# Fifth Lichuang Electronic Design Competition #fpv wheat wheel car

Note: * is required.

# [Please fill in during the registration stage↓]

## * 1. Self/Team Introduction

I am a self-taught embedded engineer who has served as a technical leader in many companies, mainly engaged in security and Internet of Things related industries. He is a creative and perseverant geek~

During 2019, he learned front-end, back-end, desktop, linux, python and other development knowledge at home. He established the Yun-Zhejiang Innovation Team and realized the Yun-Zhejiang smart home project. That’s right. , I am currently the only one in the team, hahaha~

This is my personal website [Yunzhecx Innovation] (http://www.yunzhecx.cn/).

## * 2. Briefly introduce the project.

In 2019, DJI released the Mecha Master S1, which was very cool. It also introduced me to the Mecanum wheel for the first time. The Mecha Master’s price of 3,500 yuan prohibits most people. Even if a "rich person" buys one, after installing it, he will find that he needs to buy at least one before he can play with it.

There are many makers who have designed their own cars using such interesting Mecanum wheels. If they can’t afford it, why can’t I build one?

We will spend a budget of 200 yuan to build an FPV wheat wheel car. The following are the prices of the main components:

PCB board

! [Image 20200913-008.jpg]
Motor driver chip
! [Image 20200913-007.jpg]
Main control MCU
! [Image 20200913 -004.jpg]
Wheat wheel

![Picture.png]
Reduction motor
![Image 20200913-003.jpg]
Camera module

![Image 20200913-002.jpg]
Car body

![Image 20200913-005.jpg]
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Single PCB 1 yuan + motor 11.25*4 + wheat wheel, coupling, screws 77 + material box 3.9 + microcontroller 4.85 + motor driver chip 0.36*4 + camera module 10.5 = 143.69 yuan. There

is more than 50 yuan left under the budget of 200 yuan. Comes with a battery.

# [Please fill in during the competition stage↓]

## * 1. Describe the project details.

The main components of this project are: wheat wheel, material box diy car body, reduction motor, stm32 main control, wifi camera module, battle FPV app;

## * 2. Describe the challenges faced by the project and the problems solved.

Since the customized car body is relatively expensive, we finally chose the material box as the car body. The price is 3.9 yuan with free shipping.

It is necessary to analyze the protocol of the camera module, serial port output, and conduct the operation on the mobile phone. To operate, capture different protocols, analyze the control part, and write the corresponding microcontroller program to drive the motor;

you need to master the principle of the Mecanum wheel and drive it to achieve the purpose of moving the car in different directions;

currently, the car does not have a battery and uses an external The 5V power supply is directly input, and the battery is used later, and an acrylic plate is placed in the material box for isolation, so that the goods can be placed on the top layer of the acrylic to serve as a transportation function.

## * 3. Describe the key points involved in the hardware and software parts of the project

** 6 control methods: **

![Forward.jpg] ![Backward.jpg] ![Right panning.jpg] ![Clockwise in place .jpg] ![Counterclockwise in place.jpg]
**Movement at other angles**

Controlling the rotational speed of the wheel can realize movement at other angles. This is not currently implemented, so we will not introduce it.

**Key points in the software part**

**Main function**

```
void main()
{
    while(1)
    {
        Usart1Process();
    }
}

```

The main function always executes the serial port information sent by the camera module and Process, parse into control operations and put them into global variables.

