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180 Fault Tolerant navigation system for aircraft landing
Abstracts 178 Pilot Route Choice Assistance System Yuezu Fan, Hulli Cheng, Zlhong Tong, pp 825-828 A pilot route choice assistance system is an important part of dectronic assistance system for new-generation aircraft. It can h d p pilots to rapidly make correct, best decisions on route choices in changing high-risk environments and flight manoeuvres. This paper describes the principles and an algorithm for optimal route choice. Three computing algorithms are compared: the depth-first, breadth-first and best-first algorithms. Various flight plans are simulated, using the LISP programming language. Simulation results indicate that a heuristic search is suitable for multi-target flight environments. The man-machine technique can make decisions effectively in changing environments.
179 Active Control of a Thin Airfoil: Flutter Suppression and Gust Alleviation EL ~bzbay, pp 829-832 Recently it has been shown that active flutter suppression and gust alleviation problems for a thin airfoil can be solved using standard He° and mixed H2/I-Io° control techniques. The proposed solution depends on finite-dimensional approximations of Theodorsen's function, which appears in the original infinite-dimensioual model of the airfoil. In this paper an approximation scheme is proposed for model reduction. T h e procedure described here provides a "near-optimal" fixed-order h"~ approximation of Theodorsen's function. 180 Fault Tolerant Navigation System for Aircraft Landing H.G. Zhang, H.Y. Zban~ pp 833-836 A fanlt-toleraut navigation system for aircraft landing is proposed in this paper. The fault-tolerant scheme for redundant sensor configuration is used to detect and isolate failures in on-board sensors, and ensure the reliability of the strapdown inertial navigation system. A failure detection and isolation algorithm is i~mnlented to detect the navigation aid instrument failures. ation results are used to illustrate the effectiveness of the proposed algorithms. 181 Transfer Alignment Scheme for Nonmaneuvering Flight
Zhang Changy~ pp S37-840 This paper proposes a new measured parameter-matching transfer alignment scheme to estimate the relative misaligning angle between master and slave INSs. With this scheme, the angular velocity information is used to estimate the elastic angular vibration of an aircraft's wing, while acceleration information is used to estimate the fLXedmisaligning angle. A damped vibration model is adopted as the dynamic model of wing elastic angular vibration. An excellent result is achieved by using this new scheme, regardless of whether or not a manoeuvre occurs during the course of transfer alignment. 182 A Bayesian Approach to Manoeuvre Tracktn£ and Detection AJ. IsakssombF. Gustatfssomb pp 841-846 This paper describes the general moddling of radar target tracking scenarios. Manoeuvres are modelled using a stochastic continuous-time model, and estimated in a Bayesian framework leading to a bank of Kalman filters. To reduce the number of filters a pruning algorithm is used, enabling simultaneous state estimation and manoeuvre detection. 183 Techuiques for Selecting Pose Algorithms J.E. Mclnroy, G.N. Saridls, pp 84%850 A two-stage technique for selecting one pose algorithm from m algorithms containing zero mean Ganssian errors is derived. First, the joint entropy of each algorithm is found. The algorithm with minimum entropy is shown to possess the greatest possible lowerbound reliability of meeting any quadratic specification of the pose error. In addition, the entropy of pose ~ m e n t s is shown to be invariant with respect to homogeneous coordinate transformations, so the analysis is simplified for physically distributed robotic systems. A method of calculating the actual greatest lower-hound reliability for a given quadratic specification is derived. The concepts are simulated using a visual pose measurement system developed by NASA.
