CN110733480B

CN110733480B - Brake control system lower layer controller based on feedback increment PID control

Info

Publication number: CN110733480B
Application number: CN201910994050.9A
Authority: CN
Inventors: 姜赟程; 金晓峰; 沈继伟; 刘兆勇; 柯沛
Original assignee: Shanghai Gelubo Industry Co ltd
Current assignee: Shanghai Gelubo Industry Co ltd
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2021-12-28
Anticipated expiration: 2039-10-18
Also published as: CN110733480A

Abstract

The invention discloses a lower layer controller of a brake control system based on feedback increment PID control, and relates to the technical field of control design of brake controllers. The specific control steps are as follows: the lower-layer controller body receives an expected acceleration value given by the upper-layer controller, when the expected acceleration of a given vehicle speed is a negative value, a first section of deceleration is realized by reducing power output and engine dragging, and when the ratio of braking torque to chassis torque reaches a maximum value and the first section of deceleration cannot meet requirements, the braking controller and the chassis control system respond, and actual acceleration reaches the expected acceleration in a short time through PID control feedback regulation to control the braking state of the vehicle. The invention has the advantages that: the lower layer controller optimizes parameters output by the upper layer controller, converts an expected acceleration value given by the upper layer controller into braking torque and chassis torque, and outputs optimal engine torque and master cylinder pressure to achieve more optimal control.

Description

Brake control system lower layer controller based on feedback increment PID control

Technical Field

The invention relates to the technical field of control design of brake controllers, in particular to a lower-layer controller of a brake control system based on feedback increment PID control.

Background

The brake control system is one of the subfunctions of the ADAS system, and aims to automatically control the longitudinal movement of a vehicle so as to reduce the reaction time of a driver during braking and ensure the driving safety. When the external resistance is not sufficient to meet the required acceleration while the vehicle is running, the brake control system regulates the braking of the vehicle by regulating the ratio of the braking torque to the pressure of the braking chassis. The brake controller and the brake chassis coordinate to make the vehicle reach the expected acceleration, thereby improving the safety performance in the emergency condition of driving. The brake control system mainly comprises an upper layer controller and a lower layer controller. The lower layer controller and the upper layer controller in the first section of the system play a role in the same proportion. The lower layer controller of the brake control system in the prior art adopts a traditional PID control method, so that the hysteresis is strong, and the high-precision requirement is difficult to achieve.

Disclosure of Invention

The invention aims to solve the technical problem of providing a brake control system lower layer controller based on feedback increment PID control, which utilizes feedback increment PID regulation to brake by regulating the percentage between the braking torque and the chassis torque, thereby improving the safety and comfort of a vehicle in the driving process.

In order to solve the technical problems, the technical scheme of the invention is as follows: comprises a control mechanism and an actuating mechanism; the control mechanism is a lower-layer controller body, and the execution mechanism comprises a brake controller and a chassis control system;

the specific control steps are as follows: the lower-layer controller body receives an expected acceleration value given by the upper-layer controller, the expected acceleration value is used as input, when the expected acceleration of a given vehicle speed is a negative value, the lower-layer controller body adjusts and controls braking torque and chassis torque, first-stage deceleration is realized by reducing power output and engine dragging, when the ratio of the braking torque to the chassis torque reaches the maximum value and the first-stage deceleration cannot meet the requirement, the braking controller and the chassis control system respond, according to the difference between the expected acceleration and the actual acceleration, feedback adjustment is controlled through PID (proportion integration differentiation), the actual acceleration of the vehicle reaches the expected acceleration in a short time, and the braking state of the vehicle is controlled; and the feedback increment PID control is to calculate a control quantity by using a difference value of the expected acceleration and the actual acceleration as a system error and utilizing proportion, integral and differential to control, and the acceleration and the braking are respectively controlled by adopting the feedback increment PID control.

Further, the control state of a lower-layer controller is judged according to an expected acceleration value, and when the expected acceleration value is within a control range, the ratio of the brake torque of the brake to the chassis torque is controlled to be 0-100%; when the expected acceleration is zero, the opening degree of the accelerator is reduced in a stepped linear mode, and is reduced to 0.88 times of the minimum power threshold value at the lowest, so that the vehicle reaches an expected state, and the minimum power threshold value is obtained through actual vehicle calibration; the deceleration of the engine is maximally 0.1g obtained through reverse dragging under high-speed running, and the deceleration actually provided by the engine is tabulated and called through vehicle calibration.

Furthermore, in order to ensure the stability of PID output, an amplitude limiting module and a change rate limiting module are added at the tail end of the lower-layer controller body, so that the output of the PID controller is ensured to be within a set reasonable range, and the output change rate of the PID controller is ensured to be within a set reasonable range.

The invention has the advantages that:

1. the lower layer controller optimizes parameters output by the upper layer controller, adjusts the parameters according to the internal and external environments of the vehicle, converts an expected acceleration value given by the upper layer controller into braking torque and chassis torque, and further outputs optimal engine torque and master cylinder pressure to achieve more optimal control;

2. by means of a two-stage braking mode, power reduction and engine reverse rotation dragging are fully utilized in the first stage braking process to brake, and the strategy can be directly applied to a braking energy recovery strategy through an intelligent braking system;

3. the control strategy design of the brake uses the controller based on the incremental PID, has stronger robustness and better control effect than the common PID controller, and improves the safety and comfort of the vehicle in the driving process.

