一种动态性能友好型柔性直流输电系统高频自稳控制策略

现有高频振荡有源抑制策略存在恶化柔直系统动态性能、对电网工况变化的适应性差等不足。该文提出一种动态性能友好型高频自稳控制策略,在基本不影响柔直系统动态性能的基础上,能够完全消除模块化多电平换流器(modular multilevel converter,MMC)交流端口的高频负电阻特性,对不同电网工况具有强适应性。首先,在静止坐标系中建立包含正负序分离环节、正负序电流控制环节和锁相环等的MMC高频阻抗模型,通过对比传统高频简化阻抗模型,发现锁相环对MMC高频阻抗的附加电阻效应,并进一步分析锁相环控制参数和静态工作点变化对附加电阻效应的影响。其次,阐述所提高频自稳控制策略的基本原理,并给出其参数设计方法。此外,通过建立柔直系统的动态响应模型和暂态电流模型,分析所提策略在柔直系统动态性能方面的优势。最后,通过仿真验证了所提策略能够有效适应不同电网工况,且基本不影响柔直系统的动态性能。

基于数据弥补的自稳控制交通流建模与仿真

传统车辆交通流模型根据车头距、当前速度及前车速度等数据建立,近年来,有些学者在传统交通流模型上加入了当前速度和历史速度的差,以提升交通流对小扰动传播的稳定性,并称之为自稳控制。但是这种自稳控制所需的信息容易因为一些因素丢失,导致交通流稳定性下降。本文试图在自稳数据丢失的情况下做数据的弥补,通过使用最近邻前车的相同类型的数据对丢失的自稳控制所需数据进行替换,并提出基于数据弥补的自稳控制交通流模型。为了验证对丢失数据的补偿是否能使自稳车辆稳定,对补偿方案进行了建模以及线性稳定性分析。理论分析结果表明,本文提出的补偿策略使交通流更稳定,仿真结果验证了理论分析结果的正确性。

扑翼机自稳飞控系统的模型构建与仿真研究

主要对扑翼机的自稳飞行控制系统进行了分析,从而构建模型并进行仿真研究。以鸟类扑翼飞行运动为研究对象,以扑动飞行过程中的机械结构为基础,逐步建立二维和三维运动方程,结合自动控制工程原理、高等微积分、复变函数等基础原理,对复杂的参量输入数据进行多项变换和简化处理,从而转化为可控性高、可视化效果好的信号输出。结合具体算法使用matlab软件进行优化处理,更好地对模型自稳系统做仿真数据分析。

Finite-time Stabilization of the Double Integrator Subject to Input Saturation and Input Delay

Abstract--The time-optimal control design of the double integrator is extended to the finite-time stabilization design that compensates both input saturation and input delay. With the aid of the Artstein＇s transformation, the problem is reduced to assigning a saturated finite-time stabilizer. Index Terms--Finite-time stabilization, input delay, saturated design.

Robust control with compensation of adaptive model for dual-stage inertially stabilized platform

To achieve excellent tracking accuracy,a coarse-fine dual-stage control system is chosen for inertially stabilized platform.The coarse stage is a conventional inertially stabilized platform,and the fine stage is a secondary servo mechanism to control lens motion in the imaging optical path.Firstly,the dual-stage dynamics is mathematically modeled as a coupling multi-input multi-output(MIMO)control system.Then,by incorporating compensation of adaptive model to deal with parameter variations and nonlinearity,a systematic robust H∞control scheme is designed,which can achieve good tracking performance,as well as improve system robustness against model uncertainties.Lyapunov stability analysis confirmed the stability of the overall control system.Finally,simulation and experiment results are provided to demonstrate the feasibility and effectiveness of the proposed control design method.

Dynamical output feedback stabilization for neutral systems with mixed delays

This paper is concerned with the issue of stabilization for the linear neutral systems with mixed delays. The attention is focused on the design of output feedback controllers which guarantee the asymptotical stability of the closed-loop systems. Based on the model transformation of neutral type, the Lyapunov-Krasovskii functional method is employed to establish the delay-dependent stability criterion. Then, through the controller parameterization and some matrix transformation techniques, the desired parameters are determined under the delay-dependent design condition in terms of linear matrix inequalities (LMIs), and the desired controller is explicitly formulated. A numerical example is given to illustrate the effectiveness of the proposed method.

IMPLEMENTATION OF ADAPTIVE ROBUST POLE-PLACEMENT DESIGN

n this paper an adaptive robust algorithm for pole-placement design is proposed. It consists of the refined--optimal IV parameter estimator and a robust pole--placement controller. The robustness of the algorithm means that the output of the controlled plant can be stabilized in the presence of unmodelled dynamics and bounded unmeasurable output noise. Simulation results show the effeciency of the algorithm.

