Automatic parking control method

Abstract

A control method for automatic parking comprises the following steps that (1) a first relation table and a second relation table are obtained through a calibration experiment; 2) setting a target vehicle speed initial value and an increase / decrease value, 3) starting automatic parking, and detecting the gradient by a gradient sensor to obtain a request torque initial value; 4) detecting the actual speed of the vehicle and the distance between the vehicle and the parking position; 5) calculating a control distance variation according to the control distance, calculating the change rate of the control distance variation, and looking up the table to obtain the change rate of the target vehicle speed variation; 6) if less than 0, reducing the target vehicle speed, and if greater than 0, increasing the target vehicle speed; 7) calculating a difference value between the target vehicle speed and the actual vehicle speed, controlling the actual vehicle speed to the target vehicle speed, calculating a difference value between the target vehicle speed and the actual vehicle speed, and looking up the table to obtain a request torque change rate; 8) superposing the change rate of the request torque to the initial value of the request torque to obtain a target request torque, and controlling the actual request torque to the target request torque, and 9) finishing automatic parking when the control distance is within an end threshold range.

Description

Technical Field

[0001] The present invention relates to the field of intelligent driving, and in particular to a control method for automatic parking. Background Art

[0002] Autonomous driving is a key area of ​​automotive technology development, and automated parking, as a key component, is also undergoing continuous development. However, current automated parking algorithms generally utilize PID (Proton-Derivative Processing Unit) (PID) to control vehicle speed. However, traditional PID algorithms are relatively complex and only provide closed-loop control of vehicle speed, resulting in poor robustness. Summary of the Invention

[0003] In response to the above-mentioned problems, the present invention provides a control method for automatic parking, which has high adaptability and adjustability, good algorithm robustness, and can implement a high-precision vehicle speed control method for various vehicle models, thereby achieving safe and reliable automatic parking.

[0004] The technical solution of the present invention is: a control method for automatic parking, comprising the following steps: 1) obtaining, through a calibration experiment, a first relationship table composed of a control distance in a current operating cycle of the control chip, a rate of change of a control distance between the current operating cycle and the previous operating cycle of the control chip, and a rate of change of a target vehicle speed between the current operating cycle and the previous operating cycle of the control chip; and a second relationship table composed of a difference between the target vehicle speed and the actual vehicle speed in the current operating cycle of the control chip, a difference between the target vehicle speed and the actual vehicle speed in the current operating cycle and the previous operating cycle of the control chip, and a requested torque change rate, and storing the first and second relationship tables in a vehicle control module; 2) Set the initial value of the target speed to 0, set the target speed increment to m, and m is a positive number; 3) When automatic parking begins, the slope sensor detects the slope of the current road surface and determines the initial value of the requested torque based on the slope. 4) The vehicle control module detects the actual speed of the vehicle and the distance from the parking position in real time. The distance from the vehicle to the parking position is the control distance; 5) In each operating cycle of the control chip, a change in the controlled distance is calculated based on the controlled distance, and a rate of change of the control distance between the current operating cycle and the previous operating cycle of the control chip is calculated. The rate of change of the target vehicle speed between the current operating cycle and the previous operating cycle of the control chip is obtained by querying the first relationship table; 6) If the rate of change of the target vehicle speed between the current operation cycle and the previous operation cycle of the control chip is less than 0, the target vehicle speed is reduced by m. If the target vehicle speed is less than 0 after being reduced by m, the target vehicle speed is 0. If the rate of change of the target vehicle speed between the current operation cycle and the previous operation cycle of the control chip is greater than 0, the target vehicle speed is increased by m. 7) During each operating cycle of the control chip, the difference between the target vehicle speed and the actual vehicle speed is calculated in real time, the actual vehicle speed is controlled to increase or decrease to the target vehicle speed, and the difference between the target vehicle speed and the actual vehicle speed in the current operating cycle of the control chip and the target vehicle speed and the actual vehicle speed in the previous operating cycle of the control chip is calculated, and the requested torque change rate is obtained by querying the second relationship table; 8) Adding the requested torque change rate obtained during each operating cycle of the control chip to the initial value of the requested torque to obtain the target requested torque during each operating cycle of the control chip; controlling the actual requested torque to increase or decrease to the target requested torque; 9) When the control distance is within the preset end threshold range, the control ends and automatic parking is completed.

