EPB-based anti-lock system and anti-lock method thereof
阅读说明：本技术 一种基于epb的防抱死系统及其防抱死方法 (EPB-based anti-lock system and anti-lock method thereof ) 是由 刘兆勇 顾勤冬 余子祥 刘锡彪 袁鑫淼 陈浩 张子扬 于 2020-05-12 设计创作，主要内容包括：本发明公开了一种基于EPB的防抱死系统及其防抱死方法,包含EPB控制器、汽车轮速信号源、汽车蓄电池电源、EPB开关、左EPB卡钳和右EPB卡钳,汽车轮速信号源采集汽车四个轮子的轮速信号并上传到EPB控制器；EPB控制器根据轮速信号计算得到后轮的抱死程度从而判断路面情况；EPB控制器根据不同路面情况对左EPB卡钳和右EPB卡钳执行相对应路面的夹紧力操作,重复直至汽车停止。本发明在原EPB系统的基础上,增加了应急制动时防抱死的功能,提升了电子驻车系统体系的安全性能。(The invention discloses an anti-lock system based on EPB and an anti-lock method thereof, comprising an EPB controller, an automobile wheel speed signal source, an automobile storage battery power supply, an EPB switch, a left EPB caliper and a right EPB caliper, wherein the automobile wheel speed signal source is used for acquiring wheel speed signals of four wheels of an automobile and uploading the wheel speed signals to the EPB controller; the EPB controller calculates the locking degree of the rear wheel according to the wheel speed signal so as to judge the road surface condition; and the EPB controller executes clamping force operation of corresponding road surfaces on the left EPB caliper and the right EPB caliper according to different road surface conditions, and the operation is repeated until the automobile stops. On the basis of the original EPB system, the anti-lock function during emergency braking is added, and the safety performance of the electronic parking system is improved.)
1. An EPB-based anti-lock system, characterized by: contain the EPB controller, the fast signal source of car wheel, car battery power, the EPB switch, left EPB calliper and right EPB calliper, the fast signal source of car wheel is connected with the EPB controller and is used for gathering the fast signal of the wheel of each wheel of car, car battery power is connected for each part power supply of system with the EPB controller, the EPB switch is connected with the EPB controller and is used for controlling the switch of anti-lock procedure, left EPB calliper and right EPB calliper set up respectively on car left rear wheel and right rear wheel and be connected with the EPB controller and be used for holding tightly the speed reduction to car left rear wheel and right rear wheel.
2. An EPB-based anti-lock system according to claim 1, wherein: and the automobile rear wheel speed signal source is connected with the EPB controller through a CAN line.
3. An EPB-based anti-lock system according to claim 1, wherein: the normal working voltage of the automobile storage battery power supply is 9-16V.
4. An anti-lock method of the EPB-based anti-lock system according to any one of claims 1, 2 and 3, comprising the steps of:
the method comprises the following steps: the method comprises the following steps that an automobile wheel speed signal source collects wheel speed signals of four wheels of an automobile and uploads the wheel speed signals to an EPB controller;
step two: the EPB controller calculates the locking degree of the rear wheel according to the wheel speed signal so as to judge the road surface condition;
step three: the EPB controller executes clamping force operation of corresponding road surfaces on the left EPB caliper and the right EPB caliper according to different road surface conditions;
step four: and repeating the first step to the third step until the vehicle speed is less than 3 KM/hour or the clamping pressure of an EPB caliper is kept at the wheel locking edge.
5. An anti-lock method of an EPB-based anti-lock system according to claim 4, wherein: the specific process that the EPB controller calculates the locking degree of the rear wheel according to the wheel speed signal in the second step is that
The EPB controller calculates the slip rate of the rear wheel of the automobile relative to the front wheel according to the wheel speed signal:
＝(Vt-Va)/Vt*100％
wherein Vt is the wheel speed of the front wheel of the automobile, and Va is the wheel speed of the rear wheel of the automobile;
instantaneous deceleration a during vehicle running:
a=dv/dt
dv is a wheel speed change value of the front wheel of the vehicle, dv = V1-V0, V1 is the current wheel speed of the front wheel of the vehicle, and V0 is the wheel speed of the vehicle before dt moment; dt is the time taken for the front wheel speed of the vehicle to change;
in the dynamic driving process of the vehicle, when the EPB switch executes the clamping operation, the EPB emergency braking function is triggered, the EPB controller firstly controls the left EPB caliper and the right EPB caliper to apply fixed tightening force, and the road surface condition is judged according to the tire slip rate.
