CN112590742B - A ZigBee-based Active Hydraulic Braking System and Method for Trailer - Google Patents

Abstract

The invention discloses a ZigBee-based active hydraulic braking system and method for a trailer. The system includes a detection unit of a tractor, a ZigBee communication sending unit, a ZigBee communication receiving unit of the trailer, a workshop hook force detection unit, an electronic control unit and a motor Hydraulic braking unit; firstly, the acceleration, speed and steering wheel angle of the towing vehicle are obtained through the detection unit, and then the detected state information of the towing vehicle is sent to the receiving unit of the trailer through ZigBee wireless transmission, and then the electronic control unit of the trailer is based on The motion state information of the tractor and the hooking force of the workshop are internally judged, and finally the corresponding control signal is output to the hydraulic braking unit of the motor to make the trailer brake. The invention combines ZigBee communication and vehicle braking control, can obtain vehicle status information of the tractor in time, effectively controls the trailer braking, makes the trailer braking safer and more reliable, and reduces the collision and conflict between vehicles and trains.

Description

A ZigBee-based Active Hydraulic Braking System and Method for Trailer

technical field

The invention belongs to the technical field of automobile chassis braking, and in particular relates to a ZigBee-based active hydraulic braking system and method for a trailer.

Background technique

With the rapid development of my country's transportation infrastructure construction and the urgent demand of the national economy for modern logistics, road transportation is developing in the direction of intensification, and car trains have become the main transportation in road transportation due to their high efficiency and low cost. tool. With the rapid development of automobile train transportation, road traffic safety problems have gradually emerged. According to the relevant statistics of the Traffic Administration, more than 90% of the causes of traffic accidents are caused by the collision between the front and rear vehicles caused by braking. Therefore, more and more researchers have gradually begun to pay attention to the research of trailer braking system.

Originally, in order to cooperate with tractors with different forms of braking systems, the inertia braking system is generally used in the braking system of trailers at home and abroad. However, when the mechanical inertial braking system is used, due to the low braking efficiency of the mechanical inertial braking system, there is a certain hysteresis, it is prone to side slip, the braking coordination is poor, and it is easy to produce unfavorable results such as braking shock; when the mechanical inertial braking system is used In the case of the hydraulic inertia braking system, due to the insensitive braking of the hydraulic inertia braking system, it is easy to cause the phenomenon that the tractor is driven on the top of the trailer during the turning braking process, and the braking characteristics cannot be adjusted. To this end, someone proposed an active hydraulic braking system. The hydraulic braking system on the trailer generates a braking signal based on the sensor and the braking signal of the main vehicle to actively control the braking of the trailer. For example, the Chinese invention patent "An Active Trailer" Braking system" (application number: 201810430889.5), which performs braking control on the trailer according to the braking signal of the tractor and the relative position signal between the vehicles detected by the sensor. Compared with the traditional inertial hydraulic braking system, this system is more reliable, but the installation requirements are high and not sensitive enough, and the trailer can only obtain the braking signal of the tractor through the wiring harness socket, and can no longer obtain other motion states of the tractor. information, cannot accurately deal with the braking situation under complex working conditions.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a ZigBee-based active hydraulic braking system and method for a trailer. The system introduces the concept of the Internet of Things, and through the information exchange between the front and rear cars, the information resources are effectively utilized to improve the braking situation of the car and train.

The technical solution for realizing the purpose of the present invention is: a ZigBee-based active hydraulic braking system for a trailer, comprising a detection unit, a ZigBee sending unit, a ZigBee receiving unit, a workshop hook force detection unit, an electronic control unit and a motor hydraulic braking unit;

The described detection unit packs and transmits the speed, deceleration and steering wheel angle information of the detected tractor vehicle to the ZigBee sending unit, and sends it to the ZigBee receiving unit of the trailer by means of ZigBee communication, and the hook force detection unit on the trailer detects the tractor and the tractor. The hook force between the trailers, the electronic control unit calculates through the internal algorithm according to the information sent by the ZigBee receiving unit of the trailer and the hook force detection unit, determines whether to brake the trailer, and sends the control signal output by the calculation to the motor Hydraulic brake unit.

Further, the detection unit includes a speed detection unit, a deceleration detection unit and a steering wheel angle detection unit;

The speed detection unit and the deceleration detection unit complete the task of detecting the speed and deceleration of the tractor through the speed sensor and the acceleration sensor respectively, and the steering wheel angle detection unit detects the steering wheel angle of the tractor through the angle sensor on the steering wheel.

