大系统的动态递阶伺服控制

本文针对大系统的伺服控制问题,提出了动态递阶伺服控制这一新的伺服控制方案,给出了动态递阶伺服控制器的结构及动态递阶伺服控制问题可解的条件。研究结果表明,这种伺服控制方案可用来解决有不稳定分散固定模的大系统的伺服控制问题。     

Robust control of a general servomechanism problem: The servo compensator

The robust control of a general servomechanism problem, which is an extension to the results of [1], is considered in this paper. Necessary and sufficient conditions, together with a characterization of all robust controllers which enables asymptotic tracking to occur, independent of disturbances in the plant and perturbations in the plant parameters and gains of the system, are obtained. A new type of compensator, introduced in [1], called a servo-compensator which is quite distinct from an observer is shown to play an essential role in the robust servomechanism problem. It is shown that this compensator, which corresponds to an integral controller in classical control theory, must be used in any servomechanism problem to assure that the controlled system is stabilizable and achieves robust control; in particular, it is shown that a robust controller of a general servomechanism problem must consist of two devices (i) a servo-compensator and (ii) a stabilizing compensator. A study of the stabilizing compensator is made; in particular, it is shown that a new type of stabilizing compensator called a complementary controller, may be used together with the servo-compensator to form a robust controller for the servo-mechanism problem.A study of the case when perturbations in the robust controller are also allowed is then made; this leads to the Strong robust servo limitation theorem which imposes a fundamental limitation on the ability of practical servomechanisms to regulate a system.     

The robust decentralized control of a general servomechanism problem

The decentralized robust control of a completely general servomechanism problem is considered in this paper. Necessary and sufficient conditions, together with a characterization of all decentralized robust controllers which enables asymptotic tracking to occur, independent of disturbances in the plant and perturbations in the plant parameters, and gains of the system, are obtained. A new type of compensator called a decentralized sercocompensator which is quite distinct from an observer is introduced. It is shown that this compensator, which corresponds to an integral controller in classical control theory, must be used in any decentralized servomechanism problem to assure that the controlled system is stabilizable and achieves robust control; in particular, it is shown that a decentralized robust controller of a general servomechanism problem consists of two devices 1) a decentralized servocompensator and 2) a decentralized stabilizing compensator. It is then shown that, under certain mild conditions, there almost always is a solution to the robust decentralized servomechanism problem for any composite system consisting of a number of subsystems interconnected in any arbitrary manner. This last observation has important implications for process control.     

一种自适应PID控制及其在发电机性能测试装置中的应用

针对经典PID控制参数整定困难且受时变、非线性等因素影响不能达到预期控制效果的实际情况,设计了一种具有自学习能力的自适应PID控制器,利用Widrow-Hoff学习算法实现系统在线自动调整最佳控制参数,从而提高系统的自适应能力、改善系统的动态性能,并成功地将其应用到发电机性能自动化测试装置中。     

Applications of the closed-loop stepping motor

This paper describes a bang-bang controller which, with a particular novel scheme of discrete-state variable instrumentation, operates the stepping motor as a digital servo. The near time-optimal servomechanism is designed on a second-order basis, and the rather coarse staircase approximation of the switching curve yields good results. All control circuits have been implemented with integrated circuit components. The entire package has been product tested in the field.     

转塔伺服系统的控制及仿真

介绍了一种实用的基于PC/104计算机控制系统,针对转塔伺服系统参数整定麻烦,要求精度高的问题,对其进行建模,提出了一种寻找控制器参数的方法。利用非线性PID 控制器来实现对转塔伺服系统的高精度伺服跟踪控制,其中非线性控制器中的参数由遗传算法寻优获得,它既可快速地跟踪目标,又没有太大超调。仿真结果证明,该方法寻到的参数, 可使系统运行平稳、响应迅速、精度高。     

基于CMAC的转台系统逆控制器设计及仿真

仿真转台是对飞行器进行地面物理仿真的设备,是一个具有一定非线性和不确定性的伺服控制系统。该文利用CMAC的地址映射能够高度逼近非线性函数的特点,以转台伺服系统为控制对象,采用CMAC神经网络和PD控制器相结合的方法,提出一种应用于高精度伺服系统的控制方法,使CMAC在控制的前期阶段学习系统的逆,后期阶段作为控制器。仿真实验结果表明了这种方法具有自适应和快速收敛的优点。控制器具有良好的控制品质,结构简单,易于实现。     

