http://www.ifac-papersonline.net/ en Copyright 12:26 PM Thursday 11, 2010 IFAC-PapersOnline http://www.ifacpapersonline.com 12:26 PM Thursday 11, 2010 12:26 PM Thursday 11, 2010 ET webmaster@ifac-papersonline.net webmaster@ifac-papersonline.net http://www.ifac-papersonline.net/Detailed/38618.html 04:00 PM Wednesday 31, 1969 This paper proposes a new straight forward technique based on dynamic inversion, which is applied for tracking the pilot commands in high performance aircrafts. Pilot commands assumed in longitudinal mode are normal acceleration and total velocity (while roll angle and lateral acceleration are maintained at zero). In lateral mode, roll rate and total velocity are used as pilot commands (while climb rate and lateral acceleration are maintained at zero). Ensuring zero lateral acceleration leads to a better turn co-ordination. A six degree-of-freedom model of F-16 aircraft is used for both control design as well as simulation studies. Promising results are obtained which are found to be superior as compared to an existing approach (which is also based on dynamic inversion). The new approach has two potential benefits, namely reduced oscillatory response and reduced control magnitude. Another advantage of this approach is that it leads to a significant reduction of tuning parameters in the control design process. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38614.html 04:00 PM Wednesday 31, 1969 This paper proposes an observer based adaptive Takagi-Sugeno fuzzy guidance law for a surface to air missile. An integrated guidance-control model is derived to consider target manoeuvre and missile uncertainties in the design process of the proposed guidance law, also use of adaptive intelligent system for approximation of unknown dynamic parts of the mentioned model and a high gain observer for estimation of required states caused that this approach, in contrast to guidance approaches introduced by now, use the minimum number of inputs for a robust missile guidance. Presented proofs and simulated results show the practical application and effective performance of designed guidance law. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38610.html 04:00 PM Wednesday 31, 1969 The EFIGENIA EJ-1 is an advanced aerodynamics design vehicle and avionics autopilot system design in which a digital neural network combined with a fuzzy logic system performs the best flight guidance, navigation and flight control condition operation. This paper describes the EFIGENIA EJ-1 Short or Vertical take-off and Landing (S/VTOL) autonomous intelligent Unmanned Aerial Vehicle (UAV) embedded multiprocessor fuzzy logic flight guidance and control system scheme autopilot system designed. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38603.html 04:00 PM Wednesday 31, 1969 http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38619.html 04:00 PM Wednesday 31, 1969 A guidance and control system for a "mouse-guided aircraft" is introduced. It can fly through waypoints that are designated by clicks of a pointing device. The guidance law is calculated using a trajectory-tracking approach for landing and the pure pursuit guidance law for take-off and waypoint flying. A dynamic inversion controller generates the guidance forces. This paper describes the guidance and control system of this "mouse-click guided aircraft" and simulation results. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38635.html 04:00 PM Wednesday 31, 1969 Control allocation is useful for control of overactuated aerospace systems, and deals with distributing the total control demand among the individual actuators. Using control allocation, the actuator selection task is separated from the regulation task in the control design. We propose a novel control allocation algorithm that is based on n-dimensional interval bisection techniques. Application to a reusable launch vehicle is given. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38606.html 04:00 PM Wednesday 31, 1969 This paper studies the robust attitude control of large Geosynchronous communication satellite ETS-VIII. After describing its model features and control issues, a candidate of robust controller design method is proposed. The controller has the form of two-degrees-of freedom control in order to satisfy both specifications of disturbance attenuation and attitude maneuver. The feedback control employs the symmetric controller having the salient robust stability property irrespective of the plant parameters. Its optimization scheme in the H∞ norm sense is discussed. Finally, the on-orbit control experiment plan is shown with some simulation results. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38651.html 04:00 PM Wednesday 31, 1969 LISA and the next generation of space-based laser interferometers require gravitational reference sensors (GRS) to provide distance measurements with picometer precision. To meet this goal, we describe a stand-alone GRS structure that has high sensitivity and easy integration with a satellite. The stand-alone GRS integrates balanced optical probing of the proof-mass position in its housing, and provides a correlated reference surface to an independent external interferometer. The use of optical sensing allows for a large gap between the proof-mass and housing, which is the best way to reduce many proof-mass disturbances. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38602.html 04:00 PM Wednesday 31, 1969 http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38650.html 04:00 PM Wednesday 31, 1969 MICROSCOPE is CNES fourth microsatellite based on MYRIADE platform. Its mission is dedicated to the test of the Equivalence Principle (EP) with an improved accuracy of 10-15. Therefore the satellite attitude requirement is very stringent and the payload accelerometric measurements need to be used in the control loop. This paper deals with one of the most critical issue in MICROSCOPE attitude and acceleration control : the accelero stellar hybridization in spinning mission mode. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38615.html 04:00 PM Wednesday 31, 1969 Modern aircrafts and missiles with high manoeuvrability present an interesting challenge to autopilot design, which has activated new investigations in estimating the potential and applicability of recent theoretical control methods as well as how they can meet industrial demands. In this paper, a multi-objective approach for autopilot design is introduced. The design requirements are formulated using several integral criteria. A hybrid-genetic algorithm (GA) is employed to solve the nonlinear optimization problem. The obtained results are verified using nonlinear simulations in SIMULINK® which shows performance, stability and robustness of the designed flight controller. