Control of omni-directional mobile platform with four driving wheels using torque redundancy

An omni-directional moving platform with four wheels is developed and its controller is designed for tracking desired trajectories. The four wheels of the platform are torque controlled by DC servo motors independently. The generalized coordinate of the platform is three, therefore the system has one torque redundancy and one odometry sensor redundancy which can be used for improving the control performance of the moving platform. First, ways of exploiting odometry sensor redundancy is discussed. Then a criterion for exploiting the torque redundancy is proposed to make larger the margin of driving force, and fundamental simulations and experiments are done to show the control characteristics of the developed mobile platform.