Further, the motor hydraulic braking unit includes a motor, a worm, a worm gear, a pinion, a rack, a liquid storage tank, a first piston cavity, a second piston cavity, a left brake wheel cylinder and a right wheel brake cylinder;

The control end of the motor is connected to the output end of the electronic control unit, and the motor, the worm, the worm gear, the pinion and the rack are connected in series in sequence, and the liquid storage tank is connected to the first piston cavity and the second of the brake master cylinder through the liquid pipeline. Piston cavity, left brake wheel cylinder and right brake wheel cylinder are connected;

The electronic control unit receives the motion state information of the tractor and the hook force information of the workshop, and outputs the control signal to the motor after calculation, and the motor starts to rotate. , pushes the piston in the brake master cylinder to generate pressure in the first piston cavity and the second piston cavity, so as to pressurize the left and right brake wheel cylinders to make the trailer brake.

A method for utilizing the above-mentioned control system to control, comprising the steps of:

S1) When the tractor brakes, the electronic control unit of the trailer receives the motion status information and the workshop hook force information of the tractor through the ZigBee receiving unit and the workshop hook force detection unit, and outputs the control signal through the internal algorithm to generate torque for the motor. The deceleration mechanism and the motion conversion mechanism are converted into a linear force, and act on the piston push rod of the brake master cylinder connected to it, so that the first piston chamber and the second piston chamber generate pressure, which affects the left and brake of the brake wheel cylinder. The right wheel cylinder is pressurized to force the trailer to brake. This is the process of pressurization;

S2) When the tractor releases the brake, the electronic control unit of the trailer receives the brake release signal of the tractor, and judges whether the brake control of the trailer needs to be performed according to the hook force between the vehicles. If the hook force between the vehicles exceeds a certain critical value The trailer needs to be braked, the current position of the motor rotor is maintained, and a certain braking pressure is maintained. This is the pressure maintaining process; The unit drives the motor to reverse, pulls back the piston in the brake master cylinder through the deceleration mechanism and the motion conversion mechanism, and relieves the pressure of the left and right brake wheel cylinders, which is a decompression process;

S3) When the tractor is reversing, after the electronic control unit of the trailer receives the reversing signal of the tractor, it does not consider the status information of the tractor and the trailer, and internally judges that the trailer does not need to perform brake control, and the motor does not work until the reversing task is completed , which is a pressureless process.

Compared with the prior art, the present invention has the following significant advantages:

(1) On the basis of the hydraulic braking system of the trailer, the present invention introduces the concept of the Internet of Things and adopts the ZigBee communication system, which has the characteristics of low power consumption, low cost, self-configuration and high safety, so that the trailer can quickly and accurately accept the tractor's Speed, deceleration and steering wheel angle information, the trailer electronic control unit can accurately and timely control the trailer according to these information, realize the active braking of the trailer, make the trailer braking more real-time and reliable, and greatly reduce the collision probability between cars and trains. And it can avoid the collision between the car train and other vehicles on the road during the braking process.

(2) The motor hydraulic braking system used in the present invention, by receiving the control signal of the electronic control unit, makes the motor rotate to generate torque, which is converted into a linear thrust through the deceleration mechanism and the motion conversion mechanism, and pushes the piston in the brake master cylinder, The hydraulic pressure is generated on the brake wheel cylinder to make the trailer brake, which can meet the demand of large hydraulic pressure. The motor hydraulic braking system combined with the ZigBee communication system makes the active braking of the trailer more efficient, which is beneficial to face various complex working conditions, and the installation of the ZigBee communication unit makes the layout easier and the troubleshooting more convenient.

Description of drawings

FIG. 1 is a schematic diagram of the principle of a ZigBee-based active hydraulic braking system for a trailer in the present invention.

Fig. 2 is a model diagram of an automobile train in the present invention.

FIG. 3 is a working principle diagram of the trailer motor hydraulic braking system in the present invention.

FIG. 4 is a flow chart of steps of a ZigBee-based active hydraulic braking control method for a trailer in the present invention.

Description of reference numbers:

100-detection unit, 101-ZigBee sending unit, 102-ZigBee receiving unit, 103-shop hook force detection unit, 104-electronic control unit, 105-motor hydraulic braking unit, 100a-speed detection unit, 100b-deceleration detection Unit, 100c-steering wheel angle detection unit, 110-motor, 111-worm, 112-worm gear, 113-pinion, 114-rack, 115-reservoir, 116-first piston chamber, 117-second piston chamber , 118-brake wheel cylinder left, 119-brake wheel cylinder right.

Detailed ways

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

As shown in FIG. 1 , the implementation of the ZigBee-based active hydraulic braking system for trailers in the present invention is aimed at the vehicle-train model shown in FIG. 2 , wherein the system includes a detection unit 100 for detecting tractor information, a ZigBee sending unit 101 for the tractor, The ZigBee receiving unit 102 of the trailer, the workshop hook force detection unit 103, the electronic control unit 104 for processing related information, and the motor hydraulic braking unit 105 for performing trailer braking.