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38631.html 04:00 PM Wednesday 31, 1969 This paper presents a model-predictive formation flight control technique with obstacle avoidance. The control performance and the computation time reduction of the decentralized methods are evaluated in comparison with the centralized methods in the standard leader-follower structure using nonlinear model predictive control(NMPC) formulation. Furthermore, the control input saturation and state constraints are considered as inequality constraints using Kuhn-Tucker condition in the NMPC framework, and the collision avoidance can be incorporated in real time. The numerical simulation results support the feasibility of the proposed method in terms of formation maintenance and obstacle avoidance. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38647.html 04:00 PM Wednesday 31, 1969 A model is introduced to compactly express the tie between pressure gradients on aircraft wings and the in-flow attitude angles and stream speed. The model is optimized for application in an instrumentation system inferring air-speed and angle of attack from a multi-point, redundant set of differential pressure measurements directly taken on the aircraft skin by strip-type sensors. It borrows from the analytical solutions for airfoils in subsonic flows, introducing a sufficient (yet parsimonious) parameterization enabling calibration on experimental data with good fitting for a wide range of airfoil types and sensor positioning. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38646.html 04:00 PM Wednesday 31, 1969 In this paper we present a PID+ solution to the problem of relative translational and rotational tracking, using the concept of integrator backstepping. By using an integrator augmentation technique, we include integral effect in the controller to account for the unknown orbital perturbations. The controller solution utilizes the quaternion representation to achieve a shorter rotation path on commanded attitude changes, and the equilibrium points in the closed-loop system are proved to be uniformly exponentially stable. Finally, simulation results are presented to show the controller performance. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38667.html 04:00 PM Wednesday 31, 1969 Possible approaches to the mathematical description of different types of flexible vehicles in view of oscillations of fluid in tanks and moving masses inside the vehicle are observed. Elastic bending of a body surface in interaction with a surrounding medium in a broad band of speed variation are taken into account. Problems of regulator's synthesis, damping of elastic oscillations, and also principles of construction of universal software for research of dynamic properties and simulations of elastic vehicles motion are considered. For implementation of suggested methods and algorithms the specialized program is designed. The software package is supplied with the program modules library. These modules are designed on the basis of mathematical models of the vehicle elements and control system, and also the significant physical phenomena such as flexibility, liquid oscillations, time lag of engines, local aerodynamic effects, etc. Functioning of the program is demonstrated and outcomes of calculations are presented. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38621.html 04:00 PM Wednesday 31, 1969 This paper presents a Fault Tolerant Control (FTC) strategy to provide a highly reliable reconfigurable control capacity for safety critical systems in faulty situations. The paper describes mainly the status of an on-going research work which is undertaken within GARTEUR FM-AG(16)2 Action Group. The developed techniques are applied to a faulty scenario of a realistic nonlinear benchmark of a large transport aircraft. The goal is to provide a "self-repairing" capability to enable the pilot to land the aircraft safely in the event of a stabilizer fault. Once the fault is detected by the Fault Detection and Isolation (FDI) unit, a fault compensation loop is activated. A key feature of the proposed strategy is that the design of FTC loop is done independently of the nominal autopilot and the nominal Flight Control System (FCS) in place. Nonlinear simulation results demonstrate the capability and viability of the proposed active FTC scheme. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38637.html 04:00 PM Wednesday 31, 1969 A difference between deterministic and non-deterministic architectures of digital control systems is explained. A finite-state automation model for the system units is used. A verification method for non-deterministic architecture is proposed. This method is based on graph isomorphism - comparing different parts of architectures without using specific rules or algorithms. It can be useful in multi-purpose Computer-Aided Design (CAD) tools for aerospace applications. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38653.html 04:00 PM Wednesday 31, 1969 The paper presents a stepwise procedure to develop a fault tolerant control system for small satellites. The procedure is illustrated through implementation on the AAUSAT-II spacecraft. As it is shown the presented procedure requires expertise from several disciplines that are nevertheless necessary for obtaining a complete and consistent solution. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38633.html 04:00 PM Wednesday 31, 1969 In this study, adaptive control methodology using multiple models is proposed to design a reconfigurable controller for nonlinear systems. An adaptive model and fixed parameter models are used for mode switching, and a re-initialized adaptive model is considered. The conventional mode switching method based on multiple model adaptive control does not guarantee the stability of the closed-loop system. To improve the adaptiveness of a nonlinear system while maintaining the stability, mode switching scheme is modified and a new decision logic is considered. In the mode switching control scheme, forgetting factor and adaptive time concepts are introduced based on the selected model for reconfiguration. An error threshold value is used in the decision logic. Numerical simulation is performed for a nonlinear discrete-time MIMO aircraft system to verify the effectiveness of the proposed method. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38649.html 04:00 PM Wednesday 31, 1969 The microvibration excited by on-board instruments is considered as a major factor of pointing stability deterioration. Therefore it is important to estimate the influence of the microvibration on pointing stability before the launch. In this paper, the ground test data obtained by using OICETS MTM (Mechanical Test Model) and in-orbit measured data obtained by on-board accelerometer (MVE: Micro Vibration Equipment) are analyzed. Analyzing these data with appropriate assumption, the transfer characteristics from main disturbance sources to MVE are calculated in both ground and in-orbit cases. As a result, similarity between the ground test data and the in-orbit data is evaluated, and the effectiveness of the ground test in predicting in-orbit microvibration environment is verified. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38629.html 04:00 PM Wednesday 31, 1969 The intrinsic nonlinearities of aircraft dynamics become exceptionally significant when there are demands for large maneuvers, causing aircraft to operate near the stability limits of the system, where series problems can be encountered, since the real issue becomes dealing with nonlinearities that dominate system behavior. This has eminent consequences in aerospace applications where catastrophic failure in high-performance aircraft must be prevented. Recently, a novel algorithm has been derived for nonlinear suboptimal tracking control, which can be realized for real-time computer implementation. The algorithm is based on the State-Dependent Riccati Equation (SDRE) strategy that has become well-known within the control community. This paper focuses on illustrating the application, computational advantage and validity of the proposed tracking control methodology on a realistic simulation example of a ducted fan engine model for high-performance thrust-vectored aircraft. The proposed method delivers a computationally simple, yet effective, algorithm for constructively synthesizing nonlinear suboptimal feedback controls for trajectory tracking problems. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38645.html 04:00 PM Wednesday 31, 1969 We present a passivity-based PD+ tracking controller for relative translation and rotation in a leader-follower spacecraft formation. The controller is based on a 6DOF model in the Euler-Lagrange form, which share similar properties as models of i.e robot manipulators. The purpose of this paper is to show the applicability of the 6DOF model to controller design. The controller solution utilizes the quaternion representation to achieve a shorter rotation path on commanded attitude changes, and the equilibrium points of the closed-loop system are proved to be uniformly asymptotically stable. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38625.html 04:00 PM Wednesday 31, 1969 The JAS 39 Gripen is a light weight multirole combat fighter. It has delta canard configuration with all moving canards. It has negative inherent stability in the longitudinal axes for improved performance. It has a full time three channel digital fly by wire Flight Control System (FCS). The FCS uses angle of attack, pitch rate and normal acceleration to stabilize the aerodynamically unstable aircraft in the longitudinal axes. To provide the pilot with maximum aircraft performance in every situation, without extra attention to air intake/engine envelope limits, structural overloading or departure situations, the JAS 39 Gripen has inbuilt flight control system limit functions such as angle of attack-, normal load factor-, sideslip- and roll rate limit functions, which will make the JAS 39 Gripen carefree to manoeuvre. If the pilot by mistake ends up in a low speed situation with a high aircraft nose attitude and high angle of attack, the JAS 39 Gripen FCS will automatically return the aircraft from high attitude angles, high angle of attack back to the normal angle of attack flight envelope. In order to demonstrate the JAS 39 Gripen carefree and automatic return to normal flight envelope capabilities with all types of external store configurations, extensive simulations and flight test programs have been performed, divided in a phase using an aircraft with an anti stall chute mounted and a final verification flight test phase with a production aircraft from the Swedish Air Force. Furthermore a wake vortex detection and wake vortex transient reduction flight control system has been developed and flight tested. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38641.html 04:00 PM Wednesday 31, 1969 The flight dynamics of the Yamaha RMAX unmanned helicopter has been investigated, and mapped into a six degrees of freedom mathematical model. The model has been obtained by a combined black-box system identification technique and a classic model-based parameter identification approach. In particular, the closed-loop behaviour of the built-in attitude control system has been studied, to support the decision whether to keep it as inner stabilization loop or to develop an own stability augmentation system. The flight test method and the test instrumentation are described in detail; some samples of the flight test data are compared to the model outputs as validation, and an overall assessment of the built-in stabilization system is supplied. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/38605.html 04:00 PM Wednesday 31, 1969 This paper addresses the problem of the detection and isolation of the faults affecting the thrusters of a satellite system, which is characterised by a nonlinear model, in the presence of measurement errors, uncertainty and disturbance. In particular, this work proposes a robust estimation approach to the problem of the design of residual generators in order to realise complete diagnosis schemes when realistic faults are present on the simulated system. This approach leads to dynamic observers that can achieve both good disturbance de-coupling and robustness properties with respect to linearisation error, uncertainty and measurement noise. The description of the satellite structure is provided in order to highlight the main sources of uncertainty and disturbance. The faulty behaviour of the satellite Mars Express (MEX) nonlinear model and a comparison with the existing fault diagnosis scheme implemented on-board are reported. Finally, suitable performances criteria are introduced together with the Monte Carlo analysis for assessing the robustness and performance evaluation of the suggested FDI design methodology. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif