CN105551345B - The double cars of intelligence communicate and followed experiment device for teaching and experimental method - Google Patents

Abstract

The invention discloses an intelligent two-vehicle communication and follow-up teaching experiment device and method. The device includes a front vehicle system installed on the front vehicle and a rear vehicle system installed on the rear vehicle. Both the front vehicle system and the rear vehicle system include a main control system Equipment, power supply voltage device, DC motor drive device, steering control device, wireless communication device, LCD screen, speed measuring device, distance measuring device, dial switch and key device, the front and rear vehicle systems measure the initial distance between the front and rear vehicles through the distance measuring device , the front and rear vehicle systems receive the set target speed and target angle of the vehicle in front from the PC through the wireless communication device, adjust the actual speed through incremental PID control and adjust the actual angle through the steering control device to approach the setting The value realizes the communication between the front and rear vehicles and the following teaching process; the device and method enable the experimental teaching of control and communication engineering majors in colleges and universities to obtain good teaching effects, so that students can grasp professional knowledge vividly and intuitively.

Description

Intelligent two-vehicle communication and following teaching experimental device and experimental method

technical field

The present invention relates to the field of experimental teaching instruments based on intelligent vehicles, in particular to an intelligent dual-vehicle communication system that realizes the communication between intelligent double-cars and the following driving of two vehicles, and can be used for experimental teaching of control and communication engineering majors in colleges and universities. Follow along with teaching experimental setup and experimental methods.

Background technique

At present, there are many types of experimental teaching equipment in colleges and universities, but most of them are basic experimental teaching instruments, and only a few are experimental instruments for single-vehicle control of smart cars. Experimental teaching instruments have not yet appeared. In the teaching process, the general colleges and universities use the form of software simulation to complete, and the experimental results are not intuitive and vivid, which is not conducive to students' understanding of control technology and communication technology.

Patent publication number: CN204623370U, an intelligent communication device for a fully automatic electric vehicle drive system, which realizes the connection between the central control wireless module and the mobile phone wireless module and the mobile phone system module through wireless connection; the mobile phone system module includes the mobile phone user APP interface and the mobile phone communication module and mobile phone wireless module. It realizes the communication between the mobile phone user APP and the fully automatic electric vehicle, but does not realize the communication between the two workshops.

Patent publication number: CN103496368A, Vehicle cooperative adaptive cruise control system and method with learning ability, wherein the training set and test set generation module is used to generate suitable training set and test according to the acquired driving state information of the preceding vehicle and the own vehicle The vehicle driving state set module and the inter-vehicle safety distance module select data that can accurately express the current vehicle state and inter-vehicle distance. To a certain extent, it realizes the capture of the motion state of the vehicle in front by the vehicle behind to realize the follow-up driving of the vehicle behind, but it cannot vividly show the state of the two vehicles, and cannot be effectively applied to college teaching.

Contents of the invention

To solve the above problems, the present invention proposes an experimental device for two-vehicle communication and follow-up of intelligent vehicles. The specific technical scheme is as follows:

Intelligent dual-vehicle following and communication experimental equipment, including the front vehicle system installed on the front vehicle and the rear vehicle system installed on the rear vehicle, is characterized in that:

The front vehicle system includes main control equipment, power supply voltage device, DC motor drive device, steering control device, wireless communication device, LCD screen, speed measuring device, distance measuring device, dial switch and key device and PC, the main control equipment signal The interface is connected to the signal interface of the DC motor drive device, steering control device, wireless communication device, LCD screen, speed measuring device, distance measuring device, dial switch and key device, and the main control equipment, wireless communication device, speed measuring device, distance measuring device , DIP switch and button device, LCD screen, steering control device and the voltage input interface of the DC motor drive device are respectively connected to the power supply voltage device to obtain the voltage, the gear at the output end of the DC motor drive device meshes with the rear wheel gear of the car body, and the steering The output end of the control device is connected to the steering knuckle of the front wheel of the car body through a tie rod, and the speed measuring gear at the input end of the speed measuring device meshes with the rear wheel gear of the car body;

There are timers, pulse width modulators, pulse accumulators, and timing interrupters in the main control device;

The structure of the rear vehicle system and the connection relationship between various components are the same as the above-mentioned front vehicle system. The distance measuring device in the front vehicle system is suspended and attached to the rear end of the front vehicle body. The device is suspended and attached to the steering gear of the rear car;

The PC can communicate with the front vehicle system and the rear vehicle system through the wireless communication device.

Further technical solutions:

The power supply voltage device includes a battery, a 5V voltage stabilizing module, a 3.3V voltage stabilizing module, a 6V voltage stabilizing module, a 12V voltage stabilizing module, and a pressure measuring module, and the battery is connected to the input interface of the 5V voltage stabilizing module and the 6V voltage stabilizing module , the output interface of the 5V voltage stabilizing module is connected with the input interface of the 3.3V voltage stabilizing module and the 12V voltage stabilizing module, the input interface of the pressure measuring module is connected with the battery, the output interface of the 5V voltage stabilizing module of the power supply device is connected with the main control equipment, The voltage input interface of the wireless communication device, speed measuring device, distance measuring device, dial switch and key device is connected; the output interface of the 3.3V voltage stabilizing module of the power supply voltage device is connected with the voltage input interface of the LCD screen; The output interface of the 6V voltage stabilizing module is connected with the voltage input interface of the steering control device; the output interface of the 12V voltage stabilizing module of the power supply voltage supply device is connected with the voltage input interface of the DC motor driving device.

