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The automatic generation of assembly or disassembly sequences is needed to realize assembly or disassembly tasks with a robot. This problem can be deviled into the following three stages. They are, 1. modelling or representation of the assembly or disassembly network, 2. searching method, 3. decision of the criterion function. In earlier researches, what seems to be lacking in the problem 1 or 2 is a consideration of the task environment. Also, as for the problem 3, little attention has been given to it.In this paper, we propose a new assembly or disassembly sequence planning method. Firstly, we introduce a new assembly network representation with Petri Net graph which includes the environment in the conventional AND/OR graph. Secondly, we propose three criterion functions reflecting stability, manipulability and energy. These criterions fit well with experiences of a human operator. Also, we use the multi-objective Linear Programing to search the best sequence. Finally, we show examples to verify the validity of the proposed planning method.

A method for a task division which is needed to realize an efficient parallel processing on the inverse dynamics problem is proposed. In the preprocessing step of scheduling, calculating equations are divided into many tasks which become processing units. On dividing the given equations into a task set, if the task granularity is fine, the number of tasks which can be processed simultaneously tends to increase, whereas communication overhead between processors tends to increase. The purpose of this study is to develop a task dividing method for efficient implementation of parallel processing. The inverse dynamics equations are divided into tasks by equation level. Divided tasks are composed or divided additionally considering the precedence constraints inherent in the inverse dynamics problem.