CN104176022A - Travelling crane brake pedal active control based hill-start assist system - Google Patents

Abstract

The invention discloses a slope start auxiliary system based on the active control of the service brake pedal, which is composed of a signal acquisition part, an electronic control part and an executive mechanism; the signal acquisition part detects the rotation of the vehicle wheel and the distortion that occurs when the rear axle is stressed Changes and gear positions, and provide these information to the electronic control part as auxiliary starting information; the electronic control part collects and processes the information sent by the signal acquisition part, and sends the processed control information to the executive agency; the executive agency The control information is obtained and executed, and the stepping motor is used to drive the brake pedal to assist the hill start. The beneficial effect of the invention is that the system structure is simple, the cost is low, and it can well assist the car to start on a slope.

Description

Hill start assist system based on active control of service brake pedal

technical field

The invention belongs to the technical field of auxiliary equipment for starting on a hill for automobiles, and relates to an assisting system for starting on a hill based on the active control of a service brake pedal.

Background technique

With the continuous development of my country's economy and the continuous improvement of people's living standards, more and more families began to buy cars. As of 2013, the number of cars in my country reached 137 million. However, if the car is not properly manipulated when starting on a slope, it is easy to cause the car to stall or slip backwards, or even hit the vehicle behind. Therefore, the author wants to design a hill start assist system for manual transmission cars. The assist system actively controls the brake pedal and replaces the driver when the vehicle rolls, thereby preventing It eliminates the phenomenon of the car slipping back when starting on a hill, simplifies the operation process of the car starting on a hill, relieves the driver's fear of starting on a hill, and does not affect driving on flat ground. Especially for a mountain city like Chongqing with many slopes, the car slope assist system can not only prevent the vehicle from slipping backwards, but also reduce the fuel consumption and wear when the car starts.

For the research on the Hill-start Assist System (HSS, Hill-start Assist System), some achievements have been made at home and abroad. The main research results at this stage are summarized into three categories based on the different control principles: 1. Hill start assist system of parking brake system (EPB); 2. Hill start assist system based on anti-lock brake system (ABS); 3. Other types of HAS systems.

Contents of the invention

The purpose of the present invention is to provide a hill start assist system based on the active control of the service brake pedal, which solves the problem that there is no hill start assist system for automobiles in China at present.

The technical scheme adopted by the present invention is composed of a signal acquisition part, an electronic control part and an executive mechanism;

The signal acquisition part detects the rotation of the wheels of the vehicle, the distortion change and the position of the gear position when the rear axle is stressed, and provides these information to the electronic control part as auxiliary starting information;

The electronic control part collects and processes the information sent by the signal acquisition part, and sends the processed control information to the executing agency;

The actuator obtains and executes the control information, and utilizes a stepping motor to drive a brake pedal to assist hill start.

Further, the signal acquisition part includes a wheel speed sensor, a wheel speed sensor to measure the wheel speed, a torque sensor to measure the torque, a first gear switch signal measurement module and an R gear switch signal measurement module to collect the gear state;

The electronic control part is an ECU module, and the ECU module is respectively connected with a wheel speed sensor, a torque sensor, a first gear switch signal measurement module, an R gear switch signal measurement module and a stepper motor through circuits;

The executive mechanism includes a stepping motor, a brake pedal and a braking system; the stepping motor is connected with the brake pedal, and the brake pedal is connected with the braking system.

Further, the ECU module is composed of a small system circuit formed by an AT89C51 chip.

The beneficial effect of the invention is that the system structure is simple, the cost is low, and it can well assist the car to start on a slope.

Description of drawings

Fig. 1 is a schematic structural diagram of the hill start assist system based on the active control of the service brake pedal in the present invention;

Fig. 2 is the circuit schematic diagram of the ECU module small system of the present invention;

Fig. 3 is a schematic diagram of the auxiliary control method of the present invention;

Fig. 4 is a schematic diagram of ECU monitoring, holding and releasing braking of the present invention;

Fig. 5 is a schematic diagram of the stress situation of the car ramp in the present invention.

In the figure, 1. Wheel speed sensor, 2. Torque sensor, 3. First gear switch signal measurement module, 4. R gear switch signal measurement module, 5. ECU module, 6. Stepper motor, 7. Brake pedal, 8 .Braking System.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention based on the active control of the service brake pedal 7, the MT car ramp start assist system is composed of a signal acquisition part, an electronic control part and an executive mechanism;

The signal acquisition part detects the rotation of the car wheels, the twisting change of the rear axle when the force is applied, and the gear position, and provides these information to the electronic control part as auxiliary starting information;

The electronic control part collects and processes the information sent by the signal acquisition part, and sends the processed control information to the executing agency;

The actuator obtains and executes the control information, and utilizes the stepper motor to drive the brake pedal 7 to assist hill start.

