The deployment/retrieval control of a tethered subsatellite connected through an elastic tether to a main body is studied. The dynamical model of the tether is a continuum, and the effect of tether elasticity is taken...
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The deployment/retrieval control of a tethered subsatellite connected through an elastic tether to a main body is studied. The dynamical model of the tether is a continuum, and the effect of tether elasticity is taken into account, Large deflection theory is adopted to formulate the strain of tether, The motion is described by nonlinear, partial differential, and time-varying equations and is treated directly without using any approximation of the modal analysis. The mission-function control algorithm is applied to the deployment/retrieval control of the subsatellite connected through the elastic tether. Results of numerical simulation show that the present control law works quite well for deployment/retrieval control of the subsatellite, and that the elastic vibrations of the tether are suppressed satisfactorily.
A realistic stochastic control problem for hybrid systems with Markovian jump parameters can have the switching parameters in both the state and measurement equations. Furthermore, both the "base" and jump s...
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A realistic stochastic control problem for hybrid systems with Markovian jump parameters can have the switching parameters in both the state and measurement equations. Furthermore, both the "base" and jump states, in general, are not perfectly observed. Currently, there are only two existing controllers for this problem, both with complexity exponentially increasing with time. In this note, we present a new control algorithm for stochastic systems with Markovian jump parameters. This algorithm is derived through the use of stochastic dynamic programing and is designed to be used for realistic stochastic control problems, i.e., with noisy state observations. This new scheme has fixed computational requirements per stage and a natural parallel implementation. Simulation results compare this new control algorithm to the previous schemes.
The vibration loads of a helicopter rotor are transmitted to the fuselage through gearbox support struts and cause severe vibration of the fuselage. A piezoelectric stack actuator has the advantages of light weight, a...
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The vibration loads of a helicopter rotor are transmitted to the fuselage through gearbox support struts and cause severe vibration of the fuselage. A piezoelectric stack actuator has the advantages of light weight, a large driving force, small driving displacement, a wide working frequency range, and a fast response speed;it is an ideal actuator for the active vibration control of structures. The piezoelectric stack actuators are installed on the gearbox support struts, which can effectively control the vibration of the helicopter fuselage. In this paper, the dynamic models of the piezoelectric stack actuators, the rotor/gearbox, the gearbox support struts, and the fuselage coupling system are established. Combining the adaptive harmonic synchronization identification and updating algorithm with the sliding-mode algorithm, the adaptive harmonic feedforward/sliding-mode feedback hybrid active control method for helicopter fuselage vibration is proposed. The simulation results show that, under the excitation of the rotor vibration loads with the first three rotor passing frequencies, the acceleration responses of the fuselage in three directions by using the proposed hybrid active control method are reduced by more than 98%;when the amplitudes, phases, and frequencies of the vibration loads are changed, the active control of the fuselage vibration by using the hybrid active control method has a fast convergence speed and a strong adaptive ability.
The prototype algorithm of Human Simulated Intelligent control leads to the overshoot easily, it can not simulate human control Strategies completely. The modified algorithm of HSIC which is called Human-Like Intellig...
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The prototype algorithm of Human Simulated Intelligent control leads to the overshoot easily, it can not simulate human control Strategies completely. The modified algorithm of HSIC which is called Human-Like Intelligent control is pointed out in this paper, it divides control process into three stages: initial stage, adjusting stage and eliminating disturbance stage. The different control algorithms will be used in different stage, the control method do its best to simulate human control intelligences more nearly. The test results are given , it proves that the experimental result of the prototype algorithm is relatively stable but oscillating, the experimental result of the modified algorithm is better than the prototype algorithm, there is a consistency among stability, fast response and the best accuracy. The HLIC can be used in the process control.
Modern combat aircraft can fly at unusual orientations. The spatial disorientation trainer (SDT) examines a pilot's ability to recognise these orientations, to adapt to unusual positions and to persuade the pilot ...
