Collision avoidance for two SCARA robots

A method for planning collision-free trajectories of two SCARA robots in a common workspace is described. The robots are treated as a single redundant system. A collision map representing the intersection of the robots is developed in a two-parameter space. A trajectory is planned by finding a collision-free path in the parameter space as a primary constraint and minimizing an objective function in joint space as a secondary goal. An artificial potential field facilitates path planning in the parameter space. A gradient projection method minimizes the error between the current and desired joint angles and optimizes other criteria. The proposed formulation has application in flexible assembly cells which utilize multiple SCARA robots. Two examples demonstrate the effectiveness of the method