As shown in Figure 1, the signal acquisition part includes a wheel speed sensor 1, a wheel speed sensor 1 to measure the wheel speed, a torque sensor 2 to measure the torque, a first gear switch signal measurement module 3 and an R gear switch signal measurement module 4 to collect gears state;

Described electronic control part is ECU module 5, and ECU module 5 can select AT89C51 small system circuit to form, to the signal that wheel speed sensor 1, torque sensor 2, first gear switch signal measurement module 3 and R gear switch signal measurement module 4 collect Processing, the control command is obtained and sent to the stepper motor 6, thereby controlling the brake pedal 7 through the stepper motor 6 to control the entire braking system 8;

The executive mechanism includes a stepping motor 6, a brake pedal 7 and a braking system 8. The stepping motor 6 executes control commands to directly control the braking pedal 7, and the braking pedal 7 drives the braking system 8 to brake.

Wherein, the ECU module 5 is electrically connected to the wheel speed sensor 1, the torque sensor 2, the first gear switch signal measurement module 3, the R gear switch signal measurement module 4 and the stepper motor 6, and the stepper motor 6 is mechanically connected to the brake pedal 7, and the Moving pedal 7 is mechanically connected to braking system 8.

Among them, the ECU module 5 shoulders the important task of information processing. It needs to convert the electrical signal from the sensor into a digital signal through A/D conversion for the CPU to process and calculate. Finally, the control command obtained after processing is converted from the digital signal through D/D. A is converted into an electrical signal and sent to the actuator. The ECU module 5 is the part that realizes the logic control capability of the system and is the core of the system. The hill start assist system designed by the present invention is controlled by two programs in an ECU module 5 to start on a steep slope and start on a steep slope respectively, and the start of operation needs the monitoring data of the wheel speed sensor 1 and the switch arranged on the gear position to complete , the execution part of braking is completed by the stepper motor 6 controlling the brake pedal 7 to control the braking system 8, and the torque sensor 2 is required to provide relevant detection data to terminate the assistance. For the choice of ECU module 5 single-chip microcomputer, the 80C196KC single-chip microcomputer of MCS series is adopted. This single-chip microcomputer is a 16-bit high-performance single-chip microcomputer. It is not only used in ABS, but also used in ignition system and fuel system. This is enough to prove that it is very It is suitable for highly demanding real-time control occasions, and the present invention adopts this single-chip microcomputer that responds quickly.

Choice of executive body:

Because automobiles generally use a hydraulic braking system, but the structural method of changing the braking system 8 is more complicated and the cost is higher. The present invention selects the specially made stepper motor 6 to pull the mode of brake pedal 7 to control braking system 8, compared with changing the structure of braking system 8, it has the following advantages:

1) The rotation angle of the stepping motor 6 is easy to control, and only needs open-loop control.

2) The stepper motor 6 can be rotated at a certain angle and then remain still, thus maintaining a braking state for a period of time.

3) The stepper motor 6 can rotate back and forth and can simulate the point brake that the driver often uses.

4) In this way, the changes to the car are small and the damage to the car is small.

Since the driving current of the stepping motor 6 is relatively large, the ECU module 5 uses a ULN2003 driving chip as an interface with the stepping motor 6 and a driving circuit. (a) to (c) in Figure 2 are the small system circuit diagrams of the ECU module 5, in which the small systems of the ECU module 5 are respectively connected to the signal acquisition system, and connected to the stepper motor 6 through the ULN2003 driver chip.

As shown in Figure 3, it is a schematic diagram of the auxiliary control method of the present invention, and the working process of the MT automobile hill start auxiliary system based on the active control of the service brake pedal 7 of the present invention is:

Step 1: Start the car;

Step 2: When the first gear switch signal measurement module 3 detects that the car is in gear 1, proceed to step 3, and when the R gear switch signal measurement module 4 detects that the car is in R gear, jump to step 5;

Step 3: ECU module 5 runs the ECU program on the steep slope;

Step 4: Wheel speed sensor 1 checks whether the wheel speed is 0, if it is 0, execute the forward gear start assist, if not 0, end the ECU program for uphill slope;

Step 5: ECU module 5 runs the ECU program for downhill slope;

Step 6: Wheel speed sensor 1 checks whether the wheel speed is 0, if it is 0, perform reverse gear start assistance, if not 0, end the downhill ECU program.

Since the hill start assist system designed in this paper is automatic, the judgment of the two initial operating conditions will be the key. When the 1st gear or the reverse gear is engaged and the wheel speed measured by the wheel speed sensor 1 is 0, the hill start assist program will be run accordingly, and the hill start assist system will not be activated if any of them are missing.

As shown in Figure 4, for the release of the brake, it is only necessary for the ECU to collect the torque during braking, record it and compare it with the data collected later. If the torque returns to the state on the flat road, that is, the driving force and the sliding When the force reaches a balance, the brake can be released and the vehicle can start.

In addition, this design also considers the situation that the driver may want the car to slide down sometimes, and sets up related functions. When the driver wants to slide down, he can put the shift lever into neutral gear, so that the 1st gear and reverse gear switches will not be activated, the hill start assist program will not start, and the driver can drive the car according to his own ideas. slipped.

