Cooperative control and force limitation for multiple robots in single object transportation

A cooperative control method for multiple robots of transporting single objects is proposed, which is effective in unknown environment. All robots are controlled by the same algorithm, and they can have different objective tasks simultaneously. Hence the method can deal with the situation where one robot has "trajectory tracking task" and another robot which detects an obstacle has "obstacle avoidance task". A task is expressed as the desired position of the object and the associated weight matrix, and each robot can set its own desired position and weight matrix independently of the other robots' tasks. This method requires no real-time communication among the robots. The robots can cooperatively transport the object to the composite desired position which is the weighted mid point of all desired positions. The forces between the robots and the object are controlled as equally as possible during transportation, and exceeding forces can be suppressed. The effectiveness and usefulness of the method are ascertained by computer simulation.