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ESTIMATION OF STATE VECTOR OF A LINEAR STOCHASTIC SYSTEM WITH A CONSTRAINED ESTIMATOR

IEEE TRANSACTIONS ON AUTOMATIC control 1967年第4期AC12卷 432-&页

作者： AOKI, M HUDDLE, JR Department of Engineering University of California Los Angeles CA USA Advanced Engineering Laboratory Guidance and Control Systems Division Litton Systems Inc. Woodland Hills CA USA

The paper presents a constructive design procedure for the problem of estimating the state vector of a discrete-time linear stochastic system with time-invariant dynamics when certain constraints are imposed on the number of memory elements of the estimator. The estimator reconstructs the state vector exactly for deterministic systems while the steady-state performance in the stochastic case may be comparable to that obtained by the optimal (unconstrained) Wiener-Kalman filter.

关键词： State estimation Vectors Stochastic systems Variable speed drives Steady-state Wiener filter Tin control systems Gaussian noise Q measurement

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LOOP-FREE THRESHOLD ELEMENT STRUCTURES

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IEEE TRANSACTIONS ON COMPUTERS 1969年第3期C 18卷 257-+页

作者： MOW, CW FU, KS Litton Industries Guidance and Control Systems Division Computer Laboratory Woodland Hills Calif. Department of Electrical Engineering Purdue University Lafayette Ind.

The paper deals with the problem of "compound" and "cascade threshold" element "synthesis" of an arbitrary Boolean function from the "multithreshold weight threshold vector" (MT... 详细信息

The paper deals with the problem of "compound" and "cascade threshold" element "synthesis" of an arbitrary Boolean function from the "multithreshold weight threshold vector" (MTWTV). The above synthesis procedure is presented to reveal a unique feature of the multithreshold weight threshold vector, from which several realizations of threshold element nets can be obtained from one of the multithreshold weight threshold vectors.

关键词： Cascade Threshold Networks Compound Threshold Networks Equivalent Threshold Function Input Weights Maximum Excitation Minimum Excitation Multithreshold Weight Threshold Vector NPN Operations

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NISAR spacecraft environmental torque modeling during operations

NISAR spacecraft environmental torque modeling during operat...

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AIAA Modeling and Simulation Technologies Conference, 2016

作者： Rizvi, Farheen Jet Propulsion Laboratory California Institute of Technology Dynamics & Control Engineer Guidance & Control Systems Engineering Group Guidance and Control Section Autonomous Systems Division Mail Stop 198-235 4800 Oak Grove Drive PasadenaCA91109 United States

ISBN: (数字)9781624104299

ISBN: (纸本)9781624104299

Environmental torques imparted on the NISAR spacecraft are modeled. The environmental torques comprise of the gravity gradient, atmospheric drag, and solar radiation pressure. These torques act as external disturbances on the spacecraft and cause momentum to accumulate. This momentum needs to be unloaded via attitude control hardware. In order to size the hardware, it is important to determine the environmental torques imparted on the spacecraft. The results indicate that the worst case gravity gradient, drag, and solar radiation pressure torques are 7.4x10-3 Nm, 6.01x10-3 Nm, and 14.03x10-3 Nm, respectively. © 2016 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Torque

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Reducing pointing errors during Cassini reaction control system orbit trim maneuvers

Reducing pointing errors during Cassini reaction control sys...

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AIAA guidance, Navigation, and control (GNC) Conference

作者： Rizvi, Farheen Guidance and Control Systems Engineering Group Guidance and Control Section Autonomous Systems Division Jet Propulsion Laboratory California Institute of Technology Mail Stop 230-104 4800 Oak Grove Drive Pasadena CA 91109 United States

ISBN: (数字)9781624102240

ISBN: (纸本)9781624102240

The effect of altering a gain parameter in the Cassini reaction control system (RCS) delta-V controller on the maneuver execution errors during orbit trim maneuvers (OTMs) is explored. Cassini consists of two reaction control thruster branches (A & B) each with eight thrusters. Currently, the B-branch is operational while the A-branch serves as a back-up. The four Z-thrusters control the X and Y-axes, while the four Y-thrusters control the Z-axis. During an OTM, the Z-thrusters fire to maintain the X and Y-axes pointing within an attitude control dead-zone (-10 to 10 milliradians). The errors do not remain at zero due to pointing error sources such as spacecraft center of mass offset from the geometric center of the Z-facing thrusters, and variability in the thruster forces due to the thruster hardware differences. The delta-V reaction control system (RCS) controller ensures that the attitude error remains within this dead-zone. Gain parameters within the RCS delta-V controller affect the maneuver execution errors. Different parameter values are used to explore effect on these errors. It is found that pointing error decreases and magnitude error increases rapidly for gain parameters 10 times greater than the current parameter values used in the flight software.

