Accession Number : ADA303680

Title :   A Method for Exploiting Redundancy to Accommodate Actuator Limits in Multivariable Systems.

Descriptive Note : Technical memo.,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Litt, Jonathan ; Roulette, Greg

PDF Url : ADA303680

Report Date : DEC 1995

Pagination or Media Count : 24

Abstract : This paper introduces a new method for accommodating actuator saturation in a multivariable system with actuator redundancy. Actuator saturation can cause significant deterioration in control system performance because unmet demand may result in sluggish transients and oscillations in response to setpoint changes. To help compensate for this problem, a technique has been developed which takes advantage of redundancy in multivariable systems to redistribute the unmet control demand over the remaining useful effectors. This method is not a redesign procedure, rather it modifies commands to the unlimited effectors to compensate for those which are limited, thereby exploiting the built.in redundancy. The original commands are modified by the increments due to unmet demand, but when a saturated effector comes off its limit, the incremental commands disappear and the original unmodified controller remains intact. This scheme provides a smooth transition between saturated and unsaturated modes as it divides up the unmet requirement over any available actuators. This way, if there is sufficiently redundant control authority, performance can be maintained. (AN)

Descriptors :   *SYSTEMS ANALYSIS, MATHEMATICAL MODELS, ALGORITHMS, STABILITY, CONTROL SYSTEMS, OPTIMIZATION, REAL TIME, DISTRIBUTION, MULTIVARIATE ANALYSIS, MATRICES(MATHEMATICS), INPUT OUTPUT PROCESSING, ERROR ANALYSIS, FEEDBACK, ACTUATORS, CONTROL THEORY, REDUNDANCY, CLOSED LOOP SYSTEMS.

Subject Categories : Operations Research

Distribution Statement : APPROVED FOR PUBLIC RELEASE