Approach to cooperative assembly task planning for multiple manipulators

It is very difficult to allocate the assembly tasks to multiple manipulators, because the number of manipulators is variable and each manipulator has different ability. This work presents an approach for cooperative assembly task planning for a multiple manipulators environment to improve the flexibility and reliability of the automated assembly system. In this paper, the hierarchical assembly precedence graph (HAPG) extended from the assembly precedence graph (APG) is proposed to describe the assembly sequences and the assembly process data necessary for the task allocations. The outline of the agent-based and cooperative assembly task planning system is presented, and this system starts from the HAPG and the information of the manipulator agents. For the sake of minimizing the makespan, the algorithm of task planning takes into account not only the assembly processing time but also the time needed for the manipulators to change tools. Some applications of this algorithm for a multiple manipulators environment are described.