Drawings

FIG. 1 is a feedback delta PID control diagram of the present invention;

FIG. 2 is a flow chart of the brake control of the present invention;

FIG. 3 is a logic diagram of a braking system controller according to the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and the detailed description. The following examples are presented to enable one of ordinary skill in the art to more fully understand the present invention and are not intended to limit the scope of the embodiments described herein.

As shown in FIGS. 1-3, Kp represents a proportional adjustment coefficient, Ki represents an integral adjustment coefficient, Kd represents a derivative adjustment coefficient, T represents time, Z^-1Representing dispersionThe specific implementation mode of the unit delay module adopts the following technical scheme: comprises a control mechanism and an actuating mechanism; the control mechanism is a lower-layer controller body, and the execution mechanism comprises a brake controller and a chassis control system;

the specific control steps are as follows: the lower-layer controller body receives an expected acceleration value given by the upper-layer controller, the expected acceleration value is used as input, when the expected acceleration of a given vehicle speed is a negative value, the lower-layer controller body adjusts and controls braking torque and chassis torque, first-stage deceleration is realized by reducing power output and engine dragging, when the ratio of the braking torque to the chassis torque reaches the maximum value and the first-stage deceleration cannot meet the requirement, the braking controller and the chassis control system respond, according to the difference between the expected acceleration and the actual acceleration, feedback adjustment is controlled through PID (proportion integration differentiation), the actual acceleration of the vehicle reaches the expected acceleration in a short time, and the braking state of the vehicle is controlled;

and the feedback increment PID control is to calculate a control quantity by using a difference value of the expected acceleration and the actual acceleration as a system error and utilizing proportion, integral and differential to control, and the acceleration and the braking are respectively controlled by adopting the feedback increment PID control.

Judging the control state of a lower layer controller according to the expected acceleration value, and controlling the ratio of the braking torque of the brake to the chassis torque to be 0-100% when the expected acceleration value is within a control range; when the expected acceleration is zero, the opening degree of the accelerator is reduced in a stepped linear mode, and is reduced to 0.88 times of the minimum power threshold value at the lowest, so that the vehicle reaches an expected state, and the minimum power threshold value is obtained through actual vehicle calibration; the deceleration of the engine is maximally 0.1g obtained through reverse dragging under high-speed running, and the deceleration actually provided by the engine is tabulated and called through vehicle calibration.

In order to ensure the stability of PID output, an amplitude limiting module and a change rate limiting module are added at the tail end of the lower layer controller body, so that the output of the PID controller is ensured to be within a set reasonable range, and the output change rate of the PID controller is ensured to be within the set reasonable range.

The feedback increment PID control has the advantages that: the principle is simple, and the use is convenient; the adaptability is strong; the robustness is strong, the control quality of the method is not sensitive to the change of the controlled object, and the method is very suitable for severe environment; negative feedback regulation can balance the system ecology.

The invention has the advantages that: the lower layer controller optimizes parameters output by the upper layer controller, adjusts the parameters according to the internal and external environments of the vehicle, converts an expected acceleration value given by the upper layer controller into braking torque and chassis torque, and further outputs optimal engine torque and master cylinder pressure to achieve more optimal control; by means of a two-stage braking mode, power reduction and engine reverse rotation dragging are fully utilized in the first stage braking process to brake, and the strategy can be directly applied to a braking energy recovery strategy through an intelligent braking system; the control strategy design of the brake uses the controller based on the incremental PID, has stronger robustness and better control effect than the common PID controller, and improves the safety and comfort of the vehicle in the driving process.

The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A lower layer controller of a brake control system based on feedback increment PID control is characterized in that: comprises a control mechanism and an actuating mechanism; the control mechanism is a lower-layer controller body, and the execution mechanism comprises a brake controller and a chassis control system;

the specific control steps are as follows: the lower-layer controller body receives an expected acceleration value given by the upper-layer controller, the expected acceleration value is used as input, when the expected acceleration of a given vehicle speed is a negative value, the lower-layer controller body adjusts and controls braking torque and chassis torque, first-stage deceleration is realized by reducing power output and engine dragging, when the ratio of the braking torque to the chassis torque reaches the maximum value and the first-stage deceleration cannot meet the requirement, the braking controller and the chassis control system respond, according to the difference between the expected acceleration and the actual acceleration, feedback adjustment is controlled through PID (proportion integration differentiation), the actual acceleration of the vehicle reaches the expected acceleration in a short time, and the braking state of the vehicle is controlled; the feedback increment PID control is to calculate the control quantity by using the difference value of the expected acceleration and the actual acceleration as a system error and utilizing proportion, integral and differential to control, and the acceleration and the braking control respectively adopt the feedback increment PID control;

judging the control state of a lower layer controller according to the expected acceleration value, and controlling the ratio of the braking torque of the brake to the chassis torque to be 0-100% when the expected acceleration value is within a control range; when the expected acceleration is zero, the opening degree of the accelerator is reduced in a stepped linear mode, and is reduced to 0.88 times of the minimum power threshold value at the lowest, so that the vehicle reaches an expected state, and the minimum power threshold value is obtained through actual vehicle calibration; the deceleration of the engine is maximally 0.1g obtained through reverse dragging under high-speed operation, and the deceleration actually provided by the engine is subjected to tabulation calling through vehicle calibration;