Experimental comparative study of control architectures for haptic interfaces including communication delays

The aim of this paper is to present a comparative study of control algorithms for haptic interfaces and virtual environments subject to communication delays. It is well known that the presence of delays deteriorates the overall system performance. More precisely, delays introduce a feeling of viscosity in free motion and reduce the sense of stiffness in case of hard contacts. Six methods in their basic form (classic Proportional Derivative (PD), PD with local dissipation, PD with passivity observer, PD with passive set-point modulation, wave scattering transform and Smith predictor) are analyzed and compared, using a real-time experimental platform which enables tracking the impact of delays, from the point of view of position tracking error and transparency degree.