Method for controlling drivability of automatic parking vehicle

Abstract

The invention discloses a drivability control method for an automatic parking vehicle. The drivability control method comprises the steps that a VLC restrains and controls the actual working speed of the whole vehicle through the real-time distance of an APA, the limited vehicle speed and the steering angle of a steering wheel; meanwhile, the target acceleration of the whole vehicle is restrained and controlled based on the deviation between the target vehicle speed and the actual vehicle speed, and PI D control is conducted through the real-time acceleration calculated through the real-time distance and the real-time vehicle speed. In the parking control process of the vehicle, the accurate parking distance is guaranteed, and meanwhile the drivability of low-speed driving is guaranteed through a VLC longitudinal control algorithm. Intervention values are preset according to all the working conditions, so that the longitudinal comfort and smoothness of the vehicle in the APA low-speed running process are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automatic driving control, in particular to a driving performance control method of an automatic parking vehicle. BACKGROUND

[0002] As an important function of assisted driving, automatic parking is gradually popularized and applied in vehicles, and the automatic parking function is integrated in the vehicle APA system (Automated Parking System).

[0003] When the same vehicle model is equipped with different types of electric control chassis, the driving performance of the vehicle is different when the actual VLC control is performed due to the different structures of various electric control chassis. Since the APA has a relatively high requirement for parking accuracy, when the APA longitudinal control is performed on the electric control chassis of the same industry, only the safety during the APA process is pursued, and the driving performance and comfort of the driver during the actual operation are ignored, so that the vehicle cannot meet the requirements of the driving performance and comfort of the driver during the APA control process. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a driving performance control method of an automatic parking vehicle, which optimizes and improves the driving performance and comfort during automatic parking through VLC longitudinal control, and improves the user experience of automatic parking.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a driving performance control method of an automatic parking vehicle, VLC obtains the following information, including but not limited to APA real-time distance, APA limited speed, EPS steering wheel angle and other information. According to the APA real-time distance, the APA limited speed and the EPS steering wheel angle, the current actual target speed of the VLC is determined; according to the deviation between the target speed and the current actual speed of the vehicle, the target acceleration of the vehicle is calibrated; the real-time acceleration calculated according to the real-time distance and the real-time speed is subjected to PID control with the calibrated target acceleration. The above control method solves the problem of driving performance and comfort during parking.

[0006] The WCBS controller receives the signal sent by the APA controller and the actual working speed of the vehicle is controlled by the VLC according to the signal sent by the APA.

[0007] The VLC uses smooth torque to control the actual speed of the vehicle, and when the vehicle speed fluctuates, the vehicle speed fluctuation during driving is adjusted by PID adjustment.

[0008] The current vehicle is collected and judged by a vehicle-mounted sensor whether it is in a flat ground condition, if it is in the flat ground condition and automatic parking is performed, in the starting acceleration process of the automatic parking, the VCL controls the vehicle to accelerate from the static state to the target speed according to the target speed and the target distance with the set driving torque;

[0009] In the automatic parking stable process, the preset stable torque is used to control the vehicle to keep the speed stable, and in the automatic parking deceleration parking process, the current parking distance is used to control the speed to slow down to the static state in a linear mode through the set stable torque.

[0010] In the automatic parking process of the vehicle, the actual torque of the EMS is controlled to slow down until it is exited, the gear shifting process is that the VLC requests the TCU to realize the gear shifting according to the target gear, and the VLC judges the torque control intervention time according to the actual performance of the vehicle.

[0011] The current vehicle is collected and judged by a vehicle-mounted sensor whether it is in a slope condition, if it is in the slope condition and automatic parking is performed, the slope speed is controlled to be stable, and the power system torque output is adjusted according to the speed change to control the speed to be stable.

[0012] When the automatic parking control is performed, the VLC calculates the increasing or decreasing torque value of the driving and control according to the signals received from the longitudinal acceleration sensor, the wheel speed sensor, the parking controller, the EMS / VCU controller and the TCU controller, and the torque control is performed correspondingly.

[0013] When the vehicle speed is controlled by the PID adjustment, the parking limit speed, the parking distance, the target gear, the actual torque and the driver request torque signal are received by the WCBS controller, if the parking limit speed, the parking distance, the target gear, the actual torque and the driver request torque signal are all received normally and the signal does not jump, the fluctuation of the actual speed is controlled by the PID adjustment.

