Stability and performance of haptic interface with active/passive actuators

Abstract

Haptic technology is now maturing and coming out of research laboratories and into real products and applications from nuclear teleoperation to today``s impressive nanomanipulator. A haptic interface conveys a kinesthetic sense of presence to a human operator interacting with a computer-generated environment. That is to say, a haptic interface is a human-machine interaction system, which lets the user touch, feel and manipulate virtual environments via so-called haptic devices. They incorporate actuators for force or tactile feedback to the user. The final goal of haptic interaction is achieving realism, that is to say, giving a transparent sensation to the user for physical properties of virtual environments. Key issue for achieving this transparency undoubtedly is how to improve the stability without degrading the haptic performance. This thesis is, therefore, directly dedicated to the stability and performance issues connected actuators essential to haptic interaction. Stability and performance are two wings of haptic interface. In other words, there is tradeoff between stability and performance. For example, increasing device damping in order to obtain stable operation, however, the cost of this stability is degradation of the force perception. A number of researches have concentrated issues of stability and performance of the haptic interface. They were, however, mainly focused on its control rather than just the hardware itself such as actuators. This thesis first reviews three different realizations of haptic interfaces: with active actuators, with passive actuators, and with active/passive actuators, and then discusses the stability and performance of each haptic interface. Next, a hybrid haptic interface controllable damping with active/passive actuators is proposed and as an available implementation, a hybrid haptic interface with controllable MR brake and motor is introduced. Even though the MR brake has its advantage of control various damping or fr...