Abstract
In this paper, a new set-point control method for a musculoskeletal system by combining a feedback control including a large time-delay with a muscular internal force feedforward control is proposed to accomplish a robust and rapid positioning with relatively low muscular contraction forces. It is known that feedback control under the existence of a large time-delay owns a drawback that there is a serious trade-off between a control performance and its stability. On the other hand, the muscular internal force feedforward control, which we have already proposed, also owns a drawback that it requires a large muscular contraction forces to make a good performance in a wide range. A simple linear combination of these two controllers makes it possible to improve the control performance and to complement each drawbacks each other. Firstly a two-link six-muscle arm model is given as a specific musculoskeletal system treated in this study. Secondly the new control law, which is composed of the feedback control signal including the time-delay and the internal force feedforward control signal, is constructed by only using a kinematic information of the musculoskeletal arm model. Next, a stability of the proposed method is discussed using Lyapunov-Razumikhin method. After that, results of several numerical simulations are shown to demonstrate several advantages of the proposed method.
