基于四元数的航天器姿态非线性控制器

针对由四元数描述的航天器姿态控制系统进行了非线性反馈控制器设计.首先,得到一类含角速度测量的反馈控制律.该控制律不仅可以保证闭环系统是全局渐近稳定的,而且保证了2个期望的平衡位置都是稳定的.然后,利用基于四元数的滤波器取代角速度测量,得到一类无需角速度测量的反馈控制律.该控制律同样保证了闭环系统的全局渐近稳定性和2个稳定的期望平衡位置.值得注意的是,2个稳定的期望平衡位置,将促使由任意初始姿态出发的轨迹都就近收敛至任意期望平衡位置.最后,数值仿真展示了所得反馈控制律的优势.     

一种继电自动调节系统平衡位置的全局稳定性

本文对切除硬反馈的继电自动调节系统平衡位置的全局稳定性进行了初步的讨论.利用A.M.李雅普诺夫的直接法和B.A.雅库波维奇的结果,给出系统平衡位置全局稳定性的若干频率式的充分判据.文末应用同样的方法,讨论了继电直接调节系统平衡位置的全局稳定性,得到了一个较文献[2,3]易于应用的频率式的充分判据.     

一种继电自动調节系統平衡位置的全局稳定性

本文对切除硬反馈的继电自动调节系统平衡位置的全局稳定性进行了初步的讨论.利用A.M.李雅普诺夫的直接法和B.A.雅库波维奇[1]的结果,给出系统平衡位置全局稳定性的若干频率式的充分判据.文末应用同样的方法,讨论了继电直接调节系统平衡位置的全局稳定性,得到了一个较文献[2,3]易于应用的频率式的充分判据.     

Pendubot的一种分层滑模控制方法

针对Pendubot这类二阶欠驱动系统提出了一种分层滑模控制方法.该方法将系统状态分成两个子系统,分别构造滑动平面,采用Lyapunov方法求取总控制量,该控制量可以实现Pendubot的摆起控制,当系统接近平衡位置附近时,双层滑模控制器退化成单层控制器,这样又保证了Pendubot能够稳定在最终的平衡位置上.从理论上证明了各层滑动平面的渐近稳定性,并且通过仿真实验验证了该方法的有效性以及该控制器对各类扰动的自适应性.     

一种新型自动平衡伺服装置的设计

本文详细地介绍了一种自行研制的新型自动平衡伺服装置,该装置应用闭环极点配置算法,最优化二次型系统及电机非线形补偿等控制方法,实现了对自动平衡装置中平衡位置的精密控制,并且该控制箱可以与自行研制的其它实验设备对接.系统自行构思设计并安装调试,适用于现代控制理论、经典控制理论和自动控制系统试验研究.具有广泛地实用性和通用性.     

基于T-S 模糊模型的3D 刚体摆姿态控制

3D 刚体摆的倒立平衡点附近具有不稳定的流形, 针对倒立平衡位置的姿态稳定性问题, 建立T-S 模糊模型, 并采用并行分布补偿(PDC) 法和线性矩阵不等式(LMI) 法探讨了闭环T-S 模糊控制系统的稳定性. 仿真实验表明, T-S 模糊控制对3D 刚体摆倒立平衡位置处的姿态控制是可行和有效的.

     

控制与本质非线性问题

回顾了控制理论的发展, 并讨论了线性系统、单平衡位置系统的本质特征. 重点介绍了多平衡点非线性系统的本质非线性特征, 复杂多彩的动态特性, 包括自振、混沌、同宿轨、异宿轨, 特别是讨论了高阶系统的复杂性. 进一步讨论了控制介入到本质非线性系统后可能的发展前景与挑战.     

内共振关系对弹簧摆动力学行为的影响

基于数值方法,以弹簧摆为对象,讨论了不同的内共振关系对一类平方、立方非线性系统动力学行为的影响.结果表明,对1∶1内共振的情况,两个模态的振动均可能发生在偏离原来平衡位置的新的平衡位置附近,即出现平衡位置飘移的现象.能量可以从低阶(摆动)模态传递到高阶(呼吸)模态,但不能从高阶(呼吸)模态传递到低阶(摆动)模态.然而对...     

