An Assembly Planning for Robots Based on Constraint State Transition Difficulty

Abstract

For autonomous assembly operations by a robot, it is required to build a planning function that can generate a series of operations to reach a goal state. This paper describes an automatic planning algorithm that synthesizes the assembly operation strategies. By making an criterion function based on the difficulty of state transitions be minimum, the method can find an optimal path based on the Contact State Network. The Degree of Constraint is proposed by regarding the assembly task as a process to change the constraint, state of the moving object. Then several policies for determining State Transition Difficulty are discussed where the variation of the degree of constraint and the shape information from the geometric model of objects are considered. A criterion function for state transitions is defined based on the discussed policies. Lastly, an algorithm which plans an optimal state transition path from an initial state to a goal state is proposed. Some examples are given to show the validity of this algorithm