Planning of a point to point collision-free trajectory for mobile manipulators

A method of planning sub-optimal trajectory for a mobile manipulator working in the environment including obstacles is presented. The robot´s task is to move the end-effector from a given initial to a final position in the workspace. The motions are planned in order to maximize a manipulability measure to avoid manipulator singularities. Control and mechanical constraints are taken into consideration. The method is based on using penalty function approach and a redundancy resolution at the acceleration level. The collision avoidance is accomplished by local perturbation of the mobile manipulator motion in the neighborhoods of the obstacles. Nonholonomic constraints in a Pfaffian form are explicitly incorporated into the control algorithm. A computer example involving a mobile manipulator consisting of nonholonomic platform (2,0) class and DOF RPR type holonomic manipulator operating in a three-dimensional task space is also presented.