6. An anti-lock method of an EPB-based anti-lock system according to claim 4, wherein: the step three is that the EPB controller executes clamping force operation of corresponding road surfaces on the left EPB caliper and the right EPB caliper according to different road surface conditions:
when braking is performed on a high-attachment road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficient of a road surface is large, a rear wheel cannot slip, no wheel speed deviation exists between the front wheel and the rear wheel, the slip rate is 0, and then the clamping force of the left EPB caliper and the clamping force of the right EPB caliper are gradually increased until the deceleration a is larger than the target deceleration by 0.15 g;
when braking is performed on a low-attachment road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficient of a road surface is small, the slip rate of the rear wheel is increased, the left EPB caliper and the right EPB caliper start to release when the slip rate is larger than 0.3, the left EPB caliper and the right EPB caliper apply braking force again until the wheel speed of the rear wheel is recovered to be the same as the vehicle speed, and the steps are repeated in such a circulating way until the vehicle is static;
when braking is performed on an open road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficients of road surfaces on the left side and the right side are different, a wheel on one side cannot slip, the slip rate of the wheel on the other side is gradually increased, the left EPB caliper and the right EPB caliper are independently controlled, the braking force is gradually increased on the high-attachment side until the deceleration a of the vehicle is greater than the target deceleration by 0.1g, the low-attachment side enters low-attachment control, the calipers on the low-attachment side are firstly released when the slip rate is greater than 0.3, the clamping force is applied again after the wheel speed of the wheel on the low-attachment side is recovered, and;
when braking is performed on an abutting road surface-low-attachment to high-attachment road surface: the left EPB caliper and the right EPB caliper apply fixed clamping force firstly, enter a low-attachment control stage firstly, after a running road surface is switched from low-attachment to high-attachment, the slip rate of a rear wheel is reduced, the wheel speed of the rear wheel is recovered to be consistent with that of a front wheel, the left EPB caliper and the right EPB caliper gradually apply braking force again until the deceleration a is larger than a target deceleration, and the left EPB caliper and the right EPB caliper stop acting until a vehicle is static;
when braking is performed on an abutting road surface-high attached to low attached road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the high-adhesion control process is clamped according to target deceleration, the low-adhesion road surface is switched, the adhesion coefficient is reduced, the slip rate of a rear wheel of the vehicle is increased, when the slip rate is larger than 0.3, the left EPB caliper and the right EPB caliper are released until the wheel speed is recovered, at the moment, the low-adhesion control process is started, and the operation is repeated in a circulating mode until the vehicle is static.
Technical Field
The invention relates to an anti-lock system and an anti-lock method thereof, in particular to an anti-lock system based on EPB and an anti-lock method thereof, belonging to the field of automobile parking systems.
Background
The parking system of the automobile is an indispensable system in the automobile brake system, and the automobile parking brake system can slow down or stop the automobile. The traditional mechanical hand brake automobile parking brake system determines the brake clamping force by the strength of a hand brake control mechanism of a driver, and has the problems that the wheel is locked by the driver due to overlarge clamping force when the driver brakes in emergency, the clamping force of the automobile wheel cannot be well controlled by different road conditions, and the like, so that the automobile loses the straight-line driving stability when the wheel is locked, and dangerous phenomena such as sideslip, tail flicking, sudden turning and the like occur. The EPB deceleration of the electronic parking system is a redundant emergency brake after the driving brake fails, and at present, most of electronic parking systems have almost the same functions as a mechanical hand brake, and the safety of the emergency brake is low.