一种电液伺服系统中伺服控制器的设计与应用

文章设计了一种采用双DSP结构的伺服控制器，介绍了其组成结构、功能以及在电液伺服系统控制中的应用。将DSP芯片和数字信号处理技术结合，采用模糊算法设计以及同步协调设计，完成对原有单一通道、非同步的电液伺服系统扩充。多通道多变量大容量协调同步控制的复杂电液伺服系统具有强大的数据采集能力，64通道动态数据采集，320通道静态数据采集，完全满足大型结构试验的需要。     

基于AMEsim的自适应控制在电液力伺服系统上仿真研究

由于实际电液伺服系统大量存在非线性、时变、不确定、时滞及强耦合特性等,一般无法获得精确的教学模型.为了解决参数的不确定性和随机变化性对电液力控伺服系统的影响,设计了自适应控制器.利用AMEsim和Simulink联合仿真技术建立了该电液力控制系统模型,设计一种自适应控制器,进行了电液力控伺服系统的控制仿真.仿真结果表明了自适应控制器对于系统控制的有效性和鲁棒性.     

The design of controllers for the multivariable robust servomechanism problem using parameter optimization methods

The problem of designing realistic multivariable controllers to solve the servomechanism problem is considered in this paper. Specifically, it is desired to find a controller for a plant to solve the robust servomechanism problem, so that closed-loop stability and asymptotic regulation occur, and also so that other desirable properties of the controlled system, such as fast response, low-interaction, integrity, tolerance to plant variations, etc., occur. The method of design is based on using state space methods via a two-stage process: 1) using theory, determine the existence of a solution and control structure required to solve the problem, and 2) using nonlinear programming methods, determine the unknown controller parameters so as to minimize a performance index for the system subject to certain constraint requirements. Numerous examples, varying from a single-input/single-output to a four-input/four-output system, are given to illustrate the design method, and the results obtained are compared with the results obtained by using other alternate design methods. In all cases, the controllers obtained have been highly competitive with controllers obtained by alternate design methods.     

A ripple free sampled-data robust servomechanism controller usingexponential hold

In a general command tracking and disturbance rejection problem, it is known that a sampled-data controller using zero-order hold may only guarantee the asymptotic tracking at the sampling instances, but cannot smooth out the ripples between the sampling instances. In this paper, a sampled-data robust servomechanism controller using exponential hold is developed for guaranteeing the asymptotic tracking not only at, but also between, the sampling instances. In this development, a so called “internally-reducible” condition to characterize a class of robust servomechanism controllers is derived first, then the proposed controller is shown to be contained in this class. Generally speaking, a sampled-data structure using exponential hold can provide more design freedoms so that it tends to simplify the construction of a robust servomechanism controller and facilitate the implementation on digital computers. An example for a DC motor control is presented to illustrate the advantages of this approach     

Accomodation of external disturbances in linear regulator and servomechanism problems

Modern linear regulator and servomechanism theories (of the deterministic type) either ignore system disturbances altogether or assume they can be represented by initial conditions on the plant state vector. Controllers designed by such theories may fail to meet performance specifications when the system is subjected to persistently acting disturbances. In this paper, we show how one can modify existing regulator and servomechanism theories to take into account the presence of persistent fluctuating disturbances. By this means one can design a deterministic controller which consistently maintains set-point regulation, or servotracking, in the face of a bread class of realistic external disturbances. In addition, we show how one can systematically exploit any useful effects that may be present in the action of external disturbances.     

飞行模拟转台非线性干扰观测器反步滑模控制器设计

本文针对考虑不确定性的飞行模拟转台伺服系统,提出了一种基于非线性干扰观测器的反步全局滑模补偿控制方法。该方法采用反步控制方法设计转速期望虚拟控制,然后利用非线性干扰观测器观测系统不确定干扰,进而对引入非线性干扰观测器的系统设计自适应全局滑模控制器,实现了飞行模拟转台伺服系统期望转角信号的鲁棒跟踪控制,仿真结果表明,该方法控制效果良好,具有很好的工程应用价值。     

Servo controller design using neural networks

The dynamics of a physical plant may be difficult to express as concise mathematical equations. In practice there exist uncertainties that cannot be modeled with the system equations. Hence, robustness against system uncertainties is essential in a control system design. In this article, multilayered neural networks (MNNs) are used to compensate for model uncertainties of a dynamical system. Neural network models are used along with a classical linear servo controller derived from the linear state space equations. These models are trained so that system uncertainties are compensated. The design of a servo system indicates the enhanced performance of the neural-network-based servo controller as compared to the classical servo controller.     

