Passivity Analysis And Design For Haptic Interfaces

Force sensation, the same as other sensations such as vision and hearing, is one of theimportant means of people to get information from outside, and it plays quite an importantrole in the development and application of virtual reality technology. In recent years, with thecontinuous development and progress of computer technology and robot technology, virtualreality technology, especially haptic interaction technology, gradually becomes a hot issue ofresearches at home and abroad and is given extensive attention by native and foreign expertsand scholars. Virtual reality technology is a lifelike virtual environment produced bycomputers. Through various sensor devices manipulators are involved in this virtualenvironment to achieve the interaction between manipulators and the virtual environment, andgive them a feeling of being personally on the scene.Haptic interaction system is composed of manipulators, haptic interface devices andvirtual environment. Haptic interface is the interface between manipulators and the virtualenvironment. It enables people to feel and manipulate the virtual or long-range environment.For the remote control of long-range environment, haptic interface is connected withlong-range manipulating devices through communication lines; for the interaction with virtualenvironment, haptic interface is directly connected with the virtual environment (produced bycomputers). Nowadays, haptic interface devices are widely used in many fields such asmedical training, microassembly, entertainments, education, industrial design, arts, trafficsafety, sports, flight simulation, remote surgery and virtual prototype.This essay, through in-depth analysis and induction, firstly examines the passivityconditions of haptic system which have been acquired by applying frequency domain liftingtechnique in previous literature, proves the problems during the process of induction and thelimitedness in frequency domain lifting technique itself, and verifies the conservativeness ofthe results achieved in this way with specific examples. For a specific virtual environmentmodel, the passivity conditions of this haptic interface vary with different sampling signalsand discretization methods of virtual environment, so the effects of different sampling signalinputs and different discretization methods of virtual environment on the haptic system arealso analyzed in this essay; besides, based on the real frequency quality of the samplingsystem, the passivity conditions in different situations are given, compared and analyzed.Furthermore, a simplified passivity condition and a controller index passivity design area of awider range are given based on approximation of some degrees. Moreover, the quality of haptic interface system—transparency—is taken into account in the comprehensive design ofthe system. An optimized result is achieved by involving transparency, together with passivityand the system’s bandwidth requirements, damping requirements, restrictions on samplingtime, in the design. Finally, the essay carries on a passivity design for a typical hapticinterface system—control loading system of the flight simulator by combining the twoconcepts of passivity and impedance.