Design and Development of an Autonomous Omni-Directional Mobile Robot

Abstract

The objective of this M Eng work is the design and development of a low-cost omnidirectional mobile robot that has specific required abilities that will aid it in its safe autonomous navigation in an unknown environment.

Some of the abilities are omni-directional motion capability that allows it to be holonomic, ground edge detection capabilities that will prevent the robot from experiencing a fall, obstacle avoidance which is essential as it moves to a goal location, carry a note book that will serve as a higher level control which will allow wireless communication, navigation computation and a platform for further developments (such as the attachment of a camera for vision processing) and collision detection so that the robot will be aware that it has collided into an obstacle.

A microcontroller has been custom designed for the low-level control of the mobile robot architecture. It consists of three ARM Cortex-M processors that will communicate with the three actuators and sensors on the robot. The two Slave processors on board have also been programmed to communicate reliably with a Master processor which will be the gateway for communication to the notebook for higher-level control. The communication protocol between the microcontroller and the notebook has also been set up. It will send data which will be used in the navigation computation, writing to file and be displayed on a Graphical User Interface (GUI) which has also been written.

With the aim of this project to be low cost, reliable working components were obtained where possible and fabrication was done in-house by the author. The robot?s mechanical design is built from scratch and having three wheels, the kinematics of motion that relates the overall robot?s velocity and the individual wheel?s velocities has been derived. A control algorithm of the actuator has been implemented and shows good performance. A navigation algorithm has also been implemented and efficacy has been demonstrated. Performance analysis has been performed and drawbacks to both the control and navigation algorithm are discussed. This autonomous holonomic robot is also meant to serve as a platform for future developments and it is described in this thesis.