Real-time control of robot manipulators in the presence of obstacles

A novel approach is suggested to the problem of obstacle avoidance for a point robot moving among circular or elliptical/spherical or ellipsoid obstacles. The obstacle avoidance strategy (OAS) translates each state constraint (obstacle) into a state-dependent control constraint (SDCC). Each SDCC defines a hyperplane in the control space u. The intersection of the SDCC sets with the hard control bounds forms a polygon in u. The optimal decision strategy (ODS) control algorithm is then used to find the control which lies in this polygon-assuring obstacle avoidance-and minimizes the deviation between the acceleration vector of the point robot and a desired acceleration field. Simulation results display the effectiveness of the algorithm for a workspace hosting multiple obstacles. The OAS algorithm has been implemented successfully on a small Cartesian-coordinate robot