Friction compensation in energy-based bilateral telemanipulation

In bilateral telemanipulation algorithms based on time-domain passivity, internal friction in the devices poses an additional energy drain. Based on a model of the friction, the dissipated energy can be estimated and reclaimed inside the energy balance of the control algorithm. As long as the estimate is conservative, passivity of the entire system is maintained. In this paper we consider two types of friction and discuss the influence of two types of measurement noise. Without noise compensation the dissipated energy is largely overestimated. A compensation method based on the probability density of the noise is proposed. This leads to an energy estimate which is always conservative even in the presence of measurement noise and does not require additional filtering. Simulation results are provided that show the increase in obtained transparency when this energy compensation technique is applied.