Optimal trajectory planning of robot manipulators in the presence of moving obstacles

A method for computing the optimal motions of robot manipulators in the presence of moving obstacles is presented. The algorithm considers the nonlinear manipulator dynamics, actuator constraints, joint limits and obstacle avoidance. The optimal traveling time and the minimum mechanical energy of the actuators are considered together to build a multicriterion function. Sequential unconstrained minimization techniques have been used for the optimization. Given the initial and final points the trajectories are defined using spline functions and are obtained through off-line computation for on-line operation. The obstacles are considered as objects sharing the same workspace performed by the robot. The obstacle avoidance is expressed in terms of the distances between potentially colliding parts and the motion is represented using translation and rotational matrices. Numerical applications involving a Stanford manipulator are presented.