Design and control of ball wheel omnidirectional vehicles

A new class of ball wheel mechanisms for omnidirectional vehicles is presented. This ball wheel mechanism can be designed to yield fully mobile vehicles that are not only free of any kinematic singularity but are configuration invariant in kinematic behavior. Invariant kinematics greatly simplifies the control of smooth and precise vehicle motion. Multiple displacement sensors are easily incorporated into each ball wheel mechanism. This unique feature enables the detection of slip between tires and the floor and also indicates at which tire the slip occurs. This allows traction control to be implemented to fully exploit the available floor friction while accurate dead reckoning navigation continues from two non slipping tires. A prototype vehicle with three ball wheel mechanisms is implemented. Smooth motion and precise dead reckoning are accomplished