CN117901657A - Vehicle hill start auxiliary control method - Google Patents

Abstract

The invention discloses a vehicle hill start auxiliary control method, belongs to the technical field of vehicle control, and can solve the problem of backward running of a vehicle caused by improper operation of a driver during hill start, simplify operation of the driver and improve safety of the vehicle. The method comprises the following steps: s1, collecting current state information of a vehicle; s2, when the current state information meets a first preset condition, controlling the vehicle to enter a ramp auxiliary mode; s3, acquiring the actual rotating speed and the actual rotating speed change rate of the vehicle, and calculating the auxiliary torque of the ramp according to the actual rotating speed and the actual rotating speed change rate; s4, controlling the vehicle to work according to the auxiliary torque of the ramp. The invention is used for vehicle hill start auxiliary driving.

Description

Vehicle hill start auxiliary control method

Technical Field

The invention belongs to a vehicle hill start auxiliary control method, and particularly relates to the technical field of vehicle control.

Background

With the great development and the gradual popularization of the pure electric vehicles, the requirements of people on the driving comfort and the safety technical problems of the pure electric vehicles are higher. Hill start is a complex working condition with higher occurrence frequency and higher accident rate in the running process of a vehicle, and once the vehicle is operated improperly, the vehicle is possibly accelerated suddenly due to excessive power, or the vehicle is not balanced with the back sliding force of the hill due to too little power, so that the vehicle has high requirements on the control technology of a driver. The hill start assisting system can simplify the operation of a driver and improve the safety of the vehicle.

However, the existing hill start auxiliary system generally needs to participate in a mechanical braking system and needs to be operated by a driver in a complex manner, which results in a relatively high difficulty in smoothly starting the vehicle on the hill, and thus, the safety of the vehicle is relatively poor.

Disclosure of Invention

The invention aims to solve the technical problem of providing a vehicle hill start auxiliary control method, which mainly solves the problem of backward running of a vehicle caused by improper operation of a driver during hill start, simplifies the operation of the driver and improves the safety of the vehicle.

The content of the invention comprises:

the invention provides a vehicle hill start auxiliary control method, which comprises the following steps:

S1, collecting current state information of a vehicle;

S2, when the current state information meets a first preset condition, controlling the vehicle to enter a ramp auxiliary mode;

s3, acquiring the actual rotating speed and the actual rotating speed change rate of the vehicle, and calculating the auxiliary torque of the ramp according to the actual rotating speed and the actual rotating speed change rate;

s4, controlling the vehicle to work according to the hill auxiliary torque.

Optionally, the step S3 specifically includes:

S31, acquiring the actual rotation speed of the vehicle, and calculating a difference value between a target rotation speed and the actual rotation speed as a rotation speed difference value;

s32, inputting the rotation speed difference value into a rotation speed controller, and outputting rotation speed change rate compensation;

s33, acquiring the actual rotation speed change rate of the vehicle, and calculating the difference between the rotation speed change rate compensation and the actual rotation speed change rate to serve as a rotation speed change rate difference;

s34, inputting the rotational speed change rate difference value into a rotational speed change rate controller, and outputting the hill auxiliary torque.

Optionally, the rotation speed controller and the rotation speed change rate controller are both PI controllers.

Optionally, the Kp parameter and the Ki parameter of the rotation speed controller are obtained through looking up a corresponding motor rotation speed change rate.

Optionally, the current state information includes: a key signal, a gear signal, a parking signal, an accelerator pedal signal, a brake pedal signal, and a motor rotational speed signal fed back by a motor controller of the vehicle.

Optionally, the S2 specifically includes:

s21, detecting a key signal of a vehicle, and judging whether the vehicle is electrified or not according to the key signal; if yes, executing S22, and if not, executing S27;

s22, detecting a gear signal of a vehicle, and judging whether the vehicle is in a driving gear or not according to the gear signal; if yes, executing S23, and if not, executing S27;

S23, detecting a parking signal of a vehicle, and judging whether the parking brake of the vehicle is invalid according to the parking signal; if yes, executing S24, and if not, executing S27;

S24, detecting a brake pedal signal of a vehicle, and judging whether service braking of the vehicle is invalid according to the brake pedal signal; if yes, executing S25, and if not, executing S27;

S25, detecting a motor rotating speed signal of a vehicle, and judging whether the vehicle has a backward sliding trend according to the motor rotating speed signal; if yes, executing S26, and if not, executing S27;

s26, controlling the vehicle to enter a hill-hold mode;

s27, controlling the vehicle to exit from the hill-hold mode.

