A method to estimate the axial force applied to a surgical instrument tip considering the effect of the gravity

Abstract

Force applied to the tip of a surgical instrument can be estimated by measuring reaction force to sensors attached to the drape plate and the trocar support. Effect of the gravity on the sensors attached to the instrument changes depending on the posture of the slave robot. It deteriorates the accuracy of the force estimation. This paper proposes a method to estimate the axial force applied to the instrument tip in consideration of the effect of the gravity. The effect of the gravity on the drape-plate sensor is analyzed. A calibration equation for the sensor is developed accounting the angle of pitch and yaw of the slave robot. It is possible to estimate the axial force with a L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> relative error of less than 7.79 % regardless of the changes in the gravity effect to the instrument, which depends on the slave posture.