The intelligent double-vehicle following and communication experiment method is characterized in that the steps are as follows:

Step 1: Initial distance measurement of front and rear vehicles:

The distance measuring devices in the front vehicle system and the rear vehicle system work together to measure the distance between the two vehicles by sending and receiving ultrasonic waves. The high level time of one pulse indicates the propagation time of ultrasonic waves from the front vehicle to the rear vehicle. Using the main control The time of the pulse high level measured by the timer in the device;

The formula for calculating the initial distance between two vehicles:

Initial distance L ₀ =t×v _voice

Among them, t is the pulse high level time measured by the main control device, and v _voice is the speed of sound, which is 340m/s

Step 2: The front vehicle system obtains the target speed v of the front vehicle system at the current moment and the target angle α of the front vehicle system at the current moment set by the PC:

The PC sends a signal to the wireless communication device of the front vehicle system, and the front vehicle system obtains the target speed v of the front vehicle system at the current moment and the target angle α of the front vehicle system at the current moment set by the user on the PC host computer;

Step 3: The steering control device of the front vehicle system controls the rotation angle:

The front vehicle system calculates the received target angle α of the front vehicle system at the current moment to obtain the pulse width T ₁ of the front vehicle system, and controls the rotation of the steering control device through the pulse width modulator of the main control device. The steering control of the front vehicle system The calculation formula for the relationship between the rotation angle α1' of the device and the pulse width T ₁ of the front vehicle system is:

Among them, T ₁ is the pulse width of the front vehicle system, the unit is ms; α ₁ ' is the rotation angle of the steering control device of the front vehicle system, and the pulse period is 20ms;

Step 4: The front vehicle system obtains the actual speed v ₁ (n) of the front vehicle system at time n through the speed measuring device in the front vehicle system:

Use the pulse accumulator of the main control device to capture and count the pulses, turn on the timer interrupter, and you can measure the number of pulses x within the period p of the timer interrupt

The formula for calculating the actual speed v ₁ (n) of the preceding vehicle system at time n:

Among them, x is the number of pulses, a is the number of teeth of the speed measuring gear at the input end of the speed measuring device, d is the diameter of the front wheel and rear wheel, b is the number of teeth of the front and rear axle gears, c is the number of pulses generated by one rotation of the speed measuring device, and p is Period of timed interrupt;

Step 5: Integrate the actual speed v ₁ (0), v ₁ (1), v ₁ (n) of the preceding vehicle system from 0 to n at each moment to obtain the preceding vehicle system from 0 to n The distance S ₁ (n) traveled so far:

The actual speed of the vehicle in front calculated by the master control device is a discrete variable v ₁ (i), where v ₁ (i) is the actual speed of the vehicle in front at time i, where time i is the time from time 0 to time n. any moment in a time period, so the integral formula is simplified as That is, the distance S ₁ (n) traveled by the vehicle in front from 0 to time n can be obtained by simply summing the actual speeds of the vehicle in front at each time from 0 to time n;

Step 6: Through incremental PID control, make the actual speed v ₁ (n+1) of the vehicle in front at time n+1 approach the predetermined target speed v of the vehicle in front at the current moment:

Since there is always a deviation between the actual speed and the target speed, the incremental PID speed adjustment is used to improve the stability of the vehicle speed and reduce the deviation between the actual speed and the target speed. v ₁ (n) and the target speed v of the vehicle in front at the current moment are adjusted in the proportional link and the integral link;

Let the motor voltage u _n at time n be the control quantity, and the increment of the control quantity output by the incremental PID is △u _n , then the motor voltage at time n-1 is un _-1 , and the output of the incremental PID is the control quantity The increment is △u _n-1 ;

So the motor voltage should be u _n =u _n-1 +△u _n

Incremental PID output is the increment of control quantity △u _n =un -u _{n -1} ＝A(e _n -e _n-1 )+Be _n +C(e _n -2e _n-1 +e _{n -2} );

The difference between the current target speed v of the vehicle in front and the actual speed v ₁ (n) of the vehicle in front at time n is en =vv ₁ (n), e _{n -1} =vv ₁ (n-1),e _n-2 =vv ₁ (n-2)A, B, C are undetermined parameters;

The values of the undetermined parameters A, B, and C are as follows:

First set the undetermined parameters B and C to 0, and gradually increase the undetermined parameter A from 0, and continuously run the front vehicle system or the rear vehicle system until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter A Set it to 60% to 80% of when the front vehicle system or the rear vehicle system just happens to overshoot;

Then the parameter A remains unchanged, and the undetermined parameter B is gradually increased from 0, and the front vehicle system or the rear vehicle system is continuously operated until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter B is set to the front vehicle system or 60% to 80% of when the rear vehicle system just happens to overshoot;

The last undetermined parameter C is set to 0;

Step 7: The front vehicle system sends the current target speed v of the front vehicle system to the rear vehicle system through the wireless communication device, the current target angle α of the front vehicle system at the current moment, and the distance traveled by the front vehicle system from 0 to n. The distance S ₁ (n):

All the data that the preceding vehicle system will receive from the PC include the target speed v of the preceding vehicle system at the current moment, the target angle α of the preceding vehicle system at the current moment, and the distance S traveled by the preceding vehicle system from 0 to n moments ₁ (n), sent to the rear vehicle system through the wireless communication devices in the front vehicle system and the rear vehicle system;

After the rear vehicle system receives the target angle α of the front vehicle system at the current moment and the distance S ₁ (n) traveled by the front vehicle system from 0 to time n, due to the target angle α of the front vehicle system at different times The value of is different, and the value of α at different moments is saved in the form of an array, so that α(n)=α;

Where α(n) is the target angle of the preceding vehicle system at time n, and α(n) corresponds to S ₁ (n) one-to-one

Step 8: The rear vehicle system adjusts the current target angle α ₂ of the rear vehicle system according to its own location

The speed integral of the following vehicle obtains the distance S ₂ (m) traveled by the following vehicle up to time m

by integral formula Get the distance of the rear vehicle S ₂ (m)

Measure the initial distance L ₀ of the front and rear vehicles from step 1, and then measure the body length X ₂ of the rear vehicle, so the initial distance of the rear vehicle is -(L ₀ +X ₂ ), and the distance S ₂ of the rear vehicle is -(L ₀ + Between X ₂ ) and 0, the angle of the steering gear is 0, and the distance of the rear vehicle S ₂ >0, then drive according to the data sent by the vehicle in front;

The distance S ₁ of the vehicle ahead received by the vehicle system behind and the distance S ₂ of the vehicle behind calculated by the vehicle behind are both discrete, so the distance S ₂ (m) of the vehicle behind calculated by the vehicle system behind at time m may be the Between the two adjacent distances S ₁ (n) and S ₁ (n+1) saved, the trailing vehicle system will take the average value of the two target angles corresponding to the stored two distances as the trailing vehicle The target angle α ₂ of the system at the current moment;

