We introduce a novel hybrid vision/force control strategy for robotic devices designed to obtain clear and consistent images using probe-based confocal laser endomicroscopy (pCLE). Due to the variable nature of tissue characteristics encountered during pCLE imaging, the conventional approach of pre-setting forces or focus metrics for either force or vision control is often impractical and inadequate. To address this, our strategy employs a blur metric called the CR score to assess the level of blur in pCLE images, enabling the attainment of clear and focused images. At the onset of a pCLE scan, the system autonomously determines the target CR score for vision control, in tandem with a real-time peak detection algorithm. Concurrently, force control is applied judiciously to prevent excessive force on the tissue, adjusting to ensure minimal force is applied, thus preserving image focus. This innovative approach facilitates seamless transitions between vision and force control, depending on the imaging conditions, thereby ensuring the acquisition of consistent pCLE images with minimal force. Our method marks a notable improvement over conventional PID force control techniques. By dynamically adjusting target forces and minimizing force application during operation, we not only enhance the precision and quality of pCLE imaging but also eliminate the dependency on manual pre-settings.

This paper presents the design and control of a fully handheld robot for robot-assisted microsurgery. The handheld robot incorporates a miniature 6-PUS parallel micromanipulator that can impose a remote center of motion (RCM) at the incision point of entry during microsurgery. An optimization framework is formulated to determine the geometric parameters of the micromanipulator. The optimization aims to minimize force applied on actuation modules by lateral load at the RCM. The optimization yields a base diameter of 16 mm, a top diameter of 12.6 mm, and a connecting link of 9.4 mm, which offers a cylindrical workspace 4-mm wide and 3-mm high with a 5-mm travel in linear actuation. An order of magnitude higher force capability is attained in the smaller form factor compared to the latest handheld micromanipulator. We built the fully handheld version of the microsurgical robot by incorporating embedded electronics and an EM tracker for sensing the 6-DOF pose of hand motion. The real-time control framework of the handheld robot is also presented, including motion filter for active tremor cancellation. As a result, the handheld robot can tolerate side loads up to 5.0 N for a lateral load applied at the RCM without significant degradation in control. Finally, the robot-aided operation with the active tremor cancellation shows a significant peak-force reduction compared to unaided operation during the task of maintaining contact force.