. b NASA Technical Memorandum 86793 Highly Integrated Digital Electronic Control - Digital Flight Control, Aircraft Model Identi- fication and Adaptive Engine Control Jennifer L. Baer-Riedhart and Robert J. Landy (BASA-TH-86793) EIGHLP IYTEGEATEC DIGITAL 887-226 19 ELECIROBIC CC IFlfCL: DIGITAL ELIGBI COhiTRCL, Al&CFiAPT RCDEL lGENT~FICA!IICb, AYD ADAPTIVB EIGXIIE CCHTBGZ (AASA) 16 F. Avail: NTfS Unclas LC A02/HP ibOl CSCL 21E Hl/07 0076753 March 1987 National Aeronautics and Space Administration NASA Technical Memorandum. 86793 Highly Integrated Digital Electronic Control - Digital Flight Control, Aircraft Model Identifi- cation and Adaptive Engine Control Jennifer L. Baer-Reidhart Ames Research Center, Dryden Flight Research Facility, Edwards, California Robert J. Landy McDonnell Aircraft Company, St. Louis, Missouri National Aeronautics and Space Administration Ames Research Center Dryden Flight Research Facility Edwards, California 93523 - 5000 Highly Integrated Digital Electronic Control - Digital Flight Control, Aircraft Model Identification, and Adaptive Engine Control Jennifer L. Baer-Riedhart NASA Ames Research Center, Dryden Flight Research Facility, Edwards, California 93523-5000 and Robert J. Landy b McDonnell Aircraft Company, St. Louis , Missouri ABSTRACT Center's Dryden Flight Research Facility initiated the highly integrated digital electronic control The highly integrated digital electronic con- (HIDEC) program. McDonnell Aircraft Company trol (HIDEC) program at NASA Ames Research Center, (MCAIR) is the prime contractor, with Pratt & Dryden Flight Research Facility is a multiphase Whi tney Aircraft (PWA) and Lear Siegler Incor- flight research program to quantify the benefits porated (LSI) as major subcontractors. The test of promising integrated control systems. McDonnell aircraft is an F-15, modified for installation of Aircraft Company is the prime contractor, with digital flight and engine control systems. The United Technologies Pratt R Whitney, and Lear objectives of the program are to design, imple- Siegler Incorporated as major subcontractors. ment , and flight-test selected integrated flight/ propulsion control modes which promise significant The NASA F-15A testbed aircraft was modified improvements in aircraft performance. for the HIDEC program by installing a digital elec- tronic flight control system (DEFCS) and replacing The HIDEC program is divided into five phases. the standard FlOO (Arab 3) enyines with FlOO engine These phases and the program schedule are shown nodel derivative (EMD) engines equipped with digl- in Fig. 1. Phase 1 of the HIDEC program involves tal electronic engine controls (DEEC), and integra- the flight testing of the digital electronic ting the DEEC's and DEFCS. The modified aircraft flight control system (DEFCS) in the NASA F-15 provides the capability for testing many integra- airplane. The DEFCS consists of a higher-order- ted control modes involving the flight controls, language digital flight control computer and two engine controls, and inlet controls. modified control augmentation system (CAS) analog computers used for sensor and actuator interface. This paper focuses on the first two phases of As part of phase 1, the DEFCS software is pro- the HInEC program. which are the digital flight grammed to provide a "flutter exciter" function control systemlaircraft model identification that enables the pilot to select precise fre- (DEFCVAMI) phase and the adaptive engine con- quency sweep and dwell inputs to the horizontal trol system (ADECS) phase. tails. This feature allows the acquisition of data for improving the mathematical models of INTRODUCTION flight control components and aircraft rigid and structural modes. Diyital electronic controls in new aircraft enhance vehicle preformance by providing a means Phase 2 of HIDEC, called the adaptive engine of integrating the flight and propulsion control control system (ADECS, Ref. l), consists of the systems. Substantial benefits are gained by design, implementation, and flight testing of an exploiting the additional control devices avail- integrated flight and propulsion control mode. able through digital controls on advanced design This mode uses flight control information to aircraft. These devices include symmetrical and uptrim the engine pressure ratio for improved differentially variable canards, variable leading- engine performance. Phase 3 of the program will and trailing-edge flaps, varidble geometry inlets, consist of the development and evaluation of two-dimensional thrust vectoring and reversing selected trajectory guidance algorithms. The nozzles, and other control variables associated algorithms will be tested with and without the with variable cycle engines. The complexity ADECS features. Additional