Transparency measurement of telepresence systems

Abstract

After Stability, transparency is a major goal when designing haptic telepresence schemes. Ideal transparency, where the user feels direct haptic interaction with the remote environment, becomes affected by each of the components of the teleoperation system. In an ideal scenario, the energy observed at the master side is straightforwardly conveyed to the slave side. Conversely, realistic scenarios include sources of energy leaks, such as time delays and discretization blocs, which, if stability is to be preserved, they will normally have a lossy passive nature, which therefore lowers transparency. Only a few studies on how to evaluate transparency quantitatively are reported in the literature. This work investigates and extends two methods which aim at outputting a transparency coefficient: an analytical model-based method which uses Yokokohji's Indexes of Transparency [1], and an empirical approach based on the Z width concept [2], which allows to measure transparency without the need of precise knowledge of the system. The methods are validated using a velocity-force haptic telepresence system testing for different control parameters and different time delays in channel. © 2008 Springer-Verlag Berlin Heidelberg.