915
184 Dynamic Analysis of Space Station Freedom Assembly via Continuum Modeling L.W. Taylor J r , J. Ramakrishnan, pp 851-854 The initial assembly of Space Station Freedom involves the Space Shuttle and its remote manipulating system (RMS), modeling and analysis of which is made formidable by kinematic and joint nonlinearities. In this paper, continuum models are used instead of finite dement models because of the improved accuracy, reduced number of system parameters, the avoidance of the modal-order reduction and the ability to represent the strucun'al dynamics and control system dynamics in the same system of equations. The continuum modeling approach is seen to offer an alternative to finite dement modeling. 185 A Robust Navigation System for Autonomous Vehicles Using Ultrasonics F. Figueron, A. Mahajan, pp 855-858 A navigation system has been developed for the guidance and control of autonomously guided vehicles using a novel ultrasonic 3D location system in conjunction with traditional ultrasonic rangefinders. This system is most suitable for navigation in structured environments, e.g., factories, hospitals, offices, airplane and space shuttle assembly plants, nuclear power plants and other hazardous areas. The strengths of the system are accuracy (2.54mm), ease of use, self installation/calibration and fast position update rates (>50Hz). A method for automatic modification of maps has been implemented. An object-oriented approach has been used to devdop a system that is robust and flexible. 186 Real-time Optimal Control of Moving Vehides in Changing Environments NL Papageorgiou, A. Steinkogler, pp 859-864 An optimal control approach to vehicle motion control in dynamic environments including moving obstacles is presented, along with a numerical optimization algorithm for calculation of the optimal control trajectories. Low computation times allow for the solution of the optimal motion control problem to be effected on-line, via the rolliag horizon concept, based on updated real-time measm~ments. The described approach provides high flexibility with respect to the vehicle modal, the vehicle mission, and the motion constraints to be considered. Simulation examples demonstrate the efficiency of the approach in managing complioated conflict situations. 187 Adaptive Control of an Aerospace Vehicle During an Aeroassisted OrbR Transfer M. Gugllelmi, E. Le Carpoutier, pp 865-868 The attitude control of a spacecraft with a moderate lift/drag ratio during an aeroassisted orbit transfer is considered. The system is nonlinear, and can be transformed into a linear time-varying one as a function of the aerodynamic velocity of the vehicle and the atmospheric density. The purpose of this work is to use adaptive techniques to control the attitude of the vehicle, so that the closedloop system is time-invariant. The methods proposed here are the gain-scheduling and the self-tuning-regulator techniques. 188 Nonlinear Control Approach to Reentry Guidance of a Spacecraft A. Gra~, G. Joly, J.P. Yvon, pp 869-872 This paper deals with entry guidance of a shuttle orbiter. First, it is necessary to set the trajectory on a reference curve given in the spced/aeceleration plane. This first problem can be solved with an open-lcop optimization. The second step, which is the main contribution of this paper, consists in tracking a reference profile. According to the .framework of nonlinear control theory, a lineariziag feedback is obtained after a change of variables in the state equations. The results obtained show the efficiency of this approach compared to the classical PID control policies given in the relevant literature. 189 Novel Stability and Control Problems of Aerospace Planes G. Sachs, pp 873-876 The stability and control characteristics of aerospace planes in hypersonic fright show substantial differences, compared to aircraft behaviour in the conventional speed regime. While proven control concepts can be successfully used to achieve satisfactory
179 Active Control of a Thin Airfoil: Flutter Suppression and Gust Alleviation EL ~bzbay, pp 829-832 Recently it has been shown that active flutter suppression and gust alleviation problems for a thin airfoil can be solved using standard He° and mixed H2/I-Io° control techniques. The proposed solution depends on finite-dimensional approximations of Theodorsen's function, which appears in the original infinite-dimensioual model of the airfoil. In this paper an approximation scheme is proposed for model reduction. T h e procedure described here provides a "near-optimal" fixed-order h"~ approximation of Theodorsen's function. 180 Fault Tolerant Navigation System for Aircraft Landing H.G. Zhang, H.Y. Zban~ pp 833-836 A fanlt-toleraut navigation system for aircraft landing is proposed in this paper. The fault-tolerant scheme for redundant sensor configuration is used to detect and isolate failures in on-board sensors, and ensure the reliability of the strapdown inertial navigation system. A failure detection and isolation algorithm is i~mnlented to detect the navigation aid instrument failures. ation results are used to illustrate the effectiveness of the proposed algorithms. 181 Transfer Alignment Scheme for Nonmaneuvering Flight
Zhang Changy~ pp S37-840 This paper proposes a new measured parameter-matching transfer alignment scheme to estimate the relative misaligning angle between master and slave INSs. With this scheme, the angular velocity information is used to estimate the elastic angular vibration of an aircraft's wing, while acceleration information is used to estimate the fLXedmisaligning angle. A damped vibration model is adopted as the dynamic model of wing elastic angular vibration. An excellent result is achieved by using this new scheme, regardless of whether or not a manoeuvre occurs during the course of transfer alignment. 182 A Bayesian Approach to Manoeuvre Tracktn£ and Detection AJ. IsakssombF. Gustatfssomb pp 841-846 This paper describes the general moddling of radar target tracking scenarios. Manoeuvres are modelled using a stochastic continuous-time model, and estimated in a Bayesian framework leading to a bank of Kalman filters. To reduce the number of filters a pruning algorithm is used, enabling simultaneous state estimation and manoeuvre detection. 183 Techuiques for Selecting Pose Algorithms J.E. Mclnroy, G.N. Saridls, pp 84%850 A two-stage technique for selecting one pose algorithm from m algorithms containing zero mean Ganssian errors is derived. First, the joint entropy of each algorithm is found. The algorithm with minimum entropy is shown to possess the greatest possible lowerbound reliability of meeting any quadratic specification of the pose error. In addition, the entropy of pose ~ m e n t s is shown to be invariant with respect to homogeneous coordinate transformations, so the analysis is simplified for physically distributed robotic systems. A method of calculating the actual greatest lower-hound reliability for a given quadratic specification is derived. The concepts are simulated using a visual pose measurement system developed by NASA.