**Interrupt function**

```
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
    static uint32_t t=0;
    if (htim->Instance == htim3.Instance)
    {
        t++;
        if(t%2!=0)
        {
            if( devstate.RF==HAL_TIMEOUT)
            {
                RF_standby();
            } else if(devstate.RF==HAL_OK)
            {
                RF_forward();
            }
            else if(devstate.RF==HAL_ERROR)
            {
                RF_backward();
            }

            if(devstate.RB ==HAL_TIMEOUT)
            {
                RB_standby();
            } else if(devstate.RB==HAL_OK)
            {
                RB_forward();
            }
            else if(devstate.RB==HAL_ERROR)
            {
                RB_backward();
            }

            if(devstate.LF==HAL_TIMEOUT)
            {
                LF_standby();
            } else if(devstate.LF==HAL_OK)
            {
                LF_forward();
            }
            else if (devstate.LF==HAL_ERROR)
            {
                LF_backward();
            }

            if(devstate.LB==HAL_TIMEOUT)
            {
                LB_standby();
            } else if(devstate.LB==HAL_OK)
            {
                LB_forward();
            }
            else if(devstate. LB==HAL_ERROR)
            {
                LB_backward();
            }

        }
else
        {
            RF_standby();RB_standby();LF_standby();LB_standby();
        }

    }
}

'`

The control parameters saved in devstate are executed in the interrupt function, LB is the left rear wheel, LF is the left front wheel, RB is the right rear wheel, and RF is the right front wheel; HAL\_ERROR performs reverse rotation, HAL\_OK performs forward rotation, and HAL\_TIMEOUT performs standby.

The t variable is used to implement duty cycle control of wheel speed.
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## * 4. Project material list display

! [Image 20200918-010.jpg]
## * 5. Project image upload

### 5.1. Print the competition logo image on the PCB. Failure to do so will be considered as giving up the competition

! [WeChat Picture_20200912225116.jpg]
### 5.2. Other pictures of the project

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![WeChat picture_20200912225316.jpg]
![1.jpg]
![2.jpg]
![3.jpg]
![4.jpg]
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![5.jpg]
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## * 6. Demonstrate your project and record it as a video for upload

### 6.1. Official website of the video upload contest

### 6.2. Video title of Station B and link

notes: ①: Video requirements: Please shoot horizontally, with a resolution of no less than 1280×720, format Mp4/Mov, and the size of a single video is limited to 100M; ②: Video upload: please upload to the official website of the competition and Station B simultaneously ([www.bilibili.com](www.bilibili.com)), the top 10 most popular projects at Station B will receive 1,000-5,000 yuan in cash rewards, and other uploaded projects will receive 100 yuan Lichuang Mall no-threshold coupons; ③: Video title: No. The 5th Lichuang Electronic Design Competition: {Project Name}-{Video Module Name}; such as the 5th Lichuang Electronic Design Competition: "Autonomous Driving" Project - Team Introduction.

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[The 5th Lichuang Electronic Design Competition: Personal Introduction (personal introduction using smart home projects)](https://www.bilibili.com/video/BV1Ja4y177WC)< br>

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[The 5th Lichuang Electronic Design Competition: fpv wheat wheel car-drive test](https://www.bilibili.com/video/BV18p4y1e7Vw)< br>

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[The 5th Lichuang Electronic Design Competition: Chuang Electronic Design Competition: fpv Mai Lun Car-Mobile App Connection Test](https://www.bilibili.com/video/BV1R5411b7ri)< br>

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[The 5th Lichuang Electronic Design Competition: fpv Wheat Wheel Car - Comparison between first and third perspectives](https://www.bilibili.com/video/BV1CK411P7nN/)< br>
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## * 7. Whether it is released to the public for the first time

### 7.1. If the project has been published or won an award before, please indicate that

it has not been published

### 7.2. If the project is optimized on the original basis, please indicate

whether the optimization part is

## * 8. Open source documents

[https://gitee.com/yunzhecx_cn/fpvcar-v1.0](https://gitee.com/yunzhecx_cn/fpvcar-v1.0)< br>
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## * 9. References

Click the link for more details: [https://www.szlcsc.com/go/dsxq](https://www.szlcsc.com/go/dsxq)< br>
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[ The working principle of the Mecanum wheel](https://www.zhihu.com/question/51812779/answer/576185197)< br>

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[[DJI Mecha Master] The working principle of the Mecanum wheel ](https://zhuanlan.zhihu.com/p/73359979)< br>

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