[0014] The target speed signal and the parking distance signal are sent by the APA control system, the actual control target speed is controlled by the VLC according to the signals received by the APA, and the speed is controlled by the speed change rate adjustment when the actual target speed changes.

[0015] The advantage of the application is that in the parking control process of the vehicle, the driving performance of the low-speed driving is ensured by the VLC longitudinal control algorithm while the parking distance is ensured to be accurate. BRIEF DESCRIPTION OF DRAWINGS

[0016] The following is a brief description of the contents expressed by each figure in the description of the present application and the labels in the figures:

[0017] Figure 1 The system architecture diagram corresponding to the control method of the present application;

[0018] Figure 2 The flowchart of the driving longitudinal control method of the present application;

[0019] Figure 3 The schematic diagram of the hardware system structure corresponding to the control method of the present application.

[0020] The English-Chinese translation in the figures and the description is as follows:

[0021] Abbreviations Full names APA / APS Automated Parking System WCBS Wire Controlled Brake System EMS Engine Management System TCU Transmission Control Unit VCU Vehicle Control Unit VLC Vehicle Longitudinal Control PID Proportional Integral Derivative DETAILED DESCRIPTION

[0022] The specific embodiments of the present application will be further described in detail below by comparing the figures and describing the optimal embodiments.

[0023] The purpose of the present application is to solve the problem of driver's discomfort and unevenness caused by the speed fluctuation of the vehicle due to the frequent switching of the power system and the brake system as the virtual driver in the longitudinal control of the automatic parking function in the single or mixed working conditions of the vehicle starting, accelerating, decelerating, parking, stopping and gear shifting. In the strategy, the VLC restricts the actual working speed of the vehicle through the real-time distance of the APA, the limited vehicle speed and the steering wheel angle. At the same time, based on the deviation of the target speed and the actual speed, the target acceleration of the vehicle is restricted, and the real-time acceleration calculated by the real-time distance and the real-time speed is controlled by PID. In this way, the comfort and smoothness of the vehicle are guaranteed.

[0024] The driving control strategy of the automatic parking vehicle provided in the present embodiment includes:

[0025] The VLC obtains the following information, including but not limited to the real-time distance of the APA, the limited vehicle speed of the APA, the steering wheel angle of the EPS and other information. According to the real-time distance of the APA, the limited vehicle speed of the APA and the steering wheel angle of the EPS, the current actual target speed of the VLC is determined. According to the deviation of the target speed and the current actual speed of the vehicle, the target acceleration of the vehicle is calibrated. The real-time acceleration calculated by the real-time distance and the real-time speed is controlled by PID according to the calibrated target acceleration. By using the above control method, the problem of driving performance and comfort in the parking process is solved.

[0026] VLC controls the actual working speed of the vehicle by the real-time distance, limit speed and steering wheel angle of APA; at the same time, based on the deviation of target speed and actual speed, the target acceleration of the vehicle is controlled, and the real-time acceleration calculated by real-time distance and real-time speed is controlled by PID. In this way, the comfort and smoothness of the vehicle are ensured.

[0027] The controller (WCBS) receives the parking limit speed and parking distance signal sent by the controller (APA) to control the actual working speed of the vehicle. According to the target gear position, and the actual torque, driver request torque and other signals sent by the controller (EMS or VCU), the single or mixed working conditions of the vehicle such as starting, accelerating, decelerating, parking, stopping and gear shifting are controlled.

[0028] By receiving the above signals, VLC controls the actual speed of the vehicle with a certain smooth torque, and adjusts the speed fluctuation in the driving process by PID.

[0029] VLC determines whether the vehicle needs to start, accelerate, decelerate, shift gears or park according to the current control signal state output by APA.

[0030] If automatic parking is performed on flat ground: starting and accelerating process: VLC controls the vehicle to accelerate from static to target speed with a certain relatively smooth driving torque according to the target speed and target distance (the actual speed curve rises smoothly without inflection point).

