一种抑制大型飞机液压伺服作动系统耦合振荡的方法

针对大型飞机液压伺服作动系统与飞机结构之间的耦合振荡问题,提出了一种在液压伺服作动系统中通过加装双向节流阀抑制耦合振荡的方法,具体是在液压伺服作动器的作动筒的进油通路与回油通路之间串接一个双向节流阀,增大液压伺服作动系统阻尼以增加系统的频宽,进而增大液压伺服作动系统与飞机结构之间的频宽倍比,从而有效抑制了系统的耦合振荡.该方法通过仿真分析及试验,验证了其可行性及合理性,并取得了很好的效果,为工程应用提供了依据.     

扫视眼动系统的仿真研究

眼动系统在神经系统研究及临床应用上都具有重要作用。该文针对其中的扫视眼动系统，采用仿真的方法对其特性进行了部分研究，得出如下结论：①通过对各种切换方式（包括一、二、三次切换）神经控制信号对系统影响的仿真研究，进一步阐述了神经控制信号是一次切换的时间最优控制信号；②通过神经控制信号脉冲幅度Ｆｐ及切换时间ｔ１对模型输出影响的研究，明确提出了扫视系统神经控制信号的随机性与扫视眼动过程确定性的统一观点；③     

电子横移伺服LQR最优控制器设计

为了提高系统的稳态精度和动态性能,将LQR最优控制算法应用于高速经编机电子横移伺服控制系统.建立了伺服系统状态空间模型,引入了一类具有指数衰减度的二次型函数作为系统性能指标.仿真结果表明,所提出的电子横移伺服LQR最优控制算法易于工程实现,保证了系统的稳定性,具有良好的频响特性,改善了系统的动态特性,实现了无静差高精度控制.     

具有逻辑切换的反馈控制系统的设计

为使线性系统的动态性能得到充分的改善,需实现非线性控制,如时间最短的 bang-bang 控制。这类最优控制,实质上是一种逻辑判别和切换的控制。然而这种按某种指标严格最优的控制所用的逻辑判别函数常常十分复杂,工程上不易实现,并且一般常对系     

基于时间最优的快速平息区间扰动的紧急直流功率控制策略

为了快速平息交直流互联电网的区间扰动振荡,基于等值两机两区域系统推导了2阶振荡系统的时问最优紧急直流功率支援控制策略.首先采用时间最优控制将相点快速驱动到平衡点附近,然后采用非线性控制对相点进行平衡点镇定控制.为消除直流功率的跃变和高频非线性"颤振"及防止"超调"现象,对开关曲线作了改进,并根据控制相平面推导实现最少次开关切换的直流功率控制量.最后通过仿真验证了该策略的有效性.     

采用MSP430的舵机控制系统设计及实现

航空电动舵机是飞行器控制系统的关键组成部分,为航空舵机设计高性能的控制器具有重要意义;针对航空舵机,设计并实现了一种采用MSP430单片机的稀土永磁无刷直流电机的舵机控制系统;提出系统的复合伺服控制策略并设计了控制系统结构;设计硬件与软件系统实现复合伺服控制并进行随动实验测试,实验结果显示系统跟踪误差小,无超调量和静态误差,表明系统具有很好的稳态和动态特性,控制效果良好。     

无人机鲁棒伺服LQR飞行控制律设计

为抑制无人机飞行模态切换时舵面跳变使机体产生的大过载,降低无人机对舵系统及结构可用过载的要求,将鲁棒伺服LQR方法与经典控制方法相结合设计了飞行控制律;以俯仰角控制模态为例,对鲁棒伺服LQR控制方法的特性进行了分析,俯仰角速率回路采用鲁棒伺服LQR最优控制方法设计了控制律,俯仰角回路采用经典控制方法设计了控制律,并通过非线性数字仿真对控制律的控制效果进行了验证;仿真结果表明:鲁棒伺服LQR控制比常规PID控制超调量减小50%,且大大减小了响应初期的升降舵偏角突变,降低了对机体可用过载的要求;该控制律形式简单,易于工程实现。     

电动伺服舵机系统中的迭代学习控制

电动伺服舵机控制系统采用全数字三环控制策略,分别为位置环、速度环和电流环;作为内环的电流环,应具有良好的稳态和动态特性,其输出电流要求快速准确地跟踪给定电流,以保证舵机控制系统高性能位置伺服的要求;在传统的增量式积分分离PI控制算法的基础上,引入-D型迭代学习控制前馈环节,提高了电流跟踪的快速性和跟踪精度,建立了系统的数学模型并在MATLAB上进行了系统仿真;仿真结果表明,引入D型迭代学习控制后,电流环的稳态和动态特性良好,保证了输出电流跟踪的快速性、精确性.     

