Development of an embedded servomotor controller

Abstract

This project comes within the scope of the RoboCup contest, an international robotics competition in which teams of robots play a soccer game. The motivation is to have a more effective control on robot joints than what can be achieved with commercially available technology. Those joints are made of servomotors, it is a rotary actuator that allows a precise control of angular position. The subject of this master thesis is to develop an electronic board that will provide advanced control mechanisms for a servomotor. This board will receive orders from the outside via a communication bus and will control a DC motor in order to execute the order. The specificity of this work is that the orders may take many forms, from basic angular position, torque commanded motion to more specialized operations such as a sequence of command triggered by external events. The idea behind this project is to develop a board sufficiently powerful and modular to implement easily a wide set of handcrafted commands. The servomotor Dynamixel TM MX-28 has been used as a basis, its electronic board has been removed in order to be replaced by a home-made one. The new board that was designed in the scope of this work improves and adds new functionalities to the previous one. The major improvements consist in a more accurate torque measurement, the support of CAN bus communication and the implementation of a more powerful microcontroller. The new functionalities consist in integrating a coupled accelerometer and gyroscope, a temperature sensor and an easy way to program the microcontroller by means of SWD or CAN bus. The GL-28, name given to the board, has been tested and validated for some parts. Once fully tested, such a board will be embedded in servomotors that will be assembled and commanded to achieve a robot. Some people interested in this project would like to exploit such a servomotor for other purposes, opening new perspectives.