Robust H_∞ Load Frequency Control of Multi-area Power System With Time Delay:A Sliding Mode Control Approach

This paper is devoted to investigate the robust H∞sliding mode load frequency control(SMLFC) of multi-area power system with time delay. By taking into account stochastic disturbances induced by the integration of renewable energies,a new sliding surface function is constructed to guarantee the fast response and robust performance, then the sliding mode control law is designed to guarantee the reach ability of the sliding surface in a finite-time interval. The sufficient robust frequency stabilization result for multi-area power system with time delay is presented in terms of linear matrix inequalities(LMIs). Finally,a two-area power system is provided to illustrate the usefulness and effectiveness of the obtained results.

Consensus of second-order nonlinear multi-agent systems via sliding mode observer and controller

This paper investigates the consensus problem of second-order nonlinear multi-agent systems (MASs) via the sliding mode control (SMC) approach. The velocity of each agent is assumed to be unmeasurable. A second-order sliding mode observer is designed to estimate the velocity. Then a distributed discontinuous control law based on first-order SMC is presented to solve the consensus problem. Moreover, to overcome the chatting problem, two controllers based on the boundary layer method and the super-twisting algorithm respectively are presented. It is shown that the MASs will achieve consensus under some given conditions. Some examples are provided to demonstrate the effectiveness of the proposed control laws.

Tracking consensus for nonlinear heterogeneous multi-agent systems subject to unknown disturbances via sliding mode control

We investigate the tracking control for a class of nonlinear heterogeneous leader-follower multi-agent systems（MAS）with unknown external disturbances. Firstly, the neighbor-based distributed finite-time observers are proposed for the followers to estimate the position and velocity of the leader. Then, two novel distributed adaptive control laws are designed by means of linear sliding mode（LSM） as well as nonsingular terminal sliding mode（NTSM）, respectively. One can prove that the tracking consensus can be achieved asymptotically under LSM and the tracking error can converge to a quite small neighborhood of the origin in finite time by NTSM in spite of uncertainties and disturbances. Finally, a simulation example is given to verify the effectiveness of the obtained theoretical results.

Design of a Novel Multi-Mode LED Dimming and Color Control System

Aiming at the needs of different lighting applications, combined with the characteristics of LED dimming and color control, and using MSP430 digital control technology, a novel LED intelligent dimming and color control system was designed. The system integrated Bluetooth remote, human infrared sensor, voice/gesture control and other control modes, which could achieve LED multi-mode dimming and color intelligent control. System hardware and software were designed to develop a prototype to experimental verification. The designed method proposes new ideas and information for LED control.

A Multi-Model Approach to Design a Robust SVC Damping Controller Using Convex Optimization Technique to Enhance the Damping of Inter-Area Oscillations Considering Time Delay

This paper introduces a multi-model approach to design a robust supplementary damping controller. The designed fixed-order supplementary damping controller adjusts the voltage reference set point of SVC. There are two main objectives of the controller design, damping low frequencies oscillations and enhancing power system stability. This method relies on shaping the closed-loop sensitivity functions in the Nyquist plot under the constraints of these functions. These constraints can be linearized by choosing a desired open-loop transfer function. The robust controller is designed to minimize the error between the open-loop of the original plant model and the desired transfer functions. These outcomes can be achieved by using convex optimization methods. Convexity of the problem formulation ensures global optimality. One of the advantages of the proposed approach is that the approach accounts for multi-model uncertainty. In contrast to the methods available in the literature, the proposed approach deals with full-order model (i.e., model reduction is not required) with lower controller order. The issue of time delay of feedback signals has been addressed in this paper for different values of time delay by applying a multi-model optimization technique. The proposed approach is compared to other existing techniques to design a robust controller which is based on H2 under pole placement. Both techniques are applied to the 68-bus system to evaluate and validate the robust controller performance under different load scenarios and different wind generations.

