Kou Yamada

A State Space Design Method of Stable Filtered Inverse Systems and Its Application to H 2 Suboptimal Internal Model Control

Abstract The purpose of this paper is to present a new state-space design method of stable filtered inverse system for the strictly proper system with some right half plane invariant zeros without, solving the generalized Ricoati equation. We construct the preliminary filtered-inverse system by conventional method and divide the filtered inverse system into two subsystems. Then the problem is reduced to the problem for proper system. In addition we present an application of the stable filtered inverse system to H 2 suboptimal Internal Model Control.

Repetitive control of time-delay systems

To overcome time delay, three types of modified repetitive control systems are proposed: the state predictor approach, the finite spectrum assignment approach, and the spectral decomposition approach. It is shown that the combination of delay-free reduction by the state predictor and the frequency-domain approach can stabilize the system and yield small steady-state error with respect to both the reference command and the disturbance. The stability depends on the low-pass filter q(s). To release the restriction, q(s)-independent stabilization is proposed which uses the finite spectrum assignment. Furthermore, q(s)-free stabilization is proposed which uses an attenuator and spectral decomposition. Numerical examples are given.<<ETX>>

Robust internal model servo control with control input saturation

We propose a design method of anti-windup servo control based on internal model control structure by using the idea of internal perturbed model control. We consider the reason that the error offset appears in the internal model control with control input saturation. This condition is shown by the idea of absolute stability problem.

Application of suspension mechanisms for low powered robot tasks

Presents the manipulation methods of a low powered direct‐drive robot‐arm for heavy object manipulation using a suspension device. Considers manipulation of a suspended tool in the horizontal plane. Presents the algorithm of the hybrid position/force tracking scheme with respect to the dynamic behavior of suspended tools in the horizontal plane. To manipulate the suspended robot‐arm vertically, the hybrid position/force dynamic model has been developed by considering the gravity compensation of the spring balancer. In order to show the possible industrial applications chamfering operations have been carried out. Simulations and experiments demonstrate the feasibility of the proposed systems.

Robust stabilization for the plant with varying number of unstable poles and low sensitivity characteristics

We consider the robust stability condition for single-input single-output continuous time invariant systems with varying number of unstable poles. First, we define a class of uncertainty to be considered. The necessary and sufficient robust stability condition for the system with such class of uncertainty is presented. The relation between the plant and the nominal plant that is included in such class of uncertainty, is clarified. By using this relation, we show the necessary and sufficient robust stability condition for the system with varying number of right half plane poles. In this framework, we can construct the control system with low sensitivity characteristics and robustly stable.

A new algorithm for finite spectrum assignment of multivariable systems with time delays

This paper presents a new algorithm for computing the feedback matrix of finite spectrum assignment of multivariable systems with time-delays under spectral controllability. The key is the Smith-form of the controllability matrix. That yields a weakly R-controllable system. The feedback matrix over rational functions in delay operator for a weakly R-controllable system is transformed to the feasible one with polynomials and finite Laplace transforms.

Inner-outer factorization for the discrete-time strictly proper systems

We are concerned with a method of inner-outer factorization for a discrete-time strictly proper system. A method of inner-outer factorization for the discrete-time strictly proper system is proposed. By using this method, we can obtain the inner-outer factorization by solving a Riccati equation for the bi-proper system.

Coefficient Assignment Approach to Two Disk Mixed Sensitivity Problem of Time-Delay Systems

Abstract This paper presents a control design methodology based on the coeffiocient assignment type techniques without operator-type Riccati equations for two disk mixed sensitivity problem of time delay systems. The key idea is that the sensitivity function and the complementary one are decomposed to the product of two functions. One of them is chosen to satisfy the specifications by the internal model and configuration of poles. The problem is solved by the gain adjustment of the other elements on the basis of coefficient assignment. The systematic design procedure is presented.

Unification of modeling and control for desired control performances

The purpose of this paper is to unify the modeling and the control for desired control performances. Model-independent control performances specification is presented on the basis of the parameterization of the controller. A closed-loop modeling method by using a nonlinear element is proposed, that assures robust stability and preassigned low sensitivity.

Mixed sensitivity problem of delay-free systems and time-delay systems

This paper presents a control design methodology based on pole assignment type techniques for delay-free and time-delay systems. The standard H/sub /spl infin// solution to the mixed sensitivity problem for time-delay systems requires complicated calculations because Riccati equation is of the operator-type. Here we begin H/sub 2/ approach for delay-free systems and translate it to pole assignment approach. Pole assignment approach is expanded to time-delay systems as finite spectrum assignment. The controller design for time delay systems can be done without operator-type Riccati equations by only calculation of finite spectrum assignment and Bode diagrams.