[0031] Steady state process: maintain the current speed with a certain relatively smooth torque to avoid frequent switching of the power system and the braking system, which brings the jerk of the vehicle; deceleration and parking process: according to the current parking distance, the vehicle is slowed down to static state with a certain relatively smooth braking torque (the actual speed curve decreases smoothly without inflection point);

[0032] Parking process: switching from drive to park, which is equivalent to unloading for the engine, so the EMS actual torque needs to be smoothly exited to avoid jerk; gear shifting process: VLC requests TCU to realize gear shifting according to the target gear position, at this time, the real gear position of the vehicle needs to be considered, which can be realized by the change of input shaft speed and output shaft speed of the gearbox. VLC judges the torque control intervention time according to the actual performance of the vehicle to optimize the comfort of the starting working condition after gear shifting;

[0033] If automatic parking is performed on a slope: except for the steady state control, the rest of the control is the same as that on flat ground, and the emphasis is on the speed steady state control of the slope: when parking on a slope, the load of the vehicle changes all the time, so the output torque of the power system needs to be stable. If the speed deviation is sinusoidal, the fluctuation period T needs to be greater than 2s; if the slope speed deviation control is the same as that on flat ground, the vehicle needs to be prevented from sliding during the longitudinal control process.

[0034] When the VLC receives signals from the longitudinal acceleration sensor, wheel speed sensor, parking controller, EMS / VCU controller, and TCU controller, it makes a comprehensive judgment and executes the torque increase or decrease of the drive and brake.

[0035] As shown in Figures 1-3 An automatic parking VLC longitudinal control optimization driving control strategy, the control method comprises the following steps:

[0036] A. Desired acceleration, real-time acceleration PID adjustment execution judgment: through the controller (WBCS) receiving the parking limit speed, parking distance, target gear sent by the controller (APA), and the actual torque, driver request torque and other signals sent by the controller (EMS or VCU). During the parking control process, the signals are not allowed to lose, jump and other abnormal conditions. If signal loss or jump abnormality is detected during system operation, the VLC will stop the vehicle and pull up the EPB. After the above conditions are met (i.e. APA target speed is normally sent according to actual scene, APA parking distance is linearly reduced according to radar and camera monitoring, actual gear and target gear are correctly matched, actual torque and driver torque respond to VLC target torque and torque linear change in response process), through receiving the above signals, the VLC controls the actual vehicle speed with a certain smooth torque (smooth torque, i.e. increasing or decreasing with a certain slope in transient process, and stable control process with no step or sudden change. The speed fluctuation in the driving process is adjusted by PID;

[0037] B. Smooth torque control logic:

[0038] 1. The APA control system sends target speed signal and parking distance signal, and the VLC limits the actual control target speed according to the signal sent by the APA and limits the actual target speed change slope, so as to achieve the purpose of speed comfort control;

[0039] 2. The TCU actual gear responds to the VLC target gear, so as to meet the driving direction comfort control purpose;

[0040] 3. According to the fluctuation of vehicle speed, the target acceleration of the actual vehicle speed area target speed is calculated and judged, and according to the actual target acceleration, the target torque required by the current vehicle is calculated. The EMS or VCU responds to the target torque of the VLC (response requirements: response time ≤100ms, response accuracy: 5%*target torque) to achieve the purpose of torque comfort control

[0041] C. After the above conditions in step A are met, the VLC judges whether the current vehicle needs to start, accelerate, decelerate, shift gears, or park according to the current APA output control signal state.

[0042] 1. Start: APA sends target speed signal, target distance signal, target gear signal to CAN bus, TCU correctly responds to VLC target gear, VCU / EMS maximum torque capacity value is sent to CAN bus according to self calculation, meeting the above conditions, VLC will actively release pressure and send target torque to make the vehicle start;

[0043] 2. Acceleration: when the actual vehicle speed does not reach the actual target speed, increase the target driving force to make the vehicle accelerate;

[0044] 3. Deceleration: when the actual vehicle speed exceeds the actual target speed, increase the target braking torque to make the vehicle decelerate;

[0045] 4. Gear shifting: VLC forwards the target gear D / R sent by APA to TCU, and TCU should correctly respond to the VLC target gear;

[0046] 5. Parking: after parking, TCU responds to VLC target gear P, and completes P parking and EPB parking.