Disclosure of Invention
The invention aims to provide an anti-lock system based on EPB and an anti-lock method thereof, which solve the problem that wheels of a common EPB automobile are locked when emergency braking is carried out in some emergency situations.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
an EPB-based anti-lock system, characterized by: contain the EPB controller, the fast signal source of car wheel, car battery power, the EPB switch, left EPB calliper and right EPB calliper, the fast signal source of car wheel is connected with the EPB controller and is used for gathering the fast signal of the wheel of each wheel of car, car battery power is connected for each part power supply of system with the EPB controller, the EPB switch is connected with the EPB controller and is used for controlling the switch of anti-lock procedure, left EPB calliper and right EPB calliper set up respectively on car left rear wheel and right rear wheel and be connected with the EPB controller and be used for holding tightly the speed reduction to car left rear wheel and right rear wheel.
Furthermore, the automobile rear wheel speed signal source is connected with the EPB controller through a CAN line.
Further, the normal working voltage of the automobile storage battery power supply is 9-16V.
An anti-lock method of an EPB-based anti-lock system, characterized by comprising the steps of:
the method comprises the following steps: the method comprises the following steps that an automobile wheel speed signal source collects wheel speed signals of four wheels of an automobile and uploads the wheel speed signals to an EPB controller;
step two: the EPB controller calculates the locking degree of the rear wheel according to the wheel speed signal so as to judge the road surface condition;
step three: the EPB controller executes clamping force operation of corresponding road surfaces on the left EPB caliper and the right EPB caliper according to different road surface conditions;
step four: and repeating the first step to the third step until the vehicle speed is less than 3 KM/hour or the clamping pressure of an EPB caliper is kept at the wheel locking edge.
Further, the specific process of calculating the locking degree of the rear wheel by the EPB controller according to the wheel speed signal in the second step is that
The EPB controller calculates the slip rate of the rear wheel of the automobile relative to the front wheel according to the wheel speed signal:
＝(Vt-Va)/Vt*100％
wherein Vt is the wheel speed of the front wheel of the automobile, and Va is the wheel speed of the rear wheel of the automobile;
instantaneous deceleration a during vehicle running:
a=dv/dt
dv is a wheel speed change value of the front wheel of the vehicle, dv = V1-V0, V1 is the current wheel speed of the front wheel of the vehicle, and V0 is the wheel speed of the vehicle before dt moment; dt is the time taken for the front wheel speed of the vehicle to change;
in the dynamic driving process of the vehicle, when the EPB switch executes the clamping operation, the EPB emergency braking function is triggered, the EPB controller firstly controls the left EPB caliper and the right EPB caliper to apply fixed tightening force, and the road surface condition is judged according to the tire slip rate.
Further, the third step is that the EPB controller performs clamping force operation of the corresponding road surface to the left EPB caliper and the right EPB caliper according to different road surface conditions:
when braking is performed on a high-attachment road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficient of a road surface is large, a rear wheel cannot slip, no wheel speed deviation exists between the front wheel and the rear wheel, the slip rate is 0, and then the clamping force of the left EPB caliper and the clamping force of the right EPB caliper are gradually increased until the deceleration a is larger than the target deceleration by 0.15 g;
when braking is performed on a low-attachment road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficient of a road surface is small, the slip rate of the rear wheel is increased, the left EPB caliper and the right EPB caliper start to release when the slip rate is larger than 0.3, the left EPB caliper and the right EPB caliper apply braking force again until the wheel speed of the rear wheel is recovered to be the same as the vehicle speed, and the steps are repeated in such a circulating way until the vehicle is static;
when braking is performed on an open road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficients of road surfaces on the left side and the right side are different, a wheel on one side cannot slip, the slip rate of the wheel on the other side is gradually increased, the left EPB caliper and the right EPB caliper are independently controlled, the braking force is gradually increased on the high-attachment side until the deceleration a of the vehicle is greater than the target deceleration by 0.1g, the low-attachment side enters low-attachment control, the calipers on the low-attachment side are firstly released when the slip rate is greater than 0.3, the clamping force is applied again after the wheel speed of the wheel on the low-attachment side is recovered, and;
when braking is performed on an abutting road surface-low-attachment to high-attachment road surface: the left EPB caliper and the right EPB caliper apply fixed clamping force firstly, enter a low-attachment control stage firstly, after a running road surface is switched from low-attachment to high-attachment, the slip rate of a rear wheel is reduced, the wheel speed of the rear wheel is recovered to be consistent with that of a front wheel, the left EPB caliper and the right EPB caliper gradually apply braking force again until the deceleration a is larger than a target deceleration, and the left EPB caliper and the right EPB caliper stop acting until a vehicle is static;
when braking is performed on an abutting road surface-high attached to low attached road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the high-adhesion control process is clamped according to target deceleration, the low-adhesion road surface is switched, the adhesion coefficient is reduced, the slip rate of a rear wheel of the vehicle is increased, when the slip rate is larger than 0.3, the left EPB caliper and the right EPB caliper are released until the wheel speed is recovered, at the moment, the low-adhesion control process is started, and the operation is repeated in a circulating mode until the vehicle is static.