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Modern combat aircraft can fly at unusual orientations. The spatial disorientation trainer (SDT) examines a pilot's ability to recognise these orientations, to adapt to unusual positions and to persuade the pilot to believe in the aircraft instruments for orientation and not in his own senses. The SDT is designed as a four-degree-of-freedom (4DoF) manipulator with rotational axes. Through rotations about these axes, different orientations can be achieved;different acceleration forces acting on the pilot can also be simulated. In this paper, a control algorithm of an SDT that improves the quality and safety of the SDT motion while improving position accuracy and reducing servo errors is proposed. This control algorithm uses approximate inverse dynamics based on the recursive Newton-Euler algorithm, which accounts for the motors present in the system;it calculates motor torques, as well as the forces and moments acting on the SDT links based on the achievable velocities and accelerations of the robot links. This algorithm enables accurate dimensioning of the axes bearings and links as well. The maximum possible accelerations of the SDT links are calculated in each interpolation period based on the total moments of inertia for the axes of rotation of these links, mutual influences of the link accelerations on each other, and motor capabilities. The forces, moments and torques that act on the SDT links obtained with the suggested algorithm have lower magnitude and smoother profile. In this study, the forces and angular velocities that act on the simulator pilot in the SDT are calculated along with the roll and pitch angles of the gondola for these forces. (C) 2015 Elsevier Ltd. All rights reserved.
In this study, the problem of rate damping a spacecraft by using two single-gimbal control moment gyros in an arbitrary configuration is considered. A feedback control law for a two-single-gimbal control moment gyro s...
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In this study, the problem of rate damping a spacecraft by using two single-gimbal control moment gyros in an arbitrary configuration is considered. A feedback control law for a two-single-gimbal control moment gyro system is designed based on Lyapunov analysis and is applicable to the fault-tolerant control of a redundant-single-gimbal control moment gyro system, such as a pyramid-type system. A steady-state analysis is conducted and presented in detail. Rate damping is achieved for almost all initial conditions if the total angular momentumof the spacecraft is less than the sum of the angular momenta of the single-gimbal control moment gyros, in which case the angular velocity of the spacecraft is decreased to zero. In contrast, rate damping is not achieved if the total angular momentum of the spacecraft is greater than the sum of the angular momenta of the single-gimbal control moment gyros, in which case the spacecraft converges to a spinning motion for almost all initial conditions. The results of the analysis are demonstrated through numerical simulations.
We consider the problem of constructing an adaptive control system with nonlinear reference model for a low order nonstationary dynamical object with a nonlinear actuator. We show the structure, analysis, and mathemat...
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We consider the problem of constructing an adaptive control system with nonlinear reference model for a low order nonstationary dynamical object with a nonlinear actuator. We show the structure, analysis, and mathematical modeling results for the adaptive control system.
A double-gimbal control-moment gyro (CMG) is modeled using Lagrange's equations, and an adaptive feedback control law is developed to follow a commanded CMG motion. The control law does not require knowledge of th...
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A double-gimbal control-moment gyro (CMG) is modeled using Lagrange's equations, and an adaptive feedback control law is developed to follow a commanded CMG motion. The control law does not require knowledge of the mass properties of the CMG. A Lyapunov argument is used to prove that command following is achieved globally with asymptotic convergence. Numerical simulations are performed to illustrate the command following algorithm. A CMG testbed was designed and constructed to implement and demonstrate the adaptive algorithm. This testbed is described, and experimental results are given.
The growth of electricity market due to increase in demand and infrastructure made the power system more complex. Managing the transmission congestion is one of the main challenges faced by the utilities. To relieve f...
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The growth of electricity market due to increase in demand and infrastructure made the power system more complex. Managing the transmission congestion is one of the main challenges faced by the utilities. To relieve from the bottlenecks, Flexible AC Transmission Systems (FACTS) and Distributed FACTS (D-FACTS) devices can be used in controlling the transmission line power flows. The real power flow control is realized by varying the transmission line impedance. The power flow in transmission line should satisfy inequality constraints to maintain the system in normal state. To achieve this, an algorithm is developed to control the FACTS/D-FACTS devices connected to all the transmission lines of n-bus system. The significant changes required in line impedance which will be deployed by FACTS devices are decided by the algorithm. In this paper, a 5 bus system and a 14 bus system with FACTS devices in all the transmission lines is considered. The transmission lines of the 5 and 14 bus systems are made to be overloaded in different combinations by choosing appropriate loading conditions. The control algorithm is tested on all the overloaded conditions to overcome the congestion. The FACTS devices controlled by the algorithm removes the overloading effect and improve the reliability of the network. (C) 2015 Elsevier Ltd. All rights reserved.
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