航天结构主、被动一体化振动控制技术的研究现状和进展

围绕航天结构振动的被动控制、主动控制、一体化控制和实验研究等几个方面对当前研究的现状和最新进展进行了介绍。将被动控制、主动控制结合,优点互补的体化振动控制技术是当前结构振动控制研究的一个重点。结合工程实际,开发新型振动控制材料及控制元件和装置,发展附加重量代价小、高效、能耗低和可靠性强的一体化振动控制技术,是将来的研究方向。     

Nonlinear robust and optimal control of robot manipulators

In this paper, we propose a new optimal control method for robust control of nonlinear robot manipulators. Many industrial robot systems are required to perform relatively large angular movement with sufficient accuracy. In real circumstances, highly nonlinear manipulator dynamics and uncertainties such as unknown load placed on the manipulator, external disturbance, and joint friction make the precise control of manipulators a very challenging task. The main contribution of this work is to develop a new robust control strategy to accomplish the precise control of robot manipulators under load uncertainty using a nonlinear optimal control formulation and solution. This methodology is based on the underlying relation between the robust stability and performance optimality. A class of robust control problems can be transformed to an equivalent optimal control problem by incorporating the uncertainty bounds into the cost functional. The θ-D optimal control approach is utilized to find an approximate closed-form feedback solution to the resultant nonlinear optimal control problem via a perturbation process. Numerical simulations show that the proposed robust controller is able to control the robot manipulator precisely under large load variations.     

Optimal control of structures governed by variational and hemiva-riational inequalities and applications

The optimal control problem for broad classes of structures is studied, including those structures having as state relations variational equalities, variational inequalities and hemivariational inequalities. The optimal control problem consists in the minimization of a functional (performance index) having the state relation, enlarged by the control actions, as side condition. Certain new results are given of the optimal control of structures governed by variational and hemivariational inequalities.Some propositions are proved on the existence and the approximation of the solution of the static optimal control problem of structures having a variational inequality as state relation. Then a regularization procedure is proposed for the treatment of corresponding dynamic problem, as well as for the case of hemivariational inequalities. The theory is illustrated by applications concerning convex elastoplasticity and convex and nonconvex unilateral contact problems.     

回滞非线性结构的瞬态最优控制

本文对一种国滞非线性基础隔振的主从结构模型用瞬态最优控制法进行振动控制研究。利用四阶Ｒｕｎｇｅ－Ｋｕｔｔａ积分格式统一处理最优控制方程，可直接逐步积分求出系统在瞬态最优控制下的最优控制力与系统响应。分别对主从结构无主动控制及有主动控制时的两种情况（包含或不包含ｖｂ反馈）进行计算。结果表明瞬态最优控制可有效地抑制振动。     

Control and synchronization of chaos systems using time-delay estimation and supervising switching control

In this paper, we present a new technique, developed using time-delay estimation (TDE) and supervising switching control (SSC), for the control and synchronization of chaos systems. The proposed technique consists of three units: a time-delay estimation unit that cancels system dynamics, a pole placement control unit that shapes error dynamics, and an SSC unit that is activated when the system dynamics are rapidly changing. We prove the stability of the closed-loop system using the Lyapunov analysis method. To verify the control and synchronization performance of the proposed technique (TDE-SSC), we compare it with TDC using numerical simulation. Our results indicate that the proposed scheme is an easily understood, numerically efficient, robust, and accurate solution for the control and synchronization of chaos systems.     

空间结构耦合模态控制及实验研究

智能结构以主动元件为传感器和驱动器,根据结构的动态响应和控制要求,自适应地改变结构的动态性能,实现结构特性的自调节功能,以增强结构适应于外界环境变化的能力.结构振动主动控制方法中常用的模态空间控制方法,就是将系统方程转化到模态坐标下,从而得到内部解耦的以模态坐标表示的方程组,然后根据一定的控制方法,计算出模态控制力,实现实时控制.该方法计算简单,效率高,能满足实时控制的需要.本文根据一个三层智能结构主动控制实验,介绍了耦合模态控制理论及实现方法,设计并阐述了压电主元杆件的工作原理,根据Riccati方程得到了主元杆件的最优布置.通过对实验数据运用五点滑动平均平滑法进行处理分析及频谱分析可以看到,智能结构通过主动控制,对相应的控制模态位移及加速度有很大的抑制作用,对应的模态阻尼系数得到了不同程度的提高.     

