Fast Estimation of Environment's Stiffness for Bilateral Control Systems with Communication Delay

Communication delay between a master and a slave robot destabilizes a bilateral control system. Recent researches showed that an adaptive controller that dynamically determines the master's controller gain according to the stiffness of the contact object is effective in improving stability. As the stability depends on the convergence speed of the estimated stiffness, this paper proposes an algorithm that quickly estimates the stiffness. A polynomial interpolation and a Schmitt trigger are utilized for the estimation. The validity of the algorithm is verified by simulations and experiments. The convergence speed of the position and the force is improved by the proposed algorithm.