Compared with the prior art, the invention has the following advantages and effects: on the basis of the original EPB system, the anti-lock function during emergency braking is added, and the safety performance of an electronic parking system is improved; the control algorithm with strong self-adaptation is applied to the control logic of an EPB controller of an electronic parking system, the road surface condition can be judged according to the wheel speed change of the automobile wheels, the clamping force of the EPB calipers is adjusted in real time, the braking response is fast during emergency braking, and the automobile wheels always reach the locking edge until the automobile stops; software design of the anti-lock method is directly loaded on the EPB controller, special adjustment is not needed in assembly, a control unit is not needed to be additionally added, the anti-lock method is suitable for all vehicle types containing the EPB, the applicability is good, and modification and upgrading are easy.
Drawings
FIG. 1 is a schematic diagram of an EPB-based anti-lock system according to the present invention.
FIG. 2 is a flow chart of an anti-lock method of an EPB based anti-lock system according to the present invention.
Detailed Description
To elaborate on technical solutions adopted by the present invention to achieve predetermined technical objects, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, it is obvious that the described embodiments are only partial embodiments of the present invention, not all embodiments, and technical means or technical features in the embodiments of the present invention may be replaced without creative efforts, and the present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.
As shown in fig. 1, the anti-lock braking system based on EPB of the present invention comprises an EPB controller, a vehicle wheel speed signal source, a vehicle battery power supply, an EPB switch, a left EPB caliper and a right EPB caliper, wherein the vehicle wheel speed signal source is connected to the EPB controller for collecting wheel speed signals of each wheel of the vehicle, the vehicle battery power supply is connected to the EPB controller for supplying power to each component of the system, the EPB switch is connected to the EPB controller for controlling a switch of an anti-lock braking program, and the left EPB caliper and the right EPB caliper are respectively disposed on a left rear wheel and a right rear wheel of the vehicle and connected to the EPB controller for tightly holding and decelerating the left rear wheel and the right rear wheel of the vehicle.
When the vehicle body is in a running state and the vehicle speed is more than 3KM per hour, the EPB switch executes clamping operation of calipers, and the EPB controller of the electronic parking system controls the calipers to execute clamping anti-lock operation.
Wherein, the automobile rear wheel speed signal source is connected with the EPB controller through a CAN line. The automobile storage battery power supply directly adopts the whole automobile power supply of an automobile, and the normal working voltage of the automobile storage battery power supply is 9-16V.
According to the EPB-based anti-lock brake system, the brake control structure is an independent structure and is not connected with other brake systems of the automobile.
As shown in fig. 2, an anti-lock method of an EPB-based anti-lock system includes the steps of:
the method comprises the following steps: the method comprises the following steps that an automobile wheel speed signal source collects wheel speed signals of four wheels of an automobile and uploads the wheel speed signals to an EPB controller;
step two: the EPB controller calculates the locking degree of the rear wheel according to the wheel speed signal so as to judge the road surface condition;
the specific process of calculating the locking degree of the rear wheel by the EPB controller according to the wheel speed signal is that
The EPB controller calculates the slip rate of the rear wheel of the automobile relative to the front wheel according to the wheel speed signal:
＝(Vt-Va)/Vt*100％
wherein Vt is the wheel speed of the front wheel of the automobile, and Va is the wheel speed of the rear wheel of the automobile;
instantaneous deceleration a during vehicle running:
a=dv/dt
dv is a wheel speed change value of the front wheel of the vehicle, dv = V1-V0, V1 is the current wheel speed of the front wheel of the vehicle, and V0 is the wheel speed of the vehicle before dt moment; dt is the time taken for the front wheel speed of the vehicle to change;
in the dynamic driving process of the vehicle, the EPB switch triggers an EPB emergency braking function when clamping operation is executed, the EPB controller firstly controls the left EPB caliper and the right EPB caliper to apply fixed tightening force (the force needs real vehicle calibration, and the force of each vehicle type is different according to the cylinder diameter of the calipers), and the road condition is judged according to the tire slip rate.
