A cooperation strategy for a group of object lifting robots

The ultimate goal of this research is to study information, cooperation strategies, and behaviors required by a group of behavior based mobile robots for lifting and transferring an object with unknown mass and center of gravity. This paper presents some of the investigation results of the first stage of the project, lifting the object. After discussing the problems facing a group of object lifting robots, a distributed cooperation strategy, sensory system, and required behaviors for multiple cooperative object lifting robots are introduced. In the proposed cooperation strategy, when the object's tilt angle passes a defined value, the robot(s) having the lowest contact point with the object moves upward faster while the others slow down and stop. The sensory system is designed so that each robot is able to measure the object's tilt angle and communicate with the other robots when required. Sufficient conditions for applicability of the proposed algorithm are provided and the validity of the studied approach is verified through computer simulations and experiments.