Sanjay Garg

Partitioning of centralized integrated flight/propulsion control design for decentralized implementation

The notion of partitioning a centralized controller into a decentralized, hierarchical structure suitable for integrated flight/propulsion control (IFPC) implementation is discussed. A systematic procedure is developed for determining partitioned airframe and engine subsystem controllers (subcontrollers), with the desired interconnection structure, that approximate the closed-loop performance and robustness characteristics of a given centralized controller. The procedure is demonstrated by application to IFPC design for a short take-off and vertical landing (STOVL) aircraft in the landing-approach-to-hover-transition flight phase. >

Integrated Flight/Propulsion Control Design for a STOVL Aircraft using H-Infinity Control Design Techniques

Results are presented from an application of H ? control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for a supersonic Short Take?Off and Vertical Landing (STOVL) fighter aircraft in transition flight. The emphasis is on formulating the H ? control design problem such that the resulting controller provides robustness to modelling uncertainties and model parameter variations with flight condition. Experience gained from a preliminary H ? based IFPC design study performed earlier is used as the basis to formulate the robust H ? control design problem and improve upon the previous design. Detailed evaluation results are presented for a reduced order controller obtained from the improved H ? control design showing that the control design meets the specified nominal performance objectives as well as provides stability robustness for variations in plant system dynamics with changes in aircraft trim speed within the transition flight envelope. A controller scheduling technique which accounts for changes in plant control effectiveness with variation in trim conditions is developed and off-design model performance results are presented with the scheduled controller.

A parameter optimization approach to controller partitioning for integrated flight/propulsion control application

A parameter optimization framework is presented to solve the problem of partitioning a centralized controller into a decentralized hierarchical structure suitable for integrated flight/propulsion control implementation. The controller partitioning problem is discussed and a cost function to be minimized is formulated, such that the resulting optimal partitioned subsystem controllers closely match the performance (including robustness) properties of the closed-loop system with the centralized controller while maintaining the desired controller partitioning structure. The cost function is written in terms of parameters in a state-space representation of the partitioned subcontrollers. Analytical expressions are obtained for the gradient of this cost function with respect to parameters and an optimization algorithm is developed using modern computer-aided control design and analysis software. The capabilities of the algorithm are demonstrated by application to partitioned integrated flight/propulsion control design for a modern fighter aircraft in the short approach to landing task. The partitioning optimization leads to reduced-order subcontrollers that match the closed-loop command tracking and decoupling performance achieved by a high-order centralized controller. >

Decentralized Hierarchical Partitioning of Centralized Integrated Controllers

A framework for a decentralized hierarchical controller partitioning structure is developed. This structure allows for the design of separate airframe and propulsion controllers which, when assembled, will meet the overall design criterion for the integrated airframe/propulsion system. An algorithm based on parameter optimization of the state-space representation for the subsystem controllers is described. The algorithm is currently being applied to an integrated flight propulsion control design example.