Research on Modeling the Output Behavior of Cable Drive Surgical Instruments

In robot-assisted minimally invasive surgery, surgeons operate by controlling surgical instruments inserted into the abdominal cavity. These instruments are generally elongated and narrow. To meet surgical requirements, wire transmission (referred to as "cable-driven" transmission) is commonly used. Cable-driven systems are favored for their small size and light weight. However, due to the complex path of cable transmission within the surgical instruments, the transmission of displacement and force exhibits nonlinear characteristics such as hysteresis effects. Additionally, the coupling effects between different degrees of freedom of the surgical instruments make precise control a challenging research area. This paper improves the displacement/force transmission model of the forceps' closed-loop cable-driven structure and utilizes a feedforward compensation strategy for displacement output compensation. Work on predicting gripping force was also conducted. Through experiments, we have verified that this model can effectively reduce the hysteresis errors in the motion of the cable-driven mechanism, accurately predict the gripping force exerted by the forceps, thereby enhancing the positional accuracy of the forceps and improving the accuracy of gripping force estimation in sensorless scenarios.