[0005] Preferably, in step 3), if the slope of the current road surface detected by the slope sensor is 0, the initial value of the requested torque is 0; if the slope of the current road surface detected by the slope sensor is not 0, the initial value of the requested torque is obtained based on a mapping relationship between the slope and the initial value of the requested torque obtained through a pre-calibrated experiment.

[0006] Preferably, in step 4), the vehicle control module also detects in real time whether there is an obstacle on the vehicle's trajectory. If there is an obstacle, the vehicle control module detects the distance between the vehicle and the obstacle. If the distance between the vehicle and the obstacle is less than a safety threshold, the vehicle control module requests zero torque and brakes.

[0007] Preferably, the safety threshold is 0.4-0.6m.

[0008] Preferably, in step 9), the end threshold is 0.2-0.3 m.

[0009] Preferably, in step 6), the target vehicle speed is set to a maximum value, and when the target vehicle speed increases by m and becomes greater than the maximum value, the target vehicle speed is the maximum value.

[0010] Preferably, in step 8), the target requested torque is set to a minimum value and a maximum value. If the target requested torque is less than the minimum value, the target requested torque is the minimum value; if the target requested torque is greater than the maximum value, the target requested torque is the maximum value.

[0011] The advantages of the present invention are that: the present invention calibrates the slope of the target speed differential between two cycles of the control chip and the slope of the requested torque based on actual vehicle conditions, and performs dual closed-loop control on the vehicle speed and torque, making the method highly adaptable and adjustable, with a simple algorithm and good robustness. It fully utilizes the fast response characteristics of the power system and uses closed-loop control to be applicable to speed control for automatic parking of various vehicle models. Furthermore, the present invention calibrates the first and second relationship tables separately for each vehicle model. This calibration ensures the accuracy of the slope of the target speed differential between two cycles of the control chip and the slope of the requested torque, thereby realizing a high-precision vehicle speed control method for the vehicle model and achieving safe and reliable automatic parking. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0013] See also Figure 1 , a control method for automatic parking, comprising the following steps: 1) Through calibration experiments, a first relationship table consisting of the control distance of the control chip in the current operating cycle, the rate of change of the control distance of the control chip in the current operating cycle compared with the previous operating cycle, and the rate of change of the target vehicle speed of the control chip in the current operating cycle compared with the previous operating cycle is obtained. A second relationship table consisting of the difference between the target vehicle speed and the actual vehicle speed of the control chip in the current operating cycle, the difference between the target vehicle speed and the actual vehicle speed of the control chip in the current operating cycle compared with the previous operating cycle, and the requested torque change rate is obtained. The first and second relationship tables are stored in the vehicle control module. In this embodiment, the first relationship table for calibrating a certain vehicle is shown in Table 1 below, and the second relationship table is shown in Table 2 below.

[0014] Table 1

[0015] Table 2 Among them, X1 in Table 1 is the control distance of the control chip in this operating cycle, Y1 is the rate of change of the control distance of the control chip in this operating cycle and the previous operating cycle, and Z1 is the rate of change of the target vehicle speed of the control chip in this operating cycle and the previous operating cycle; X2 in Table 1 is the difference between the target vehicle speed and the actual vehicle speed of the control chip in this operating cycle, Y2 is the difference between the target vehicle speed and the actual vehicle speed of the control chip in this operating cycle and the previous operating cycle, and Z2 is the requested torque change rate. After storing the first and second relationship tables in the vehicle control module, the vehicle control system will fit the data according to the relationship table to obtain the corresponding mapping relationship. That is, even if there is data in the table later, the corresponding data can be queried through the mapping relationship obtained by fitting.

