Roboticslab based simulation for extraction of reaction force in multi DOF surgical robot dynamic system and analysis

Abstract

In modern robotic Surgery, the surgical systems are being involved with multiple degrees of freedom to facilitate dexterity and precise operation in human body. In previous studies, it has shown that, the perturbation observer of sliding mode control with sliding perturbation observer (SMCSPO) can estimate the reaction force acting on the instrument tip. The perturbation is defined as the combination of the uncertainties and nonlinear terms where the major uncertainties arise from the reaction force. However in presence of external dynamics, the vertical instrument inside the body has some effects during operation. Therefore the reaction force estimated by SPO will be a combination of actual reaction force and external disturbances. It is necessary for the surgeon to measure the disturbance effects on the instrument during operation for the sake of safety. This paper studies about dynamic disturbances acting on the instrument using SMCSPO algorithm. A three DOF robot has formed with surgical instrument in RoboticsLab environment. Simulation has shown that SPO of SMCSPO can estimate the actual reaction force quite correctly when the surgical robot is fixed. However, it shows that SPO does not have satisfactory results when the instrument carrying robot's joint are free to move. It has seen that the estimated perturbation of each joint of robot has no relation with each other. Therefore measuring disturbances of the robot joints can be calculated using forward kinematics laws.