For example: at time m, the following vehicle system detects that its current distance is S ₂ (m), and the following vehicle system receives _two sets of data S _{1 (} n), S ₁ (n+1), wherein, S ₁ (n) is the distance traveled by the vehicle in front from 0 to moment n, and S ₁ (n+1) is the distance traveled by the vehicle in front from 0 to time n. The distance traveled by the vehicle in front until time n+1

The angle corresponding to the distance S ₁ (n) traveled by the vehicle in front from 0 to time n is the target angle α(n) of the vehicle in front at time n;

The angle corresponding to the distance S ₁ (n+1) traveled by the vehicle in front from 0 to time n+1 is the target angle α(n+1) of the vehicle in front at time n+1;

Then the target angle α ₂ of the rear vehicle system at the current moment satisfies the following relationship:

α ₂ =α(n) (S ₂ (m)=S ₁ (n))

α ₂ =(α(n)+α(n+1))/2 (S ₁ (n)<S ₂ (m)<S ₁ (n+1))

α ₂ =α(n+1) (S ₂ (m)=S ₁ (n+1))

Step 9: The rear vehicle system controls the steering control device to realize steering according to the target angle α ₂ of the rear vehicle system at time m, and according to the target speed v of the front vehicle system at time m and the actual speed v ₂ (m) of the rear vehicle system at time m Control the actual speed v ₂ (m+1) of the smart car at time m+1 through PID adjustment;

After calculating the pulse width T2 of the rear vehicle system and controlling the steering through the steering control device, the calculation _{formula for the relationship between the rotation angle α 2 '} of the steering control device of the rear vehicle system and the pulse width T2 of the rear vehicle system is _:

Among them, T ₂ is the positive pulse width (ms); α ₂ ' is the rotation angle of the steering control device of the rear vehicle system; the pulse period is 20ms

Then use the pulse counter of the main control device to capture and count the pulses, turn on the timer interrupt, and you can measure the number of pulses x within the period p of the timer interrupt

The calculation formula of the actual speed v ₂ (m) of the following vehicle system at time m:

Among them, x is the number of pulses, a is the number of teeth of the speed measuring gear at the input end of the speed measuring device, d' is the diameter of the rear wheel of the rear car, b' is the number of teeth of the rear axle gear of the rear car, and c is the number of pulses generated by one rotation of the speed measuring device. p is the period of the timer interrupt;

Then through incremental PID control:

Since there is always a deviation between the actual speed and the target speed, the incremental PID speed adjustment is used to improve the stability of the vehicle speed, reduce the deviation between the actual speed and the target speed, and obtain the actual speed of the rear vehicle system at the time m from the speed measuring device v ₂ (m) is adjusted with the target speed v of the vehicle in front at the current moment in the proportional link and the integral link;

Let the motor voltage u _m at time m be the control quantity, and the increment of the control quantity output by the incremental PID is △u _m , then the motor voltage at time m-1 is u _m-1 , and the output of the incremental PID is the control quantity The increment is △u _m-1 ;

So the motor voltage should be u _m =u _m-1 +△u _m

Incremental PID output is the increment of control quantity △u _m ＝u _m -u _m-1 ＝A(e _m -e _m-1 )+Be _m +C(e _m -2e _m-1 +e _{m -2} );

The difference between the target speed v of the front vehicle system at the current moment and the actual speed v ₂ (m) of the rear vehicle system at time _m is em =vv ₂ (m), em _-1 =vv ₂ (m-1), e _m-2 ＝vv ₂ (m-2)A, B, C are undetermined parameters;

The values of the undetermined parameters A, B, and C are as follows:

First set the undetermined parameters B and C to 0, and gradually increase the undetermined parameter A from 0, and continuously run the front vehicle system or the rear vehicle system until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter A Set it to 60% to 80% of when the front vehicle system or the rear vehicle system just happens to overshoot;

Then the parameter A remains unchanged, and the undetermined parameter B is gradually increased from 0, and the front vehicle system or the rear vehicle system is continuously operated until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter B is set to the front vehicle system or 60% to 80% of when the rear vehicle system just happens to overshoot;

The last undetermined parameter C is set to 0;

Step 10: The wireless communication device of the rear vehicle system sends the actual speed v ₂ (m) of the rear vehicle system at time m and the distance S ₂ (m) traveled by the rear vehicle system at time m to the PC, and the information is displayed on the PC. show.

The beneficial effects of the present invention are:

1. Through the PC operating system software, the user can set the target corner and target speed of the vehicle in front according to the actual situation and experimental needs; at the same time, the user can intuitively understand the driving status of the smart dual vehicle.

2. Through the communication between the PC wireless communication device and the intelligent double workshop, relevant debugging can be realized according to the user's wishes.

3. Through the two-car communication, the front vehicle system can send its own parameters and status to the rear vehicle system in time, so that the rear vehicle system can realize the communication and follow-up of the intelligent two vehicles through calculation and processing.

4. The invention is easy to operate and easy to debug, so that users can easily grasp the working principle of the main control equipment and the communication principle of the wireless communication device, and can vividly and intuitively display the results of smart car control, which helps to improve students' interest in learning.

Description of drawings:

Fig. 1 is a schematic diagram of the connection relationship of each component of the front vehicle system and the rear vehicle system of the intelligent two-vehicle communication and following teaching experimental device of the present invention;

Fig. 2 is a schematic diagram of the overall physical structure of the front vehicle system of the intelligent two-vehicle communication and following teaching experimental device of the present invention;

Fig. 3 is a schematic diagram of the overall physical structure of the rear vehicle system of the intelligent two-vehicle communication and following teaching experimental device of the present invention;

Fig. 4 is the block flow diagram of intelligent two-vehicle communication of the present invention and following teaching experiment method;

In the figure: 1. Main control equipment, 2. Power supply device, 3. DC motor drive device, 4. Steering control device, 5. Wireless communication device, 6. LCD screen, 7. Speed measuring device, 8. Distance measuring device , 9. DIP switch and key device, 10. Battery.

