三轴稳定挠性卫星姿态机动时变滑模变结构和主动振动控制

针对带有控制受限的挠性卫星的姿态机动和振动控制问题, 给出了一类仅利用输出信息的变结构控制和 基于智能材料的主动振动控制技术相结合的复合控制方法. 首先给出变结构姿态控制器的设计来完成卫星姿态机动, 并给出一种切换机制以实现挠性卫星快速姿态机动; 其次, 采用分布式压电元件作为作动器, 设计了应变速率反馈补偿器以增加挠性结构的阻尼, 使其振动能够很快衰减. 最后, 将本文提出的方法应用于三轴稳定挠性卫星的姿态机动控制, 仿真结果表明: 在推力器的控制受限条件下, 完成姿态机动的同时, 有效地抑制挠性附件的振动.     

Feedback control design with vibration suppression for flexible air-breathing hypersonic vehicles

This paper investigates the problem of feedback control design with vibration suppression for a flexible air-breathing hypersonic vehicle （FAHV）. FAHV includes intricate coupling between the engine and flight dynamics, as well as complex interplay between flexible and rigid modes, which results in an intractable system for the control design. In this paper, a longitudinal model, which is described by a coupled system of ordinary differential equations （ODEs） and partial differential equations （PDEs）, is adopted. Firstly, a linearized ODE model for the rigid part is established around the trim condition, while vibration of the fuselage is described by PDEs. Secondly, based on the Lyapunov direct method, a control law via ODE state feedback and PDE boundary output feedback is designed for the system such that the closed-loop exponential stability is ensured. Finally, simulation results are given to illustrate the effectiveness of the proposed design method.     

柔性机械臂的变结构振动控制研究

当机械臂的质量很轻,尤其是空间应用场合,机器人系统将受到高度柔性限制并且不可避免地产生机械振动.本文为了证实提出的控制不期望残余振动的方法,设计并建立了柔性机器人实验平台.控制方案采用交流伺服电机通过谐波齿轮减速器驱动柔性机械臂,利用粘贴在柔性臂上的压电陶瓷片(PZT)作为传感器来检测柔性臂的振动.对由于环境激励,尤其是在电机转动(机动)时由于电机力矩产生的振动,采用了几种主动振动控制器包括模态PD控制,软变结构控制(VSC)和增益选择变结构方法,进行柔性臂的振动主动控制实验研究.通过实验比较研究,结果表明采用的控制方法可以快速抑制柔性结构的振动,采用的控制方法是有效的.     

挠性航天器姿态机动的变结构主动振动抑制

针对挠性航天器大角度姿态机动的振动抑制问题, 提出了一种双回路鲁棒主动振动控制方法. 首先, 对各低阶振动模态设计正位置反馈补偿器, 增加挠性模态的阻尼, 使其振动能够快速衰减; 然后, 基于变结构输出反馈控制理论, 给出控制器的设计方法. 最后, 将该方法应用于挠性航天器姿态机动控制, 仿真结果表明, 所提出的方法是可行而有效的.     

挠性系统的鲁棒控制设计

提出一种新的鲁棒设计思想：将挠性模态部分的Nyquist图线安排到右半平面。由于综合运用了频域分析、极点配置、正实性引理、线性矩阵不等式等概念和算法，使得这种鲁棒控制设计得以实现，且简单直观。通过两个算例说明了该设计方法的有效性。     

Robust control of flexible structures with stable bandpass controllers

In this paper, a control law for the active vibration control of mechanical flexible systems is considered. The proposed strategy minimizes an index and results in a stable stabilizing controller with bandpass frequency shape, due to the presence of zeros at the origin. The control authority is thus effective in a chosen band of frequency, resulting in a selective broadband control action, as opposed to narrow-band (tonal) vibration reduction. Moreover, the explicit closed-form solution of the controller is also obtained, thus avoiding numerical calculation of the solution of the Riccati equations, which can be ill-conditioned in the case of very high-order, poorly damped flexible systems. The parametrization of all the controllers is also given and a family of controllers with the above properties is deduced. The case is also obtained as a byproduct. The controller is based on a colocated actuators/sensors pair strategy and numerical simulations are presented, showing the robustness of the proposed approach even for systems with zero damping. Finally, experimental results on a skin panel of a Boeing 717 aircraft also prove the effectiveness of the proposed approach in practical complex applications, with global vibration reduction performances.     

