TWO TUTORIAL EXAMPLES OF MULTIVARIABLE CONTROL SYSTEM DESIGN.

Two tutorial examples are presented which illustrate different methods of designing practical multivariable control systems using frequency-domain techniques. In the first case eigenvector alignment techniques are used to manipulate and shape the generalized Nyquist diagrams, while in the second case LQG theory in conjunction with singular value plots is employed. In both cases the designs are carried out on a modern computer-aided control-system design package.

ROBOT DYNAMIC CONTROL INSTABILITIES.

The authors demonstrate that a widely proposed method of robot dynamic control can be inherently unstable, due to an algebraic feedback loop condition causing an ill-posed feedback system. By focussing on the concept of ill-posedness a necessary and sufficient condition is derived for instability in robot manipulator systems which incorporate online acceleration cross-coupling control. Also demonstrated is a quasilinear multivariable control framework useful for assessing the robustness of this type of control when the instability condition is not obeyed.

CLADP: THE CAMBRIDGE LINEAR ANALYSIS AND DESIGN PROGRAMS.

An interactive software facility for designing multivariable control systems is described. The paper discusses the desirable characteristics of such a facility, the particular capabilities of CLADP and the numerical algorithms which lie behind them.

Tutorial on loop shaping using H-infinity robust stabilization

A new method for multivariable control was proposed in McFarlane and Glover (1988 CDC). This method involved shaping the open-loop singular values with pre and/or post compensators and then designing a controller to robustly stabilize a normalized coprime factorization of this weighted plant. The method has many attractive features including guaranteed loop shape and robust stability and performance. This talk will outline the rationale of this method and illustrate its use on a number of applications.