Stable Multirate Control Algorithm for Haptic Dental Training System

This paper proposes a multirate control algorithm to guarantee the stability of haptic dental training system. In terms of a high-frequency force interpolating model, a multirate system with two levels up-sampling is introduced. The first level up-sampling achieves the haptic rendering with 1K Hz and the second level achieves the interpolating algorithm with 10K Hz or higher. Due to the slow velocity of dental training system, the complex virtual tooth surface can be regarded as a series of consecutive virtual tangent planes, in which the interpolating algorithm is designed with virtual wall model. Theoretical analysis proves that the multirate control algorithm can enlarge the range of virtual stiffness and improve the stability. Numerical and experimental results of a three degree-of-freedom haptic device demonstrate the effectiveness of the proposed method.