DIY Quadcopter

Introduction

Project 2: Quadcopter

Vg100

Professors: Shane Johnson

Andrew Yang

Teaching Assistants: Alien Dong

Frank Xu

Jackie Zhang

Team Prometheus

Team Members: Christopher Yuan, 5133709024,

Gu Nan, 5133709166

Chen Yutian, 5133709264

Yang Yichao, 5133709211

Ye Chu’nan, 5133709271

Jul. 29th, 2014

The University
of Michigan Shanghai Jiao Tong University Joint Institute, or commonly abbreviated to JI, is a collaboration project between the school administrations between China and the United States in order to promote mutual growth and to nurture the next generation of engineering minds for the betterment of both countries. JI is currently located at the Minhang campus of Shanghai Jiaotong University in Shanghai, China.

Our Quadcopter

Our quadcopter contains six main parts, the frame, the driving system, the control system, camera system, phone module and power set. The main frame is a kind of specific frame made of carbon and nylon, which is a specialized design for the quadcopter. The driving system contains four propellers and four brushless motors which can provide enough lift force. We make the quadcopter move forward by adding the power to the two rear motors so that the entirety can lead forward to get a trusting force. Moving backward and sideward uses the same principle. As for turning, we adjust the power of the motor to change the torque, which enables the quadcopter twist. The control system contains a gyroscope and an auxiliary program to keep the quadcopter balance. In addition, a remoter controls the direction and the movement of the quadcopter. The camera system contains a camera module and a wifi module which transfers the videos or photos back to the computer terminal. The phone module enables people communicate through a microphone and a computer in real-time and the power set provide all the power needed.

This task is quite complex if you have no experience of dealing with

speed controllers. For simplicity, we use servo library to imitate the function of the special program for speed controller initialization. If you buy the speed controller, it will be a detailed description for how to initialize them. Here we will give some general instructions. The code can be found easily online. We are not going to provide our code because the value of the parameters may not fit your speed controller. The algorithm works in this way:

Consider the brushless motors as servos and map the rotating speed of the motors to an input signal for a servo. Start the motor with the lowest input signal (which is usually 37) and then adjust it to the highest input signal (which is usually 150). If the sound is right, then the initialization is done. After that, given an input signal between 37 and 150, it will rotate with a relative low or high rpm.

Then fix the four brushless motors on the four side of the structure

with screws. Connect the brushless motors and the four speed controllers and attach the speed controllers under the stand of the structure with cable ties.

Fix the Ardunio board on the structure and fix the gyroscope

horizontally close to the center of the structure. NOTICE: the gyroscope must be placed as horizontal as possible and it will be better if it is placed at the center.

Upload the MWC program into the Arduino board. The MWC program is an

open source program that can control the flight of an aircraft including but not limited to quadcopter. The algorithm is already finished and we can directly use it. However, some of the parameters depend on the individual quadcopter and needs our modification.

Fix the remote signal receiver and set up the remoter. You can

follow the instructions attached by the remoter of how to make the remoter work along with the MWC program. Connect the wires that are needed for the remoter.

Fix the battery and connect the wires that provide power. (Please

make sure you connect the battery before you fix the propeller, or you will take the risk of being cut).

Fix the four propellers. Make sure that they are tight enough or it

can be very dangerous if high speed propellers fly out.

Test and modify the parameters. The MWC program is based on the PID

algorithm, which use three parameters kp, ki and kd to adjust the positon of the aircraft. Different values of these parameters represent different reaction when the quadcopter meets the same situation. First, we set all these parameters at 0 and then increase them slowly in order to get a relatively stable flight. Set kp first, then ki and then kd. The best parameters will be used to control the quadcopter’s flight.

NOTICE: the testing can be very dangerous because the wrong parameters may make the quadcopter do crazy motion and cut you. In case accidents happen, we highly recommend you restrict the quadcopter by tying 4 strings under the structure.

After making the quadcopter fly, you can attach any functional module as you like.

For example, a camera or a talk back system, you can play with it in a totally different way.

1. Assemble orders can be changed but we highly recommend you connect the battery not so early in case there occurs an accident.

2. Initializing speed controllers and modifying the MWC program are quite complex. Fortunately, there are many tutorial articles online. If you have any difficult, search online is a good choice.

3. SAFETY FIRST! The brushless motors are VERY POWERFUL and being cut may cause very severe injury. Please make sure that you are well protected before you do any step.