As part of my time spent in Reutlingen I did some reasearch work for Prof. Dr -Ing Gruhler of the Mechatronics Department of the Hochschule Reutlingen. I ended up compiling two reports. The first was a purely research based one and the second included some practical work on a mobile robot. The work on the second report was used in a journal article available here.
Summary of Omni-Directional Drive Choices
This report briefly introduces the concept of an omni-directional drive. It then proceeds to give overviews of many of the the currently available and in use methods of achieving omni-directional drive. Both units which have received commercial use, and those restricted to hobby robotics have been listed. Because no specific application was in mind, no recommendation towards a specific drive method was made. The appendix includes some further information and links to a design report and video demonstration of most of the drive methods listed in the report.
Drive types mentioned include: Omni-Wheels, Anisotropic Wheels, Omni-Ball, Mecanum Wheel, Swerve Drive, Ball Drive, Vuton Tracks, Omni-Crawler, Hemispherical Gimbaled.
The report can be downloaded here (4.5 MB PDF)
Notes on Robot Odometry
In this report a pre-built omnidirectional robot is modified to allow for better odometry as well as control. The report investigates several possibilities for odometry, and then making use of available equipment adds a proximity sensor to the robot for accurate tracking. In addition to this the movement control code is replaced with PID controllers for both directions of movement. Slight adjustments are made to the visual interface with the robot and a Wi-Fi connection is re-established.
The full report can be downloaded here (2.1 MB PDF)