关键词： Orbits

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Modeling SMAP spacecraft attitude control estimation error using signal generation model

Modeling SMAP spacecraft attitude control estimation error u...

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AIAA Modeling and Simulation Technologies Conference, 2016

作者： Rizvi, Farheen Jet Propulsion Laboratory California Institute of Technology United States Guidance and Control Systems Engineering Group Guidance and Control Section Autonomous Systems Division Mail Stop 198-235 4800 Oak Grove Drive PasadenaCA91109 United States

ISBN: (数字)9781624103872

ISBN: (纸本)9781624103872

Two ground simulation software are used to model the SMAP spacecraft dynamics. The CAST software uses a higher fidelity model than the ADAMS software. The ADAMS software models the spacecraft plant, controller and actuator models, and assumes a perfect sensor and estimator model. In this simulation study, the spacecraft dynamics results from the ADAMS software are used as CAST software is unavailable. The main source of spacecraft dynamics error in the higher fidelity CAST software is due to the estimation error. A signal generation model is developed to capture the effect of this estimation error in the overall spacecraft dynamics. Then, this signal generation model is included in the ADAMS software spacecraft dynamics estimate such that the results are similar to CAST. This signal generation model has similar characteristics mean, variance and power spectral density as the true CAST estimation error. In this way, ADAMS software can still be used while capturing the higher fidelity spacecraft dynamics modeling from CAST software. © 2016, American Institute of Aeronautics and Astronautics Inc. All rights reserved.

关键词： Dynamics

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Flight results of hyflex onboard measurements

Flight results of hyflex onboard measurements

引用

Space Plane and Hypersonic systems and Technology Conference, 1996

作者： Inouye, Y. Fujii, K. Takizawa, M. Takaki, R. Watanabe, S. Ito, T. National Aerospace Laboratory 7-44-1 Jindaiji-Higashi-Machi Chofu Tokyo182 Japan Aerodynamic Engineering Laboratory Aerodynamics Division Control Systems Division Computational Sciences Division Aerodynamics Division Advanced Aircraft Research Group

One of the objectives in HYFLEX (Hypersonic Flight Experiment) is to get the aerodynamic and aerothermodynamic data along flight path by measurements aboard besides other data. These data provides with basic information of the flight environment along the trajectory, and also with values of a variety of aerothermodynamic properties which serve to establish the reliable design methods through comparison with predictions made by ground tests, analysis and CFD. Data of about 250 items were obtained aboard HYFLEX vehicle and successfully sent during its flight on February 12, 1996. They consist of aerodynamic/aerothermodynamic, structural, G/N, housekeeping etc. In this paper, first of all, the HYFLEX onboard measurement system is briefly reviewed. The inferred atmospheric properties by use of the NOM meteorological satellite data are presented. Results and comparison with predictions are reported and discussed mainly on some measured aerothermodynamic quantities: aerodynamic heating over various parts of the fuselage, pressure distribution on the nose for Flush Air Data System and on a stabilizing fin for RCS gas jet interference characteristics, and plasma density downstream of nose related to RF black-out. Data of the structural strain is also introduced. Flight data were all in good qualities, and are shown in good agreement with respective predictions. © 1996 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Forecasting

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Stability analysis of human–adaptive controller interactions

Stability analysis of human–adaptive controller interaction...

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AIAA guidance, Navigation, and control Conference, 2017

作者： Yucelen, Tansel Yildiz, Yildiray Sipahi, Rifat Youse, Ehsan Nguyen, Nhan Department of Mechanical Engineering University of South Florida TampaFL United States Mechanical Engineering Department Systems Laboratory at Bilkent University Ankara Turkey Mechanical and Industrial Engineering Department Complex Dynamic Systems and Control Laboratory Northeastern University BostonMA United States Advanced Control and Evolvable Systems Group Intelligent Systems Division Ames Research Center of the National Aeronautics and Space Administration Moffett FieldCA United States

ISBN: (数字)9781624104503

ISBN: (纸本)9781624104503

In this paper, stability of human in the loop model reference adaptive control architectures is analyzed. For a general class of linear human models with time-delay, a fundamental stability limit of these architectures is established, which depends on the parameters of this human model as well as the reference model parameters of the adaptive controller. It is shown that when the given set of human model and reference model parameters satisfy this stability limit, the closed-loop system trajectories are guaranteed to be stable. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Closed loop systems

