This paper addresses the problem of optimal motion control for teleoperated surgical robots, which must maneuver in constrained workspaces, often through a narrow entry portal into the patient's body. The control problem is determining how best to use the available degrees of freedom of a surgical robot to accomplish a particular task, while respecting geometric constraints on the work volume, robot mechanism, and the specific task requirements. We present a method of formulating desired motions as sets of task goals in any number of coordinate frames (task frames) relevant to the task, optionally subject to additional linear constraints in each of the task frames. Mathematically, the kinematic control problem is posed as a constrained quadratic optimization problem and is shown to be computable in real time on a PC. We will present experimental results of the application of this control methodology to both kinematically deficient and kinematically redundant robots. Specifically, we will discuss the control issues within the context of a representative set of tasks in robot-assisted laparoscopy, which includes (but is not limited to) teleoperated navigation of a laparoscopic camera attached to a surgical robot. A system based on this control formalism has been used in preclinical in vivo studies at the Johns Hopkins University Medical Center and the early experience with the system will be summarized.

This paper describes the control and ergonomic evaluation of a ceiling mounted (or support frame suspended) 7-axis surgical robot (HISAR) for laparoscopic camera navigation. A key feature of the robot is that it incorporates a passive wrist for natural compliance with the port of entry into the patient. The use of a previously reported constrained Cartesian controller is motivated and demonstrated, and the results of successfully applying this control methodology to the manipulator are presented. The significance of the control strategy is the ease with which control of passive axes, the fulcrum constraint, and the motion inversion effect created by the fulcrum are accommodated. We also report on the results of laboratory evaluations of the arm in terms of its work volume, ergonomic factors, ease of control, and overall design within the context of laparoscopic camera control.