[0047] D. If the above step A conditions are met in flat ground conditions (whether the road surface is flat is calculated by the vehicle inertia measurement unit), automatic parking is performed:

[0048] Start-up acceleration process: VLC controls the vehicle to accelerate from static to target speed (actual speed curve smoothly rises without inflection point) according to target speed and target distance with certain relatively smooth driving torque (according to actual target speed, calculate the required acceleration, calculate the required target driving torque through F=ma);

[0049] Steady state process: maintain the current speed with certain relatively smooth torque to avoid frequent switching of power system and braking system causing vehicle jerk (whether smooth through subjective experience and IMU);

[0050] Deceleration and parking process: according to the current parking distance, make the vehicle slow down to static with certain relatively smooth braking torque (actual speed curve smoothly decreases without inflection point); smooth torque refers to torque change when controlling vehicle speed reduction, torque reduction is controlled according to the set change rate, so as to meet the purpose of slow and smooth.

[0051] Parking process: switch from drive to park, which is equivalent to unloading for the engine, so EMS actual torque needs to be smoothly exited to avoid jerk;

[0052] Shift process: VLC requests TCU to implement gear shift according to target gear, at this time, the real gear of the vehicle should be considered, which can be determined by the change of input shaft speed and output shaft speed of the gearbox. VLC determines the torque control intervention time according to the actual performance of the vehicle to optimize the comfort of the starting condition after gear shift. Intervention time determination: TCU will respond to the target gear of VLC, but at this time, there is a possibility of false (TCU's own demand) TCU actual gear (which can be determined by the change of input shaft speed and output shaft speed of the gearbox), at this time, VLC needs to determine the torque intervention time according to the change of shaft speed, that is, according to the actual performance of the vehicle, a certain period of time is waited before torque request (the specific time can be corrected according to the actual performance of the vehicle).

[0053] If automatic parking is performed on a slope: in addition to steady state control, the rest of the control is the same as on flat ground, here the emphasis is on the speed steady state control of the slope: when parking on a slope, the load of the vehicle is changing all the time, the output torque of the power system needs to be stable and follow (response requirement: response time ≤ 100 ms, response accuracy: 5%*target torque), if the actual speed deviation changes sinusoidally, the fluctuation period T needs to be greater than 2s; if the slope speed deviation control is the same as the flat ground control, the vehicle needs to be guaranteed not to slide during the longitudinal control process.

[0054] E、When VLC receives signals from longitudinal acceleration sensor, wheel speed sensor, parking controller, EMS / VCU controller, TCU controller, it makes comprehensive judgment and executes torque increase or decrease of driving and braking.

[0055] Torque increase and decrease logic:

[0056] 1. Flat ground condition: when the actual vehicle speed is lower than the actual target vehicle speed, the current vehicle acceleration is calibrated, according to Newton's second law, the target driving torque is converted to achieve the purpose of torque increase; when the actual vehicle speed is higher than the actual target vehicle speed, the vehicle deceleration is calibrated, according to Newton's second law, the target braking torque is converted to achieve the purpose of torque decrease;

[0057] 2. Slope condition: uphill condition is the same as flat ground condition. Downhill condition: according to the component force of the vehicle load along the slope, at this time, the driving torque does not need to be increased or decreased. When the actual vehicle speed is lower than the actual target vehicle speed, the current vehicle deceleration is calibrated, according to Newton's second law, the target braking torque is converted to achieve the purpose of torque increase; when the actual vehicle speed is higher than the actual target vehicle speed, the vehicle deceleration is calibrated, according to Newton's second law, the target braking torque is converted to achieve the purpose of torque decrease.

[0058] Compared with the prior art, the application ensures the drivability of low-speed driving by the VLC longitudinal control algorithm while ensuring the parking distance accuracy during the parking control process of the vehicle.

