Abstract
In this paper, a parallel control system for continuous architecture formed by bimorph piezoelectric actuators has been developed and verified. Finite Element Method (FEM) is adopted as the control scheme for it is capable of expressing the circumstances of whole system by stiffness equations only. Conventional control system has necessity to change state equations slightly, depending on shape of the system or quantity of the linked members. Although FEM is mainly a computational tool for analyzing structures, fluids, etc., the capability of expressing the whole continuous system can be applied to parallel control schemes, and may be practical if the computational time is reduced to real-time use. An inverse theory, which is simplified by using the linearity of voltage distribution in bimorph piezoelectric actuators, is applied for calculating control voltage of the actuators. The algorithm using this theory consumes less computational memories, and runs faster than the numerical schemes using generalized inverse matrices. This paper seeks the reduction of number of elements and thus the computational time, by implementing noncompatible four-node element to the FEM control program. The finite element allows in-plane bending mode by considering noncompatible mode in shape functions, and can obtain practical solutions by minimum number of elements. By examining the experiments on static displacement control of connected piezoelectric actuators, the validity of the FEM parallel control system has been confirmed.