Design and development of a novel omni-directional platform

Abstract

This thesis presents the design and development of a unique omni-directional platform known as the Omnibot which was built in the Mechatronic and Robotic Systems Laboratory at UOIT. The Omnibot's layout is novel because its drive axes do not intersect with the geometric center of the body, which is typical for omni-directional platforms using segmented omni-directional wheels. This design enables the center of mass to be lower in the design and increases the stability. A suspension system was designed for each of the four wheels to limit vibrations and to ensure contact between the wheels and operating surface. The Omnibot was built to modularly support many systems, including a robot arm, without altering the mechanical design of the frame. Two control modes were developed: local and global. Commands to drive the Omnibot can be received from either a joystick that can be directly interfaced with the controller or with commands that are sent from other systems that are either on or o of the Omnibot. Both control modes require encoder feedback to ensure commanded velocities are being executed as specified. Global control requires feedback from an indoor localization system to determine the Omnibot's pose. Early implementation of the localization system is discussed. An open source robotics software, known as Robot Operating System (ROS) was selected for implementation of the Omnibot systems. ROS serves as a middleware which allows components, such as the localization system and remote desktop, to communicate with each other through a decoupled messaging system. ROS is modular and exible, allowing for easy adaptation of future components. Test results of the Omnibot in operation are presented.