The detection unit 100 includes a speed detection unit 100a, a deceleration detection unit 100b and a steering wheel angle detection unit 100c. The speed detection unit 100a is used to measure the speed of the tractor, and the deceleration detection unit 100b is used to detect the acceleration of the tractor, the steering wheel angle. The detection unit 100c is used to detect the rotation angle of the steering wheel of the tractor. The sensor of the speed detection unit 100a can be installed on the transmission of the tractor to detect the rotational speed of the output axle, or it can be installed on the wheel of the tractor to detect the angular velocity on the wheel; the sensor of the deceleration detection unit 100b is installed on the brake of the tractor On the pedal, the displacement of the driver's brake pedal is sensed; the steering wheel angle detection unit 100c is installed on the steering wheel of the tractor, and detects the degree of the steering wheel angle of the tractor.

The workshop hooking force detection unit 103 is installed at the connection device between the tractor and the trailer, and can detect the hooking force between the vehicles in time and transmit the information to the electronic control unit 104 of the trailer.

The ZigBee communication unit is a low-speed wireless personal area network technical specification adopted on the physical layer and the medium access control layer defined by IEEE 802.15.4. In the ZigBee network, there are three kinds of network nodes, which are the coordinator node, the router node and the terminal device node. The coordinator node initializes the ZigBee network, and shuts down the node after completing the ZigBee network initialization, which will not affect the network that has already been initialized; the router node is always in the open state during the network operation, and has no effect on the relationship between each node in the network. The terminal equipment node receives the information when it is working, does not have the forwarding function, and enters the sleep mode to reduce power consumption when it is not working. Through the ZigBee network, the motion state information of the read sensor is packaged to the ZigBee sending unit 101 and sent to the outside world, and the data packets received by the ZigBee receiving unit 102 are parsed into valid information (speed, deceleration, steering wheel angle) and sent to the electronic control The unit 104 performs calculation and estimation based on the acquired vehicle state information to realize braking control and reduce transportation risks.

As shown in FIG. 3 , the motor hydraulic braking unit 105 of the trailer includes a motor 110, a worm 111, a worm wheel 112, a pinion 113, a rack 114, a liquid storage tank 115, a first piston cavity 116, a second piston cavity 117, a brake The moving wheel cylinder left 118 and the brake wheel cylinder right 119.

The motor 110, the worm 111 and the worm gear 112 of the deceleration mechanism, the pinion 113 and the rack 114 of the motion conversion mechanism are connected in series in sequence, and the liquid storage tank 115 is connected to the first piston cavity 116 and the second cylinder of the brake master cylinder through the liquid pipeline. The piston chamber 117 , the left wheel cylinder 118 and the right wheel cylinder 119 are connected.

The working principle of the motor hydraulic braking system of the trailer is that the electronic control unit 104 receives the motion state information of the tractor and the hook force information of the workshop, and outputs the control signal to the motor 110 after calculation, and the motor 110 starts to rotate to generate torque. The speed reduction mechanism composed of the worm gear 112 and the motion conversion mechanism composed of the pinion 113 and the rack 114 are converted into linear thrust, which pushes the piston in the brake master cylinder to generate pressure in the first piston chamber 116 and the second piston chamber 117, thereby giving The left wheel cylinder 118 and the right wheel cylinder 119 are pressurized, causing the trailer to brake.

As shown in FIG. 4 , the ZigBee-based active hydraulic braking control method of a trailer uses the detection unit 100 of the tractor, the ZigBee sending unit 101, the ZigBee receiving unit 102, the workshop hook force detection unit 103, the electronic control unit 104 and the motor hydraulic brake The unit 105 realizes the control of the trailer braking system, and the specific control method includes the following steps:

S1) When the tractor is braking, the electronic control unit 104 of the trailer receives the motion state information and the workshop hook force information of the tractor through the ZigBee receiving unit 102 and the workshop hook force detection unit 103, and outputs the control signal to the motor 110 through the internal algorithm to generate Torque, the torque is converted into a linear force after passing through the reduction mechanism and the motion conversion mechanism, and acts on the piston push rod of the brake master cylinder connected to it, so that the first piston cavity 116 and the second piston cavity 117 generate pressure, and the pressure is reduced. The left wheel cylinder 118 and the right wheel cylinder 119 are pressurized to force the trailer to brake, which is a pressurization process.

S2) When the tractor releases the brakes, the electronic control unit 104 of the trailer receives the brake release signal of the tractor, and judges whether it is necessary to brake the trailer according to the inter-vehicle hook force. If the inter-vehicle hook force exceeds a certain threshold If the value of the brake is required to brake the trailer, the current position of the rotor of the motor 110 is maintained, and a certain braking pressure is maintained. This is the pressure-holding process; The electronic control unit 104 drives the motor 110 to reverse, pulls back the piston in the brake master cylinder through the deceleration mechanism and the motion conversion mechanism, and relieves the pressure of the left wheel cylinder 118 and the right wheel cylinder 119, which is a decompression process. .

