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Wang H.,Beijing Institute of Control Engineering
IEEE Transactions on Automatic Control | Year: 2017

In this note, we investigate the adaptive control problem for robot manipulators with both the uncertain kinematics and dynamics. We propose two adaptive control schemes to realize the objective of task-space trajectory tracking irrespective of the uncertain kinematics and dynamics. The proposed controllers have the desirable separation property, and we also show that the first adaptive controller with appropriate modifications can yield the improved performance, without the expense of the conservative gain choice. The performance of the proposed controllers is shown by numerical simulations. © 1963-2012 IEEE.


Wang H.,Beijing Institute of Control Engineering
IEEE Transactions on Automatic Control | Year: 2016

This technical note addresses the second-order consensus problem of multiple underactuated thrust-propelled vehicles (TPVs) on directed graphs containing a directed spanning tree. We propose an adaptive control approach to resolve this problem, and the proposed controller does not rely on the commonly used backstepping methodology and the exact knowledge of the mass properties of the TPVs. In addition, the resultant complexity is reduced and the requirement on the interaction graph is relaxed. Using an input-output analysis, we show that the proposed controller realizes second-order consensus of the TPVs, i.e., the position and velocity consensus errors between the TPVs converge to zero, and moreover the velocities of the TPVs converge to the weighted average of their initial values. The performance of the proposed control approach is shown by a numerical simulation. © 1963-2012 IEEE.


Wan R.-G.,CAS Xi'an Institute of Optics and Precision Mechanic | Zhang T.-Y.,CAS Xi'an Institute of Optics and Precision Mechanic | Kou J.,Beijing Institute of Control Engineering
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We propose a scheme for two-dimensional atom localization based on the coherent controlled absorption and gain of a weak probe field in a four-level double-Λ system, in which the atom interacts with two orthogonal standing-wave fields. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom passing through the standing waves can be directly determined by measuring the resulting absorption and gain spectra. The phase-sensitive property of the atomic system significantly reduces the uncertainty in the position measurement of the atom. It is found that, by properly varying the parameters of the system, we can achieve sub-half-wavelength atom localization with high precision. Especially the probability of finding the atom at a particular position can be 100% when a photon with certain frequency is absorbed or amplified. Numerical calculations and qualitative analyses show that the enhancement of precision in the position measurement of the atom is attributed to the interference between the one-photon excitation and the phase-dependent three-photon excitation from the closed interacting contour in the laser-driven atomic system. © 2013 American Physical Society.


Wang H.,Beijing Institute of Control Engineering
Automatica | Year: 2015

In this paper, we investigate the visual tracking problem for robotic systems without image-space velocity measurement, simultaneously taking into account the uncertainties of the camera model and the manipulator kinematics and dynamics. We propose a new image-space observer that exploits the image-space velocity information contained in the unknown kinematics, upon which, we design an adaptive controller without using the image-space velocity signal where the adaptations of the depth-rate-independent kinematic parameter and depth parameter are driven by both the image-space tracking errors and observation errors. The major superiority of the proposed observer-based adaptive controller lies in its simplicity and the separation of the handling of multiple uncertainties in visually servoed robotic systems, thus avoiding the overparametrization problem of the existing work. Using Lyapunov analysis, we demonstrate that the image-space tracking errors converge to zero asymptotically. The performance of the proposed adaptive control scheme is illustrated by a numerical simulation. © 2015 Elsevier Ltd.


Wang H.,Beijing Institute of Control Engineering
Automatica | Year: 2013

This paper investigates the flocking problem of networked nonlinear Euler-Lagrange systems with parametric uncertainties, and they are assumed to interact on directed graphs with a directed spanning tree. We propose an adaptive controller to achieve the flocking objective, and the resultant closed-loop networked system bears the cascade structure. Using a new similarity decomposition approach, a critical-characteristic-root based approach, and the input-output stability analysis, we demonstrate the convergence of the position/velocity synchronization errors among the uncertain nonlinear Euler-Lagrange agents. We also show that the velocities of the Euler-Lagrange systems converge to the weighted average velocity value. Simulation results are provided to demonstrate the performance of the proposed controller. © 2013 Elsevier Ltd. All rights reserved.


