Optimizing transparency of haptic device through velocity estimation

In this paper, the conception and optimization of a new dual-stage haptic device is described. A particular attention is given to the choice of encoder. Compact, consumer grade, but low resolution encoders are particularly used. An issue arising from this particularity is the deterioration of the velocity measurement when Finite Difference method is used. Moreover, when encoders resolution decreases, velocity estimation becomes noisy. From haptic point of view, this noise destroys the realism of the rendered force. To deal with this problem, numerous methods have been proposed to offer a noiseless estimation. Here, advanced methods such as Low-Pass Filter, First Order Adaptive Windowing, Kalman Filter are proposed. Performances of theses methods are verified and experimentally compared to a conventional finite difference method. Here, we show that Kalman filter and First Order Adaptive Windowing offers a good trade-off between estimation and noise rejection.