Representation of Chiseling Operation Using Force Display with Two Degree-of-freedom Admittance Control

Abstract

This study addressed an advanced force display control system for a virtual surgical training simulator. In oral and orthopedics surgeries, a surgeon uses a chisel and a mallet for chiseling or cutting hard tissues such as bones and teeth. In order to construct the virtual reality training simulator for the chiseling and the cutting operations, it is necessary that the force display device as a human-machine interface has high stiffness and high responsiveness against the impact forces generated by pounding the chisel with the mallet. Therefore, we develop the force display device with ball-screw for obtain the high realistic sensation, and 2 degree-of-freedom (DOF) admittance control is applied for the moving parts of the force display device to react instantaneously. In the analysis of the force display control system using 2 DOF admittance control, the responsiveness can be enhanced by increasing the gain on high-frequency region in the feedback controller. However, to increase the gain on the high-frequency region, the force display device can be vibrated by the excitation of the sensor noise and the vibrational mode in this device. Therefore, we apply PD control using the incomplete derivative term to reduce the excessive high gain of high-frequency region in the feedback controller. And, to obtain the chiseling operation with high realistic sensation, the virtual model in the feedforward controller is applied the spring-mass-damper system with movement of supported object. The efficacy of the proposed device and control system is verified by creating the virtual experiences to operate the chisel.