Robust adaptive vibration control for an uncertain flexible Timoshenko robotic manipulator with input and output constraints

The problems of the constraints and the vibration suppression are investigated for the flexible Timoshenko robotic manipulator in this paper. Robust adaptive boundary control laws with the disturbance observes are designed to guarantee the convergence of the feedback flexible Timoshenko robotic manipulator system with the uncertain parameters and the states are proven to be uniform bounded. In addition, the proposed boundary controls are verified to be effectiveness by the numeral experiments.     

带刚性基柔性附件振动鲁棒控制

研究了刚体基上柔性附件的振动鲁棒控制问题.介绍了结构奇异值μ理论,基于此理论设计鲁棒控制器,用压电材料作传感器和作动器(μ),用输出乘性不确定性结构来描述低阶标称模型与实际系统的误差,给出了系统μ控制器综合框架.以柔性梁附件为对象示例了分析过程.数值仿真结果表明μ控制器具有良好的鲁棒性能,用于振动控制是必要且可行的.     

Inertia‐free attitude stabilization for flexible spacecraft with active vibration suppression

This paper addresses the inertia‐free attitude control problem for flexible spacecraft in the presence of inertia uncertainties, external disturbances, actuator faults, measurement errors, and input magnitude and rate constraints (MRCs). By analyzing the influence of external disturbances, faulty signals, and actual inertial matrix, a lumped disturbance is reconstructed to facilitate the controller design. Then, a new intermediate observer is developed to estimate the attitude and modal information and the lumped disturbance. The Lyapunov stability analysis shows that the developed controller can achieve the objectives of the attitude stabilization and vibration suppression with input MRCs. Finally, numerical simulations are performed to demonstrate the effectiveness and superiority of the proposed control method.     

大型挠性空间机械臂振动抑制的一种关节控制策略

大型空间机械臂在操作过程中,一个突出的问题是超低频挠性,不仅存在机械臂的弯曲振动,而且还存在关节的扭转变形振动;另外一个不能忽视的问题就是减速器的扭矩传递特性,以及机械臂关节运动与基座扰动（空间站）之问的耦合特性,这就要求根据关节结构和传感器配置实现关节位置控制,同时稳定和衰减机械臂及其关节的低频挠性振动．本文运用集中参数法对空间机械臂的挠性动力学进行建模,设计了工程可实现的单个关节控制策略及其控制律,分析和数值仿真了其稳定性,对未来空间站的大型挠性空间机械臂设计、动力学与控制的研究具有一定的参考价值．     

Boundary control of flexible aircraft wings for vibration suppression

In this paper, we propose a boundary control strategy for vibration suppression of two flexible wings. As a basic approach, Hamilton's principle is used to ascertain the system dynamic model, which includes governing equations – four partial differential equations and boundary conditions – several ordinary differential equations. Considering the coupled bending and torsional deformations of flexible wings, boundary control force and torque act on the fuselage to regulate unexpected deformations of flexible wings. Then, we present the stability analysis of the closed-loop system through Lyapunov's direct method. Simulations are carried out by using finite difference method. The simulation experimental results illustrate the significant effect of the developed control strategies.     

Lookup table control method for vibration suppression of a flexible manipulator with optimization of the minimum settling time and energy consumption

Active vibration suppression of flexible manipulators is important in many engineering applications, such as robot manipulators and high‐speed flexible mechanisms. The demand for a short settling time and low energy consumption of vibration suppression requires consideration of optimal control. Under a wide range of operating conditions, however, the fixed optimal parameters determined for a control algorithm might not produce the best performance. Therefore, to enhance performance, this paper suggests a lookup table control method for a flexible manipulator. This method can tune itself to the optimal parameters on the basis of initial maximum responses to the controlled system. In this study, a multi‐objective genetic algorithm is used to search for optimal parameters with regard to positive position feedback to the control algorithm. In turn, with the optimal parameters, the multi‐objective functions of the settling time and energy consumption during the vibration control of a flexible manipulator can be minimized. The simulation and experimental results both indicate that the energy consumption can be reduced significantly if the settling time is slightly increased. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Position/vibration control of two-degree-of-freedom arms having one flexible link with artificial pneumatic muscle actuators