无刷直流电机启动过程仿真研究

研究无刷电机启动优化稳定性控制问题,在无刷直流电机启动过程中,预定位阶段转子到达平衡位置时会出现震荡现象,加速阶段电机换相时间曲线难以确定,电机启动的稳定性变差。为了使电机能够快速平稳启动,提出用三段式启动方式,采用一种电机外加电压逐渐增加的转子预定位方法。首先利用Park变换和Clark变换对转子预定位过程进行数学建模分析,同时对强推加速阶段进行仿真。仿真结果可以表明方法可以使转子平稳旋转到平衡位置,并通过研究换相时,减小了对启动过程的影响,为实际无刷直流电机优化控制设计提供理论依据。     

啤酒发酵过程计算机控制系统

介绍一个已成功应用的啤酒发酵过程控制系统.具体介绍了该系统涉及的对象特性、发酵温度的测量与控制,以及软硬件配置等.由于采用了集成电路温度传感器和多模态优化采样控制,取得了很好的控制精度、稳定性和可靠性.     

Generation of stable oscillations in uncertain nonlinear systems with matched and unmatched uncertainties

ABSTRACT

In this paper, a robust limit cycle control technique is proposed for generation of stable oscillations in a class of uncertain nonlinear systems with both matched and unmatched uncertainties. For this purpose, first, the modified Lyapunov function is introduced which is appropriate for stability analysis of invariant sets (instead of equilibrium points). The structure of the proposed Lyapunov function is related to the shape of the desirable limit cycle. Next, in order to design the robust limit cycle control input, the backstepping and Lyapunov redesign methods are employed, simultaneously. The The classical Lyapunov redesign controller is discontinuous and robust with respect to matched uncertainties. To overcome unmatched uncertainties, a modified version of the Lyapunov redesign controller is suggested in each step of backstepping which results in a continuous robust control law. Furthermore, the convergence of the phase trajectories of the uncertain closed-loop system to the target limit cycle is proved using the extended Lyapunov stability theorem. Finally, computer simulations are performed to show the applicability of the given approach. In this regard, two uncertain nonlinear practical systems are considered and robust stable oscillations are generated in these systems via the proposed controller. Simulation results confirm the effectiveness of the proposed technique.     

基于输出反馈的欠驱动TORA系统的有界输入控制

针对欠驱动TORA(Translational oscillations with a rotational actuator)系统,设计了一种具有执行器饱和约束的输出反馈等[7]特别地,由Rand学者提出的TORA系统,最初控制器.与其他现有方法相比,本文方法不仅考虑了执行器饱和约束和作为双自旋航天器的简化模型用于研究自振现象.后来由于速度信号不可测情形,而且考虑了旋转小球可能存在的循环行为.具体而TORA系统具有强耦合、高度非线性、欠驱动等特性,而被言,首先根据TORA系统模型分析了TORA系统的控制目标;随后,作为一种非线性基准系统主要用于非线性控制器设计、验证构造了一种新颖的能量函数,在此基础上设计了一种考虑执行器饱和约非线性控制算法的控制性能或教学研究.目前国内外已有多束的输出反馈控制器,并通过严格的数学分析证明了闭环系统关于平衡点的稳定性;最后,借助数值仿真测试检验了所提控制器的控制性能,并所高校和研究机构针对TORA系统的控制问题展开研究.对与已有方法进行了对比.仿真测试结果表明本文所提方法具有更好的控法制性能.     

Set stability of controlled Chua’s circuit under a non-smooth controller with the absolute value

Chua’s circuit is a typical system with the piecewise-smooth vector field via the absolute value. A new piecewise-linear feedback control scheme with the absolute value is introduced to realize stabilization of sets of the controlled Chua’s circuit. The equilibrium sets and the global asymptotical stability with respect to several invariant sets, which may consist of both admissible and boundary equilibrium points or equilibrium manifolds, are investigated for the controlled Chua’s circuit system. The non-smooth controller has a simple structure and available control properties, and it is easy to be applied in engineering practice. It is shown by numerical simulations that this controller can effectively realize chaos control and stabilization of equilibrium states.     

欠驱动TORA系统的自耦PID控制策略

针对欠驱动旋转激励平移振荡器(translational oscillations with a rotational actuator,TORA)系统的控制问题,使用一种自耦PID(self-coupling proportional-integral-differential,SCPID)控制方法.该方法首先利用坐标变换使TORA系统的质心映射为Huygens振动中心,以实现新系统控制输入解耦,避免零动态不稳定问题;然后对Huygens振动中心设计平移位置的SCPID控制器,同时获得小球偏转角度的虚拟指令,进而设计小球偏转角度的SCPID控制器,从而实现TORA系统的平衡点跟踪控制;最后在复频域对闭环控制系统的稳定性进行严格的数学分析和证明.仿真及与其他方法的结果对比表明,所设计的控制算法简单高效,在欠驱动控制系统领域具有实际的应用价值.     

