Showing papers in "International Journal of Applied Mathematics and Computer Science in 1998"

The Implicit Daisy-Chaining Property of Constrained Predictive Control

Abstract: Systems with redundant control actuators are sometimes arranged so that a new actuator comes into play if the one normally used becomes saturated. We call this 'daisy-chaining'. Such an arrangement also provides a degree of fault- tolerance against actuator failures. This paper points out that a similar property is implicit in constrained predictive control, as it is usually formulated. Predictive control therefore has a degree of implicit fault-tolerance. In order to obtain this property the predictive control must have explicit constraints on the input levels (actuator positions) and the usual disturbance model, which results in integral action arising in the controller. The general considerations dealt with in the paper are illustrated by a simplied example, based on the liquefaction of natural gas.

Adaptive compensators for perturbed positive real infinite-dimensional systems

Abstract: The aim of this investigation is to construct an adaptive observer and an adaptive compensator for a class of infinitedimensional plants having a known exogenous input and a structured perturbation with an unknown constant parameter, such as the case of static output feedback with an unknown gain. The adaptive observer uses the nominal dynamics of the unperturbed plant and an adaptation law based on the Lyapunov redesign method. We obtain conditions on the system to ensure uniform boundedness of the estimator dynamics and the parameter estimates, and the convergence of the estimator error. For the case of a known periodic exogenous input we design an adaptive compensator which forces the system to converge to a unique periodic solution. We illustrate our approach with a delay example and a diffusion example for which we obtain convincing numerical results.

An extension of the Cayley-Hamilton theorem for a standard pair of block matrices

Abstract: The Cayley-Hamilton theorem is extended for a standard pair of matrices partitioned into blocks that commute in pairs. Victoria's theorem (1982) is a particular case for E=I of the extended Cayley-Hamilton theorem.

Active noise and vibration control

Abstract: 3. Importance 4. Alternatives 5. Maturity and Risk 1. Maturity of Technology 1. Noise Cancellation Headsets (Commercial) 2. Active Muffler or Silencer (prototype) 3. Noise Reduction in Ducts (Commercial) 4. Vehicles (Developmental and Commercial) 5. Turboprop Aircraft (Developmental) 6. Transformers (Commercial) 7. Noise Reduction in Engines (Commercial) 8. Precision Machining (Developmental and Commercial) 9. Active Strut Member (Developmental) 10. Active Suspension (Developmental and Commercial) 11. Airframe Vibration Control (Developmental) 12. Flutter Control (Developmental)

The use of sliding modes to simplify the backstepping control method

Abstract: We propose a simple sliding mode based controller for nonlinear systems with mismatched uncertainties. The design methodology is similar to backstepping and multiple surface control method but with the inclusion of sliding mode filters for estimating the derivatives of the plant output.