CN106004838A - Auxiliary downhill control system and control method based on retarder - Google Patents

Abstract

The invention discloses a retarder-based downhill auxiliary control system and its control method. The downhill auxiliary control system of the present invention consists of three parts: a signal acquisition unit, an electronic control unit and a retarder, wherein the signal acquisition unit It is used to collect brake pedal opening signal, accelerator pedal opening signal and vehicle speed signal. The electronic control unit makes logical judgments based on the above three signals, and automatically starts or exits the downhill auxiliary control program. After starting the downhill assistance control program, the electronic control unit calculates the braking torque according to the vehicle state, and controls the retarder to output the braking torque, so that the vehicle speed is at an appropriate level and the vehicle speed does not increase. The invention takes the retarder as the control object, establishes a control system, formulates a control strategy, realizes the automatic start and exit of the downhill assist mode, and keeps the vehicle speed at an appropriate level to ensure that the vehicle speed will not increase, effectively improving the vehicle's safety. Active safety, and reduce the driver's driving burden.

Description

A retarder-based downhill assist control system and control method

technical field

The present invention relates to the technical field of vehicle downhill assistance, in particular to a retarder-based downhill assistance control system and control method.

Background technique

With the development of vehicle electronic control technology, the market has put forward higher requirements for vehicle safety and driving comfort, and the active safety and assisted driving technology of vehicles has also received more and more attention. Among them, the downhill assist technology can realize that the driver does not need to control the brake pedal and accelerator pedal during the downhill process of the vehicle. Vehicle speed no longer increases. This not only improves the active safety of the vehicle, but also reduces the driver's operational burden.

At the same time, as an important auxiliary braking device, the retarder has been widely used in vehicles. Developed countries such as the United States and Europe have adopted the retarder as a standard configuration. use. As far as its control method is concerned, it is developing from manual switch control to electronic automatic control. The importance of the control system in the retarder system is further enhanced, which largely determines the level of braking efficiency of the system. The retarder control The core technology of the system is still in the hands of foreign companies, occupying most of the market share, and there is an urgent need to develop a retarder control system with independent intellectual property rights in China. In addition, in the existing research in China, most of the control of the retarder is manual, and the automatic opening and exiting of the downhill assistance has not been realized.

Therefore, a set of downhill assist control system is developed with the retarder as the carrier, and the automatic control method is used to realize the automatic start and exit of the downhill assist mode, and to control the vehicle speed at an appropriate level to ensure that the vehicle speed will not increase. It has good application value and market prospect.

Contents of the invention

The object of the present invention is to provide a retarder-based downhill assist control system and a corresponding control method. According to the state of the vehicle and the driver's intention, the downhill assistance mode is automatically activated and exited, reducing the driver's previous manual operation. And in the downhill assist mode, the auxiliary braking of the retarder is used to control the vehicle speed at an appropriate level to ensure that the vehicle speed will not increase and improve the active safety of the vehicle.

To achieve the above object, the present invention takes the following technical solutions:

A downhill auxiliary control system for a hydraulic retarder, which consists of three parts: a signal acquisition unit, an electronic control unit and a retarder, of which

The signal acquisition unit is used to collect brake pedal opening signal, accelerator pedal opening signal and vehicle speed signal, and send these signals to the electronic control unit. Area Network) collection.

The electronic control unit includes an analog input interface circuit, a CAN communication interface, a processor and an output interface circuit. Among them: the input circuit of the analog input interface circuit is connected with the sensor, the output circuit is connected with the processor; the CAN communication interface is connected with the CAN bus of the vehicle, and connected with the processor; the control program is written inside the processor, according to The signal received from the analog input interface and the CAN communication interface is logically judged, and the control electrical signal is output to the output interface circuit; the input circuit of the output interface circuit is connected to the processor, and the output circuit is connected to the retarder.

The retarder is the executive device of the control system, which is used to output the braking torque, and it can be a hydraulic retarder or an eddy current retarder.

The invention also discloses a retarder-based downhill assist control method, which automatically starts and exits the downhill assist working mode:

When the opening of the accelerator pedal and the opening of the brake pedal are both zero and the vehicle speed increases, it is judged that the vehicle is in the state of accelerating and coasting on a downhill road, which has potential safety hazards. Therefore, the downhill assist mode is activated at this time. The state calculates the braking torque, which is output by the retarder, and then controls the vehicle speed at an appropriate level to keep the vehicle speed from increasing.

