Force control of laparoscopy grasper using antagonistic shape memory alloy

Abstract

Using special tools at the end-effectors of Minimally Invasive Surgery (MIS) robots has an important role in building a simple and well controlled system that increases dexterity of surgeons. Having local, lightweight and powerful actuators at end-effectors could help to simplified wrist design and saving the number of degrees-of-freedom (DOFs). Shape Memory Alloy (SMA) actuators considered as good candidates and presented significant behaviors in producing the force needed for gripping. In order to have force and tactile information of gripper, local sensors are needed to give force feedback which helps to have control over wire tension and prevent exceeding force causing tissue damages. In this paper a novel design of forceps that uses antagonistic SMA actuators is presented. This configuration helps to increase force and speed and eliminates bias spring used in similar works. Moreover, this antagonistic design makes it possible to provide sensors needed for force control and place them at the back part of the forceps instead of attaching them to jaws which will result in a smaller forceps design. To control the exerted force, a force control method is also presented using the feedback obtained through the sensors. This enhanced design seems to address some of the existing shortcomings of similar models and remove them effectively.