A synchro-caster drive system for holonomic and omnidirectional mobile robots

A holonomic and omnidirectional vehicle based on a new type of wheel drive system is presented in this paper Multiple drive-casters are mounted on a drive unit where wheel axes and steering axes are mechanically coupled by transmissions respectively and driven and oriented by respective common motors. Omnidirectional translational motion of the vehicle is controlled by the motors driving and orienting the drive-casters. This drive train is similar to a conventional synchronous drive system with two motors for nonholonomic mobile robots, called "synchrodrive". However, proposed system needs the third motor for orienting a vehicle frame relating to the drive unit. Thus 3 DOF of the vehicle can be controlled by three motors, then the vehicle has no over constraint. First the concept of the original caster-drive is mentioned briefly, followed by the kinematics and statics analysis of the new drive mechanism. All wheel driving with individual suspensions, decoupled control without over constraint would be achieved with the proposed synchro-caster drive system.