Cooperative grasping control of multiple mobile manipulators with obstacle avoidance

We present a novel cooperative grasping control framework for multiple kinematic nonholonomic mobile manipulators, which enables them to drive the grasped object with velocity commands, while rigidly maintaining the grasping shape with no dedicated grasp-enforcing fixtures and also avoiding obstacles either via their whole formation maneuver or internal formation reconfiguration. For this, nonholonomic passive decomposition [1], [2] is utilized to split the robots' motion into the three aspects (i.e., grasping shape; grasped object maneuver; internal motions) so that we can control these aspects simultaneously and separately. Peculiar dynamics of the internal motions is exploited to achieve obstacle avoidance via the formation reconfiguration. Simulations are performed to support the theory.