A Comparison of Multivariable Control Design Techniques for a Turbofan Engine Control

Stephen R. Watts, Sanjay Garg
1995 Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; IGTI Scholar Award   unpublished
areavailable for themathematicalformulationand sample applica-This paper compares twopreviously published design proc.edums tions ofthesetwodesign techniques with specific application profor twodifferent multivariable control design techniques forap-oedures (Athans, 1986andGarg, 1993). Bothofthesedesign techphcation to alinear engine modelof a jet engine.The twomultivari-niques have been reviewed when applied to aircraft flight control ablecon_ol design techniquescomparedwere theLinear
more » ... systems, thispaperreviews the design techniques and application Gaussian with Loop TransferRecovery (LQG/LTR)and the H-In-procedures when applied to the turbofan engine control problem. finity(Hoo)synthesis.Thetwocontroldesigntechniqueswereused The work described herein compares the resulting overall system with specific previously publisheddesign procedures to synthesize performance and implementationissues for the two multivariable controls which wouldprovide equivalent closed loop frequency re-control designs and is not intended to be a detailed review of the sponsefor the primary control loops while assuring adequate loop design steps for the two designprocedures, nor does it suggest any de-coupling.The resultingcontrollerswere then reducedin order to possible variationsto these designprocedures. Rather,ithighlights minimize the programmingand data storagerequirementsfor a typ-the design procedures andprovidesall Pertinentreferencesrequired ical implementation.The reduced order linear controllers designed torecreate the analysis. by each method were combined with the linear model of an ad- The discussion is organized in the following manner.The linear vancedturbofan engine and the system performancewas evaluated engine model and actuator model that are used for the controller for the continuouslinear system.Included in the performanceanal-synthesis will be defined.The selected control mode for the controlysis are the resulting frequency and transient responses as well as ler synthesis will be identified. The two controller synthesis techactuatorusage and rate capabilityforeach design method.The con-rdqueswill be brieflyoutlined.The method for reducingthe cona'oltrois were also analyzed for robustnesswith respect to structured ler order will then be discussed, and the computational uncertaintiesin the unmodeled system dynamics. The two controls requirements of the reduced order controllers will be reviewed. were then compared for performance capability and hardware ira-These controllers will then be exercisedtransiently and system perplementation issues, formance will be compared. The issue of robustness for structured uncertainties in the unmodeled system dynamics will then be ex-
doi:10.1115/95-gt-258 fatcat:ovw4xldyprdxhlkzh5ejizbymq