Motion planning for mobile surgery assistant.

The paper presents a method of motion planning for a mobile manipulator acting as a helper providing the necessary tools or a surgery assistant carrying out pre-planned procedures. Mobility of this system makes it possible to reach the position which will give optimal access to the operating field. The path of the end-effector, determined during operation pre-planning, is defined as a curve parameterised by any scaling parameter, the reference trajectory of a mobile platform is not needed. The motion of the mobile manipulator is planned in order to maximise the manipulability measure, thus to avoid manipulator singularities. The method is based on a penalty function approach and a redundancy resolution at the acceleration level. Constraints connected with the existence of mechanical limits for a given manipulator configuration, collision avoidance conditions and control constraints are considered. A computer example involving a mobile manipulator consisting of a nonholonomic platform (2,0) class and a 3 DOF RPR type holonomic manipulator operating in a three-dimensional task space is also presented.