Delayed-input power system stabilizer using supplementary remote signals

The design of a local H_∞-based power system stabilizer controller, using wide area or global signals as additional measuring information considering time delay, is presented in this paper. The wide area signals are taken from suitable remote network locations where the oscillations are well observable. A long time delay introduced by remote signal transmission and processing in wide area measurement system (WAMS) may harm system stability and degrade system robustness. Three methods for dealing with the effects of time delay are presented in this paper. To provide robust behavior, H_∞ control theory together with an algebraic Riccati equation (ARE) approach has been applied to design the controllers. The effectiveness of the resulting robust H_∞-based PSS controllers is demonstrated through digital simulation studies conducted on a test power system. The simulation results show that the proposed controller contributes significantly to the damping of inter-area oscillations and the enhancement of small-signal stability in the presence of uncertainty in time delay under a wide range of system operating conditions.     

Improved Design of Interval Type-2 Fuzzy based Wide Area Power System Stabilizer for Inter-area Oscillation Damping

The interconnection of power system due to the ever-time increase in power demand has caused inter-area oscillations as a challenge to power system stability. The present paper proposes the novel design of an Interval Type-2 Fuzzy based Wide Area Power System Stabilizer to damp the inter-area mode of oscillations for improving the power system stability. The usage of Wide Area Measurement Systems for continuous monitoring of the power grid plays a significant role in maintaining the stability of the power grid. The proposed controller uses wide-area signals from WAMS as the input signals. The controllability index calculation performs the selection of the most affected wide-area signals. The participation factor is used to identify the location of the controller. Sliding Surface approach is introduced in the controller to upgrade the performance of the controller during different operating conditions. The sliding surface approach has made the system insensitive to the parameter variations. The interval type-2 fuzzy control is a model-free approach with better control performance, due to its higher degree of freedom of interval type-2 fuzzy sets. Finally, the optimal tuning of sliding surface parameters has been considered as an optimization problem with the minimization of Integral Time Square Error using Real Coded Genetic Algorithm to enhance the damping control. The proposed Fuzzy controller has been tested in two area, four machine, 11 bus IEEE benchmark system. From the simulation responses and the comparison with different controllers, the proposed controller shows robustness and effectiveness with more accurate dynamic response and better damping of inter-area oscillations under different system operating conditions and load perturbations.     

一类欧-拉系统的全系数自适应控制研究

对于动力学方程未知的全驱动多变量欧-拉系统,进行了基于特征模型的全系数自适应控制方法研究.根据全系数自适应控制思想,针对全驱动欧-拉系统提出了差分方程形式的特征模型,并得到该特征模型各系数的一些性质.基于建立的特征模型,提出多变量黄金分割控制律和相应的自适应控制策略,并对闭环系统的稳定性进行了分析.最后对两连杆的空间机器人进行了仿真,仿真结果表明了该自适应控制方法的优越性.     

Plasma vertical stabilization with actuation constraints in the DIII-D tokamak

In the advanced tokamak (AT) operating mode of the DIII-D tokamak, an integrated multivariable controller takes into account highly coupled influences of plasma equilibrium shape, profile, and stability control. Time-scale separation in the system allows a multi-loop design: the inner loop closed by the nominal vertical controller designed to control a linear exponentially unstable plant and the outer loop closed by the nominal shape controller designed to control a linear stabilized plant. Due to actuator constraints, the nominal vertical controller fails to stabilize the vertical position of the plasma inside the tokamak when large or fast disturbances are present or when the references coming from the shape controller change suddenly. Anti-windup synthesis is proposed in this paper to find a nonlinear modification of the nominal vertical controller that prevents vertical instability and undesirable oscillations but leaves the inner loop unmodified when there is no input saturation.     

Nonlinear oscillations in magnetic bearing systems

Nonlinear oscillations in magnetic bearings caused by gyroscopic effects at high speeds are analyzed. First a nonlinear model for the magnetic bearing is set in state-variable form using airgap flux, gap displacement, and velocity as state variables. The system, which is unstable in nature, is stabilized locally around the equilibrium point of zero speed using an optimal robust servo controller. It is shown that as the speed changes the system undergoes Hopf bifurcation to periodic solutions around some critical speed. The periodic solutions are shown to be unstable, so the methods of nonlinear bifurcation control are used to stabilize them. An easily implemented nonlinear feedback control of quadratic order is derived to control the Hopf bifurcation occurring in the system. The transient response of the system with and without nonlinear feedback is obtained to show the effectiveness of nonlinear feedback     

Stabilization of the Furuta pendulum around its homoclinic orbit

We present an energy based control approach to control the Furuta pendulum. A controller is proposed for swinging the pendulum and raise it to its uppermost unstable equilibrium position. The passivity properties of the system are used as a guideline in the control strategy. The stability analysis is carried out by using a Lyapunov technique.