915
184 Dynamic Analysis of Space Station Freedom Assembly via Continuum Modeling L.W. Taylor J r , J. Ramakrishnan, pp 851-854 The initial assembly of Space Station Freedom involves the Space Shuttle and its remote manipulating system (RMS), modeling and analysis of which is made formidable by kinematic and joint nonlinearities. In this paper, continuum models are used instead of finite dement models because of the improved accuracy, reduced number of system parameters, the avoidance of the modal-order reduction and the ability to represent the strucun'al dynamics and control system dynamics in the same system of equations. The continuum modeling approach is seen to offer an alternative to finite dement modeling. 185 A Robust Navigation System for Autonomous Vehicles Using Ultrasonics F. Figueron, A. Mahajan, pp 855-858 A navigation system has been developed for the guidance and control of autonomously guided vehicles using a novel ultrasonic 3D location system in conjunction with traditional ultrasonic rangefinders. This system is most suitable for navigation in structured environments, e.g., factories, hospitals, offices, airplane and space shuttle assembly plants, nuclear power plants and other hazardous areas. The strengths of the system are accuracy (2.54mm), ease of use, self installation/calibration and fast position update rates (>50Hz). A method for automatic modification of maps has been implemented. An object-oriented approach has been used to devdop a system that is robust and flexible. 186 Real-time Optimal Control of Moving Vehides in Changing Environments NL Papageorgiou, A. Steinkogler, pp 859-864 An optimal control approach to vehicle motion control in dynamic environments including moving obstacles is presented, along with a numerical optimization algorithm for calculation of the optimal control trajectories. Low computation times allow for the solution of the optimal motion control problem to be effected on-line, via the rolliag horizon concept, based on updated real-time measm~ments. The described approach provides high flexibility with respect to the vehicle modal, the vehicle mission, and the motion constraints to be considered. Simulation examples demonstrate the efficiency of the approach in managing complioated conflict situations. 187 Adaptive Control of an Aerospace Vehicle During an Aeroassisted OrbR Transfer M. Gugllelmi, E. Le Carpoutier, pp 865-868 The attitude control of a spacecraft with a moderate lift/drag ratio during an aeroassisted orbit transfer is considered. The system is nonlinear, and can be transformed into a linear time-varying one as a function of the aerodynamic velocity of the vehicle and the atmospheric density. The purpose of this work is to use adaptive techniques to control the attitude of the vehicle, so that the closedloop system is time-invariant. The methods proposed here are the gain-scheduling and the self-tuning-regulator techniques. 188 Nonlinear Control Approach to Reentry Guidance of a Spacecraft A. Gra~, G. Joly, J.P. Yvon, pp 869-872 This paper deals with entry guidance of a shuttle orbiter. First, it is necessary to set the trajectory on a reference curve given in the spced/aeceleration plane. This first problem can be solved with an open-lcop optimization. The second step, which is the main contribution of this paper, consists in tracking a reference profile. According to the .framework of nonlinear control theory, a lineariziag feedback is obtained after a change of variables in the state equations. The results obtained show the efficiency of this approach compared to the classical PID control policies given in the relevant literature. 189 Novel Stability and Control Problems of Aerospace Planes G. Sachs, pp 873-876 The stability and control characteristics of aerospace planes in hypersonic fright show substantial differences, compared to aircraft behaviour in the conventional speed regime. While proven control concepts can be successfully used to achieve satisfactory