Friction-model-based estimation of interaction force of a surgical robot

This paper reports a method to estimate the interaction forces between the surgical robot instrument and the organ tissues. A previous estimation method uses the kinematical relationship of the surgical robot instrument to estimate the interaction force at the distant tip. It is experimentally found that there is non-ignorable estimation error due to some torque loss and the friction forces inside the instrument attributes to the torque loss. In this paper, a friction model is developed to more accurately estimate the interaction force considering the structure of the instrument. The friction model also reflects the effects of the tendon-driven mechanism inside the instrument on the estimation error. Experimental result shows that the estimation error can be reduced approximately 80% in single degree of freedom free motion compared to when the friction force model was not used.