陀螺数字PID温度控制系统设计与实现

介绍了陀螺温控系统的传统控制方法,并在此基础上提出了基于PC/104的数字PID控制的陀螺温度控制方法。实验结果表明这种控制方法能够满足陀螺快速启动、并保持其内部工作温度恒定的精度要求。     

SBLI control for wings and inlets

Flow control can be applied to shock wave/boundary layer interactions to achieve two different goals;the delay of shock-induced separation and/or the reduction ofstagnation pressure losses, which cause wave drag or inletinefficiencies. This paper introduces the principles and maintechniques for both approaches and assesses their relativesuitability for practical applications. While boundary layersuction is already in wide use for separation control, themost promising novel device is the micro-vortex generator,which can deliver similar benefits to traditional vortex generatorsat much reduced device drag. Shock control is notyet used on practical applications for a number of reasons,but recent research has focused on three-dimensional deviceswhich promise to deliver flow control with improved offdesignbehaviour. Furthermore, there are some indicationsthat a new generation of control devices may be able to combinethe benefits of shock and boundary layer control andreduce shock-induced stagnation pressure losses as well asdelay shock-induced separation.     

Elliptic adaptive grid generation and area equidistribution

The derivation of elliptic adaptive grid control functions which satisfy the area equidistribution concept is presented. The resulting expressions are derived without approximation and are shown to provide explicit control over cell area distributions. A modification to the equidistribution concept which yields control functions that enable additional control of the near‐boundary grid resolution is also proposed. A computer code which incorporates these control functions has been developed and is applied to a series of complex fluid flows to demonstrate the validity and utility of the derived expressions. Copyright © 1999 John Wiley & Sons, Ltd.     

Assessment of shunted piezoelectric devices for simultaneous noise and vibration reduction: comparison of passive,active and hybrid networks

Structural vibration and noise control of a cavity-backed three-layered smart piezo-coupled rectangular panel system under harmonic or transient loads is achieved by using purely active, passive, and hybrid active/passive piezoelectric shunt networks. Problem formulation is based on the classical lamination plate theory, Maxwell’s equation for piezoelectric materials, linear circuit theory, and wave equation for the enclosed acoustic domain. The orthogonal mode expansions along with the modal coupling theory are employed to obtain the coupled differential equations of the electro-mechanical-acoustic system, which are then put into the convenient state-space form, and subsequently solved numerically in both frequency and time domains. A triple-mode hybrid RLC shunt circuit, in series with an external active voltage source and connected to a single electroded piezoelectric segment, is tuned to the dominant resonance frequencies of the composite structure. The linear quadratic optimal control (LQR) theory is adopted for obtaining the active control gains. The frequency and time domain performances of the passive, active and hybrid multi-modal piezoelectric systems are calculated and discussed in terms of sensor output voltage, local sound pressure, and control effort. It is found that the hybrid control methodology with properly tuned circuit parameters can be an excellent candidate for simultaneous vibration and structure-borne noise control of the cavity-coupled smart panel with decreased control effort. Also, the active control strategy integrated in the hybrid control system is demonstrated to enhance the overall system damping characteristics and improve the control authority at frequencies where the passive shunt network performs weakly. Limiting cases are considered and correctness of the mathematical model is verified by using a commercial finite element software as well as by comparisons with the literature.     

全弹性平面运动机器人的高精度运动控制和振动抑制算法研究

为实现对基座、关节和臂均存在弹性的空间机器人运动高精度控制及多重振动抑制,建立了基座、关节和臂全弹性空间机器人动力学模型,并采用运动有限维PD重复学习控制及振动同步抑制方案进行研究.首先,利用线性弹簧、扭转弹簧和欧拉-伯努力梁理论,假设模态法和动量守恒定律,采用拉格朗日方程建立了弹性基座、柔性关节和柔性臂空间机器人动力学模型,之后,选取反映柔性臂振动的前两阶模态及基座和关节刚性运动变量为慢变子变量,选取基座和关节弹性振动变量为快变子变量,根据奇异摄动理论将系统降维分解成慢、快变子系统.最后设计了慢变子系统的运动有限维PD重复学习控制及快变子系统的线性最优双重减振控制构成的总控制器.数值仿真结果验证了算法的有效性.     

Dynamics of cantilever plates and its hybrid vibration control

Applying Lagrange–Germain’s theory of elastic thin plates and Hamiltonian formulation, the dynamics of cantilever plates and the problem of its vibration control are studied, and a general solution is finally given. Based on Hamiltonian and Lagrangian density function, we can obtain the flexural wave equation of the plate and the relationship between the transverse and the longitudinal eigenvalues.Based on eigenfunction expansion, dispersion equations of propagation mode of cantilever plates are deduced. By satisfying the boundary conditions of cantilever plates, the natural frequencies of the cantilever plate structure can be given.Then, analytic solution of the problem in plate structure is obtained. An hybrid wave/mode control approach, which is based on both independent modal space control and wave control methods, is described and adopted to analyze the active vibration control of cantilever plates. The low-order(controlled by modal control) and the high-order(controlled by wave control) frequency response of plates are both improved. The control spillover is avoided and the robustness of the system is also improved. Finally, simulation results are analyzed and discussed.     