ADECS modes and involved in the integration of these systems enhancements to the basic features will be devel- is governed by the digital logic. The integra- oped and tested during phase 4 of the HIDEC pro- tion of these systems enhances aircraft maneuver- gram. Phase 5 will involve efforts in the area of ability, improves trajectory control for terrain performance-seeking controls with the integration following, terrain avoidance, and weapon delivery, of the aircraft inlets to the engine and flight and shortens takeoff and landing distances. control systems. This paper concentrates on Energy management techniques, when combined phases 1 and 2 of the HIDEC program, and includes with trajectory control, can result in signif- discussions on the ADECS control system design. icant fuel and cost savings. the computational architecture, the developmental testing, the built-in-test and in-flight integrity To devplop and demonstrat? Integrated flight management system, and the plans for the flight and propul si on techno1 ogy , NASA Ames Research tests included in these two phases. Projections for engine performance improvements MCAIR McDonnel Aircraft Company during the HIDEC program are contained in Ref. 1 and 2. MUX mu1 ti plex NOMENCLATURE NC I navigation control indicator A DC air data computer N1 engine fan speed ADECS adaptive engine control system N1C2 engine fan speed, corrected to engine inl et cond iti ons All I aircraft model identification N1/fi engine fan speed, corrected AS alternate shape, AKI excitation a- lateral acceleration nY A(w) amplitude, waveform frequency n2 normal acceleration HIT hui 1 t-in test b P pitch CAS computer B UC hyd rome hanical backup engine control programmable asynchronous serial com- CAS controi augmentation system PA SC OT mun icat i on transl ator cc central computer PC D pitch CAS defeat c ID Correct on indicator display PLA power lever angle CP cockpit PSC performance-seeki ng controls UEEC digital electronic engine control PT 2 fan inlet total pressure UtFCS digital electronic flight control system PTZ. 5 fan discharge total pressure DFCC digital flight control computer PT 6 turbine discharge total pressure EIlU engine model derivative PWA Pratt 8 Whitney Aircraft E PR engine pressure ratio P roll rate EPRc' engine pressure ratio command q pitch rate EPRp engine pressure ratio, predicted 9 pitch rate change FFT fast Fourier transform RF radio frequency F1 at lateral stick force RMDU remote multiplex/demultiplex unit FI ong longitudinal stick. force R/Y rolllyaw CAS computer F PR fan pressure ratio r yaw rate Frud rudder pedal force STF -F CL software test facil ity-flight control lab FTIT fan turbine inlet temperature Tamb ambient temperature e FTITca fan turbine inlet temperature conmand TH/ E NG throttle/engine HIDEC highly integrated digital electronic TRAJ t r aj ec tory control t time H009 data bus nomenclature UART universal asynchronous receiver/ HUD head-up display transmitter data bus IFIll in-flight integrity management v &V verification and validation INS inertial navigation set Wac engine airflow, corrected i AMI command 2 engine airflow, corrected to engine inlet LS I Lear Siegler Incorporated Wrap wraparound software logic 2 anyle of attack microprocessor with 490 kops and 26K memory, and four channels for communication; (2) MIL-STD-1553A angle of attack predi c ted multiplex interface; (3) PASCAL as the higher- order language; and (4) hardware that enables the angle of sidesl P system to be reconfigured as a triplex, quadru- plex, or dual-dual system. angle of sidesl p, predicted A significant feature for HIDEC is the higher- order-language compatibility which enables cost- stabilator deflection effective programming of the DFCC for the subse- quent HIDEC phases. rudder deflection The execution of the DFCC executive program, change input-output program, and flight control laws takes approximately one-half of the 12.5-msec duty frequency cycle time and only about one quarter of the avail- able memory. Thus there is ample cycle time and AIRCRAFT DESCRIPTION memory available to accomplish integrated control law calculations in the DFCC for the HIDEC phases. The test vehicle for this program is an F-15 airplane. modified with a digital electronic Engine flight control system (DEFCS). The airplane is a high-performance. twin-engine fighter capable of The FlOO END engine (Ref. 3) is an upgraded speeds to Mach 2.5. The engine inlets are of the version of the FlDO-PW-100 engine that currently two-dimensional external compression type with powers the production F-15 airplanes. The engine three raiips, and feature variable capture area. is built by Pratt 8 Whitney Aircraft and has a The F-15 airplane is powered by two FlOO engine company designation of PW 1128. The