A new class of angular velocity-free attitude stabilization controllers that can be viewed as generalizations of the existing passivity-based control algorithms in the sense of providing an additional provision for in...
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A new class of angular velocity-free attitude stabilization controllers that can be viewed as generalizations of the existing passivity-based control algorithms in the sense of providing an additional provision for integral feedback action was designed. Global asymptotic stability for the full state of the rigid-body rotational motion was demonstrated when the external disturbances are absent. The disturbance rejection aspect was illustrated using a linearized setting of the problem. The controller structure includes a low-pass filter state that is derived without explicit differentiation of attitude to synthesize angular velocity-like signals.
A mathematical model is developed and analytical evaluations are made for angular revolutions of a (return space vehicle) RSV during formation of the stable balance equilibrium on large angles of attack without applic...
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A mathematical model is developed and analytical evaluations are made for angular revolutions of a (return space vehicle) RSV during formation of the stable balance equilibrium on large angles of attack without application of control moment. The special balance mode permits RSV to widen a touchdown area after orbital departure. Results obtained are of practical significance in designing of promising RSVs including reusable launch vehicles for servicing ISS and in development of program and algorithm software including an onboard control algorithm to orient the lift force in space.
An experiment of adaptive polarization mode dispersion (PMD) compensation for 40-Gb/s return-to-zero (RZ) optical communication system is reported. In the experiment, degree of polarization (DOP) is used as feedback s...
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An experiment of adaptive polarization mode dispersion (PMD) compensation for 40-Gb/s return-to-zero (RZ) optical communication system is reported. In the experiment, degree of polarization (DOP) is used as feedback signal and particle swarm optimization (PSO) method is adopted as logic control *** compensation time is about 200 ms, the compensated differential group delay (DGD) is up to 30 ps,and bit error rate (BER) of 10-9 is reached when PMD compensation is employed.
To lower satellite orbital maintenance cost, spacecraft designers are seeking flight software that provides more autonomy. Longitude and eccentricity are good candidates for autonomous control of geostationary spacecr...
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To lower satellite orbital maintenance cost, spacecraft designers are seeking flight software that provides more autonomy. Longitude and eccentricity are good candidates for autonomous control of geostationary spacecraft. The algorithm presented couples longitude control with eccentricity control. Longitude drift is modeled as one-degree-of-freedom motion and controlled with a quadratic equation predicting the subspacecraft Earth reference longitude after a predetermined amount of time. After formulation of the basic longitude control algorithm, addition of a differential corrections scheme resulted in an improved longitude error of +/-0.015degrees longitude. Finally, implementation of longitude control and two-part maneuvers for eccentricity control successfully met the desired mission constraints. The algorithms developed form the basis for preparation of flight software for a geostationary spacecraft scheduled to launch in the next few years.
With the development of the intelligent construction in China, the research on the control method of its environment temperature has become an important subject for the related research field. Based on the dynamic ana...
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With the development of the intelligent construction in China, the research on the control method of its environment temperature has become an important subject for the related research field. Based on the dynamic analysis of the room temperature and air-condition system, the serial control strategy is presented in this paper, in which the master loop concerns with the control of the room temperature, and the slave loop is the control of the parameter delivering wind. Through the deep analysis of its work performance, it is proved that the serial control strategy is better than the single loop control because it can decrease the dynamic gain of the second interference for the loop of the room temperature. In the end, its control algorithm, whose master loop is PID and slave loop is PI, is investigated, and the good control effects about decreasing the dynamic error and compressing response time are gained by an experiment.
This paper focuses on the robustness analysis of a simple (second-order) control algorithm for data transfer in high-speed networks. The model under consideration (derived using a fluid approximation technique) can be...
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This paper focuses on the robustness analysis of a simple (second-order) control algorithm for data transfer in high-speed networks. The model under consideration (derived using a fluid approximation technique) can be found in Izmailov (1996). The novelty of the approach lies in characterizing the stability of the scheme in the delay-parameter space (where the delays correspond to the control-time interval, and to the round-trip time, respectively), and its interest is due to the computation of some delay-insensitive measures for the algorithm which give upper and lower bounds for the uncertainty in the knowledge of the round-trip times.