Design of model-following servo controller

A servo controller is designed so that the step response of the plant is as close as possible to that of a model system while the output regulation condition is satisfied. The controller is named "the model-following servo" and its control law is determined by optimization. The associated algorithm is presented. An example is included to illustrate the procedure.     

Continuous-time optimal robust servo-controller design with internal model principle

The linear quadratic design of an optimal robust servo–controller for a continuous–time control system is described. It introduces a servo–control performance measure which accommodates the internal model principle. The measure selectively discounts penalties on control effort of desirable frequencies and provides complete flexibility in the selection of weighting matrices. The proposed servo–controller uses plant state feedback, signal state feedforward and a servo–compensator for ensuring robust asymptotic command tracking and disturbance rejection. An informal alternate proof of the internal model principle in the state variable domain is presented using an operator-transformation technique. Where necessary, observers are used to complement the servo-controller. The proposed optimal robust servo–controller yields the expected superior performance in terms of response and error minimization. An illustrative example is given.     

基于高速同步485总线通信的多通道伺服控制器设计

文章介绍了一种四通道数字伺服控制器的系统设计和实现方案;针对研制任务中高通信波特率和多路控制的要求,设计了以XC164为主控制芯片,基于JS71175型485协议处理器的高速同步485总线通信的多通道伺服控制器,该控制器在提高了同步485通信速率的同时可以实现四路伺服机构的控制、伺服机构动作的锁定及解除锁定,具有体积小、功率大、集成度高特点;实验结果表明,在保证通信稳定的前提下,通信波特率可达2 Mbit/s ,总功率可达1 600 W,满足任务要求。     

Time delay and sampling rate effect on dual-stage servo control performance

Dual-stage servo control loops are modeled for hard disk drives (HDDs) with the consideration of time delay which is due to the time taken for position error signal measurement and controller computing. The time delays are involved in controller design and the closed servo control loop is investigated to show the effects of the time delay on servo control performance. The studied actuation system is a PZT milliactuator based dual-stage servo system. The delay time within and over the sampling interval is separately considered for 62.5 kHz sampling rate. To show the effect of sampling rate on servo control performance, a control system designed with 40 kHz sampling rate is also studied. As a result, significant improvement of servo performance is attained with this increased sampling rate and a reasonable time delay for the dual-stage actuation system.     

The design of servomechanism controllers for uncertain plants

The design of multivariable servomechanism controllers is considered here for plants whose parameters are uncertain or perturbed within a cone-bounding criterion. The solution comes from a controller design problem as an LQ optimal control problem in which the gain matrices result in a quadratic performance upper bound (similar to that described by Gilman and Rhodes (1976() which depends on the uncertainty. Under conditions on the nominal plant and on the uncertainty, a resulting linear time-invariant controller is guaranteed to achieve the objectives of robust tracking and regulation with closed-loop stability.     

Feedback design for robust tracking and robust stiffness in flight control actuators using a modified QFT technique

The problem of dynamic stiffness of hydraulic servomechanisms has often been recognized as a significant performance issue in a variety of applications, the most notable of which includes flight control actuation. When a hydraulic actuator such as this is operated in position control, an aerodynamic flutter load on the control surface manifests itself as a force disturbance on the system. Although this would appear to be a standard disturbance rejection problem, the disturbance does not enter the system as in the classical sense (i.e. at the plant output) and hence, this problem must be considered in a modified formulation. A hydraulic servomechanism is said to be 'stiff' if it exhibits acceptable rejection of force disturbances within the control bandwidth. In this paper, an approach to feedback design for robust tracking and robust disturbance rejection is developed via the quantitative feedback theory (QFT) technique. As a result, it is shown that reasonable tracking and disturbance rejection specifications can be met by means of a fixed (i.e. non-adaptive), single loop controller. The methodology employed in this development is the sensitivity-based QFT formulation. As a result, robust tracking and robust disturbance rejection specifications are mapped into equivalent bounds on the (parametrically uncertain) sensitivity function; hence, the frequency ranges in which tracking or disturbance rejection specifications dominate become immediately obvious. In this paper, a realistic non-linear differential equation model of the hydraulic servomechanism is developed, the linear parametric frequency response properties of the open loop system are analysed, and the aforementioned QFT design procedure is carried out. Analysis of the closed loop system characteristics shows that the tracking and disturbance rejection specifications are indeed met.