Absolute Stability for Lurie Control System with Unbound Time Delays

Time delay existes widely in various real engineering systems and can result in unsatisfactory performance or even an instability of control systems. Therefore, to investigate the stability for time delay systems is of vitul importance in control theory and its applications. Many researchers have studied the stability criteria of systems with constant delay or bound varying time delay, but few of them studied large time delay or unbound time delay. Large time delay existes commonly in various engineering applications. In this paper, the absolute stability of Lurie type direct control systems and indirect control systems with several time delays are discussed. Based on Lyapunov theory, the new delay dependent absolute stability criteria are derived. In our theorem, time delays can be unbound functions, which shows that the results are less conservative than that of existed criteria.

Robust stabilization of general nonlinear systems with structural uncertainty

This paper deals with the robust stabilization and passivity of general nonlinear systems with structural uncertainty. By using Lyapunov function, it verifies that under some conditions the robust passivity implies the zero-state detectability, Furthermore, it also implies the robust stabilization for such nonlinear systems. We then establish a stabilization method for the nonlinear systems with structural uncertainty. The smooth state feedback law can be constructed with the solution of an equation. Finally, it is worth noting that the main contribution of the paper establishes the relation between robust passivity and feedback stabilization for the general nonlinear systems with structural uncertainty. The simulation shows the effectiveness of the method.

STATE-FEEDBACK ADAPTIVE STABILIZING CONTROL DESIGN FOR A CLASS OF HIGH-ORDER NONLINEAR SYSTEMS WITH UNKNOWN CONTROL COEFFICIENTS

In this paper, a new approach is successfully addressed to design the state-feedback adaptive stabilizing control law for a class of high-order nonlinear systems in triangular form and with unknown and nonidentical control coefficients, whose stabilizing control has been investigated recently under the knowledge that the lower bounds of the control coefficients are exactly known. In the present paper, without any knowledge of the lower bounds of the control coefficients, based on the adaptive technique and appropriately choosing design parameters, we give the recursive design procedure of the stabilizing control law by utilizing the approach of adding a power integrator together with tuning functions. The state-feedback adaptive control law designed not only preserves the equilibrium at the origin, but also guarantees the global asymptotic stability of the closed-loop states and the uniform boundedness of all the other closed-loop signals.

Robust adaptive cross-coupling position control of biaxial motion system

The stability and synchronous performance are usually hard to be improved simultaneously in the biaxial cross-coupling position motion control system.Based on analyzing the characteristics of the cross-coupling control system,a robust adaptive cross-coupling control strategy is proposed.To restrict influences of destabilizing factors and improve both of stability and synchronous performance,the strategy forces dual axes to track the same reference model using Narendra adaptive control theory.And then,a robust parameters adaptive law is proposed.The stability analysis of the proposed strategy is conducted by applying Lyapunov stability theory.Related simulations and experiments indicate that the proposed strategy can improve synchronous performance and stability simultaneously.

ADAPTIVE SET STABILIZATION OF THE ATTITUDE OF A RIGID SPACECRAFT WITHOUT ANGULAR VELOCITY MEASUREMENTS

The global adaptive set stabilization problem of the attitude of a rigid spacecraft is addressed in this paper. Two different cases are considered. First, by using adaptive backstepping method, the authors design a global adaptive control law for the attitude control system with unknown inertia matrix such that the attitude and the angular velocities can be globally asymptotically stabilized to a set consisting of two equilibria. And then, based on the obtained backstepping adaptive law, the authors consider the case that the angular velocities are not measurable. By introducing an auxiliary state, a semi-global adaptive set stabilization law without angular velocity measurements is also designed. It is rigorously proved that, for the two cases, both of the closed loop systems satisfy the set stability. The effectiveness of the proposed methods is verified by simulation results.

Adaptive fuzzy sliding mode control for coordinated longitudinal and lateral motions of multiple autonomous vehicles in a platoon

In this paper, the platoon control problem of autonomous vehicles in highway is studied. Since the autonomous vehicles have the characteristics of nonlinearities, external disturbances and strong coupling, a novel adaptive fuzzy sliding coordinated control system is constructed to supervise the longitudinal and lateral motions of autonomous vehicles, in which the fuzzy system is employed to approximate the unknown nonlinear functions. Due to the low sensitivity to disturbances and plant parameter variations, the proposed control approach is an efficient way to handle with the complex dynamic plants operating under un-certainty conditions. The asymptotic stability of adaptive coordinated platoon close-loop control system is verified based on the Lyapunov stability theory. The results indicate that the presented adaptive coordinated platoon control approach can accurately achieve the tracking performance and ensures the stability and riding comfort of autonomous vehicles in a platoon. Finally,simulation test is exploited to demonstrate the effectiveness of the proposed control approach.