Solid State Phenomena Vols. 147-149 (2009) pp 231-236 Online available since 2009/Jan/06 at www.scientific.net (2009) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/ssp.147-149.231 Flight Simulator as a Tool for Flight Control System Synthesis and Handling Qualities Research Tomasz Rogalski 1, a, Andrzej Tomczyk 1, b, Grzegorz Kopecki 1, c 1 Rzeszow University of Technology, Dept. of Avionics and Control Systems, Powstańców Warszawy 8, 35-959 Rzeszów, Poland a orakl@prz.edu.pl, b atomczyk@prz.edu.pl, c gkopecki@prz.edu.pl Keywords: aircraft control systems, flight simulator, handling qualities, hardware in the loop simulation, in-flight tests, aircraft control, crew management and cooperation, flight safety At the Department of Avionics and Control Systems problems of aeronautical control systems have been dealt with for years. Several different kinds of aeronautical control systems have been designed, prototyped and tested. These control systems are intended for general aviation aircraft and unmanned aircraft. During all research projects computer simulations and laboratory tests were made. However, since in some cases such tests were insufficient, in-flight tests were conducted leading to a series of reliable results. The in-flight tests were made with the use of M-20 Mewa aircraft (autopilot for a GA aircraft) and PZL-110 Koliber aircraft (control system for UAV and indirect flight control system for a GA aircraft). Nevertheless, in-flight testing is very expensive and problematic. To avoid some problems appearing during in-flight tests and their preparation, a simulator which is normally used for professional pilot training can be used. The Aviation Training Center of the Rzeszów University of Technology possesses the ALSIM AL-200 MCC flight simulator. We have started preparing this simulator for the research. It is possible to control the simulated aircraft with the use of an external control system. The solution proposed enables testing the aircraft control algorithms, indirect control laws (e.g. control laws modifying handling qualities), as well as testing and assessment of the students pilotage skills. Moreover, the solution makes it possible to conduct tests connected with aircraft control, crew management, crew cooperation and flight safety. The simulator allows us to test dangerous situations, which because of safety reasons is impossible during in-flight testing. This paper presents modifications to the simulator s hardware and additional software, which enable the described research. Introduction At the Department of Avionics and Control Systems problems of aeronautical control systems have been dealt with for years [5]. Several different kinds of aeronautical control systems have been designed, prototyped and tested. These control systems are intended for general aviation aircraft [1][6] and unmanned aircraft [2]. During all research projects computer simulations and laboratory tests were made. However, since in some cases such tests were insufficient, in-flight tests were conducted leading to a series of reliable results. During design and testing of the control system for UAV, as well as control systems for general aviation aircraft, for in-flight tests on aircraft belonging to the Aviation Training Centre of Rzeszów University of Technology was used. In all in-flight testing series necessary equipment was assembled onboard the aircraft. The aviation law requires special permissions for modified aircraft in-flight testing. Since after research the aircraft was used for the pilot training, additional equipment had to be disassembled. In the in-flight testing we obtained reliable results. However, real in-flight experiments are very expensive (aircraft maintenance, pilot s salary, assembling and disassembling of the tested equipment). There appeared also organizational problems with in-flight tests. For example, in-flight tests had to be realized during the period of time specified by the Civil Aviation Office. Sometimes, because of unexpected reasons it was difficult to carry out the research in these time frames. To avoid series of such problems, for future tests the simulator ALSIM AL-200 will be used. The simulator is being prepared for in-flight testing. This equipment is normally used for pilot s All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 130.203.136.75, Pennsylvania State University, University Park, United States of America-04/06/14,05:04:16)
