control method according to claim 1, characterized in that, When the U-turn status indicator is at position 2, the U-turn status indicator will be changed to position 3 if any of the following conditions are met: Condition 11: The hand force torque is greater than the preset second minimum torque, and the duration is greater than the fourth threshold. Condition 12: The steering wheel angle is greater than the preset minimum angle, and the duration is greater than the second threshold. Condition 13: The steering wheel speed is greater than the preset minimum speed, and the duration is greater than the third threshold. Condition 14: The requested angle signal is greater than the preset angle signal, and the duration is greater than the fifth threshold. Condition 15: The requested angular velocity signal is greater than the preset angular velocity signal, and the duration is greater than the sixth threshold. Condition 16: The absolute value of the difference between the requested angle signal and the steering wheel angle is greater than the preset angle difference, and the duration is greater than the seventh threshold. Condition 17: The vehicle speed is greater than the preset minimum speed.

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