Dynamic displacement sensing, system identification, and control of a speaker-based tendon vibrator via accelerometers

In this paper, we develop a speaker-based tendon vibrator capable of applying vibrations with sustained amplitudes and desired time-frequency profiles to be used in inducing kinesthetic illusions. For modeling and control of the tendon vibrator, we propose and experimentally validate a method for real-time dynamic displacement sensing based on accelerometers. We tested the accuracy of displacement measurements by comparing the movements of the vibrator measured with differential accelerometers to those measured by a high resolution optical encoder. We completed frequency domain system identification of the vibrator and obtained a parametric transfer function model via displacements sensed by the encoder and by analog and digital integration. We show that within the frequency range of interest 20 -100 Hz, analog and digital integration methods were successful in capturing an accurate model of the vibrator. Under feedforward control, developed tendon vibrator is able to generate sustained 2-mm peak-to-peak vibrations throughout the frequency range of interest.