After the downhill assist mode is turned on, if the accelerator pedal opening or the brake pedal opening is not zero, it is judged that the driver wishes to control the vehicle speed to increase or decrease autonomously, so exit the downhill assist mode at this time, and the retarder output The braking torque gradually decreases to zero, and the vehicle speed is autonomously controlled by the driver.

The present invention adopts the above scheme, and compared with the prior art, the beneficial effect is: taking the retarder as the control object, the downhill auxiliary braking of the vehicle is realized, and the automatic start and exit of the downhill auxiliary mode is realized, which reduces the driving force. driver's driving burden.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present invention.

Fig. 2 is a control strategy diagram of the present invention.

In Figure 1: 1-brake pedal opening acquisition unit 2-accelerator pedal opening acquisition unit 3-vehicle speed acquisition unit 4-analog input interface circuit 5-CAN communication interface circuit 6-processor 7-output interface circuit 8- retarder

detailed description

The present invention is described in detail below in conjunction with accompanying drawing:

As shown in Figure 1, a downhill auxiliary braking control system for a hydraulic retarder includes the following parts: brake pedal opening acquisition unit 1, accelerator pedal opening acquisition unit 2, vehicle speed acquisition unit 3, analog Input interface circuit 4, CAN communication interface circuit 5, processor 6, output interface circuit 7 and retarder 8, wherein:

The brake pedal opening signal can be obtained through the brake pedal sensor.

Accelerator pedal opening signal can be obtained through accelerator pedal sensor. It can also be obtained from the accelerator pedal opening signal of the ECM (Engine Control Module) node through the CAN bus.

The vehicle speed signal can be obtained through the vehicle speed sensor, or through the CAN bus, the output shaft speed signal of the TCU (Transmission Control Unit automatic transmission control unit) node, combined with the transmission ratio of the transmission system.

The function of the acquisition unit is to send the collected vehicle status and driving intention signals to the electronic control unit 4 for logical judgment by the electronic control unit.

The analog input interface circuit 4 is used to realize signal conversion, and converts the analog electrical signal output by the sensor into an electrical signal that can be processed by the processor; in the same way, the CAN communication interface circuit 5 is connected to the CAN bus of the whole vehicle for receiving The received CAN message signal is converted into an electrical signal that can be processed by the processor; the processor 6 is internally written with a control program, which judges the state of the vehicle and the driver's intention according to the received signal, and outputs to start or exit the downhill assisting work Mode command, in addition, in the downhill assist mode, the processor is also responsible for calculating the braking torque according to the vehicle state, and controlling the retarder to output; the output interface circuit 7 mainly realizes power amplification, and the output signal power of the processor is relatively small. It is not enough to drive the retarder, so the output interface circuit is needed to amplify the output signal of the processor.

Retarder 8 is the execution device of the system and is used to output braking torque.

Control logic of the present invention is shown in formula (1):

Among them, DAC is the control logic of the downhill auxiliary braking system, 1 means that the auxiliary braking is enabled, 0 means that the auxiliary braking is disabled, "&" means the logic "and", "|" means the logic "or", _PAPS means the accelerator pedal is on P _APS means the driver does not step on the accelerator pedal, P _BPS means the opening of the brake pedal, P _BPS means the driver does not step on the brake pedal, and V means the vehicle speed. The control logic will be described in detail below.

1. The judgment conditions for automatic activation of downhill assist are: the opening of the accelerator pedal and the brake pedal are both zero, and the vehicle speed increases.

At this time, it is determined that the vehicle is speeding up and sliding on a downhill road, and there is a certain potential safety hazard, and the auxiliary brake needs to be turned on. Control the retarder to apply braking torque to ensure that the vehicle speed is within an appropriate range and is no longer higher than the target vehicle speed.

2. The judging condition for the automatic exit of the downhill assist is: on the premise that the downhill assist has been turned on, the opening of the accelerator pedal is not zero or the opening of the brake pedal is not zero. The control logic of the two cases is discussed below:

(1) After the downhill assist is turned on, if the accelerator pedal opening is not zero.

