Proxy based sliding mode control augmented with friction compensator for use in 1-DOF freehand ultrasound probe

This paper presents three contributions in the filed of medical imaging applications using hand-held ultrasound probe: 1) a new type of belt-driven mechanism for force-controlled ultrasound probe (FCUS) and 2) a safe and precise position controller and 3) a new algorithm for endpoint avoidance in the limited motion range. To enhance the image quality, the probe-patient contact force is controlled. In such case, to achieve both safe contact within limited range of motion and accurate positioning, proxy-based sliding mode control augmented with friction compensation is proposed. Due to proxy-based sliding mode control, the proposed controller is advantageous in that it guarantees overdamped response and the system model, which is difficult to obtain for probe-patient interaction system, does not appear in the controller. Due to friction compensation, the controller provides accurate positioning. The new algorithm for endpoint avoidance enables continuous motion in the limited motion range. The proposed controller is validated experimentally.