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[en] Feedback control protocols can stabilize and enhance the operation of quantum devices, however, unavoidable delays in the feedback loop adversely affect their performance. We introduce a quantum control methodology, combining open-loop control with quantum filtering, which is not constrained by feedback delays. For the problems studied (rapid purification and rapid measurement) we analytically derive lower bounds on the control performance that are comparable with the best corresponding bounds for feedback protocols.
[en] Highlights: • Combination of voltage open loop control and current limiting control is proposed to get the maximum current rising rate of active feedback control coils. • Experimental results prove that voltage mode can greatly improve the ability to suppress vertical unstable displacement of plasma in Tokamak device. - Abstract: To achieve the maximum current rising rate and obtain a high precision, the second-generation EAST active feedback power supply applies voltage mode while retaining current tracking mode of the first-generation power supply. In voltage mode, power supply outputs an average voltage linear to the reference signal. When high output voltage is applied to the load inductance, output current increases approximate linearly. Over-current protection is activated to turn off the power transistors once increasing current exceeds a certain threshold. The power stored within the load inductance will be released through the inverse parallel diodes of the IGBTs to DC side, which leads to rising of the voltage on DC side and it becomes easier to cause over-voltage protection. So current limiting protection is triggered after over-current protection to maintain the permissible maximum output current. Experimental results prove that voltage mode can greatly improve the ability to suppress vertical unstable displacement of plasma in Tokamak device.
[en] The inverse Volterra operators have been proposed as an open look control for sensors and actuators systems. Large mathematical development has been done in the area, however the implementation of a continuous time model of the inverse Volterra may be difficult. That is why in this work a discrete version of the Associated Linear Equations for the inverse operator is proposed. The control strategy is tested on an analog electronic Duffing oscillator system.
[en] In spacecraft, severe vibrations induced by the launch vehicle may cause damage to the precision payload. Therefore active adapters with vibration suspending characteristics are needed. This paper presents theoretical studies of the active vibration control characteristics of conical shells with laminated piezoelectric actuators. A diagonal piezoelectric actuator is proposed to control the axial, lateral and transverse vibrations of the conical shell. Modal functions are designed to represent the free vibrations of the conical shell with clamped-free boundary conditions. General formulae of the modal control force and corresponding components are derived based on the converse piezoelectric effects and then specified for the diagonal actuators. By using an open-loop control method, the modal control characteristics of diagonal actuator segments at different locations are investigated and compared, and the axial, lateral and transverse vibrations of two conical shell models are evaluated. The optimal locations of actuator segments for the control of different natural modes are also investigated
[en] Resolved motion control enables the end effector to be moved as a rigid body in space without having to work out manually the joint combinations needed. Since a rigid body in space has three independent translational and three independent rotational movements, a manipulator with at least six joints can be controlled in this way. Normally the manipulator has more than six joints providing an infinite number of ways of moving the tip in the desired direction and this redundancy can be exploited in a variety of ways. Resolved motion tests performed on a hydraulically operated heavy duty manipulator at the Dungeness nuclear power plant are described. The results have shown that manipulators with as many as ten joints can be controlled under resolved tip motion and the areas which are critical to the performance of this type of control have been identified. (UK)
[en] A Lyapunov (open-loop) control is often confronted with uncertainties and errors in practical applications. In this paper, we analyse the robustness of the Lyapunov control against the uncertainties and errors in quantum control systems. The analysis is carried out by examining the uncertainties and errors and calculating the control fidelity under the influence of the certainties and errors. Two examples, a closed control system and an open control system, are presented to illustrate the general formalism, discussions on the effect caused by the uncertainties and errors are given.
[en] Interacting surface waves, parametrically excited by two commensurate frequencies, yield a number of nonlinear states. Near the system's bicritical point, a state, highly disordered in space and time, results from competition between nonlinear states. Experimentally, this disordered state can be rapidly stabilized to a variety of nonlinear states via open-loop control with a small-amplitude third frequency excitation, whose temporal symmetry governs the temporal and the spatial symmetry of the selected nonlinear state. This technique also excites rapid switching between nonlinear states
[en] This paper addresses the development of new formulations for estimating modeling errors or unmeasured disturbances to be used in Model Predictive Control (MPC) algorithms during open-loop prediction. Two different formulations were developed in this paper. One is used in MPC that directly utilizes linear models and the other in MPC that utilizes non-linear models. These estimation techniques were utilized to provide robust performance for MPC algorithms when the plant is open-loop unstable and under the influence of modeling error and/or unmeasured disturbances. For MPC that utilizes a non-linear model, the estimation technique is formulated as a fixed small size on-line optimization problem, while for linear MPC, the unmeasured disturbances are estimated via a proposed linear disturbance model. The disturbance model coefficients are identified on-line from historical estimates of plant-model mismatch. The effectiveness of incorporating these proposed estimation techniques into MPC is tested through simulated implementation on non-linear unstable exothermic fluidized bed reactor. Closed-loop simulations proved the capability of the proposed estimation methods to stabilize and, thereby, improve the MPC performance in such cases. (Author)
[en] In this paper, an electromechanical, two axes sun tracking system is designed and constructed. The programming method of control with an open loop system is employed where the programmable logic controller is used to control the motion of the sun tracking surface. An experimental study was performed to investigate the effect of using two axes tracking on the solar energy collected. The collected energy was measured and compared with that on a fixed surface tilted at 32 deg. towards the south. The results indicate that the measured collected solar energy on the moving surface was significantly larger than that on a fixed surface. The two axes tracking surface showed a better performance with an increase in the collected energy of up to 41.34% compared with the fixed surface
[en] We demonstrate the destruction of attractors in the logistic map with time delayed feedback by means of a weak harmonic modulation applied in different ways. The ability of the method to select a desired state is illustrated through codimensional-two bifurcation diagrams in the parameter space of the frequency and amplitude of the control modulation. We compare the efficiencies of different kinds of the open-loop control in annihilating attractors, in particular, when the modulation is applied to a feedback variable, feedback strength or multiplicative parameter. The comparative analysis shows that modulation of the parameter is the most efficient way for destroying the attractors