Semi-active Sliding Mode Control of Vehicle Suspension with Magneto-rheological Damper

The vehicle semi-active suspension with magneto-theological damper（MRD） has been a hot topic since this decade, in which the robust control synthesis considering load variation is a challenging task. In this paper, a new semi-active controller based upon the inverse model and sliding mode control （SMC） strategies is proposed for the quarter-vehicle suspension with the magneto-rheological （MR） damper, wherein an ideal skyhook suspension is employed as the control reference model and the vehicle sprung mass is considered as an uncertain parameter. According to the asymptotical stability of SMC, the dynamic errors between the plant and reference systems are used to derive the control damping force acquired by the MR quarter-vehicle suspension system. The proposed modified Bouc-wen hysteretic force-velocity （F-v） model and its inverse model of MR damper, as well as the proposed continuous modulation （CM） filtering algorithm without phase shift are employed to convert the control damping force into the direct drive current of the MR damper. Moreover, the proposed semi-active sliding mode controller （SSMC）-based MR quarter-vehicle suspension is systematically evaluated through comparing the time and frequency domain responses of the sprung and unsprung mass displacement accelerations, suspension travel and the tire dynamic force with those of the passive quarter-vehicle suspension, under three kinds of varied amplitude harmonic, rounded pulse and real-road measured random excitations. The evaluation results illustrate that the proposed SSMC can greatly suppress the vehicle suspension vibration due to uncertainty of the load, and thus improve the ride comfort and handling safety. The study establishes a solid theoretical foundation as the universal control scheme for the adaptive semi-active control of the MR full-vehicle suspension decoupled into four MR quarter-vehicle sub-suspension systems.

Aircraft Landing Gear Control with Multi-Objective Optimization Using Generalized Cell Mapping

This paper presents a numerical algorithm tuning aircraft landing gear control system with three objectives,including reducing relative vibration, reducing hydraulic strut force and controlling energy consumption. Sliding mode control is applied to the vibration control of a simplified landing gear model with uncertainty. A two-stage generalized cell mapping algorithm is applied to search the Pareto set with gradient-free scheme. Drop test simulations over uneven runway show that the vibration and force interaction can be considerably reduced, and the Pareto optimum form a tight range in time domain.

Dynamic Modeling and Adaptive Fast Nonsingular Terminal Sliding Mode Control for Satellite with Double Rotary Payloads

A robust attitude control methodology is proposed for satellite system with double rotary payloads. The dynamic model is built by the Newton-Euler method and then the dynamic interconneetion between satellite＇s main body and payloads is described precisely. A nonlinear disturbance observer is designed for satellite＇s main body to estimate disturbance torque acted by motion of payloads. Meanwhile, the adaptive fast nonsingular terminal sliding-mode attitude stabilization controller is proposed for satellite＇s main body to quicken convergence speed of state variables. Similarly, the adaptive fast nonsingular terminal sliding-mode attitude maneuver controller is designed for each payload to weaken the disturbance effect of motion of satellite＇s main body. Simulation results verify the effectiveness of the proposed method.

Adaptive Sliding Mode Control for MIMO Nonlinear Systems Based on Fuzzy Logic Scheme

In this study an indirect adaptive sliding mode control (SMC) based on a fuzzy logic scheme is proposed to strengthen the tracking control performance of a general class of multi-input multi-output (MIMO) nonlinear uncertain systems. Combining reaching law approach and fuzzy universal approximation theorem, the proposed design procedure combines the advantages of fuzzy logic control, adaptive control and sliding mode control. The stability of the control systems is proved in the sense of the Lyapunov second stability theorem. Two simulation studies are presented to demonstrate the effectiveness of our new hybrid control algorithm.

Robust Formation Maneuvers Through Sliding Mode for Multi-agent Systems With Uncertainties

This paper develops a robust control method for formation maneuvers of a multi-agent system. The multi-agent system is leader-follower-based, where the graph theory is utilized to describe the information exchange among the agents. The control method is exercised via sliding mode methodology where each agent is subjected to uncertainties. The technique of nonlinear disturbance observer is adopted in order to overcome the adverse effects of the uncertainties. Assuming that the uncertainties have an unknown bound, the formation stability conditions are investigated according to a given communication topology. In the sense of Lyapunov, not only the formation maneuvers of the multi-agent system have guaranteed stability, but the desired formations of the agents are also realized. Compared with other two control approaches, i.e., the basic sliding mode approach and the fuzzy sliding mode approach, some numerical results are presented to illustrate the effectiveness, performance and validity of the robust control method for formation maneuvers in the presence of uncertainties.

