DETC2005-84349 HYBRID TARGET TRACKING MANIPULATION THEORIES FOR COMBINED FORCE AND POSITION CONTROL IN OPEN AND CLOSED LOOP MANIPULATORS

ABSTRACT This paper presents a new manipulation theory for controlling compliant motions of a robotic manipulator. In previous closed loop control methods, both direct kinematics and inverse kinematics of a manipulator must be resolved to convert feedback force and position data from Cartesian space to joint space. However, in many cases, the solution of direct kinematics in a parallel manipulator or the solution of inverse kinematics in a serial manipulator is not easily available. In this study, the force and position data are packed into one set of "motion feedback," by replacing the force errors with virtual motion quantities, or one set of "force feedback," by replacing motion errors with virtual force quantities. The joint torques are adjusted based on this combined feed back package. Since only Jacobian of direct kinematics or Jacobian of inverse kinematics is used in the control scheme, the computational complexity is reduced significantly. The applications of this theory are demonstrated in simulation experiments with both serial and parallel manipulators. KEYWORDS Target tracking, open loop, closed loop, manipulation, hybrid control INTRODUCTION In many applications such as deburring, grinding, scribing and contour following, a manipulator is required to follow a predefined position trajectory in the tangent direction of a surface while maintaining a contact force in the normal direction. These tasks need appropriate control of motion and force. In the beginning, a typical force control strategy was used to command an actuator torque. This strategy combined feedback of force with feedback of position (and velocity) and corrected the error through a common controlle