A modular force-controlled robotic instrument for minimally invasive surgery - efficacy for being used in autonomous grasping against a variable pull force.

BACKGROUND: Many deficiencies of minimally invasive robotic surgery systems can be eliminated by using automated laparoscopic tools with force measurement and control capability. METHOD: A fully modular, automated laparoscopic instrument with a proximal force sensory system was designed and fabricated. The efficacy of the instrument was evaluated experimentally when functioning in an autonomous force-controlled grasping scheme. RESULTS: The designed instrument was shown to work easily with standard laparoscopic tools, with the whole distal part detachable for autoclave sterilization. The root mean squared error (RMSE) of the actual pinch force from the target ramp was 0.318 N; it was 0.402 N for a sinusoidal pull force, which dropped by 21% using a static friction compensation. A secure grasping condition was achieved, in spite of this error, by applying a sufficiently large margin from the slip boundary. CONCLUSIONS: With a simple and practical design, the instrument enjoys affordability, versatility and autoclave sterilizability for clinical usage, with an acceptable performance for being used in an auto-grasping control scheme. Copyright © 2016 John Wiley & Sons, Ltd.