Wang H.,Beijing Institute of Control Engineering
Automatica | Year: 2013

This paper investigates the problem of synchronization of networked robotic systems with uncertainties in both kinematics and dynamics. Passivity of the robotic agents is established through adaptation to both the kinematic and dynamic uncertainties. This input-output passivation framework provides the basis for the inter-coupling inclusion between the robotic agents, even in the case of non-uniform constant communication delays. An adaptive scheme is proposed to achieve controlled synchronization of the networked robotic systems on strongly connected graphs. With a weighted Lyapunov-Krasovskii function, we show that both the task-space tracking errors and synchronization errors of the networked robotic agents converge to zero. Simulation results are provided to demonstrate the performance of the proposed control scheme. © 2012 Elsevier Ltd. All rights reserved.


Wang H.,Beijing Institute of Control Engineering
Robotics and Autonomous Systems | Year: 2011

This paper is devoted to the investigation of adaptive inverse dynamics for free-floating space manipulators (FFSMs) suffering from parameter uncertainties/variations. To overcome the nonlinear parametric problem of the dynamics of FFSMs, we introduce a new regressor matrix called the generalized dynamic regressor. Based on this regressor, and with Lyapunov stability analysis tools, we obtain a new parameter adaptation law and show that the closed-loop system is stable, and that the joint tracking errors converge asymptotically to zero. Simulation results are provided to illustrate the performance of the proposed adaptive algorithm. Furthermore, we conduct a comparative study between adaptive inverse dynamics, prediction error based adaptation, and passivity based adaptation. © 2011 Elsevier B.V. All rights reserved.


Patent
Beijing Institute of Control Engineering | Date: 2014-05-20

A liquid storage device for a propellant tank in a spacecraft includes a gas-guide tube, a cover plate, a housing, blades, a supporting column, a base, a passage-window pressing plate, a passage-window mesh piece, a liquid-storage-device mesh piece, a fixing block, and a pressing plate for the liquid-storage-device mesh piece. The blades are uniformly distributed on and fixed to the support column in a radial direction to form an integral structure, and the integral structure is mounted on and fixed to a circular partition plate in the base. The liquid-storage-device mesh piece is pressed on the circular partition plate in the base by the pressing plate for the liquid-storage-device mesh piece and then is fixed. The passage-window mesh piece is pressed on the outer side of a cylinder wall of the base by the passage-window pressing plate and then is fixed.


Wang H.,Beijing Institute of Control Engineering
IEEE Transactions on Automatic Control | Year: 2014

This technical note addresses the consensus problem of networked uncertain mechanical systems which interact on directed graphs containing a spanning tree and are subjected to nonuniform communication delays. The challenge lies in the unclear input-output property of a linear networked system containing communication delays and the unclear convergent property of this system under an external input. We establish a new input-output property of this linear networked system and moreover its convergent property under an external input, upon which, we establish a unified framework to resolve the consensus problem of multiple mechanical systems. The proposed consensus framework unifies/extends the existing results and in addition yields a fully cascaded closed-loop system. With Lyapunov-like analysis and frequency domain input-output analysis, we show that the proposed unified consensus control scheme ensures consensus without the integral action of the sliding vector, and scaled weighted average consensus with the integral action of the sliding vector. Simulation results are provided to demonstrate the performance of the proposed consensus schemes. © 1963-2012 IEEE.


Wang H.,Beijing Institute of Control Engineering
IEEE Transactions on Automatic Control | Year: 2013

In this technical note, we investigate the task-space synchronization for networked robots interconnected on strongly connected graphs with both the uncertain kinematics and dynamics. A cascade framework is proposed to facilitate the synchronization controller design for networked robotic systems. Under this framework, we propose an adaptive task-space synchronization scheme with indirect/direct kinematic parameter adaptations and a direct dynamic parameter adaptation for the networked robots. We employ the passive decomposition approach to show the asymptotic task-space synchronization of the networked system, and we demonstrate that the proposed control is capable of ensuring the weighted average consensus of the networked uncertain robots. Simulation results are provided to demonstrate the performance of the proposed control approach. © 1963-2013 IEEE.

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