一种基于混合视觉伺服的切换控制方法

为解决目标远离摄像机视野问题,本文提出了一种基于混合视觉伺服的切换控制方法,根据目标在图像平面的位置,通过在两种具有不同特性的控制策略之间进行切换完成视觉伺服任务.采用的混合视觉伺服方法实现了平动和转动自由度的解耦,当目标位于图像平面中心区域时,采用控制策略使转动自由度误差指数级减小;当目标位于边界区域时,切换到另一种控制策略,使目标重新回到中心区域,通过切换控制最终完成伺服任务.仿真实验验证了提出的基于混合视觉伺服切换控制方法的有效性.     

基于DSP+CPLD可重构数控系统的设计

针对柔性化制造的要求.构建了以DSP CPLD为基础的数控系统平台.该平台集成度高、稳定性强,能实现生产过程的高速度、高精度要求,实现了基于CPLD的可重构设计,提高了系统的柔性.在控制算法上,采用单神经元PID及CMAC相结合的伺服运动控制算法,仿真显示较常规P1D控制有更好的动态特性、控制精度、抗干扰能力.     

Time-optimal control and high-gain linear state feedback

It is known that the fastest possible response of a linear system under input constraints is typically achieved using extreme control efforts at all times, or bang-bang control. However, closed-loop minimum-time control is very difficult to implement except for a few simple second-order systems, since a closed-form solution for the time-optimal switching hypersurface usually cannot be found for high-order systems. In this paper the connection between linear state feedback and time-optimal control is explored. It is shown that for a class of systems an equivalent time-optimal, linear, switching hypersurface exists corresponding to an initial condition. Based on these switching planes, a high-gain linear state feedback law can be used to achieve minimum-time control on systems of order higher than two, provided that the feedback coefficients are adjusted according to the initial conditions at the start of each operation. Three different cases are investigated in detail: a second-order DC servo drive, a third-order servo system including actuator dynamics, and a fourth-order flexible mechanism. Since the proposed algorithm resembles in form a sliding-mode controller, the similarities and differences between the two control algorithms are also discussed.     

Composite nonlinear feedback control for linear systems with input saturation: theory and an application

We study in this paper the theory and applications of a nonlinear control technique, i.e., the so-called composite nonlinear feedback control, for a class of linear systems with actuator nonlinearities. It consists of a linear feedback law and a nonlinear feedback law without any switching element. The linear feedback part is designed to yield a closed-loop system with a small damping ratio for a quick response, while at the same time not exceeding the actuator limits for the desired command input levels. The nonlinear feedback law is used to increase the damping ratio of the closed-loop system as the system output approaches the target reference to reduce the overshoot caused by the linear part. It is shown that the proposed technique is capable of beating the well-known time-optimal control in the asymptotic tracking situations. The application of such a new technique to an actual hard disk drive servo system shows that it outperforms the conventional method by more than 30%. The technique can be applied to design servo systems that deal with "point-and-shoot" fast targeting.     

Robust near time-optimal control

A robust control algorithm for a realization of nearly time-optimal control of double integrator plants is presented. The technique involves the combination of traditional bang-bang time-optimal control with the methods of sliding-mode control. The result is a nonlinear feedback scheme for maintaining a desired functional relationship among dynamic variables, in this case imitating the idealized dynamics of time-optimal control. The approach is nearly time optimal rather than exactly time optimal, since the bang-bang control components are restricted to values below full actuator saturation, thus reserving some actuator effort for compensation of disturbances and model imperfections. The algorithm blends smoothly into a linear controller near a stable goal location     

交流位置伺服系统的时间次优滑模控制器设计

为了提高伺服系统定位过程中的动态特性和鲁棒性,提出一种新的时间次优滑模控制器的设计方法。首先,借鉴时间最优控制对伺服定位过程中的系统状态进行规划,得到时间最优的位置和速度响应轨迹,从而保证定位的快速性。其次,针对传统时间最优控制鲁棒性差和工程实现较难等问题,根据期望的时间最优状态轨迹设计非线性滑模面,并采用鲁棒趋近律方法设计滑模控制律,实现了伺服定位的鲁棒时间次优控制,仿真结果验证了该方法的有效性。最后,在永磁同步电机伺服控制器开发平台中进行了实验分析,结果表明所提出的控制方法具有很好的动态响应性能和鲁棒     