A manipulator with a light and thus flexible link would be advantageous over a rigid link in the sense that it is physically safer when it comes into contact with its environment than a manipulator with a rigid and thus heavy link, even though it is harder for a flexible link manipulator to be robustly controlled. On the other hand, if an actuator can deliver enough force while maintaining proper compliance, it would be advantageous for the sake of safety. An artificial pneumatic muscle-type actuator is an adequate choice in this case. In this work, position control problem of a two-degree-of-freedom arm system having a flexible second link with artificial pneumatic muscle-type actuators is addressed. A composite controller design method is proposed in the framework of the singular perturbation method. Various robust control schemes are designed in order to meet with payload variation, parameter uncertainty, unmodeled vibration mode, actuator dynamics both in the slow and the fast subsystems.     

Robust stability—degree assignment and its applications to the control of flexible structures

A new method of robust controller synthesis is introduced which is an extension of robust stabilization to robust stability-degree assignment. This method guarantees a lower bound of stability degree for all uncertainties within a prescribed magnitude band. The method is applied to the control of four types of flexible structures, namely, colocated beam, non-colocated beam, beam with moving base and large scale satellite model. Excellent performances have been obtained experimentally with respect to the response speed and the robustness.     

Vibration suppression of a flexible robot manipulator with a lightweight piezo-composite actuator

The increasing demand for high-speed performance and low energy consumption has necessitated the design of lightweight mechanical systems. The active vibration suppression of a flexible manipulator is important in many engineering applications, such as robot manipulators and high-speed flexible mechanisms, because the flexibility of lightweight manipulators induces a vibration problem. Frequently, the optimal parameters determined for a certain control algorithm might not cover a wide range of operating conditions. Hence, we have proposed and developed a lookup table control method for a flexible manipulator that can tune itself to optimal parameters on the basis of the initial maximum responses of the controlled system and a genetic algorithm. The genetic algorithm is used to search for optimal parameters with regard to positive position feedback and thereby minimizes the objective functions determined from the initial maximum responses. Our lookup table, which has the optimal parameters of the positive position feedback as a function of the initial maximum responses, can be used in a real-time control algorithm. Recommended by Editorial Board member Hyoukryeol Choi under the direction of Editor Jae-Bok Song. This work was supported by the Korea Research Foundation under grant KRF 2006-005-J03302 and the Korea Science and Engineering Foundation under grant KOSEF R0A-2007-000-20012-0. Van Phuoc Phan received the BS (2006) from the Department of Aeronautical Engineering, HCM University of Technology, Vietnam. Currently, he is a Master student at the Department of Advanced Technology Fusion, Konkuk University in Seoul, Korea. His interests are structural dynamics of small systems, smart structure and material, and finite element analysis. Nam Seo Goo graduated from the Department of Aeronautics Engineering of Seoul National University with honors in 1990, and got master and Ph.D. degrees in Department of Aerospace Engineering at the same university in 1992 and 1996, respectively. His Ph.D. degree was on the structural dynamics of aerospace systems. As soon as he got a Ph.D. degree, he entered the agency for defense development as a Senior Researcher. After four years’ service, he joined Department of Aerospace Engineering in Konkuk University, Seoul, Korea in 2002, currently serving an Associate Professor of Department of Advanced Technology Fusion. His current research interests are structural dynamics of small systems, smart structure and material, and MEMS applications. Hoon Cheol Park received his BS (1985) and MS(1987) degrees from Seoul National University in Seoul, Korea and Ph.D.(1994) degree from the University of Maryland at College Park, MD, USA. He joined the Department of Aerospace Engineering, Konkuk University in Seoul, Korea in 1995, and he is currently a Professor in the Department of Advanced Technology Fusion. His professional experience includes Kia Motors (1986–1988) and Korea Aerospace Research Institute (1994–1995). His specialty is the finite element analysis and recent research topic is mainly biomimetics.     

