Path planning for two cooperating robot manipulators

The authors investigate the path-planning problem for two planar robot manipulators which cooperate in carrying a rectangular object from an initial position and orientation to a destination position and orientation in a two-dimensional environment. To approach the problem, they model the robot arms, the carried object, and the straight line connecting two of the robot bases as a six-link closed chain. The path-planning problem for the six-link closed chain is solved by the collision-free feasible configuration finding algorithm and the collision-free path-finding algorithm. The former finds all collision-free feasible configurations (CFFCs) for the six-link closed chain at each quantized interval for two of the six joint angles. The latter builds a connection graph of the CFFCs and the transitions between any two groups of CFFCs at adjacent joint intervals. A graph search method is used to find a collision-free path for each robot joint. The algorithms can deal with cluttered environments and can be proved to converge