Detailed ways:

The front vehicle system includes main control equipment 1, power supply device 2, DC motor drive device 3, steering control device 4, wireless communication device 5, LCD screen 6, speed measuring device 7, distance measuring device 8, dial switch and key device 9 and PC, signal interface of main control equipment 1 and signals of DC motor drive device 3, steering control device 4, wireless communication device 5, LCD screen 6, speed measuring device 7, distance measuring device 8, dial switch and key device 9 The main control device 1, the wireless communication device 5, the speed measuring device 7, the distance measuring device 8, the dial switch and the key device 9, the liquid crystal screen 6, the steering control device 4 and the voltage input interface of the DC motor drive device 3 are respectively connected to the The power supply voltage device 2 is connected to obtain voltage, the gear at the output end of the DC motor drive device 3 meshes with the rear wheel gear of the car body, the output end of the steering control device 4 is connected with the steering knuckle of the front wheel of the car body through a pull rod, and the speed measuring device 7 is at the input end of the speed measuring gear Mesh with the rear wheel gear of the car body;

The main control device 1 has a timer, a pulse width modulator, a pulse accumulator, and a timing interrupter;

The structure of the rear vehicle system and the connection relationship between the components are the same as the above-mentioned front vehicle system. The distance measuring device 8 in the front vehicle system is suspended and attached to the rear end of the front vehicle body. Suspended from the device 8 and attached to the steering gear of the rear car;

The PC can communicate with the front vehicle system and the rear vehicle system through the wireless communication device 5 .

The power supply device 2 includes a battery 10, a 5V voltage stabilizing module, a 3.3V voltage stabilizing module, a 6V voltage stabilizing module, a 12V voltage stabilizing module, a pressure measuring module, and the input of the battery 10 and the 5V voltage stabilizing module and the 6V voltage stabilizing module The interfaces are connected, the output interface of the 5V voltage stabilizing module is connected with the input interface of the 3.3V voltage stabilizing module and the 12V voltage stabilizing module, the input interface of the pressure measuring module is connected with the battery 10, and the output interface of the 5V voltage stabilizing module of the power supply device 2 It is connected with the voltage input interface of the main control equipment 1, the wireless communication device 5, the speed measuring device 7, the distance measuring device 8, the dial switch and the key device 9; The voltage input interface of 6 is connected; the output interface of the 6V regulator module of the power supply device 2 is connected with the voltage input interface of the steering control device 4; the output interface of the 12V regulator module of the power supply device 2 is connected with the DC motor drive device 3 connected to the voltage input interface.

The main chips used in the 5V voltage stabilizing module of the power supply voltage supply device 2 are LM2940 or TPS7350; the main chips used in the 3.3V voltage stabilizing module are AMS1117 and TPS7333; The main chip used in the compression module is MC34063.

The DC motor drive device 3 includes a drive circuit module and a DC motor.

In the drive circuit module, the voltage input interface is connected to the output interface of the 12V voltage stabilizing module, the signal input interface is connected to the main control device 1 pulse width modulator interface, and the output interface is connected to the DC motor input interface. The drive circuit module adopts the H-bridge 4mos tube scheme and the dual IR2104 drive scheme.

The input interface of the DC motor is connected with the output interface of the drive circuit module, and the gear at the output end meshes with the rear wheel gear of the smart car body.

The steering control device 4 uses a steering gear to realize steering control.

For the steering gear, the voltage input interface is connected to the output interface of the 6V voltage regulator module, the signal input interface is connected to the pulse width modulator of the peripheral interface of the main control device 1, and the output end is connected to the front wheel steering knuckle of the smart car body through a tie rod.

In the wireless communication device 5, the voltage input interface is connected to the output interface of the 5V voltage stabilizing module, the signal input interface is connected to the asynchronous serial interface of the peripheral interface of the main control device 1, and the wireless communication device 5 communicates with the PC.

The liquid crystal screen 6 is connected to the voltage input interface with the output interface of the 3.3V voltage stabilizing module, and the signal input interface is connected to the I/O interface of the peripheral interface of the main control device 1 .

The speed measuring device 7 adopts a photoelectric encoder as the speed measuring device 7.

The voltage input interface of the distance measuring device 8 is connected to the output interface of the 5V voltage stabilizing module, and the signal output interface is connected to the analog-to-digital conversion module of the peripheral interface of the main control device 1 .

The dial switch and key device 9 are connected to the voltage input interface with the output interface of the 5V voltage stabilizing module, and the signal output interface is connected to the peripheral interface I/O interface of the main control device 1 .

The steps of the intelligent two-vehicle following and communication experiment method are as follows:

Step 1: Initial distance measurement of front and rear vehicles

The distance measuring device 8 in the front vehicle system and the rear vehicle system cooperates to use ultrasonic transmission and reception to measure the distance between the two vehicles. One of the pulse high level time represents the propagation time of the ultrasonic wave from the front vehicle to the rear vehicle. The time of the pulse high level measured by the timer in the control device 1;

The formula for calculating the initial distance between two vehicles:

Initial distance L ₀ =t×v _voice

Among them, t is the pulse high level time measured by the main control device 1, and v _voice is the speed of sound, which is 340m/s

Step 2: The front vehicle system obtains the target speed v of the front vehicle system at the current moment and the target angle α of the front vehicle system at the current moment set by the PC:

The PC sends a signal to the wireless communication device 5 of the front vehicle system, and the front vehicle system obtains the target speed v of the front vehicle system at the current moment and the target angle α of the front vehicle system at the current moment set by the user on the PC host computer;

Step 3: The steering control device 4 of the front vehicle system controls the rotation angle

The front vehicle system calculates the received target angle α of the front vehicle system at the current moment to obtain the pulse width T ₁ of the front vehicle system, and controls the rotation of the steering control device 4 through the pulse width modulator of the main control device 1. The formula for calculating the relationship between the rotation angle α ₁ ′ of the steering control device 4 and the pulse width T ₁ of the preceding vehicle system is:

Where T ₁ is the pulse width of the front vehicle system, the unit is ms; α ₁ ' is the rotation angle of the steering control device 4 of the front vehicle system, and the pulse period is 20ms;

