Motion modelling and error compensation of a cable-driven continuum robot for applications to minimally invasive surgery

Background The continuum robot is widely used in minimally invasive surgery (MIS) because of its flexibility, dexterity and safety. However, because of the friction in the transmission system, backlash, and shape error from nominal kinematics, the tracking accuracy of the continuum robot is low, which may damage the tissues and organs during surgery. A novel error compensation method is presented to improve control. Methods Considering the nonlinear friction and coupling effects, the static model of a robot is derived based on the principle of virtual work. A modified Capstan equation including bending rigidity and nonlinear friction is established to analyze the transmission characteristics of a cable-pulley system. Results The results of the experiments conducted with a continuum robot indicate the validity of the proposed compensation method. Conclusions The established model and the proposed compensation method can be used for the cable-driven continuum robot to guarantee safety and stability in MIS.