Step three: the EPB controller executes clamping force operation of corresponding road surfaces on the left EPB caliper and the right EPB caliper according to different road surface conditions;
when braking is performed on a high-attachment road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficient of a road surface is large, a rear wheel cannot slip, no wheel speed deviation exists between the front wheel and the rear wheel, the slip rate is 0, and then the clamping force of the left EPB caliper and the clamping force of the right EPB caliper are gradually increased until the deceleration a is larger than the target deceleration by 0.15 g;
when braking is performed on a low-attachment road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficient of a road surface is small, the slip rate of the rear wheel is increased, the left EPB caliper and the right EPB caliper start to release when the slip rate is larger than 0.3, the left EPB caliper and the right EPB caliper apply braking force again until the wheel speed of the rear wheel is recovered to be the same as the vehicle speed, and the steps are repeated in such a circulating way until the vehicle is static;
when braking is performed on an open road (one side is high and the other side is low): the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the friction coefficients of road surfaces on the left side and the right side are different, a wheel on one side cannot slip, the slip rate of the wheel on the other side is gradually increased, the left EPB caliper and the right EPB caliper are independently controlled, the braking force is gradually increased on the high-attachment side until the deceleration a of the vehicle is greater than the target deceleration by 0.1g, the low-attachment side enters low-attachment control, the calipers on the low-attachment side are firstly released when the slip rate is greater than 0.3, the clamping force is applied again after the wheel speed of the wheel on the low-attachment side is recovered, and;
when braking is performed on an abutting road surface-low-attachment to high-attachment road surface: the left EPB caliper and the right EPB caliper apply fixed clamping force firstly, enter a low-attachment control stage firstly, after a running road surface is switched from low-attachment to high-attachment, the slip rate of a rear wheel is reduced, the wheel speed of the rear wheel is recovered to be consistent with that of a front wheel, the left EPB caliper and the right EPB caliper gradually apply braking force again until the deceleration a is larger than a target deceleration, and the left EPB caliper and the right EPB caliper stop acting until a vehicle is static;
when braking is performed on an abutting road surface-high attached to low attached road surface: the left EPB caliper and the right EPB caliper firstly apply fixed clamping force, the high-adhesion control process is clamped according to target deceleration, the low-adhesion road surface is switched, the adhesion coefficient is reduced, the slip rate of a rear wheel of the vehicle is increased, when the slip rate is larger than 0.3, the left EPB caliper and the right EPB caliper are released until the wheel speed is recovered, at the moment, the low-adhesion control process is started, and the operation is repeated in a circulating mode until the vehicle is static.
Step four: and repeating the first step to the third step until the vehicle speed is less than 3 KM/hour or the clamping pressure of an EPB caliper is kept at the wheel locking edge.
The method software of the EPB controller of the electronic parking system is designed to calibrate anti-lock data when emergency braking is carried out on different automobile types.
On the basis of the original EPB system, the anti-lock function during emergency braking is added, and the safety performance of an electronic parking system is improved; the control algorithm with strong self-adaptation is applied to the control logic of an EPB controller of an electronic parking system, the road surface condition can be judged according to the wheel speed change of the automobile wheels, the clamping force of the EPB calipers is adjusted in real time, the braking response is fast during emergency braking, and the automobile wheels always reach the locking edge until the automobile stops; software design of the anti-lock method is directly loaded on the EPB controller, special adjustment is not needed in assembly, a control unit is not needed to be additionally added, the anti-lock method is suitable for all vehicle types containing the EPB, the applicability is good, and modification and upgrading are easy.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.