Design of Magnetic Brake with Adjustable Braking Force and Its Application to Haptic Device

Abstract

Along with the development of robotic systems, the robot technology began to be applied to surgery. Robotic surgery brings faster recovery of minimally invasive surgery, improvement of the accuracy, reduction of side effects, reduction of radiation exposure and reduced fatigue of operation. Recently, automatic surgical robot system is popular. This system is controlled by microprocessor and motor, and thus a small failure of such components often exists. However, even a small mistake in surgical procedures could cause a big damage and side effects to patient. In light of this fact, this thesis suggests design of passive surgical robot system with adjustable braking forces. When the passive surgical robot system is employed for surgical operation, using a brake system is indispensable to avoid damaging important organs. Specifically, this thesis investigates a magnetic brake as the candidate of brake for passive surgical robot system. However, the magnetic brake is being used in an on-off fashion and thus the range of adjustable braking force is so limited. Therefore, this thesis proposes a multi-layered magnetic brake with adjustable braking forces. For this, a mathematical model of normal magnetic brake on the shelf is introduced. Through simulation and the experimental study, its limitation is found. Based on this result, mathematical modeling of a novel multi-layered magnetic brake is performed and its characteristic is analyzed through simulation and experiment. Lastly, this multi-layered magnetic brake is applied to a 2DOF haptic system. The effectiveness of the multi-layered magnetic brake is tested through control of braking force of the 2DOF haptic system.