This repository is part of OmniCar project and represents program for Arduino MEGA that solves omni platform kinematics to get wheel odometry solution and reach desired velocity. It utilitizes PID-controllers based on feedback from incremental encoders to control JGB37-520 DC motors. Also it can communicate via UART in half-duplex mode.
Arduino MEGA runs code of this repository and placed on the 1st floor of the mobile platform. It has Freeduino Motor Shield V3 and special power board (reduces wiring) mounted on top of it.
The platform has 4 mecanum wheels based on JGB37-520 DC motors with incremental encoders. Each encoder uses 2 interrupt pins.
Chosen configuration has only 4 free interrupt pins (other ones are used or unreachable because of motor shield): 18, 19, 20, 21 - they are used by 2 front wheels. Two rear wheels use "fake" interrupts via PinChangeInterrupt library: 50, 51, 52, 53.
The project structure consists of two blocks: car control (Car) and serial communication (SerialTransceiver).
Car controls 4 wheels with tuned PID-controllers and calculates robot velocity by solving inverse kinematics problem and robot position by solving forward kinematics problem (dedicated theory described in Modern Robotics book, p.519).
SerialTransceiver receives control vector from Raspberry Pi (3 bytes) and transmits robot position in global coordinate system (12 bytes). It uses CRC8 algorithm to check message integrity.
This project was created using PlatformIO IDE, so you need to install it to load code on your Arduino MEGA (or just copy all classes to Arduino IDE).