pic: SimSwerve Omnidirectional Drive System

[Ian Mackenzie]

Originally Posted by ZACH P.

May I ask why this is nessecary?

We wanted a 'strafing' (omnidirectional) drive system, but also one that would be able to climb the deck. The solution we came up with was to have two driven, independently steerable wheels and two ball casters, each of which could raise and lower independently. The robot then climbed the deck by raising up each wheel as it came in contact with the deck. The main advantages were extreme manoeuvrability on th floor, the ability to climb the deck from any direction, and the ability to move sideways on the upper platform to defend against other robots.

Getting on the deck from any direction was particularly useful - if someone pushed us as we were climbing and turned the robot, we could still climb (usually, in fact, the pushing robot actually helped). The vertical sliding action isn't all that obvious in this photo, although you can see the two sets of linear bearings that the gearbox assembly slid on - check out the discusssion thread for the white paper on the design for CAD models in various formats.

Although admittedly complex, the gearboxes worked very well - we had one shaft snap once, but that was it. The design won Leadership in Control in Pittsburgh (where we were finalists), Delphi Driving Tomorrow's Technology in Long Island (champions), and both Xerox Creativity and Motorola Quality at the Canadian Regional (finalists).