Step 4: The front vehicle system obtains the actual speed v ₁ (n) of the front vehicle system at time n through the speed measuring device 7 in the front vehicle system

Use the pulse accumulator of the main control device 1 to capture and count the pulses, and turn on the timer interrupter to measure the number of pulses x within the period p of the timer interrupt

The formula for calculating the actual speed v ₁ (n) of the preceding vehicle system at time n:

Where x is the number of pulses, a is the number of teeth of the speed measuring gear at the input end of the speed measuring device 7, d is the diameter of the front and rear wheels, b is the number of teeth of the front and rear axle gears, c is the number of pulses generated by the speed measuring device rotating one revolution, p is the period of the timer interrupt;

Step 5: Integrate the actual speed v ₁ (0), v ₁ (1), v ₁ (n) of the preceding vehicle system from 0 to n at each moment to obtain the preceding vehicle system from 0 to n The distance traveled so far S ₁ (n)

The actual speed of the vehicle in front calculated by the main control device 1 is a discrete variable v ₁ (i), where v ₁ (i) is the actual speed of the vehicle in front at time i, where time i is from time 0 to time n At any moment in this time period, the integral formula is simplified as That is, the distance S ₁ (n) traveled by the vehicle in front from 0 to time n can be obtained by simply summing the actual speeds of the vehicle in front at each time from 0 to time n;

Step 6: Make the actual speed v ₁ (n+1) of the preceding vehicle system at time n+1 close to the predetermined current moment target speed v of the preceding vehicle system through incremental PID control;

Incremental PID control:

Since there is always a deviation between the actual speed and the target speed, the incremental PID speed adjustment is used to improve the stability of the vehicle speed and reduce the deviation between the actual speed and the target speed. The speed v ₁ (n) and the target speed v of the vehicle in front at the current moment are adjusted by the proportional link and the integral link;

Let the motor voltage u _n at time n be the control quantity, and the increment of the control quantity output by the incremental PID is △u _n , then the motor voltage at time n-1 is un _-1 , and the output of the incremental PID is the control quantity The increment is △u _n-1 ;

So the motor voltage should be u _n =u _n-1 +△u _n

Incremental PID output is the increment of control quantity △u _n =un -u _{n -1} ＝A(e _n -e _n-1 )+Be _n +C(e _n -2e _n-1 +e _{n -2} );

The difference between the current target speed v of the vehicle in front and the actual speed v ₁ (n) of the vehicle in front at time n is en =vv ₁ (n), e _{n -1} =vv ₁ (n-1),e _n-2 =vv ₁ (n-2)A, B, C are undetermined parameters;

The values of the undetermined parameters A, B, and C are as follows:

First set the undetermined parameters B and C to 0, and gradually increase the undetermined parameter A from 0, and continuously run the front vehicle system or the rear vehicle system until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter A Set it to 60% to 80% of when the front vehicle system or the rear vehicle system just happens to overshoot;

Then the parameter A remains unchanged, and the undetermined parameter B is gradually increased from 0, and the front vehicle system or the rear vehicle system is continuously operated until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter B is set to the front vehicle system or 60% to 80% of when the rear vehicle system just happens to overshoot;

The last undetermined parameter C is set to 0;

Step 7: The front vehicle system sends the current target speed v of the front vehicle system to the rear vehicle system through the wireless communication device 5, the current target angle α of the front vehicle system at the current moment, and the current speed of the front vehicle system from 0 to n. Distance traveled S ₁ (n):

All the data that the preceding vehicle system will receive from the PC include the target speed v of the preceding vehicle system at the current moment, the target angle α of the preceding vehicle system at the current moment, and the distance S traveled by the preceding vehicle system from 0 to n moments ₁ (n), sent to the rear vehicle system by the wireless communication device 5 in the front vehicle system and the rear vehicle system;

After the rear vehicle system receives the target angle α of the front vehicle system at the current moment and the distance S ₁ (n) traveled by the front vehicle system from 0 to time n, due to the target angle α of the front vehicle system at different times The value of is different, and the value of α at different moments is saved in the form of an array, so that α(n)=α;

Where α(n) is the target angle of the preceding vehicle system at time n, and α(n) corresponds to S ₁ (n) one-to-one

Step 8: The rear vehicle system adjusts the current target angle α ₂ of the rear vehicle system according to its own location

The speed integral of the following vehicle obtains the distance S ₂ (m) traveled by the following vehicle up to time m

by integral formula Get the distance of the rear vehicle S ₂ (m)

Measure the initial distance L ₀ of the front and rear vehicles from step 1, and then measure the body length X ₂ of the rear vehicle, so the initial distance of the rear vehicle is -(L ₀ +X ₂ ), and the distance S ₂ of the rear vehicle is -(L ₀ + Between X ₂ ) and 0, the angle of the steering gear is 0, and the distance of the rear vehicle S ₂ >0, then drive according to the data sent by the vehicle in front;

The distance S ₁ of the vehicle ahead received by the vehicle system behind and the distance S ₂ of the vehicle behind calculated by the vehicle behind are both discrete, so the distance S ₂ (m) of the vehicle behind calculated by the vehicle system behind at time m may be the Between the two adjacent distances S ₁ (n) and S ₁ (n+1) saved, the trailing vehicle system will take the average value of the two target angles corresponding to the stored two distances as the trailing vehicle The target angle α ₂ of the system at the current moment;

For example: at time m, the following vehicle system detects that its current distance is S ₂ (m), and the following vehicle system receives _two sets of data S _{1 (} n), S ₁ (n+1), wherein, S ₁ (n) is the distance traveled by the vehicle in front from 0 to moment n, and S ₁ (n+1) is the distance traveled by the vehicle in front from 0 to time n. The distance traveled by the vehicle in front until time n+1

The angle corresponding to the distance S ₁ (n) traveled by the vehicle in front from 0 to time n is the target angle α(n) of the vehicle in front at time n;

The angle corresponding to the distance S ₁ (n+1) traveled by the vehicle in front from 0 to time n+1 is the target angle α(n+1) of the vehicle in front at time n+1;

