Active Vibration Suppression via LQG/LTR; Analytic and Experimental Results for the PACOSS Dynamic Test Article
Report Number: WL-TR-91-3078 Volume I, p. CAA-1 thru CAA-22
Author(s): Gehling, Russell N.
Corporate Author(s): Martin Marietta Astronautics Group
Laboratory: Wright Laboratory
Date of Publication: 1991-08
Pages: 22
Contract: Laboratory Research - No Contract
DoD Project: 2401
DoD Task: 2401-04
Identifier: This paper is part of a conference proceedings. See ADA241311
Abstract:
Future large space systems (LSS) will possess high modal density at low frequencies, and mission performance requirements will necessitate control bandwidths encompassing these modal frequencies. This situation has potential for adverse controls/structure interaction (CSI) detrimental to system performance. The Passive and Active Control of Space Structures (PACOSS) program has investigated the design, analysis, and verification of passive and active damping strategies applied to LSS. This paper discusses the results of an experiment in which a Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) design technique was applied to the PACOSS Dynamic Test Article (OTA) for the purpose of high authority vibration suppression. In general, the LQG/LTR control demonstrated high sensitivity to design model accuracy. Actual performance was significantly less than predicted, even though the control design utilized an accurate test-verified model. The results of this experiment indicate that analytic LSS models which are quite accurate by structural dynamics standards may be insufficient for use as design models in modern control algorithms. However, passive damping designed into LSS flexible modes will simplify the active control design and implementation in terms of sensor/actuator requirements, design model order, real time computing requirements, and overall system robustness.
Author(s): Gehling, Russell N.
Corporate Author(s): Martin Marietta Astronautics Group
Laboratory: Wright Laboratory
Date of Publication: 1991-08
Pages: 22
Contract: Laboratory Research - No Contract
DoD Project: 2401
DoD Task: 2401-04
Identifier: This paper is part of a conference proceedings. See ADA241311
Abstract:
Future large space systems (LSS) will possess high modal density at low frequencies, and mission performance requirements will necessitate control bandwidths encompassing these modal frequencies. This situation has potential for adverse controls/structure interaction (CSI) detrimental to system performance. The Passive and Active Control of Space Structures (PACOSS) program has investigated the design, analysis, and verification of passive and active damping strategies applied to LSS. This paper discusses the results of an experiment in which a Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) design technique was applied to the PACOSS Dynamic Test Article (OTA) for the purpose of high authority vibration suppression. In general, the LQG/LTR control demonstrated high sensitivity to design model accuracy. Actual performance was significantly less than predicted, even though the control design utilized an accurate test-verified model. The results of this experiment indicate that analytic LSS models which are quite accurate by structural dynamics standards may be insufficient for use as design models in modern control algorithms. However, passive damping designed into LSS flexible modes will simplify the active control design and implementation in terms of sensor/actuator requirements, design model order, real time computing requirements, and overall system robustness.