Optionally, after the step S3, the method further includes:

s5, acquiring driving intention information, and controlling the vehicle to exit from the ramp auxiliary mode when the driving intention information meets a second preset condition.

Optionally, the driving intention information includes an accelerator pedal signal and a request torque information;

the step S5 specifically comprises the following steps:

And when an accelerator pedal signal is detected and a request torque of a driver is detected to be larger than the hill-assist torque, controlling the vehicle to exit from the hill-assist mode.

Optionally, after S2, the method further includes:

s6, after entering the hill-hold mode for a preset period of time, controlling the vehicle to exit the hill-hold mode.

Optionally, the S4 specifically is:

And transmitting the ramp auxiliary torque to a motor controller of the vehicle so that the motor controller controls a motor of the vehicle to work according to the ramp auxiliary torque.

The beneficial effects of the invention are as follows:

According to the vehicle hill start auxiliary control method provided by the invention, on the premise of not adding the sensor and the executing mechanism, the time of hill start auxiliary intervention is judged, the motor is controlled by the double closed loop PI controller to output the hill start auxiliary torque, so that the vehicle rapidly reaches a balanced state on the hill, the hill start auxiliary function is realized within an acceptable backward sliding distance range, the vehicle hill start is realized, the operation of a driver is simplified, and the safety of the vehicle is improved.

Drawings

FIG. 1 is a flowchart of a vehicle hill start assist control method according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a vehicle ramp starting assist system according to an embodiment of the present invention;

FIG. 3 is a decision chart of a hill start assist mode for a vehicle according to an embodiment of the present invention;

fig. 4 is a torque control block diagram of a vehicle hill start assist system according to an embodiment of the present invention.

Detailed Description

The present invention is described in detail below with reference to examples, but the present invention is not limited to these examples.

The power of the pure electric vehicle is derived from the driving motor, the driving motor can output peak torque under the low-speed working condition and the locked-rotor working condition, and the torque output has the characteristics of high precision and quick response. The invention provides a method for hill start auxiliary control of a pure electric vehicle, which does not need to participate in a mechanical braking system or increase a sensor, and can balance with the hill backward sliding force only by controlling the output driving torque of a motor, thereby realizing the stable hill start of the vehicle. The hill start auxiliary system is divided into a decision making mechanism and an executing mechanism, wherein the decision making mechanism is a whole vehicle controller, and the executing mechanism is a motor and a controller.

Specifically, as shown in fig. 1 to fig. 4, the present invention provides a vehicle hill start auxiliary control method, which includes:

s1, collecting current state information of a vehicle.

The whole vehicle controller collects the current state information of the vehicle, and specifically collects: a key signal, a gear signal, a parking signal, an accelerator pedal signal, a brake pedal signal, and a motor rotational speed signal fed back by a motor controller of the vehicle.

S2, when the current state information meets a first preset condition, controlling the vehicle to enter a ramp auxiliary mode.

The vehicle controller makes a mode decision to determine when to enter a hill-hold mode and when to exit the hill-hold mode, as shown in fig. 2, and specifically includes:

S21, detecting a key signal of the vehicle, and judging whether the vehicle is electrified according to the key signal; if yes, S22 is executed, and if no, S27 is executed. Specifically, the whole vehicle controller detects the key signal, judges whether the vehicle is electrified, if so, enters a subsequent flow, otherwise, exits the hill auxiliary mode.

S22, detecting a gear signal of the vehicle, and judging whether the vehicle is in a driving gear or not according to the gear signal; if yes, S23 is executed, and if no, S27 is executed. Specifically, the whole vehicle controller detects a gear signal, judges whether the vehicle is in a driving gear, enters a subsequent flow if the vehicle is in the driving gear, and exits the hill-hold mode if the vehicle is not in the driving gear.

S23, detecting a parking signal of the vehicle, and judging whether the parking brake of the vehicle is invalid according to the parking signal; if yes, executing S24, and if not, executing S27; specifically, the vehicle controller detects a parking signal, judges whether the parking brake is effective, enters a subsequent procedure if the parking brake is ineffective, and exits the hill-hold auxiliary mode if the parking brake is not effective.

S24, detecting a brake pedal signal of the vehicle, and judging whether the service brake of the vehicle is invalid according to the brake pedal signal; if yes, executing S25, and if not, executing S27; specifically, the vehicle controller detects a brake pedal signal, judges whether the service brake is effective, if the service brake is ineffective, enters a subsequent flow, and otherwise exits the hill auxiliary mode.

