Washout Control for Manual Operations

Abstract

Abstract-It is known that limitations of human accuracy in manual manipulation hinder the quality of work performed by human operators of manual control systems. Indeed, movements of operators are apt to cause undesirable vibrations in manual control systems. In this paper, we propose a new operator-support control scheme for suppressing harmful oscillatory motions in such systems without disturbing human operator's manipulation. The proposed scheme is based on the fact that steady-state blocking zeros of a feedback controller do not affect the steady-state control input. A finite-dimensional feedback controller with steady-state blocking zeros, called a washout controller in this paper, plays the central role in support for operator's manipulation. However, the dynamics of a manual control system may become different significantly from its initial model used for the design of an initial washout controller when it is applied to the manual control system. Such difference can result in poor performance of operator-support control. In order to improve it, an iterative procedure is presented for redesign of washout controllers based on closed-loop subspace identification. Closed-loop identification is performed to refine the model for the control design, and then a more sophisticated washout controller is obtained using the identified model. The effectiveness of the proposed scheme is demonstrated by an experiment on manual control of an inverted pendulum.

Washout control for inverted pendulum mobile robots with sensor drifts

“…Therefore, the design of feedback parameters 1 and 2 stabilizing the closed-loop system (23) can be cast into that of the state feedback gain¯stabilizing the closed-loop system (24).…”

“…Moreover, in [17]- [24], a control method for stabilizing equilibrium points of nonlinear dynamical systems without their exact information was discussed. In stabilization of the uncertain equilibrium point, the uncertainty of the equilibrium point is equivalent to the nonzero steady-state signals of the output of the systems.…”