Visual Dead-Reckoning for Motion Control of a Mecanum-Wheeled Mobile Robot

Given an omni-directional mobile platform using four Mecanum wheels, it requires further a capability being programmed to achieve various motion behaviours and intelligence. This paper describes an undergraduate solution to the problem involving both hardware and software developments. With a path following behaviour as the aim, the research focused mainly upon sensors for dead-reckoning, motor drive, closed-loop feedback control, and microcontroller interfacing and programming. A four channel high power MOSFET and relay H-Bridge driver circuit board was designed for driving four motors, two optical mice were attached to the front and rear of the robot giving positional feedback for closed-loop control and dead-reckoning for navigation and a Mitsubishi M16C/62 microcontroller was interfaced to all those TTL compatible devices and subsequently programmed to implement various robotic behaviours. A closed-loop control scheme using three independent PID controllers was implemented to follow three degrees-of-freedom motions, i.e., x and y-movement and rotation motions. The path following performance of the robot was tested in both open-loop and closed-loop modes and the optical mice were found to be a promising but inexpensive sensor to the dead-reckoning for robot motion control.