S25, detecting a motor rotation speed signal of the vehicle, and judging whether the vehicle has a backward slip trend according to the motor rotation speed signal; if yes, executing S26, and if not, executing S27; specifically, the vehicle controller detects a motor rotation speed signal, and considers that the vehicle has a backward slip trend when the motor rotation speed is smaller than-3 r/min, if the vehicle has the backward slip trend, the vehicle enters a hill auxiliary mode, and if the vehicle does not have the backward slip trend, the vehicle exits the hill auxiliary mode.

S26, controlling the vehicle to enter a hill auxiliary mode;

S27, controlling the vehicle to exit the hill-hold mode.

Further, after S3, the method further includes:

S5, acquiring driving intention information, and controlling the vehicle to exit from the ramp auxiliary mode when the driving intention information meets a second preset condition.

Wherein the driving intention information includes an accelerator pedal signal and requested torque information;

Correspondingly, S5 is specifically: when an accelerator pedal signal is detected and it is detected that the requested torque of the driver is greater than the hill assist torque, the vehicle is controlled to exit the hill assist mode.

After entering the hill-hold mode, if the driver depresses the accelerator pedal and the driver request torque is greater than the hill-hold torque, the driver has an intention to drive off the hill, and exits the hill-hold mode.

Further, after S2, the method further comprises:

s6, after entering the hill-hold mode for a preset period of time, controlling the vehicle to exit the hill-hold mode.

The preset time length is a preset time length, which can be set by a person skilled in the art according to actual situations, and the embodiment of the invention is not limited to this. In practical applications, the preset duration may be set to 5 seconds.

Because the driving motor cannot be locked for a long time, the timing is started after the driving motor enters the hill-hold mode, and if the time exceeds 5 seconds, the driving motor exits the hill-hold mode.

S3, acquiring the actual rotating speed and the actual rotating speed change rate of the vehicle, and calculating the auxiliary torque of the ramp according to the actual rotating speed and the actual rotating speed change rate.

The method specifically comprises the following steps:

S31, acquiring the actual rotation speed of the vehicle, and calculating a difference value between the target rotation speed and the actual rotation speed as a rotation speed difference value.

S32, inputting the rotation speed difference value into a rotation speed controller, and outputting rotation speed change rate compensation.

S33, acquiring the actual rotation speed change rate of the vehicle, and calculating the difference between the rotation speed change rate compensation and the actual rotation speed change rate as a rotation speed change rate difference.

S34, inputting the speed change rate difference value into a speed change rate controller, and outputting the auxiliary torque of the ramp.

The rotating speed controller and the rotating speed change rate controller are PI controllers. The Kp parameter and the Ki parameter of the rotating speed controller are obtained by looking up the magnitude of the change rate of the rotating speed of the motor when the vehicle slides backwards, so that the gradient magnitude and the vehicle load condition can be reflected.

After entering the hill auxiliary mode, the motor rotation speed needs to be controlled to be 0r/min rapidly and stably, so that the driving motor is kept in a locked state, and the vehicle is prevented from sliding backwards. In the prior art, acceleration in the advancing direction of a vehicle is obtained by means of an acceleration acquisition chip, a road ramp angle is calculated by means of a longitudinal dynamics equation of the vehicle, and initial motor torque is estimated according to the ramp angle. The invention designs a double closed loop PI controller (proportional integral controller) aiming at the condition of no sensor, and adaptively adjusts the auxiliary torque of the ramp, thereby realizing accurate and rapid control, and the framework is shown in figure 3.

Setting the target rotating speed to 0r/min, taking the difference value between the target rotating speed and the actual rotating speed as the input of a rotating speed PI controller, and performing closed-loop control to output rotating speed change rate compensation. The rotational speed PI controller can realize that the rotational speed change rate compensation dynamically changes along with the deviation of the actual rotational speed and the target rotational speed. Under the condition that a driver does not intervene, the vehicle slides backwards faster when the gradient is larger; the greater the vehicle weight, the faster the vehicle will roll back. Therefore, kp (proportion) and Ki (integral) parameters corresponding to the rotating speed PI controller can be searched through the motor rotating speed change rate, and larger Kp and Ki parameters are used when the motor rotating speed change rate is larger, so that the system response speed is increased; and when the change rate of the motor rotation speed is smaller, smaller Kp and Ki parameters are used, so that the response stability of the system is improved. For the whole double closed loop PI controller, the speed PI controller realizes the speed adjustment of the target speed approaching the actual speed.

And taking the difference value between the rotational speed change rate compensation output by the rotational speed PI controller and the actual rotational speed change rate as the input of the rotational speed change rate PI controller, and outputting target torque, namely the hill auxiliary torque in a closed loop manner. The rotational speed change rate deviation existing in the current system can be converted into target torque through the rotational speed change rate PI controller. Since the upper-stage rotation speed PI controller takes the influence of gradient and vehicle weight on the system into consideration, the Kp and Ki parameters of the rotation speed change rate PI controller are used as constants.