As shown in Figure 5, it is a schematic diagram of the force on the ramp of the car. When the vehicle is parked on the ramp and ready to start, there will be an action and a state, which are respectively in gear and zero wheel speed. These two conditions are the car Conditions for Hill Start Assist to start working. In order to realize the functions of the hill assist system to prevent backward slipping when starting uphill and prevent forward slipping when starting downhill, the uphill start and downhill start are respectively controlled according to the obtained signals. Here we assume that it is starting on an uphill hill. First, the driver will engage the first gear when starting, and then the ECU will first collect the data of the wheel speed sensor to monitor whether the vehicle has slipped during the next starting process, so as to To judge whether it is necessary to activate the hill assist system, but the auxiliary system is designed to prevent the car from sliding when starting. If there is no slide (the driver operates properly and starts perfectly), there is no need to activate the auxiliary system. When the vehicle slides, the wheels will rotate backwards. This phenomenon will be detected by the wheel speed sensor and the data will be transmitted to the ECU. After receiving the signal, the ECU will send a control signal to the stepping motor to let the stepping motor replace it. The driver depresses the brake pedal 7 to the deepest point and keeps the brakes, so the anti-rolling work is completed, and the function of the auxiliary system has also been realized in half.

When the car completes the starting operation, the vehicle needs to release the brake to move forward. After the stepping motor completes the braking operation, the ECU begins to collect the signal of the torque sensor. When the vehicle is on a slope, it should have slipped back under the action of the sliding force F generated by its own weight, and the wheels should have rotated counterclockwise, but under the action of braking, the tires were Locked, the sliding force F is offset by the friction force f given to the wheel by the ground, so that the vehicle can stop on the slope. Although the tire stops moving, there is still a tendency to rotate counterclockwise under the action of the sliding force. This tendency is reflected by the brake disc to the brake caliper that prevents the brake disc from rotating, so that the brake caliper is at the position where it is in contact with the brake disc. Subjected to the friction force tangential to the round edge of the brake disc f caliper. The brake caliper is installed on the rear axle through the bracket. The rear axle is coaxial with the brake disc and connected with the body. The function of the axle is to transmit various forces and moments between the tire and the body. There is a distance between the caliper and the rear axle in the vertical direction of the f caliper, which produces an anticlockwise torque on the rear axle (accurately speaking, on the axle housing). The torsion value is detected by the torque sensor 2 and transmitted to the ECU. As long as the torque value exists, the ECU will not release the brake. When the driver slowly lifts the clutch pedal and simultaneously depresses the accelerator pedal, the driving force of the car gradually increases, and the driving force is transmitted to the driving half shaft through the drive shaft, final reducer, and differential, and the half shaft drives the brake disc to generate a clockwise rotation. The movement tendency gradually overcomes the counterclockwise rotation tendency due to the sliding force, which gradually reduces the torque on the axle. When the torque sensor 2 detects that the torque value on the rear axle is 0, or even detects a clockwise torque on the rear axle, it means that the driving force has overcome the sliding separation at this time, which is enough to make the car on the slope move forward. At this time, the ECU sends an instruction to the stepper motor to release the brake, so that the car starts smoothly.

As for going downhill, it is actually the same reason to put reverse gear and start backward. After the reverse gear is engaged, the reverse gear switch is connected, and the reverse gear ECU starts to work to detect the wheel speed. If the wheel speed is 0, it will start hill assist. If the vehicle slips forward Just take braking, the data of the detected torque sensor 2 when releasing the braking is contrary to the foregoing text.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Any simple modifications made to the above embodiments according to the technical essence of the present invention, equivalent changes and modifications, all belong to this invention. within the scope of the technical solution of the invention.

Claims (3)

1. The hill start assist system based on the active control of the service brake pedal, which is characterized in that it is composed of a signal acquisition part, an electronic control part and an actuator; The signal acquisition part detects the rotation of the wheels of the vehicle, the distortion change and the position of the gear position when the rear axle is stressed, and provides these information to the electronic control part as auxiliary starting information; The electronic control part collects and processes the information sent by the signal acquisition part, and sends the processed control information to the executing agency; The actuator obtains and executes the control information, and utilizes a stepping motor to drive a brake pedal to assist hill start. 2. The hill start assist system based on the active control of the service brake pedal according to claim 1, characterized in that: The signal acquisition part includes a wheel speed sensor (1), a wheel speed sensor (1) for measuring wheel speed, a torque sensor (2) for measuring torque, a first gear switch signal measurement module (3) and an R gear switch signal measurement module (4 ) to collect the gear state; The electronic control part is an ECU module (5), and the ECU module (5) is respectively connected to the wheel speed sensor (1), the torque sensor (2), the first gear switch signal measurement module (3), and the R gear switch signal measurement module through circuits. (4) and stepper motor (6); The actuator includes a stepper motor (6), a brake pedal (7) and a brake system (8); the stepper motor (6) is connected to the brake pedal (7), and the brake pedal (7) is connected to the brake system (8). 3. The hill start assisting system based on the active control of the service brake pedal according to claim 1, characterized in that: the ECU module (5) is composed of a small system circuit composed of an AT89C51 chip.