Then the target angle α ₂ of the rear vehicle system at the current moment satisfies the following relationship:

α ₂ =α(n) (S ₂ (m)=S ₁ (n))

α ₂ =(α(n)+α(n+1))/2 (S ₁ (n)<S ₂ (m)<S ₁ (n+1))

α ₂ =α(n+1) (S ₂ (m)=S ₁ (n+1))

Step 9: The rear vehicle system controls the steering control device 4 to realize steering according to the target angle α ₂ of the rear vehicle system at time m, and realizes steering according to the target speed v of the front vehicle system at time m and the actual speed v ₂ (m ) control the actual speed v ₂ (m+1) of the smart car at the moment m+1 through PID regulation;

After calculation, the pulse width T2 of the rear vehicle system is obtained and the steering is controlled by the steering control device 4. The calculation _formula for the relationship between the rotation angle _α2 ' of the steering control device ₄ of the rear vehicle system and the pulse width T2 of the rear vehicle system is:

Wherein T ₂ is the positive pulse width (ms); α ₂ ' is the rotation angle of the steering control device 4 of the rear vehicle system; the pulse period is 20ms

Then use the pulse counter of the main control device 1 to capture and count the pulses, and turn on the timing interrupt to measure the number of pulses x within the period p of the timing interrupt.

The calculation formula of the actual speed v ₂ (m) of the following vehicle system at time m:

Where x is the number of pulses, a is the number of teeth of the speed measuring gear at the input end of the speed measuring device 7, d' is the diameter of the rear wheel of the rear car, b' is the number of teeth of the rear axle gear of the rear car, and c is the number of pulses generated by the speed measuring device rotating one revolution , p is the period of the timer interrupt;

Then through incremental PID control:

Since there is always a deviation between the actual speed and the target speed, the incremental PID speed adjustment is used to improve the stability of the vehicle speed and reduce the deviation between the actual speed and the target speed. The speed v ₂ (m) is adjusted with the target speed v of the vehicle in front at the current moment in the proportional link and the integral link;

Let the motor voltage u _m at time m be the control quantity, and the increment of the control quantity output by the incremental PID is △u _m , then the motor voltage at time m-1 is u _m-1 , and the output of the incremental PID is the control quantity The increment is △u _m-1 ;

So the motor voltage should be u _m =u _m-1 +△u _m

Incremental PID output is the increment of control quantity △u _m ＝u _m -u _m-1 ＝A(e _m -e _m-1 )+Be _m +C(e _m -2e _m-1 +e _{m -2} );

The difference between the target speed v of the front vehicle system at the current moment and the actual speed v ₂ (m) of the rear vehicle system at time _m is em =vv ₂ (m), em _-1 =vv ₂ (m-1), e _m-2 ＝vv ₂ (m-2)A, B, C are undetermined parameters;

The values of the undetermined parameters A, B, and C are as follows:

First set the undetermined parameters B and C to 0, and gradually increase the undetermined parameter A from 0, and continuously run the front vehicle system or the rear vehicle system until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter A Set it to 60% to 80% of when the front vehicle system or the rear vehicle system just happens to overshoot;

Then the parameter A remains unchanged, and the undetermined parameter B is gradually increased from 0, and the front vehicle system or the rear vehicle system is continuously operated until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter B is set to the front vehicle system or 60% to 80% of when the rear vehicle system just happens to overshoot;

The last undetermined parameter C is set to 0;

Step 10: The wireless communication device 5 of the rear vehicle system sends the actual speed v ₂ (m) of the rear vehicle system at time m and the distance S ₂ (m) traveled by the rear vehicle system at time m to the PC, and transmits it to the PC. displayed on the machine.

Claims (2)

