Cooperative Behavior of a Mechanically Unstable Mobile Robot for Object Transportation

Cooperative transportation of an object by two or more mobile robots requires each robot to exert an appropriate force to support and move the object, to move along the object, and to maintain the robot’s attitude stably. Studies of cooperative transportation by multiple robots so far have scarcely considered the stability of the robot’s attitude influenced by the force from the object. To take part in cooperative transportation, a mechanically unstable robot, such as a wheeled inverted pendulum, needs to control the force and follow the object as standing stably against the force in an integrated manner. We call this a cooperative behavior. To realize this behavior of a wheeled inverted pendulum, we built a control system to estimate the external force and maintain standing and to exert a specified force. Experiments were conducted of cooperative transportation between a human and the robot.