Drive Straight: Enhancing Espro Robot Navigation with MPU6050 and PID

Introduction

Gyro  is one of the most commonly used electronic component  in human society. From large devices like rockets, satellites, and torpedoes, to small ones like smartphones and toy drones, we all use gyros.

In this course, we will learn how to program a gyroscope with Arduino to optimize the OSOYOO Robot Car’s performance.

Hardware Required by this project:
 1)OSOYOO Espro All-in-one ESP32 motor controller (fully support Arduino Programming IDE)

2)MPU6050 Gyro Module:
Shopping Link: https://osoyoo.store/products/mpu6050-gyroscope-module

3)Robot car chassis system including: Motors+ wheels+Chassis+Battery , you can make to order a customized chassis system  in following link:
https://osoyoo.com/osoyoo-general-robot-car-make-to-order/

Hardware Installation:

Simply insert your MPU6050 module into the Espro  board gyro slot. Then install the Espro board onto the chassis, insert the left motor onto the K3/K4 slot. Insert to right motor to K1/K2 slot in Espro board.

Install Arduino Libraries

We need following libraries Adafruit MPU6050/Adafruit Unified Sensor library and PID library to run the sample code of this lesson. There are two methods to install these two libraries;
Method 1 : Install from Arduino IDE
In Arduino IDE top menu -> Sketch ->Include Library->Manage Libraries
Search MPU6050_light , you will find a library “MPU6050_light by   rfetick”,

Click Install, then Install ALL to install MPU6050_light  library.

Similarly,  install PID library from Arduino IDE as following :

Method 2: Install from Zip File
Download 6 zip files from following links:
https://osoyoo.com/driver/2wd/MPU6050_light.zip
https://osoyoo.com/driver/2wd/PID.zip

Once you have downloaded above 6 zip files, do NOT unzip them, open Arduino IDE ->Sketch ->Include Library ->Add Zip Library. Then upload above 6 zip files to Arduino One by One.

Run Sample Code :
Step 1)Download https://osoyoo.com/download/osoyoo-gyro-car2.zip , unzip the file and uploaded osoyoo-gyro-car.ino file to Arduino IDE
In Serial Monitor, set baud rate to 9600, then you should see:

Now you can put the car onto the ground, turn on the power. You will see the car will stay freeze for a while waiting the Arduino to initialize the gyro. Then the car will move straight forward .  If you use your foot to force the car change direction, the car will automatically go back to its original direction.

A Brief Explanation to  the Principle and Arduino code 

1)MPU6050 Coding Introduction

After initialization, the gyroscope MPU6050 can consistently determine its orientation relative to its starting direction. When our robot car moves and deviates from this initial direction, the MPU6050 reports the amount of this deviation back to the Arduino.

In our code, the Direction variable  represents the car’s orientation at the moment it was placed on the ground (we assume it’s facing forward, so we set Direction to 0).

After the calculations in the first few lines of the loop() function, we obtain the car’s current orientation in the currentAngle variable on line 129.

2)Introduction about   PID  and Code:

1. P (Proportional): How far am I from the center of the lane right now?
2. I (Integral): Have I been consistently off-center for the past few moments?
3. D (Derivative): Am I swerving towards or away from the center too quickly?

// We tell the PID controller what to watch and what to control.
PID myPID(&Input, &Output, &Setpoint, Kp, Ki, Kd, DIRECT);

Direction = 0; // Our TARGET is to have an angle of 0 degrees.
myPID.SetMode(AUTOMATIC); // Turn on the controller.

// 1. We get the sensor reading and put it into the Input variable.
Input = currentAngle; 

// 2. We call the compute function. This is where the PID magic happens!
myPID.Compute(); 

// 3. We use the result to control the motors.
int speedL = baseSpeed - Output;
int speedR = baseSpeed + Output;
move(speedL, speedR);