232 Mechatronic Systems and Materials III training at the Aviation Training Centre of Rzeszów University of Technology. The simulator use for research was planned at the time of its purchase. The producer was obliged to supply necessary tools allowing monitoring and acquisition of all flight parameters. These tools allow also aircraft control. For simulated in-flight testing, design of some additional hardware and minor changes in the simulator structure were necessary. Flight simulator AL-200MCC The flight simulator AL-200 MCC belonging to the Aviation Training Centre of Rzeszów University of Technology was produced in 2002/2003. It is certified by the Civil Aviation Office in Poland as training equipment FNPT II (Flight avigation Procedure Trainer level II) with the possibility of MCC (Multi Crew Cooperation) training. Because of the producer s conception of the hardware architecture and chosen technical solution the presented simulator is one of the most modern of simulators available in its class. The equipment presented is not only a simulator of one kind of aircraft but AL-200 MCC enables simulations of chosen class of airplanes. This idea offers a number of possibilities of flight simulation. With the use of one simulator, software change enables the simulation of: small one engine aircraft (Socata TB-20 dynamics) light two engine executive aircraft (PZL M-20 dynamics), small turboprop aircraft (BeechCraft Be-200). The simulator consists of the cockpit imitating the aircraft cockpit with two steering wheels, a few sets of switches, regulating units and onboard displays placed at the instrument panel of the middle console and the upper panel. The instructor s stand is placed at the back side of the cockpit. The processing unit necessary for flight dynamics simulation and visualization of aircraft environment consists of five PC computers. Each of them is responsible for a different part of the visualization and simulation process. The communication between computers, instructor s stand and aerodynamic forces simulation system is realized via a local Ethernet network. The visualization system (visualization angle 210 degrees in horizon) is based on three multimedia projectors. Each projector is connected to a different PC computer. Simulator modifications enabling research The modification of the AL 200 MCC simulator made at the Department of Avionics and Control System makes it possible to: test the aircraft automatic control system equipment, test the control algorithms. The described modifications do not lead to the loss of certificates required for pilot s training. One of the most important problems during the use of the simulator for research is the access to the simulated aircraft flight parameters. Tools provided by the producer, as well as technical documentation were used. To the internal simulator s computer network an additional computer with software enabling visualization and registration of chosen flight parameters was connected. The computer network mentioned is a classical Ethernet connecting PC computers. This additional computer connection did not result in the simulator modifications (Fig. 1). For simulated aircraft controlling it is necessary to provide the system with the actual parameters of the steering wheel and rudder bar position. These parameters give information about control surfaces position. In simulator AL-200 MCC the steering wheel and rudder bar position are measured by electrical sensors. The analog signal (voltage) with information about the position is sent to one of computers. The signal is processed by a special measuring card and then converted to a digital form and transmitted via Ethernet to the other computers (Fig. 2).
Solid State Phenomena Vols. 147-149 233 Fig. 1. Additional computer connected to simulator s Ethernet Fig. 2. Measurement of control wheels position scheme It is impossible to change the Ethernet data transmission without interference into the producer s software. In consequence, there is no possibility of delivering the information on the control wheel position to the system. Therefore another solution was applied. The control wheel position was simulated. Fig. 3. Connection of control wheels position imitator The simulated position influenced the aircraft dynamics. This solution required some further modifications in the simulator design. Potentiometers measuring the control wheel position were disconnected from the computer responsible for measurement. To the computer s measurement card external signals imitating control wheels positions were connected (Fig. 3). This modification enables safe switching between signals from control wheels and control wheels position imitator (Fig. 4). Such design changes do not lead to a conflict between the simulator application for research and for pilots training. Fig. 4. Connection of control wheels position imitator into simulator