Boundary antisaturation vibration control design for a flexible Timoshenko robotic manipulator

This article focuses on the angle positioning and vibration isolation of flexible Timoshenko manipulators possessing extraneous disturbances and saturation nonlinearities. Boundary control strategies with auxiliary systems are presented to achieve the expected angle, suppress the shear deformation and elastic oscillation, and mitigate the saturation nonlinearities effect. With the constructed controllers, a controlled system is ensured and certified to be exponentially stable. The simulation and comparison results show the control performance of the suggested approach.     

A discrete-time approach to impulse-based adaptive input shaping for motion control without residual vibration

Modifying a command or actuation signal by convolving it with a sequence of impulses is a useful technique for eliminating structural vibration in rest-to-rest motion of mechanical systems. This paper describes an adaptive discrete-time version of this approach where amplitude and timing of impulses are tuned during operation to match the system under control. Solutions giving zero residual vibration are formulated in terms of a quadratic cost function and constructed by iterative operations on measured sets of input–output data. The versatility of the approach is demonstrated by simulated test cases involving (1) amplitude optimization of impulses with fixed timings, (2) timing optimization of impulses with fixed amplitudes and (3) combined timing and amplitude optimization. The approach is model-free and directly applicable to multi-mode systems. Moreover, fast adaptation within a single rest-to-rest maneuver can be achieved.     

Modeling and vibration control for a flexible pendulum inverted system based on a PDE observer

This study addresses the problem of trajectory control of a flexible pendulum inverted system on the basis of the partial differential equation (PDE) and ordinary differential equation (ODE) dynamic model. One of the key contributions of this study is that a new model is proposed to simplify the complex system. In addition, this study proposed a nonlinear PDE observer to estimate distributed positions and velocities along flexible pendulum. Singular perturbation method is proposed to solve the coupling system of nonlinear PDE observer. The nonlinear PDE observer is divided into a fast subsystem and a slow subsystem by the use of the singular perturbation method. To stabilise this fast subsystem, a boundary controller is proposed at the free end of the beam. The sliding-mode control method is proposed to design controller for slow subsystems. The asymptotic stability of both the proposed nonlinear PDE observer and controller is validated by theoretical analysis. The results are illustrated by simulation.     

力矩受限的柔性空间机器人模糊神经网络自适应跟踪控制及振动抑制

针对力矩受限和存在参数不确定情况下,自由漂浮柔性空间机器人（FFFSR）关节轨迹跟踪控制与柔性振动抑制的问题,利用奇异摄动法将系统分解为关节轨迹跟踪的慢变子系统和描述柔性振动的快变子系统,进而提出含慢、快变控制项的组合控制器。对于慢变子系统,设计一种无需模型的模糊径向基函数（RBF）神经网络（FRBFNN）自适应跟踪控制方案,利用神经网络观测器估计关节角速度信息,并对系统的未知非线性函数进行逼近;对于快变子系统,采用扩张状态观测器（ESO）对不易测量的柔性模态坐标导数和不确定扰动进行估计,并结合线性二次调节器（LQR）方法抑制柔性振动。数值仿真结果表明,当控制力矩限制在±20 N·m和±10 N·m范围内时,该组合控制器能够在2.5 s实现稳定的关节轨迹跟踪,并将柔性振动幅值限制在±1×10^-3 m内。     

Boundary feedback stabilisation of a flexible robotic manipulator with constraint

In this paper, the flexible robotic manipulator is modelled as a distributed parameter system, represented by a group of partial differential equations and ordinary differential equations. Control is designed at the boundary of the robotic manipulator based on integral-barrier Lyapunov function to suppress the vibration of the elastic deflection and track the desired angular position. With the proposed boundary control, the manipulator can be driven to the desired set-point with angular position and elastic deflection stay under the former setting constraint. Uniformed boundedness of the closed-loop system under the unknown time-varying disturbance is achieved. Stability analysis of the closed-loop system is given by employing the Lyapunov stability theory. Simulation results illustrate the effectiveness of the proposed boundary controller for ensuring output constraint and suppressing vibrations.