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Lunar descent using sequential engine shutdown

Lunar descent using sequential engine shutdown

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AIAA/AAS Astrodynamics Specialist Conference, 2006

作者： Springmann, Philip N. Proulx, Ronald J. Fill, Thomas J. Northrop Grumman Corporation Chantilly VA 20151 United States Charles Stark Draper Laboratory Inc. Cambridge MA 02139 United States Advanced Missions Division TASC AIAA United States Department of Aeronau Tics and Astronautics Massachusetts Institute of Technology Cambridge United States Guidance Navigation and Control Systems Division

ISBN: (纸本)1563478226

Sequential engine shutdown refers to the use of multiple fixed thrust engines in place of a single continuously throttleable one. Downrange position control is provided by properly timed engine shutdowns. The principal advantage offered is the potential cost savings that would result from the elimination of the development costs associated with a new throttleable rocket engine. A sequential engine shutdown-based guidance scheme is developed for the braking phase of powered lunar descent. The guidance scheme consists of a biased ignition point and an algorithm for calculating shutdown times combined with a linear tangent steering law to provide full terminal state control. The performance of the sequential engine shutdown guidance scheme is assessed against two alternative approaches. A statistical picture of the performance of each guidance scheme is obtained via Monte Carlo trials of a lunar descent simulation that captures, to first order, the interaction between the descent propulsion system, the navigation filter, and the guidance function. While the performance observed with sequential engine shutdown does not match that observed with a throttleable engine, the results suggest that it may be a viable solution to the lunar descent guidance problem. Copyright © 2006 by The Charles Stark Draper laboratory, Inc.

关键词： Lunar missions

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Direct trajectory optimization and costate estimation via an orthogonal collocation method

Direct trajectory optimization and costate estimation via an...

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AIAA guidance, Navigation, and control Conference 2006

作者： Benson, David A. Huntington, Geoffrey T. Thorvaldsen, Tom P. Rao, Anil V. Charles Stark Draper Laboratory 555 Technology Square Cambridge MA 02139 United States Draper Laboratory United States Dept. of Aeronautics and Astronautics MIT United States Tactical ISR Division Guidance Navigation and Control Systems Division United States Dept. of Mechanical and Aerospace Engineering University of Florida Gainesville FL 32611 United States

ISBN: (纸本)1563478196

A pseudospectral method, called the Gauss pseudospectral method, for solving nonlinear optimal control problems is presented. In the method presented here, orthogonal collocation of the dynamics is performed at the Legendre-Gauss points. This form of orthogonal collocation leads a nonlinear programming problem (NLP) whose Karush-Kuhn-Tucker (KKT) multipliers can be mapped to the costates of the continuous-time optimal control problem. In particular the Legendre-Gauss collocation leads to a costate mapping at the boundary points. The method is demonstrated on an example problem where it is shown that highly accurate costates are obtained. The results presented in tills paper show that the Gauss pseudospectral method is a viable apprach for direct trajectory optimization and costate estimation. Copyright © 2006 by The Charles Stark Draper laboratory, Inc.

关键词： Nonlinear control systems

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Using front and back information for tight vehicle following maneuvers

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IEEE Transactions on Vehicular Technology 1999年第1期48卷 319-328页

作者： Y. Zhang B. Kosmatopoulos P.A. Ioannou C.C. Chien Center for Advanced Transportation Technologies Department of Electrical Engineering Systems University of Southern California Los Angeles CA USA Department of Electronics Control Division of Information Storage Opto-Electrons System Laboratory Industrial Research Institute Hsinchu Taiwan

During manual driving, most human drivers often use information about the speed and position of the preceding and following vehicles in order to adjust the position and speed of their vehicles. The purpose of this paper is to design an autonomous intelligent cruise control (AICC) which mimics this human driving behavior. The proposed AICC law uses relative speed and spacing information from the preceding and following vehicles in order to choose the proper control action for smooth vehicle following and for maintaining a desired intervehicle spacing specified by the driver. The vehicle stability and platoon stability (in the case of multiple vehicles) in both directions (backward and forward) are guaranteed by the proposed AICC law. Furthermore, platoon stability is guaranteed for a speed-dependent desired spacing (time headway approach) as well as for a constant desired spacing at all speeds.

关键词： Intelligent control Intelligent vehicles Remotely operated vehicles Mobile robots Vehicle driving Stability Vehicle safety Automatic control Humans control systems

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