At this time, it is considered that the driver wants to increase the vehicle speed. If the downhill assist mode is immediately exited, the braking torque of the retarder will be reduced to zero immediately, which may cause a rapid increase in vehicle speed, and there is a certain potential safety hazard. Therefore, after the downhill auxiliary brake is turned on, if the opening of the accelerator pedal increases from zero to a certain value, the electronic control unit should first control the retarder to gradually reduce the braking torque, and when the braking torque After decreasing to zero, the vehicle accelerates in response to the acceleration request of the accelerator pedal. The downhill assist automatically exits, and the driver independently controls the vehicle to accelerate.

(2) After the downhill assist is turned on, if the brake pedal opening is not zero.

At this time, it is considered that the driver wants to control the vehicle speed autonomously through the service brake. If the downhill assist mode is exited immediately, the braking torque of the retarder will be reduced to zero immediately, which will instantly increase the working load of the service brake system. The braking system causes a shock. Therefore, in the same way, after the downhill auxiliary brake is turned on, if the brake pedal opening is not zero, as the brake pedal opening gradually increases, the braking torque of the service brake system gradually increases, and the electronic control unit should control The retarder makes the braking torque gradually decrease to zero, the downhill assist automatically exits, and the service brake system works alone.

3. When the downhill assistance is not activated and the retarder is not working, if the opening of the brake pedal or the accelerator pedal is not zero, it is regarded as the normal braking or acceleration of the vehicle. If the opening of the brake pedal and the accelerator pedal are both is zero, but the vehicle speed decreases, it is regarded as conventional deceleration coasting.

The invention takes the retarder as the control object, realizes the automatic start and exit of the downhill assist mode, reduces the driving burden of the driver's manual control, and controls the vehicle speed within an appropriate range in the downhill assist mode to ensure the vehicle speed No longer increase, reducing potential safety hazards, effectively improving the active safety of vehicles.

Claims (4)

1. A retarder-based downhill assist control system, which consists of three parts: a signal acquisition unit, an electronic control unit and a retarder; the signal acquisition unit is responsible for collecting vehicle status signals and driver intention signals, and inputting them to the electronic In the control unit: the electronic control unit performs logic judgment according to the signal, and automatically starts or exits the downhill auxiliary control program. When the controller starts the downhill assistance control program, it calculates the corresponding braking torque through the vehicle state, and outputs it from the retarder, so as to control the vehicle speed at an appropriate level, so that the vehicle speed will not increase any more; the retarder is the key of the system The actuator is used to output braking torque. 2. A kind of downhill assist control system based on retarder according to claim 1, characterized in that: the signal acquisition unit is composed of brake pedal opening acquisition unit (1), accelerator pedal opening acquisition unit (2) and The vehicle speed acquisition unit (3) is composed; Among them: the brake pedal opening signal can be obtained through the brake pedal sensor; the accelerator pedal opening signal can be obtained through the accelerator pedal sensor, or can be obtained from the ECM accelerator pedal opening signal through the CAN bus; the vehicle speed signal can be obtained through the vehicle speed sensor , can also be obtained from the output shaft speed signal of the TCU node and the transmission ratio of the transmission system through the CAN bus. 3. A kind of downhill auxiliary control system based on retarder according to claim 1, characterized in that: its electronic control unit is composed of analog quantity input interface circuit (4), CAN communication interface (5), processor ( 6) and an output interface circuit (7); Among them: the input circuit of the analog input interface circuit is connected with the sensor, the output circuit is connected with the processor; the CAN communication interface is connected with the CAN bus of the vehicle, and connected with the processor; the control program is written inside the processor, according to The signal received from the analog input interface and the CAN communication interface is logically judged, and the control electrical signal is output to the output interface circuit; the input circuit of the output interface circuit is connected to the processor, and the output circuit is connected to the retarder. 4. A retarder-based downhill assist control method according to claim 1, wherein the control logic is: 1) The judgment conditions for the automatic start of the downhill assist are: the opening of the accelerator pedal and the brake pedal are both zero, and the vehicle speed increases. At this time, the electronic control unit starts the downhill assist control, calculates the braking torque, and controls the retarder to apply the braking torque to ensure that the vehicle speed does not increase. 2) The judgment condition for automatically exiting the downhill assist is: on the premise that the downhill assist has been turned on, the opening of the accelerator pedal is not zero or the opening of the brake pedal is not zero. That is, after the downhill assist brake is turned on, when the driver steps on the brake pedal or the accelerator pedal, the downhill assist will automatically exit, realizing the driver's independent control of the vehicle speed.