[0016] 2) Set the initial value of the target speed to 0, set the target speed increase or decrease value to m, and m is a positive number; the target speed increase or decrease value is set according to the specific conditions of the vehicle model, and can be set to 1, 2, 3, etc. 3) When automatic parking begins, the slope sensor detects the slope of the current road surface. If the slope sensor detects a slope of 0 (i.e., a flat road), the initial value of the requested torque is 0. If the slope sensor detects a non-zero slope, the initial value of the requested torque is determined based on a pre-calibrated slope-to-initial torque mapping relationship. Calibration of this mapping relationship also requires consideration of factors such as vehicle mass and wheel diameter. Therefore, different vehicle models have different slope-to-initial torque mapping relationships and require separate calibration.

[0017] 4) The vehicle control module detects the vehicle's actual speed and the distance from the parking position in real time. The distance from the vehicle to the parking position is the control distance. The vehicle control module also detects in real time whether there are any obstacles on the vehicle's trajectory. If there are obstacles, the module detects the distance from the vehicle to the obstacle. If the distance from the vehicle to the obstacle is less than 0.4 to 0.6 meters, it requests 0 torque and braking, then exits automatic parking and waits until the obstacle is removed, such as pedestrians or animals walking beyond the safety threshold, or the driver gets out of the vehicle and moves the obstacle away, before restarting automatic parking.

[0018] 5) In each operating cycle of the control chip, a change in the controlled distance is calculated based on the controlled distance, and a rate of change of the control distance between the current operating cycle and the previous operating cycle of the control chip is calculated. The rate of change of the target vehicle speed between the current operating cycle and the previous operating cycle of the control chip is obtained by querying the first relationship table; 6) If the rate of change of the target vehicle speed between the current operating cycle of the control chip and the previous operating cycle is less than 0, the target vehicle speed is reduced by m. If the target vehicle speed is less than 0 after being reduced by m, the target vehicle speed is 0. If the rate of change of the target vehicle speed between the current operating cycle of the control chip and the previous operating cycle is greater than 0, the target vehicle speed is increased by m. The target vehicle speed has a maximum value. When the target vehicle speed is greater than the maximum value after increasing by m, the target vehicle speed is the maximum value. The maximum value of the target vehicle speed is set according to different vehicles in order to ensure that the vehicle speed is not too high to avoid safety accidents. In this embodiment, the minimum value of the target vehicle speed is 0 and the maximum value is 100 dkm / h.

[0019] 7) During each operating cycle of the control chip, the difference between the target vehicle speed and the actual vehicle speed is calculated in real time, the actual vehicle speed is controlled to increase or decrease to the target vehicle speed, and the difference between the target vehicle speed and the actual vehicle speed in the current operating cycle of the control chip and the target vehicle speed and the actual vehicle speed in the previous operating cycle of the control chip is calculated, and the requested torque change rate is obtained by querying the second relationship table; 8) The requested torque change rate obtained during each operating cycle of the control chip is added to the initial value of the requested torque to obtain the target requested torque during each operating cycle of the control chip. The target requested torque has a minimum and maximum value. If the target requested torque is less than the minimum value, the target requested torque is the minimum value. If the target requested torque is greater than the maximum value, the target requested torque is the maximum value. The maximum and minimum values ​​of the target requested torque are set specifically for different vehicles to avoid safety accidents and control the actual requested torque to increase or decrease to the target requested torque. 9) When the control distance is within the preset end threshold range, where the end threshold is 0.2 to 0.3 meters, the control ends and automatic parking is completed.

[0020] In this embodiment, in order to improve the control accuracy of the algorithm, a special unit of vehicle speed, dkm / h, is set, which is one tenth of the unit km / h, that is, 1km / h=10dkm / h. In this embodiment, the unit of actual vehicle speed and target vehicle speed during the automatic parking process is both dkm / h.

