Propulsion Controls, 1979

The state of the art of multivariable engine control is examined in order to determine future needs and problem areas and to establish the appropriate roles of government, industries, and universities in addressing these problems

Alternatives for Jet Engine Control. Volume 1: Modelling and Control Design with Jet Engine Data

This document compiles a comprehensive list of publications supported by, or related to, National Aeronautics and Space Administration Grant NSG-3048, entitled "Alternatives for Jet Engine Control". Dr. Kurt Seldner was the original Technical Officer for the grant, at Lewis Research Center. Dr. Bruce Lehtinen was the final Technical Officer. At the University of Notre Dame, Drs. Michael K. Sain and R. Jeffrey Leake were the original Project Directors, with Dr. Sain becoming the final Project Director. Publications cover work over a ten-year period. The Final Report is divided into two parts. Volume i, "Modelling and Control Design with Jet Engine Data", follows in this report. Volume 2, "Modelling and Control Design with Tensors", has been bound separately

Modelling and Control of Aircraft Gas Turbine Engines

In this thesis the main theme is to demonstrate the potential performance improvements of gas turbine engines that are brought about by using multivariable control systems. Particular emphasis is on designing such control systems using the well-established engine thermodynamic models since these models are considered as the true representations of engine thermodynamic process and enable engine variable geometry features to be easily incorporated and their effects studied

A scientometric analysis and critical review of gas turbine aero-engines control: From Whittle engine to more-electric propulsion

The gas turbine aero-engine control systems over the past eight decades have been thoroughly investigated. This review purposes are to present a comprehensive reference for aero-engine control design and development based on a systematic scientometric analysis and to categorize different methods, algorithms, and approaches taken into account to improve the performance and operability of aircraft engines from the first days to present to enable this challenging technology to be adopted by aero-engine manufacturers. Initially, the benefits of the control systems are restated in terms of improved engine efficiency, reduced carbon dioxide emissions, and improved fuel economy. This is followed by a historical coverage of the proposed concepts dating back to 1936. A comprehensive scientometric analysis is then presented to introduce the main milestones in aero-engines control. Possible control strategies and concepts are classified into four distinct phases, including Single input- single output control algorithms, MIN-MAX or Cascade control algorithms, advanced control algorithms, More-electric and electronic control algorithms and critically reviewed. The advantages and disadvantages of milestones are discussed to cover all practical aspects of the review to enable the researchers to identify the current challenges in aircraft engine control systems

Multivariable PID control with application to gas turbine engines.

To meet increasing and often conflicting demands on performance, stability, fuel consumption and functionality, modem jet engines are becoming increasingly complex. Improved compressor performance is a major factor in this development process. Optimum compressor efficiency is achieved in operating regions close to flow instability. Surveying basic concepts and control methods of compressor instabilities, an overview of the fundamentals of surge and rotating stall is presented. To maximise the potential of an aero gas turbine compression system, it is proposed to use more advanced control strategies, such as multi variable control. Multivariable control may offer the prospect of lower safety margin requirements leading to greater compressor efficiency. Alternatively, it may result in more agility in combat through improved engine responses and prolonged engine life. A multivariable control technique is proposed and tested on a Rolls-Royce three-spool high bypass ratio turbofan engine. Since elements of the 2x2 system can be represented by linear third order models, a muItivariable PID controller will be sufficient provided the design requirements are not too rigorous. To have a simple and efficient design, a systematic decentralised PI (PID) control design strategy is developed. Decoupling a given 2x2 process by a stable decoupler, the elements of the resulting diagonal matrix are approximated by first (second) order plus dead time processes using the proposed model reduction techniques. Then, SISO controllers are designed for each element using the developed tuning formulae. Any practical design method should be simple, easy to apply, flexible, generic or extendable, and applicable to complex control schemes to fulfil more demanding control requirements. It will be advantageous if the design algorithm can also directly address the design requirements, be repeatable for any control objective, constraint and category of processes, have a design parameter, and can consider any number of objectives and constraints. Formulating the PI (PID) control design problem as an optimisation problem, a non-dimensional tuning (NDT) method satisfying the above-mentioned design properties is presented. For a given first (second) order plus dead time process, the NOT method is used in conjunction with either a single-objective or a multi-objective optimisation approach to design PI (PID) controllers satisfying conflicting design requirements. In addition, considering load disturbance rejection as the primary design objective, a simple analytical PI tuning method is presented. The design problem is constrained with a specified gain or phase margin. Compared to the corresponding conventional SISO controller, it is demonstrated that the resulting decentralised controller considerably improves the overall surge risk to the engine during the transient manoeuvres while maintaining similar thrust levels. Due to non-linearity of jet engine models, gain scheduling is necessary. Designing decentralised controllers at various operating points, the gain-scheduled controller accommodates the non-linearity in engine dynamics over the full thrust range