1. Intelligent dual-vehicle following and communication experiment method, using intelligent dual-vehicle following and communication experimental equipment, including the front vehicle system installed on the front vehicle and the rear vehicle system installed on the rear vehicle. The front vehicle system includes the main control equipment ( 1), power supply voltage device (2), DC motor drive device (3), steering control device (4), wireless communication device (5), LCD screen (6), speed measuring device (7), distance measuring device (8 ), DIP switch and button device (9) and PC, main control equipment (1) signal interface and DC motor drive device (3), steering control device (4), wireless communication device (5), LCD screen (6 ), the speed measuring device (7), the distance measuring device (8), the dial switch and the signal interface of the button device (9), the main control equipment (1), the wireless communication device (5), the speed measuring device (7), the measuring The voltage input interfaces of distance device (8), dial switch and key device (9), liquid crystal screen (6), steering control device (4) and DC motor drive device (3) are respectively connected with power supply voltage device (2) In order to obtain the voltage, the gear at the output end of the DC motor driving device (3) meshes with the rear wheel gear of the car body, the output end of the steering control device (4) is connected with the steering knuckle of the front wheel of the car body through a pull rod, and the speed measuring device (7) at the input end of the speed measuring gear Mesh with the rear wheel gear of the car body; there are timers, pulse width modulators, pulse accumulators, and timing interrupters in the main control device (1); Similarly, the distance measuring device (8) in the front vehicle system is suspended and attached to the rear end of the front vehicle body, and the distance measuring device (8) in the rear vehicle system is suspended and attached to the steering gear of the rear vehicle; The PC can communicate with the front vehicle system and the rear vehicle system through the wireless communication device (5), and it is characterized in that the steps are as follows: Step 1: Initial distance measurement of front and rear vehicles: The distance measuring device (8) in the front vehicle system and the rear vehicle system works together to measure the distance between the two vehicles by sending and receiving ultrasonic waves, and one pulse high level time represents the propagation time of ultrasonic waves from the front vehicle to the rear vehicle. Use the time of the pulse high level measured by the timer in the main control device (1); The formula for calculating the initial distance between two vehicles: Initial distance L ₀ =t×v _voice Where t is the pulse high level time measured by the main control device (1), and v _voice is the sound velocity, which is 340m/s Step 2: The front vehicle system obtains the target speed v of the front vehicle system at the current moment and the target angle α of the front vehicle system at the current moment set by the PC: The PC sends a signal to the wireless communication device (5) of the front vehicle system, and the front vehicle system obtains the target speed v of the front vehicle system at the current moment and the target angle α of the front vehicle system at the current moment set by the user on the PC host computer; Step 3: The steering control device (4) of the front vehicle system controls the rotation angle: The front vehicle system calculates the received target angle α of the front vehicle system at the current moment to obtain the pulse width T ₁ of the front vehicle system, and controls the rotation of the steering control device (4) through the pulse width modulator of the main control device (1), The calculation formula for the relationship between the rotation angle α ₁ ′ of the steering control device (4) of the vehicle in front and the pulse width T ₁ of the vehicle in front is: <mrow><msub><mi>T</mi><mn>1</mn></msub><mo>=</mo><mn>1.5</mn><mo>&amp;PlusMinus;</mo><mfrac><mrow><msup><msub><mi>&amp;alpha;</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow><mn>90</mn></mfrac></mrow> Wherein T ₁ is the pulse width of the front vehicle system, the unit is ms; α ₁ ' is the rotation angle of the steering control device (4) of the front vehicle system, and the pulse period is 20ms; Step 4: The front vehicle system obtains the actual speed v ₁ (n) of the front vehicle system at time n through the speed measuring device (7) in the front vehicle system: Use the pulse accumulator of the main control device (1) to capture and count the pulses, and turn on the timer interrupter to measure the number of pulses x within the period p of the timer interrupt The formula for calculating the actual speed v ₁ (n) of the preceding vehicle system at time n: Where x is the number of pulses, a is the number of teeth of the speed measuring gear at the input end of the speed measuring device (7), d is the diameter of the front and rear wheels, b is the number of teeth of the front and rear axle gears, and c is the number of pulses generated by the speed measuring device rotating one revolution , p is the period of the timer interrupt; Step 5: Integrate the actual speed v ₁ (0), v ₁ (1), v ₁ (n) of the preceding vehicle system from 0 to n at each moment to obtain the preceding vehicle system from 0 to n The distance S ₁ (n) traveled so far: The actual speed of the vehicle in front calculated by the main control device (1) is a discrete variable v ₁ (i), where v ₁ (i) is the actual speed of the vehicle in front at time i, where time i is from time 0 to Any time in the time period of time n, so the integral formula is simplified as That is, the distance S ₁ (n) traveled by the vehicle in front from 0 to time n can be obtained by simply summing the actual speeds of the vehicle in front at each time from 0 to time n; Step 6: Through incremental PID control, make the actual speed v ₁ (n+1) of the vehicle in front at time n+1 approach the predetermined target speed v of the vehicle in front at the current moment: Since there is always a deviation between the actual speed and the target speed, the incremental PID speed adjustment is used to improve the stability of the vehicle speed and reduce the deviation between the actual speed and the target speed. The actual speed v ₁ (n) and the target speed v of the vehicle in front at the current moment are adjusted by the proportional link and the integral link; Let the motor voltage u _n at time n be the control quantity, and the increment of the control quantity output by the incremental PID is △u _n , then the motor voltage at time n-1 is un _-1 , and the output of the incremental PID is the control quantity The increment is △u _n-1 ; So the motor voltage should be u _n =u _n-1 +△u _n Incremental PID output is the increment of control quantity △u _n =un -u _{n -1} ＝A(e _n -e _n-1 )+Be _n +C(e _n -2e _n-1 +e _{n -2} ); The difference between the current target speed v of the vehicle in front and the actual speed v ₁ (n) of the vehicle in front at time n is en =vv ₁ (n), e _{n -1} =vv ₁ (n-1),e _n-2 =vv ₁ (n-2), A, B, C are undetermined parameters; The values of the undetermined parameters A, B, and C are as follows: First set the undetermined parameters B and C to 0, and gradually increase the undetermined parameter A from 0, and continuously run the front vehicle system or the rear vehicle system until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter A Set it to 60% to 80% of when the front vehicle system or the rear vehicle system just happens to overshoot; Then the parameter A remains unchanged, and the undetermined parameter B is gradually increased from 0, and the front vehicle system or the rear vehicle system is continuously operated until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter B is set to the front vehicle system or 60% to 80% of when the rear vehicle system just happens to overshoot; The last undetermined parameter C is set to 0; Step 7: The front vehicle system sends the current target speed v of the front vehicle system to the rear vehicle system through the wireless communication device (5), the current target angle α of the front vehicle system at the current moment, and the front vehicle system from 0 to n. The distance traveled by the system S ₁ (n): All the data that the preceding vehicle system will receive from the PC include the target speed v of the preceding vehicle system at the current moment, the target angle α of the preceding vehicle system at the current moment, and the distance