[0021] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A control method for automatic parking, characterized in that: The following steps are involved: 1) obtaining, through a calibration experiment, a first relationship table composed of a control distance in a current operating cycle of the control chip, a rate of change of a control distance between the current operating cycle and the previous operating cycle of the control chip, and a rate of change of a target vehicle speed between the current operating cycle and the previous operating cycle of the control chip; and a second relationship table composed of a difference between the target vehicle speed and the actual vehicle speed in the current operating cycle of the control chip, a difference between the target vehicle speed and the actual vehicle speed in the current operating cycle and the previous operating cycle of the control chip, and a requested torque change rate, and storing the first and second relationship tables in a vehicle control module; 2) Set the initial value of the target speed to 0, set the increase or decrease value of the target speed to m, and m is a positive number; 3) When automatic parking begins, the slope sensor detects the slope of the current road surface and determines the initial value of the requested torque based on the slope. 4) The vehicle control module detects the actual speed of the vehicle and the distance from the parking position in real time. The distance from the vehicle to the parking position is the control distance; 5) In each operating cycle of the control chip, a change in the controlled distance is calculated based on the controlled distance, and a rate of change of the control distance between the current operating cycle and the previous operating cycle of the control chip is calculated. The rate of change of the target vehicle speed between the current operating cycle and the previous operating cycle of the control chip is obtained by querying the first relationship table; 6) If the rate of change of the target vehicle speed between the current operation cycle and the previous operation cycle of the control chip is less than 0, the target vehicle speed is reduced by m. If the target vehicle speed is less than 0 after being reduced by m, the target vehicle speed is 0. If the rate of change of the target vehicle speed between the current operation cycle and the previous operation cycle of the control chip is greater than 0, the target vehicle speed is increased by m. 7) During each operating cycle of the control chip, the difference between the target vehicle speed and the actual vehicle speed is calculated in real time, the actual vehicle speed is controlled to increase or decrease to the target vehicle speed, and the difference between the target vehicle speed and the actual vehicle speed in the current operating cycle of the control chip and the target vehicle speed and the actual vehicle speed in the previous operating cycle of the control chip is calculated, and the requested torque change rate is obtained by querying the second relationship table; 8) Adding the requested torque change rate obtained during each operating cycle of the control chip to the initial value of the requested torque to obtain the target requested torque during each operating cycle of the control chip; controlling the actual requested torque to increase or decrease to the target requested torque; 9) When the control distance is within the preset end threshold range, the control ends and automatic parking is completed.

2. The automatic parking control method according to claim 1, characterized in that: In step 3), if the slope of the current road surface detected by the slope sensor is 0, the initial value of the requested torque is 0. If the slope of the current road surface detected by the slope sensor is not 0, the initial value of the requested torque is obtained based on a mapping relationship between slope and initial value of requested torque obtained through a pre-calibrated experiment.

3. The automatic parking control method according to claim 1, characterized in that: In step 4), the vehicle control module also detects in real time whether there are obstacles on the vehicle's trajectory. If there are obstacles, the vehicle's distance from the obstacle is detected. If the distance from the vehicle to the obstacle is less than a safety threshold, zero torque is requested and braking is requested.

4. The automatic parking control method according to claim 3, characterized in that: The safety threshold is 0.4 to 0.6 m.

5. The automatic parking control method according to claim 1, characterized in that: In step 9), the end threshold is 0.2 to 0.3 m.

6. The automatic parking control method according to claim 1, characterized in that: In step 6), the target vehicle speed is set to a maximum value. When the target vehicle speed increases by m and becomes greater than the maximum value, the target vehicle speed is at the maximum value.

7. The automatic parking control method according to claim 1, characterized in that: In step 8), the target requested torque is set to a minimum value and a maximum value. If the target requested torque is less than the minimum value, the target requested torque is the minimum value. If the target requested torque is greater than the maximum value, the target requested torque is the maximum value.

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