A 'smart' mild steel damper is proposed in this paper to provide active damping for seismic control of structures. Smart material, which is bonded to the surface of hysteric dampers, is employed as actuator to...
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A 'smart' mild steel damper is proposed in this paper to provide active damping for seismic control of structures. Smart material, which is bonded to the surface of hysteric dampers, is employed as actuator to exert active control force to increase damping effect for the vibration reduction of structural systems. 'Smart' finite element formulation is outlined for the numerical analysis of the proposed control device. Two control algorithms were adopted to regulate active control forces. The results of numerical simulation with two example models show the effectiveness of smart material used for active damping. (C) 2003 Elsevier Science Ltd. All rights reserved.
The motion control problem for a class of mechanical systems is addressed. The system configuration can be represented in terms of a set of generalized coordinates in R-n and 1 rotation matrices in the special orthogo...
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The motion control problem for a class of mechanical systems is addressed. The system configuration can be represented in terms of a set of generalized coordinates in R-n and 1 rotation matrices in the special orthogonal (SO)(3) group. A key point is the choice of a globally valid parameterization of SO(3) in lieu of the usual three-parameter representations. To this end, the unit quaternion is adopted. A novel control law is proposed that is based on a velocity observer to avoid velocity measurements. Exponential tracking of the commanded motion trajectory is proven via the Lyapunov direct method. The proposed controller-observer scheme is first applied in a simulation case study to the attitude control of a rigid spacecraft. Then, the problem of position and orientation control of the end effector of a robot manipulator is considered. For the latter case, experimental results are provided to show the potential of the approach in tackling practical problems.
In this study a general approach is introduced for the design of a robust control law for suppression of structure borne vibration. This control law is based on a passive design in the form of dynamic vibration absorb...
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In this study a general approach is introduced for the design of a robust control law for suppression of structure borne vibration. This control law is based on a passive design in the form of dynamic vibration absorbers. Passive absorbers minimize vibration at a specific frequency, but their performance is improved by introducing adaptive tuning of the absorber. An adaptive dynamic vibration absorber is tuned to the forcing frequency, using classical methods. The tuning ratio is time varying and adapts itself to variations in the forcing frequency. However, the uniqueness of the approach in this study is that the damping parameter of the absorber is continuously varied by means of a fuzzy-logic control algorithm to provide a lower sound pressure level. The inputs of:the fuzzy control law are the displacement and velocity of the main structure: The effectiveness of the control algorithm for active vibration control is demonstrated using MATLAB(R) simulations of a single-degree-of-freedom plant. This methodology provides superior performance in the presence of significant mistuning compared to a more conventional approach.
Active control systems for the attenuation of pressure oscillations in unstable combustors have been under development by a wide variety of investigators. Whereas many of these applications have been in simplified, be...
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Active control systems for the attenuation of pressure oscillations in unstable combustors have been under development by a wide variety of investigators. Whereas many of these applications have been in simplified, bench-scale combustors, some significant efforts have been made in realistic systems including full-scale gas turbine engines. Results from these efforts, although generally positive, have been varied. As the technology has matured, the understanding of the factors that currently limit its capability has improved. Some of these factors and how they may be quantified through experiments, models, or combined approaches are addressed. The application focus was lean, premixed combustors for industrial gas turbines. Both gas- and liquid-fueled systems were considered. In particular, the effects of actuation system time delay and actuated fuel mixing are examined, and the fundamental limits of control in systems with time delay are considered. The results indicate that the mixing of the actuated fuel with the remainder of the premixed reactants is significant in determining control authority. The effects of system time delays are shown to result in a peak splitting phenomenon, which limits the degree to which pressure oscillations can be reduced. A further examination of the fundamental limits of control demonstrates that it is not possible to arbitrarily decrease the level of pressure oscillations using linear controllers. The factors that limit the achievable reduction level are the time delay, the combustor damping, and the actuator bandwidth.
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