Laser car chasing system

1. ** Task: Design and produce a laser car chasing system, including a homemade remote control car and a homemade laser aiming device. The aiming device includes a camera and a laser pointer. The system composition is shown in Figure 1. Figure 1 2. **Requirement 1** . Basic requirements (1) Equipped with a display screen to display the speed of the car in real time in RPM. (10) (2) The speed of the car is adjustable through buttons and can be divided into at least three levels of speed, with obvious speed differences. (10) (3) The car is required to automatically travel in a straight line for a specified distance (any number within 20-50cm), with an error less than 10%, and the driving distance is input by pressing the keys. (10) (4) Based on (3), the display screen displays the traveling distance in real time. (10) 2 **. Part of the play (1) The car has an attitude detection function, which can realize in-situ rotation of 45°, 90°, 120°, and 180°. The specified rotation angle can be input through the buttons, and the angle of rotation during the rotation process will be displayed on the display screen in real time. (20) (2) As shown in Figure 1, the initial orientation of the camera is randomly placed. The car is randomly placed anywhere in area A (within the camera's field of view). The camera is started by pressing the button. The camera is required to point to the car from the starting position. , use the laser pointer to illuminate the car as an indicator. The laser pointer should illuminate the car continuously for at least 5 seconds. (20) (3) The remote-controlled car is driving in area A, and the camera is required to follow the car and illuminate the car with a laser pointer as an instruction. (20) 3. ** Note 1. The remote control and the car are all homemade, and commercial products are not allowed. The remote control and the car use wireless communication. The remote control needs to be able to operate the car to move forward, backward, turn, and accelerate. , deceleration and other routine actions. 2. The color and shape of the car can be customized, and the type of microcontroller and display used can be customized. E-2* 3. A 1m 1m white drawing board is provided at the evaluation site, and the angle is compared with the drawing. The vertical height of the camera and the horizontal distance between the camera and the board are customized. 4. Performance requirements (3) are controlled remotely by the assessment examiner. 5. Performance requirements (3) When the camera follows the car, if the laser pointer shines on the car body or the driving path, it will be regarded as following. If there is deviation, points will be deducted as appropriate. Awards: This project won the second prize in the points competition of Nanjing University of Posts and Telecommunications Team information: Liu Junjie, Zhang Hanxiao, Li Junjie Instructors: Wang Jian, Lin Xiaoyong

The bottom board of this car uses tiva-M4 as the main control board, which integrates a variety of power interfaces, step-down voltage stabilizing modules, motor drives, qei input and other basic functions required by the DC motor bottom board. In addition, it also expands many functions at appropriate locations. A servo output interface, Bluetooth module, OLED and other parts. It can realize basic functions such as driving the car and qei detection. In addition, it is equipped with a multi-channel PWM output interface, which can be easily connected to control the steering gear. In addition, it is equipped with an OLED display module to support the analysis of the car's rotation angle, driving speed and other information in the competition questions. show.

Competition report:

Laser car chasing system

【** Junior ** Group】

1. ** System Solution**

This system mainly consists of a remote control car, a remote controller, and a laser aiming system. The selection of these modules is demonstrated below.

1. Demonstration and selection of main control device**

1.1.1 Controller selection

Microcontroller comparison

Option 1: Use TI's MSP430 microcontroller .

     MSP430 has the characteristics of strong processing power, fast computing speed, ultra-low power consumption, etc. It has rich internal resources and is easy to develop.

Option 2: Use  TI’s TM4C123GXL microcontroller.

TM4 has high main frequency , high performance, low power consumption and high integration. It is faster than MSP430 in terms of computing speed, and its simple development interface can fully meet the system control requirements.

    By comparison, we choose option two.

1.1.2 Control system solution selection

Option 1: Build a simple microcontroller system on a breadboard

    Building a remote control car system on a breadboard makes it easy to modify the hardware at any time and is easy to build. However, the system has many connections, which not only interfere with each other and make the circuit cluttered, but also has low system reliability, making it unsuitable for this system.

Option 2: Draw a circuit board to build the system

    The appearance is beautiful and simple, which reduces mutual interference and significantly increases circuit stability, making it very suitable for the design of this system.

 Based on the above two options, choose option two. 

    Based on the above three options, choose option two.

2. Argument and selection of ** laser aiming **

Solution 1: OpenMV+ TM4C123GXL . OpenMV is simple to operate, has complete library functions, and is very easy to use. However, it needs to be paired with TM4C123GXL as the information processing system, which increases the delay and increases the complexity of the solution.

Option 2: Raspberry Pi + OpenCV. It has high precision, complete library functions, and a built-in processing system. It can directly output PWM waves without relying on an external microcontroller, making the system response faster and more accurate.

Based on the above three options, choose option two

2** , **Circuits and Programming

The power supply consists of model aircraft battery and voltage transformer and voltage stabilizing module lm2596s. Provide 3V, 5V and 12V voltage for the car system to ensure the normal and stable operation of the circuit. This part of the circuit is relatively simple, so it will not be described in detail.

2. ** Program Design**

(1) ** Program function description and design ideas**

1. Program function description

1) Press the remote control button to switch modes. In different modes, you can input the straight-line driving distance, the required fixed angle, and remote control.

2) The car can receive remote control instructions and execute them, and the OLED displays the required information.

2. The laser tracking system processes the car's position information through OpenMV, and feeds it back to the servo gimbal in the form of PWM waves to adjust the laser position.

3** , **Test plan and test results

1. ** Test plan**

Use a multimeter to check that each module of the circuit is well connected. The power output is stable, the signal transmission is stable and smooth, and the motor responds quickly. Burn the code and check the running status.

2. ** Test conditions and instruments**

Test conditions: Check multiple times. The simulation circuit and hardware circuit must be exactly the same as the system schematic diagram, and the check is correct. The hardware circuit must be free of soldering.

Test instruments: digital oscilloscope, digital multimeter.

3. ** Test results and analysis**

(1) ** Test results ( data **)

The driving fixation test results are shown in the table below: (unit: cm)

The results of rotating a fixed angle are shown in the table below: (unit °)

(2) ** Test analysis and conclusion**

Based on the above test data, the following conclusions can be drawn:

1. The car can travel a fixed distance and turn a fixed angle according to instructions, and it is relatively accurate.

2. The car can respond quickly according to serial port instructions, and the OLED can display the required information in real time.

3. The laser can locate the car relatively quickly and can track it in real time.

To sum up, this design meets the design requirements.