Aeronautical Engineering: A continuing bibliography, supplement 120

This bibliography contains abstracts for 297 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1980

Controllers, observers, and applications thereof

Controller scaling and parameterization are described. Techniques that can be improved by employing the scaling and parameterization include, but are not limited to, controller design, tuning and optimization. The scaling and parameterization methods described here apply to transfer function based controllers, including PID controllers. The parameterization methods also apply to state feedback and state observer based controllers, as well as linear active disturbance rejection (ADRC) controllers. Parameterization simplifies the use of ADRC. A discrete extended state observer (DESO) and a generalized extended state observer (GESO) are described. They improve the performance of the ESO and therefore ADRC. A tracking control algorithm is also described that improves the performance of the ADRC controller. A general algorithm is described for applying ADRC to multi-input multi-output systems. Several specific applications of the control systems and processes are disclosed

Application of an Integrated Methodology for Propulsion and Airframe Control Design to a STOVL Aircraft

An advanced methodology for integrated flight propulsion control (IFPC) design for future aircraft, which will use propulsion system generated forces and moments for enhanced maneuver capabilities, is briefly described. This methodology has the potential to address in a systematic manner the coupling between the airframe and the propulsion subsystems typical of such enhanced maneuverability aircraft. Application of the methodology to a short take-off vertical landing (STOVL) aircraft in the landing approach to hover transition flight phase is presented with brief description of the various steps in the IFPC design methodology. The details of the individual steps have been described in previous publications and the objective of this paper is to focus on how the components of the control system designed at each step integrate into the overall IFPC system. The full nonlinear IFPC system was evaluated extensively in nonreal-time simulations as well as piloted simulations. Results from the nonreal-time evaluations are presented in this paper. Lessons learned from this application study are summarized in terms of areas of potential improvements in the STOVL IFPC design as well as identification of technology development areas to enhance the applicability of the proposed design methodology

A Practical Approach to Disturbance Decoupling Control

In this paper, a unique dynamic disturbance decoupling control (DDC) strategy, based on the active disturbance rejection control (ADRC) framework, is proposed for square multivariable systems. With the proposed method, it is shown that a largely unknown square multivariable system is readily decoupled by actively estimating and rejecting the effects of both the internal plant dynamics and external disturbances. By requiring as little information on plant model as possible, the intention is to make the new method practical. The stability analysis shows that both the estimation error and the closed-loop tracking error are bounded and the error upper bounds monotonously decrease with the bandwidths. Simulation results obtained on two chemical process problems show good performance in the presence of significant unknown disturbances and unmodeled dynamics

A Practical Approach to Disturbance Decoupling Control

In this paper, a unique dynamic disturbance decoupling control (DDC) strategy, based on the active disturbance rejection control (ADRC) framework, is proposed for square multivariable systems. With the proposed method, it is shown that a largely unknown square multivariable system is readily decoupled by actively estimating and rejecting the effects of both the internal plant dynamics and external disturbances. By requiring as little information on plant model as possible, the intention is to make the new method practical. The stability analysis shows that both the estimation error and the closed-loop tracking error are bounded and the error upper bounds monotonously decrease with the bandwidths. Simulation results obtained on two chemical process problems show good performance in the presence of significant unknown disturbances and unmodeled dynamics