An omnidirectional mobile robot with active caster wheels

This video shows a holonomic omnidirectional mobile robot with two active and two passive caster wheels. Each active caster is composed of two actuators. The first actuator drives a wheel; the second actuator steers the wheel orientation. Although the mechanical structure of the driving mechanisms becomes a little complicated, conventional tires can be used for omnidirectional motions. Since the robot is overactuated, four actuators should be carefully controlled.