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Transparency enhancement of haptic systems based on compensation of device dynamics

Tajaddodianfar, F ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1115/IMECE2009-10921
  3. Abstract:
  4. Transparency is a measure of performance in haptic devices. In order to improve transparency and reduce the difference between the impedance transmitted to the user and the target impedance it is necessary to compensate for the dynamics of the haptic device. Due to stability reasons improvement of transparency is limited. Passivity as a stability criterion has been used widely in design and analysis of haptic devices, Since passivity is a conservative criterion, it acts as an obstacle in improving transparency of the haptic interfaces. In this paper instead of passivity, robust stability of the interaction is studied in the presence of parametric uncertainties due to variations in user hand dynamics. Two design methods are implemented and their performance and stability are evaluated. The first strategy is based on H-infinity controller synthesis technique applied to a generalized control plant which involves the target impedance as a performance weighting function. Human hand dynamics is not present in the controller synthesis stage, because it does not affect the robot impedance and consequently has no effect on performance. The obtained results depend on the weighting function parameters. In the second approach a controller is designed based on the inverse model of the device. The advantage of the latter method is that it can reduce the device impedance in a wide frequency range and results in non-passive robot impedance which is much more transparent than the impedances obtained by passivity based methods. Simulation results confirm the effectiveness of the proposed methods
  5. Keywords:
  6. Dynamics ; Haptic interfaces ; Mechanical engineering ; Passivation ; Stability criteria ; System stability ; Transparency ; A-stability ; Controller synthesis ; Design and analysis ; Design method ; Generalized control plant ; H-infinity control ; H-infinity controller ; Haptic devices ; Haptic systems ; Haptics ; Human hands ; Impedance control ; Inverse models ; Measure of performance ; Parametric uncertainties ; Passive robot ; Passivity based ; Robust stability ; Simulation result ; Weighting functions ; Wide frequency range ; Controllers
  7. Source: ASME International Mechanical Engineering Congress and Exposition, Proceedings, 13 November 2009 through 19 November 2009 ; Volume 10, Issue PART A , 2010 , Pages 103-110 ; 9780791843833 (ISBN)
  8. URL: http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1641622