Estimating Tool–Tissue Forces Using a 3-Degree-of-Freedom Robotic Surgical Tool

Abstract

Robot-assisted minimally invasive surgery (MIS) has gained popularity due to its high dexterity and reduced invasiveness to the patient; however, due to the loss of direct touch of the surgical site, surgeons may be prone to exert larger forces and cause tissue damage. To quantify tool-tissue interaction forces, researchers have tried to attach different kinds of sensors on the surgical tools. This sensor attachment generally makes the tools bulky and/or unduly expensive and may hinder the normal function of the tools; it is also unlikely that these sensors can survive harsh sterilization processes. This paper investigates an alternative method by estimating tool-tissue interaction forces using driving motors' current, and validates this sensorless force estimation method on a 3-degree-offreedom (DOF) robotic surgical grasper prototype. The results show that the performance of this method is acceptable with regard to latency and accuracy. With this tool-tissue interaction force estimation method, it is possible to implement force feedback on existing robotic surgical systems without any sensors. This may allow a haptic surgical robot which is compatible with existing sterilization methods and surgical procedures, so that the surgeon can obtain tool-tissue interaction forces in real time, thereby increasing surgical efficiency and safety.

A sensorless force-feedback system for robot-assisted laparoscopic surgery

“…Burying gum or plastic lumps into tissue is a common method to simulate tumors [23,24], a polymeric cylinder (U7 mm  3.5 mm and stiffness about 3 GPa) was embedded along the edge of a freshly harvested porcine liver to imitate the existence of an artificial tumor, as shown in Figure 9. There was no visual cue to tell the location of the tumor, and our preliminary test showed that the stiffness of the tumor location was about two times higher than that of other locations [21], which is a typical case for the stiffness difference between healthy and cancerous tissue [25,26].…”

“…Figure 1(b) shows a picture of the grasper prototype. Since each of its joints is driven independently by only one motor, the external force at the tool tip on each DOF can be estimated by the corresponding motor's driving current, which is acquired from the motor driver at 2kHz and processed with a low-pass filter [21]. Equation (1) shows the linear relation between a joint's external force and its driving motor's current.…”

Reference tool kinematics-kinetics and tissue surface strain data during fundamental surgical acts

“…Characterizing the interaction between soft tissue and surgical tools is a fundamental part of realistic surgical simulations 1 , accurate robot-assisted surgery 2,3 , and the design of autonomous surgical systems 4 . The resultant force feedback, or haptics, used in simulations and surgeries can be improved with load data from commonly performed surgical techniques.…”

Design of a tether‐driven minimally invasive robotic surgical tool with decoupled degree‐of‐freedom wrist

“…A decoupled wrist could provide a less complicated control strategy for controlling the tool since each drive motor individually controls one DoF . Such a wrist with decoupled DoF enables sensor‐less force estimation for haptic feedback by direct measurement of drive tether tension . From the surgical safety point of view, Kuo et al have pointed out that decoupled motion for mechanisms of a surgical robot is preferred.…”