Dynamic behavior and vibration control of a tensegrity structure

Tensegrities are lightweight space reticulated structures composed of cables and struts. Stability is provided by the self-stress state between tensioned and compressed elements. Tensegrity systems have in general low structural damping, leading to challenges with respect to dynamic loading. This paper describes dynamic behavior and vibration control of a full-scale active tensegrity structure. Laboratory testing and numerical simulations confirmed that control of the self-stress influences the dynamic behavior. A multi-objective vibration control strategy is proposed. Vibration control is carried out by modifying the self-stress level of the structure through small movement of active struts in order to shift the natural frequencies away from excitation. The PGSL stochastic search algorithm successfully identifies good control commands enabling reduction of structural response to acceptable levels at minimum control cost.     

结构-模态主动控制系统的最大允许时滞及稳定性探讨

根据Ｎｙｑｕｉｓｔ稳定性准则、特征值原理和ＬＱＲ控制原理,导出了结构－模态控制系统的位移速度反馈的时滞计算公式,进而可求得结构－模态主动控制系统的最大允许时滞。数值分析表明,用两种不同稳定判据得到的两个最大允许时滞计算公式的计算结果是接近的。研究了时滞补偿后结构－模态主动控制系统的稳定性问题。从具有时滞补偿控制系统的特征方法知,具有时滞补偿的控制系统保持理想控制系统的特征值,既时滞补偿结构－模态主     

柔性变截面滑移式机器人手臂的动力学与控制

本文研究柔性变截面滑移式机械手的动力学与控制。首先利用Ｋａｎｅ方法分析柔性机械手的振动特性；然后基于有限元法导出一种控制机械手振动的模型，将控制过发为“粗控”和“精控”两步进行；最进行了数值模拟。     

Nonlinear modeling and control of flexible-link manipulators subjected to parametric excitation

This paper presents nonlinear dynamic modeling and control of flexible-link manipulators subjected to parametric excitation. The equations of motion are obtained using the Lagrangian-assumed modes method. Singular perturbation methodology is developed for the nonlinear time varying equations of motion to obtain a reduced-order set of equations. Control strategies, computed torque control and a composite control, based on the singular perturbation formulation developed, are utilized to reduce mechanical vibrations of the flexible-link and enable better tip positioning. Under the composite control technique, the effect of the value of perturbation parameter on the control signal is investigated. Numerical simulations supported by real-time experiments show that the singular-perturbation control methodology developed for the nonlinear time-varying system offers better system response over the computed torque control as the manipulator is commanded to follow a certain trajectory.     

互联结构振动控制元件参数研究

针对双塔结构所具有的模型不精确及承受随机外力作用这一特点，在控制方法选择方面，为保证系统控制的顺利实现，本文引入了能够对模型不精确具有较好控制效果的广义预测控制策略；在优化目标选择方面，为降低控制系统的能量，以控制增益矩阵的Frobenius范数做为优化目标；在优化算法方面，为降低计算工作量，引入并改进了传统的遗传算法。通过优化计算得到系统参数几组次优解，这些解可以供设计者进行选择。最后给出了计算实例。算例表明这一方法是有效的。     

Control and Parameter Optimization of Flexible Robots*

A hierarchical control concept for flexible robot manipulators is presented. The equations of motion are derived using the multibody system method, incorporating flexible links equipped with surface bonded actuating and sensing devices. Exploiting the structure of the dynamic model, the control concept allows combination of any joint level control for the gross motion of the manipulator with decentralized linear control of the elastic deformation of each flexible link. Therefore, the approach is capable of solving both the problem of fast and precise point-to-point motion, with acceptable vibration characteristics, and the problem of accurate trajectory tracking of the end-effector. Control parameters are found through parameter optimization. In order to verify the proposed control strategy, a SCARA robot with one flexible link is considered.     

智能结构有限元动力模型的建立及主动振动控制和抑制

采用一种新的压电板单元，建立了含有分布压电传感元件和执行元件结构（智能结构）的有限元动力模型。利用两种反馈控制律，研究了智能结构振动控制与抑制的问题，并提出了智能结构主动振动控制和抑制的一种方法。最后，提供了数值示例，说明本文提出方法的应用。     

四旋翼飞行器建模及位置跟踪控制(英文)

相对其他无人飞行器平台,四旋翼飞行器有其独特的优势,因而受到广泛的关注。位置跟踪控制对四旋翼飞行器的应用非常重要。在阐述四旋翼飞行器的飞行原理和操控机制的基础上,研究了其动力学模型,并提出了一种简化的数学模型。四旋翼飞行器是欠驱动耦合系统,为了实现系统解耦并得到清晰的控制回路,设计了多回路PID控制方案,其控制目标是位置和偏航角,而姿态角和横滚角由位置误差调节。最后,通过仿真验证了控制方法的有效性。