Particle swarm optimization for time-optimal control design

In this paper,a particle swarm optimization(PSO)based method is proposed to obtain the time-optimal bang-bang control law for both linear and nonlinear systems.By introducing a penalty function,the method can be modified to deal with systems with constraints.Compared with existing computational methods,the proposed method can be implemented in a straightforward manner.The convergent solutions can be achieved by selecting suitable PSO parameters regardless of the initial guess of the switching times.A double integrator and a third-order nonlinear system are used to demonstrate the effectiveness and robustness of the proposed method.The method is applied to obtain the time-optimal control law for a high performance linear motion positioning system.The results show the practicality of the proposed algorithm.     

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.     

Computation of time-optimal controls applied to rigid manipulators with friction

We present a numerical procedure to compute non-singular, time-optimal solutions for non-linear systems that are linear in the control and have fixed initial and final states and bounded control. Part of our procedure is a new numerically computable test that determines whether bang-bang solutions satisfy Pontryagin's minimum principle. This test reveals the new important fact that, for non-linear systems, with linear control and dimension n, the probability that a bang-bang solution with more than n - 1 switches satisfies Pontryagin's Mini mum Principle is almost zero. Using a parameter optimization procedure we search for bang-bang solutions with up to n - 1 switches which transfer the system from the initial to the final state. If no controls with up to n - 1 switches can be found to satisfy Pontryagin's Minimum Principle the problem is very likely singular. We apply our procedure to the time-optimal control problem for rigid manipulators where friction may be included in the dynamics. We will demon strate that some solutions mentioned in the literature to satisfy Pontryagin's minimum principle do not. A class of time-optimal control problems turns out to be singular. To solve these problems we propose and demonstrate the method of control parametrization.     

车载发射转塔高性能随动系统智能控制策略研究

现代战争对车载防空武器的低空高速目标的快速跟踪能力提出了很高的要求;为实现某车载发射转塔随动系统的高速高精度控制任务,抑制系统中齿隙引起的极限环振荡,提出了一种将智能分区PID反馈控制与前馈控制相结合的位置随动控制策略,并给出了易于工程实现的PID参数调整规则;设计了以嵌入式计算机PC104为核心的车载发射转塔数字交流随动系统;应用机理分析与实验相结合的方法建立了该系统的数学模型;系统仿真和实际控制结果表明,采用本文所提控制策略,可有效解决随动系统设计中快速性和稳态精度的矛盾,使系统在获得良好动、静态性能的同时,避免了极限环振荡;该方法具有较好的实用性。     

The practical implementation of time-optimal control for robotic manipulators

This paper presents experimental results for time-optimal control of robotic manipulators along specified paths. The implementation of time-optimal control represents several unique problems: (1) the control is generally discontinuous (bang-bang), (2) actuator dynamics are usually ignored in order to reduce the system order, and (3) the optimal control leaves no control authority to compensate for tracking errors caused by unmodeled dynamic and the delays introduced by the on-line feedback controller. To overcome these difficulties, we compensate for motor dynamics using a simplified friction model, and account for the dynamics of the feedback controller using trajectory preshaping. Implemented for the UCLA Direct Drive Arm, this is shown to drastically reduce the tracking errors compared to the errors obtained with no preshaping and no compensation for motor dynamics. The experimental results demonstrate the merit of time optimal control for reducing motion time as well as for increasing tracking accuracy.     

Generalized bang-bang control for feedforward constrained regulation

In the behavioral framework for continuous-time linear scalar systems, simple sufficient conditions for the solution of the minimum-time rest-to-rest feedforward constrained control problem are provided. The investigation of the time-optimal input-output pair reveals that the input or the output saturates on the assigned constraints at all times except for a set of zero measure. The resulting optimal input is composed of sequences of bang-bang functions and linear combinations of the modes associated to the zero dynamics. This signal behavior constitutes a generalized bang-bang control that can be fruitfully exploited for feedforward constrained regulation. Using discretization, an arbitrarily good approximation of the optimal generalized bang-bang control is found by solving a sequence of linear programming problems. Numerical examples are included.