S traveled by the preceding vehicle system from 0 to n moments ₁ (n), sent to the rear vehicle system through the wireless communication device (5) in the front vehicle system and the rear vehicle system; After the rear vehicle system receives the target angle α of the front vehicle system at the current moment and the distance S ₁ (n) traveled by the front vehicle system from 0 to time n, due to the target angle α of the front vehicle system at different times The value of is different, and the value of α at different moments is saved in the form of an array, so that α(n)=α; Where α(n) is the target angle of the preceding vehicle system at time n, and α(n) corresponds to S ₁ (n) one-to-one Step 8: The rear vehicle system adjusts the current target angle α ₂ of the rear vehicle system according to its own location The speed integral of the following vehicle obtains the distance S ₂ (m) traveled by the following vehicle up to time m by integral formula Get the distance of the rear vehicle S ₂ (m) Measure the initial distance L ₀ of the front and rear vehicles from step 1, and then measure the body length X ₂ of the rear vehicle, so the initial distance of the rear vehicle is -(L ₀ +X ₂ ), and the distance S ₂ of the rear vehicle is -(L ₀ + Between X ₂ ) and 0, the angle of the steering gear is 0, and the distance of the rear vehicle S ₂ >0, then drive according to the data sent by the vehicle in front; The distance S ₁ of the vehicle ahead received by the vehicle system behind and the distance S ₂ of the vehicle behind calculated by the vehicle behind are both discrete, so the distance S ₂ (m) of the vehicle behind calculated by the vehicle system behind at time m may be the Between the two adjacent distances S ₁ (n) and S ₁ (n+1) saved, the trailing vehicle system will take the average value of the two target angles corresponding to the stored two distances as the trailing vehicle The target angle α ₂ of the system at the current moment; At time m, the following vehicle system detects that its current distance is S ₂ (m), and the following vehicle system receives two sets of data S ₁ (n) within the distance S ₁ of the preceding vehicle that is closest to S ₂ (m) in Step 7 , S ₁ (n+1), where S ₁ (n) is the distance traveled by the vehicle in front from 0 to moment n, and S ₁ (n+1) is the distance traveled by the vehicle in front from 0 to n+ 1 The distance traveled by the preceding vehicle system up to the moment The angle corresponding to the distance S ₁ (n) traveled by the vehicle in front from 0 to time n is the target angle α(n) of the vehicle in front at time n; The angle corresponding to the distance S ₁ (n+1) traveled by the vehicle in front from 0 to time n+1 is the target angle α(n+1) of the vehicle in front at time n+1; Then the target angle α ₂ of the rear vehicle system at the current moment satisfies the following relationship: α ₂ =α(n) (S ₂ (m)=S ₁ (n)) α ₂ =(α(n)+α(n+1))/2 (S ₁ (n)<S ₂ (m)<S ₁ (n+1)) α ₂ =α(n+1) (S ₂ (m)=S ₁ (n+1)) Step 9: The rear vehicle system controls the steering control device (4) to realize steering according to the target angle α ₂ of the rear vehicle system at time m, and the target speed v of the front vehicle system at time m and the actual speed v ₂ of the rear vehicle system at time m (m) Control the actual speed v ₂ (m+1) of the smart car at the moment of m+1 through PID adjustment; After calculating the pulse width T2 of the rear vehicle system and controlling the steering through the steering control device (4), the relationship between the rotation angle α ₂ ' of the steering control device ( _{4 )} of the rear vehicle system and the pulse width T2 of the rear vehicle system The calculation formula is: <mrow><msub><mi>T</mi><mn>2</mn></msub><mo>=</mo><mn>1.5</mn><mo>&amp;PlusMinus;</mo><mfrac><mrow><msup><msub><mi>&amp;alpha;</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup></mrow><mn>90</mn></mfrac></mrow> Wherein T ₂ is the positive pulse width (ms); α ₂ ' is the rotation angle of the steering control device (4) of the rear vehicle system; the pulse period is 20ms Then use the pulse counter of the main control device (1) to capture and count the pulses, turn on the timer interrupt, and you can measure the number of pulses x within the period p of the timer interrupt The calculation formula of the actual speed v ₂ (m) of the following vehicle system at time m: Among them, x is the number of pulses, a is the number of teeth of the speed measuring gear at the input end of the speed measuring device (7), d' is the diameter of the rear wheel of the rear car, b' is the number of teeth of the rear axle gear of the rear car, and c is the number of teeth generated by the speed measuring device rotating one circle. The number of pulses, p is the period of the timing interrupt; Then through incremental PID control: Since there is always a deviation between the actual speed and the target speed, the incremental PID speed adjustment is used to improve the stability of the vehicle speed and reduce the deviation between the actual speed and the target speed. The actual speed v ₂ (m) and the target speed v of the vehicle in front at the current moment are adjusted by the proportional link and the integral link; Let the motor voltage u _m at time m be the control quantity, and the increment of the control quantity output by the incremental PID is △u _m , then the motor voltage at time m-1 is u _m-1 , and the output of the incremental PID is the control quantity The increment is △u _m-1 ; So the motor voltage should be u _m =u _m-1 +△u _m Incremental PID output is the increment of control quantity △u _m ＝u _m -u _m-1 ＝A(e _m -e _m-1 )+Be _m +C(e _m -2e _m-1 +e _{m -2} ); The difference between the target speed v of the front vehicle system at the current moment and the actual speed v ₂ (m) of the rear vehicle system at time _m is em =vv ₂ (m), em _-1 =vv ₂ (m-1), e _m-2 ＝vv ₂ (m-2), A, B, C are undetermined parameters; The values of the undetermined parameters A, B, and C are as follows: First set the undetermined parameters B and C to 0, and gradually increase the undetermined parameter A from 0, and continuously run the front vehicle system or the rear vehicle system until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter A Set it to 60% to 80% of when the front vehicle system or the rear vehicle system just happens to overshoot; Then the parameter A remains unchanged, and the undetermined parameter B is gradually increased from 0, and the front vehicle system or the rear vehicle system is continuously operated until the front vehicle system or the rear vehicle system just happens to overshoot, and the undetermined parameter B is set to the front vehicle system or 60% to 80% of when the rear vehicle system just happens to overshoot; The last undetermined parameter C is set to 0; Step 10: The wireless communication device (5) of the rear vehicle system sends the actual speed v ₂ (m) of the rear vehicle system at time m and the distance S ₂ (m) traveled by the rear vehicle system at time m to the PC, and Displayed on the PC. 2. The intelligent two-vehicle following and communication experiment method according to claim 1, characterized in that: the power supply device (2) comprises a battery (10), a 5V voltage stabilizing module, a 3.3V voltage stabilizing module, a 6V stabilizing Voltage module, 12V voltage regulator module, pressure measuring module, battery (10) is connected with the input interface of 5V voltage regulator module, 6V voltage regulator module, 5V voltage regulator module output interface is connected with 3.3V voltage regulator module, 12V voltage regulator module The input interface is connected, the input interface of the pressure measurement module is connected with the battery (10), the output interface of the 5V voltage stabilizing module of the power supply device (2) is connected with the main control equipment (1), the wireless communication device (5), the speed measuring device ( 7), the distance measuring device (8), the dial switch and the voltage input interface of the button device (9) are connected; the output interface of the 3.3V voltage stabilizing module of the power supply device (2) is connected with the voltage input of the LCD screen (6) The interface is connected; the output interface of the 6V voltage stabilizing module of the power supply voltage device (2) is connected with the voltage input interface of the steering control device (4); the output interface of the 12V voltage stabilizing module of the power supply voltage device (2) is connected with the DC motor drive The voltage input interface of the device (3) is connected.