S4, controlling the vehicle to work according to the auxiliary torque of the ramp.

The method comprises the following steps: and transmitting the ramp auxiliary torque to a motor controller of the vehicle so that the motor controller controls the motor of the vehicle to work according to the ramp auxiliary torque.

The whole vehicle controller calculates the auxiliary torque of the ramp and sends the auxiliary torque to the motor controller. The motor and the controller thereof receive and respond to the auxiliary torque of the ramp issued by the whole vehicle controller, so that the vehicle can quickly reach an equilibrium state on the ramp.

According to the vehicle hill start auxiliary control method provided by the invention, on the premise of not adding the sensor and the executing mechanism, the time of hill start auxiliary intervention is judged, the motor is controlled by the double closed loop PI controller to output the hill start auxiliary torque, so that the vehicle rapidly reaches a balanced state on the hill, the hill start auxiliary function is realized within an acceptable backward sliding distance range, the vehicle hill start is realized, the operation of a driver is simplified, and the safety of the vehicle is improved.

While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.

Claims (10)

1. A vehicle hill start assist control method, characterized by comprising:

S1, collecting current state information of a vehicle;

S2, when the current state information meets a first preset condition, controlling the vehicle to enter a ramp auxiliary mode;

s3, acquiring the actual rotating speed and the actual rotating speed change rate of the vehicle, and calculating the auxiliary torque of the ramp according to the actual rotating speed and the actual rotating speed change rate;

s4, controlling the vehicle to work according to the hill auxiliary torque.

2. The method of claim 1, wherein S3 specifically comprises:

S31, acquiring the actual rotation speed of the vehicle, and calculating a difference value between a target rotation speed and the actual rotation speed as a rotation speed difference value;

s32, inputting the rotation speed difference value into a rotation speed controller, and outputting rotation speed change rate compensation;

s33, acquiring the actual rotation speed change rate of the vehicle, and calculating the difference between the rotation speed change rate compensation and the actual rotation speed change rate to serve as a rotation speed change rate difference;

s34, inputting the rotational speed change rate difference value into a rotational speed change rate controller, and outputting the hill auxiliary torque.

3. The method of claim 2, wherein the rotational speed controller and the rotational speed change rate controller are both PI controllers.

4. A method according to claim 3, wherein the Kp parameter and Ki parameter of the rotational speed controller are obtained by looking up a corresponding motor rotational speed change rate.

5. The method of claim 1, wherein the current state information comprises: a key signal, a gear signal, a parking signal, an accelerator pedal signal, a brake pedal signal, and a motor rotational speed signal fed back by a motor controller of the vehicle.

6. The method of claim 5, wherein S2 specifically comprises:

s21, detecting a key signal of a vehicle, and judging whether the vehicle is electrified or not according to the key signal; if yes, executing S22, and if not, executing S27;

s22, detecting a gear signal of a vehicle, and judging whether the vehicle is in a driving gear or not according to the gear signal; if yes, executing S23, and if not, executing S27;

S23, detecting a parking signal of a vehicle, and judging whether the parking brake of the vehicle is invalid according to the parking signal; if yes, executing S24, and if not, executing S27;

S24, detecting a brake pedal signal of a vehicle, and judging whether service braking of the vehicle is invalid according to the brake pedal signal; if yes, executing S25, and if not, executing S27;

S25, detecting a motor rotating speed signal of a vehicle, and judging whether the vehicle has a backward sliding trend according to the motor rotating speed signal; if yes, executing S26, and if not, executing S27;

s26, controlling the vehicle to enter a hill-hold mode;

s27, controlling the vehicle to exit from the hill-hold mode.

7. The method of claim 6, wherein after S3, the method further comprises:

s5, acquiring driving intention information, and controlling the vehicle to exit from the ramp auxiliary mode when the driving intention information meets a second preset condition.

8. The method of claim 7, wherein the driving intent information includes an accelerator pedal signal and requested torque information;

the step S5 specifically comprises the following steps:

And when an accelerator pedal signal is detected and a request torque of a driver is detected to be larger than the hill-assist torque, controlling the vehicle to exit from the hill-assist mode.

9. The method according to claim 6 or 7, wherein after S2, the method further comprises:

s6, after entering the hill-hold mode for a preset period of time, controlling the vehicle to exit the hill-hold mode.

10. The method according to claim 1, wherein S4 is specifically:

And transmitting the ramp auxiliary torque to a motor controller of the vehicle so that the motor controller controls a motor of the vehicle to work according to the ramp auxiliary torque.