[0059] The target vehicle speed and the parking distance sent by the parking control system in real time, the VLC system coordinates the power system and the brake system to perform longitudinal control on the driving torque, the gear and the brake torque, avoids the vehicle unevenness caused by frequent switching of the brake and the drive; the distance sent by the APA, the vehicle speed sent by the APA, the steering wheel angle, the changes of the input shaft and the output shaft of the speed reducer are used to adjust the actual internal target vehicle speed of the VLC and the real gear of the vehicle to determine the torque intervention time; then the deviation between the target vehicle speed and the actual vehicle speed during the parking process is used to constrain the vehicle acceleration to perform PID adjustment, that is, the deviation between the actual vehicle speed and the actual target vehicle speed is used to adjust the driving torque and the brake torque intervention time, the deviation between the actual acceleration and the target acceleration is used to adjust the size of the driving torque and the brake torque, the vehicle motion or stop is controlled by a certain relatively smooth acceleration, the comfort of the vehicle is ensured, and a good parking experience is provided for the driver.

[0060] Obviously, the specific implementation of the application is not limited by the above-mentioned mode, and various non-essential improvements made by adopting the method concept and technical scheme of the application are within the protection scope of the application.

Claims

1. A method for controlling drivability of an automatically parked vehicle, characterized by: The target acceleration required for the vehicle is calibrated according to the deviation between the target speed and the current actual speed of the vehicle, and PID control is performed by comparing the real-time acceleration calculated during the vehicle movement with the calibrated expected target acceleration.

2. The drivability control method for an automatically parked vehicle according to claim 1, wherein: The method includes collecting first information and determining the current actual target speed of the VLC according to the collected first information; the WCBS controller receives a signal from the APA controller and the VLC performs constraint control on the actual working speed of the vehicle according to the signal from the APA.

3. The drivability control method for an automatically parked vehicle according to claim 2, wherein: VLC uses smooth torque to control the actual speed of the vehicle. When the speed fluctuates, it adjusts the speed fluctuation during driving through PID adjustment.

4. The drivability control method for an automatically parked vehicle according to any one of claims 1 to 3, wherein: The on-board sensors collect and determine whether the vehicle is currently on level ground. If so, during the automatic parking start acceleration process, the VCL controls the vehicle's acceleration from rest to the target speed using the set drive torque based on the target speed and target distance. During the automatic parking smooth process, the preset smooth torque is used to control the vehicle to maintain a stable speed; during the automatic parking deceleration and parking process, the set smooth torque is used to control the vehicle speed to slowly decelerate to a standstill in a linear manner based on the current parking distance.

5. The drivability control method for an automatically parked vehicle according to any one of claims 1 to 3, characterized in that: When the vehicle is in the automatic parking process, the EMS controls the actual torque to slowly decrease until it exits; during the gear shifting process: the VLC requests the TCU to implement gear shifting according to the target gear, and the VLC determines the timing of torque control intervention based on the actual performance of the vehicle.

6. The drivability control method for an automatically parked vehicle according to any one of claims 1 to 3, characterized in that: The vehicle's on-board sensors collect and determine whether the vehicle is currently on a slope. If it is on a slope and automatic parking is being performed, the vehicle speed on the slope is controlled in a steady state. The power system torque output is adjusted according to the changes in vehicle speed to keep the vehicle speed stable.

7. The drivability control method for an automatically parked vehicle according to any one of claims 1 to 3, characterized in that: When performing automatic parking control, the VLC calculates the value of increasing or decreasing the torque for driving and braking based on the signals received from the longitudinal acceleration sensor, wheel speed sensor, parking controller, EMS / VCU controller, and TCU controller, and performs torque control accordingly.

8. The drivability control method for an automatically parked vehicle according to any one of claims 1 to 3, wherein: When the vehicle speed is PID-regulated and controlled, the parking limit speed, stopping distance, target gear sent by the APA controller, as well as the actual torque and driver-requested torque signals sent by the EMS or VCU controller are received through the WCBS controller. If the parking limit speed, stopping distance, target gear, actual torque, and driver-requested torque signals are all received normally and there is no signal jump, the fluctuation of the actual vehicle speed is controlled through PID regulation.

9. The drivability control method for an automatically parked vehicle according to any one of claims 1 to 3, characterized in that: The APA control system sends a target speed signal and a stopping distance signal. The VLC controls the actual target speed based on the signals received from the APA and controls the speed by adjusting the speed change rate when the actual target speed changes.

10. The drivability control method for an automatic parking vehicle according to any one of claims 1 to 3, characterized in that: The first information includes APA real-time distance, APA speed limit, and EPS steering wheel angle.

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