S3) When the tractor is reversing, after the electronic control unit 104 of the trailer receives the reversing signal of the tractor, it does not consider the status information of the tractor and the trailer, and judges that the trailer does not need to perform braking control, and the motor 110 does not work until the reversing is completed. task, this is a stress-free process.

The present invention is briefly described above. By adopting the ZigBee communication method for the trailer braking system, the trailer can react more intelligently and in time, effectively and smoothly brake, and avoid collision between cars and trains. The protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be included within the protection scope of the present invention.

Claims (1)

1. A method of utilizing a ZigBee-based active hydraulic braking system for a trailer, wherein the braking system comprises a detection unit (100), a ZigBee sending unit (101), a ZigBee receiving unit (102), a workshop hook force A detection unit (103), an electronic control unit (104), and a motor hydraulic brake unit (105); the detection unit (100) packages the detected speed, deceleration and steering wheel angle information of the towing vehicle to the ZigBee sending unit (101), sent to the ZigBee receiving unit (102) of the trailer by means of ZigBee communication, the hook force detection unit (103) on the trailer detects the hook force between the tractor and the trailer, and the electronic control unit (104) according to the trailer The information sent by the ZigBee receiving unit (102) and the hook force detection unit (103) is calculated by an internal algorithm to determine whether to brake the trailer, and the control signal output by the calculation is sent to the motor hydraulic braking unit (105) ; the detection unit (100) comprises a speed detection unit (100a), a deceleration detection unit (100b) and a steering wheel angle detection unit (100c); The speed detection unit (100a) and the deceleration detection unit (100b) complete the task of detecting the speed and deceleration of the tractor through a speed sensor and an acceleration sensor, respectively, and the steering wheel angle detection unit (100c) detects through an angle sensor on the steering wheel The steering wheel angle of the tractor; the motor hydraulic braking unit (105) includes a motor (110), a worm (111), a worm gear (112), a pinion (113), a rack (114), and a liquid storage tank (115) , the first piston chamber (116), the second piston chamber (117), the left brake wheel cylinder (118) and the right wheel brake cylinder (119); The control end of the motor (110) is connected to the output end of the electronic control unit (104), and the motor (110), the worm (111), the worm wheel (112), the pinion (113) and the rack (114) are connected in series in sequence , the liquid storage tank (115) is connected with the first piston chamber (116) and the second piston chamber (117) of the brake master cylinder, the left brake wheel cylinder (118) and the right wheel brake cylinder (119) through the liquid pipeline connected; The electronic control unit (104) receives the motion state information of the tractor and the workshop hooking force information, and outputs a control signal to the motor (110) after calculation, and the motor (110) starts to rotate, and the worm (111), the worm wheel (112) The motion conversion mechanism composed of the speed reduction mechanism, pinion (113) and rack (114) pushes the piston in the brake master cylinder to generate pressure in the first piston chamber (116) and the second piston chamber (117), Thereby pressurizing the left brake wheel cylinder (118) and the right wheel brake cylinder (119), prompting the trailer to brake; The method includes the following steps: S1) When the tractor is braking, the electronic control unit (104) of the trailer receives the motion state information of the tractor and the information of the workshop hook force through the ZigBee receiving unit (102) and the workshop hook force detection unit (103), and outputs it through the internal algorithm The control signal generates torque for the motor (110), the torque is converted into a linear force after passing through the deceleration mechanism and the motion conversion mechanism, and acts on the piston push rod of the master cylinder connected to it, so that the first piston cavity (116) and the The second piston chamber (117) generates pressure to pressurize the left wheel brake cylinder (118) and the right wheel brake cylinder (119), thereby forcing the trailer to brake, which is a pressurizing process; S2) When the tractor releases the brake, the electronic control unit (104) of the trailer receives the brake release signal of the tractor, and judges whether the brake control of the trailer needs to be performed according to the force of the hook between the vehicles. The trailer needs to be braked at a certain critical value, and the current position of the rotor of the motor (110) is maintained, and a certain braking pressure is maintained. This is the pressure-holding process; if the hook force between the vehicles does not reach a certain critical value, the trailer does not need to be braked. Brake, the electronic control unit (104) drives the motor (110) to reverse, pulls back the piston in the brake master cylinder through the deceleration mechanism and the motion conversion mechanism, and the left (118) and right brake wheel cylinders (119) Perform pressure relief, which is a decompression process; S3) When the tractor is reversing, after the electronic control unit (104) of the trailer receives the reverse signal of the tractor, it does not consider the status information of the tractor and the trailer, and internally judges that the trailer does not need to perform brake control, and the motor (110) does not Work until the reversing task is completed, which is a stress-free process.

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