234 Mechatronic Systems and Materials III Fig. 5. PC 104 connection scheme Control wheels position imitator is based on PC104 computer with external cards: analog input card, analog output card, CAN bus card,network card (NE2000 standard). The PC 104 network card enables connection with the simulator s Ethernet. This enables the acquisition of simulated aircraft parameters data. Finally, the solution presented enables us to read the flight parameters (Fig. 5). Moreover, with the modification presented it is possible to test the control algorithms implemented in PC104. The computer PC104 is equipped with the CAN bus card. It enables communication between PC104 and other hardware via the CAN bus, such as the autopilot module or control console. The modification described allows us to test not only the control algorithms, but also the complete control system. The tested hardware receives via CAN bus all necessary flight parameters. The calculated control signal can be sent to the simulated aircraft in two ways: via CAN bus to the PC104 computer. PC104 converts the signal and transmits it as a voltage signal to the simulator (Fig. 6), or directly from the tested hardware as a voltage signal to the simulator s computer responsible for measurements (Fig. 7). Fig. 6. Connection of tested equipment via PC104
Solid State Phenomena Vols. 147-149 235 Fig. 7. Connection of tested hardware, analog signal from potentiometers measuring control wheels position is replaced by calculated control signal from the tested hardware (autopilot) The choice of connection depends on tested hardware properties. The first possibility (via CAN bus to the PC104) appears to be more typical. This solution is also more flexible and its properties can be modified in a wide range. Software necessary for the PC104-simulator communication was developed. The simulator was equipped with additional hardware equipment. The modifications enable most of experiments in testing control systems. Fig. 8. The placement of PC104 measuring and simulating unit in simulator Exemplary research with the use of AL-200 MCC simulator ALSIM 200MCC was used for research during cooperation with the Air Force Institute of Technology [4]. Our task was to choose the critical flight maneuver, in which the pilot received the maximum measurement information. Licensed professional pilots with different qualifications took part in the tests. The research was based on theoretical analyses, opinions of experimental pilots and opinions of pilots with different aviation experience. One of the flight maneuvers tested with the use of ALSIM simulator was the holding. Figs. 9 and 10 present the correct and incorrect flight trajectories. The use of simulator in the presented research was necessary. It verified the definition of the critical task. The research confirmed the possibility of realization of proposed tasks by experienced pilots and showed the level of difficulties in the case of less experienced pilots.
236 Mechatronic Systems and Materials III Fig. 9. Correct holding over NDB beam with attitude changing Fig. 10. Exemplary incorrect holding: the loss of control by pilot and wrong altitude control Summary The article presented proposition of hardware and software modifications, which enable the use of flight simulator AL-200 MCC for research. Because of the simulator use for professional pilot training process, simulator could not lose certifications, what was strongly taken into considerations. The simulator with additional modules is ready for different kind of research. The first research with the use of simulator was described as the example. The results were very important and necessary for the whole problem presented in the paper. References [1] Bociek S., Dołęga B., Tomczyk A.: Synthesis of the Microprocessor Digital Autopilot. Systems Science, Vol. 18, No 4, Wrocław 1992 [2] Gruszecki J. (red): Bezpilotowe aparaty latające. Systemy sterowania i nawigacji, Oficyna Wydawnicza Politechniki Rzeszowskiej, Rzeszów 2002 [3] T. Rogalski, A. Tomczyk.: Handling Qualities of the General Aviation Analysis on the Flight Simulation Experiment. International Conference AVIATION 2007, 18 April [4] Rzucidło P. (red.): Opracowanie technologii oraz stanowiska do optymalizacji interfejsu człowiek maszyna w kokpitach wojskowych statków powietrznych, ITWL 3335/51, s. 69, Warszawa 2007. [5] Tomczyk A.: Badania naukowe w Katedrze Awioniki i Sterowania Politechniki Rzeszowskiej, Journal of Aeronautica Integra 1/2006 (1), Rzeszów 2006. [6] Tomczyk A.: Preliminary Evaluation of the Indirect Flight Control System for General Aviation Aircraft, AIAA Paper 2007-6526, CD-ROM, http://www.aiaa.org (also: AIAA Guidance, Navigation, and Control Conference, Hilton Head, SC, 20-23 August 2007) [7] Tomczyk A.: Proposal of the Experimental Simulation Method for Handling Qualities Evaluation. Accepted for printing at: Aircraft Engineering and Aerospace Technology: An International Journal, vol. 3, 2008.
Mechatronic Systems and Materials III 10.4028/www.scientific.net/SSP.147-149 Flight Simulator as a Tool for Flight Control System Synthesis and Handling Qualities Research 10.4028/www.scientific.net/SSP.147-149.231