Robust Region Tracking for Swarms via a Novel Utilization of Sliding Mode Control

Control of multi-agent autonomous swarms is studied for targeted flocking exercises. The desired decentralized control takes into account robustness against modeling uncertainties as well as bounded unknown forces. In this analysis, we consider the task of driving multiple agents to a moving “target region”, as inter-agent repulsive forces help spread out the agents within the region. An unconventional form of sliding mode control is implemented to provide the robust attraction towards the region’s center. For robustness a finite “boundary layer” is conceived, which corresponds to the desired target region. The flocking control forces are intentionally softened inside this target region, allowing agents to create a uniformly spaced formation guided by the inter-agent repulsion forces. Examples are given for moving circular and elliptical regions which illustrate the effectiveness of the proposed strategy.

内置温控多模耦合半导体激光器研究

随着半导体激光光源在通信、探测等领域应用的不断扩展,常规多模半导体光纤耦合模块功率温度特性不能满足使用需求,因此有必要研制高稳定性多模耦合半导体激光器。研制了一种内置温控的多模耦合半导体激光器。针对器件的封装耦合进行了光纤耦合设计和散热设计,并对制作的器件的光电参数进行了测试,重点测试了宽温范围内的输出功率与功率变化率。测试结果表明:光纤芯径为105μm、数值孔径(NA)为0.22时,室温下光纤输出功率大于3.1 W,耦合效率达到94%以上;在温度范围-45~70℃内,典型温度点下输出功率变化率低于1%。该内置温控多模耦合半导体激光器的研制为半导体激光器在泵浦领域的进一步应用提供了技术参考。

基于轨迹修正的曲面抛光机器人终端滑模导纳控制

针对传统抛光机器人力控制算法在位置内环控制上稳定性差的问题,同时为减小力/位控制算法相互切换导致的抛光轨迹误差,提出一种基于轨迹修正的终端滑模导纳控制方法。在抛光过程中,将力传感器反馈的参数与期望力的差值作用于导纳模型产生位置修正量,设计了终端滑模控制模型作为位置内环控制环节,并通过实时反馈位置修正量进行轨迹跟踪。通过实际轨迹信息修正规划轨迹来减小抛光力误差,达到高精度抛光的效果。仿真实验表明,终端滑模导纳控制效果良好,在对轨迹进行修正后抛光力误差相对于修正前有明显改善。利用该模型抛光后表明,轮廓算数平均偏差达到0.035μm,抛光质量得到明显提高。

基于事件触发的多智能体固定时间滑模一致性控制

针对具有未知扰动的非线性领导跟随多智能体系统一致性问题,提出一种基于自适应事件触发机制的分布式积分滑模固定时间一致性控制方法。考虑到未知外部扰动会使系统出现抖振,设计基于连续积分滑模面的分布式控制协议;为降低系统中各智能体的事件触发次数及能源损耗,保证向邻居智能体更新并传递采样信息,设计基于状态误差的自适应事件触发机制;采用固定时间稳定性理论证明设计的控制协议和事件触发机制可确保系统能迅速稳定;与有限时间相比,固定时间理论可使系统的稳定时间摆脱初值限制。仿真结果表明,相同条件下所提方法分别和引入连续积分滑模面的静态事件触发控制方法以及引入不连续积分滑模面的自适应事件触发控制方法相比可将触发次数分别平均降低32.01%和20.24%,在系统存在未知扰动的情况下5.2 s内即可达到状态一致,减少收敛时间的同时保证各跟随者的跟踪误差始终保持在±0.05以内。

基于等效阻抗渐变变压器的宽带压控振荡器

设计了一种基于65 nm CMOS工艺的毫米波宽带压控振荡器(VCO)。分析了应用于宽带VCO的宽带化技术。针对高频相位噪声性能恶化这一问题,提出并设计了一种等效阻抗渐变变压器,以优化VCO高频段相位噪声。该压控振荡器输出信号频率为20.4~40.2 GHz,覆盖24~26 GHz、38~39 GHz两个5G毫米波通信频段。全频带内,相位噪声小于-102 dBc/Hz,品质因子大于180.9 dBc/Hz。

基于分布式滑模控制的微电网二级电压控制策略

微电网是由分布式电源(DG)、负荷、储能和控制装置等构成的可控系统,能够充分高效地利用分布式能源资源。提出了一种基于分布式滑模控制的微电网二级电压滑模控制方法,基于图论和多智能体系统原理设计了分布式滑模控制器,该滑模控制器通过通信网络获取与其相邻分布式电源的电压信息,并利用Pade近似方法对通信网络中所产生的时间延迟进行补偿。在MATLAB/Simulink平台中对该控制方法进行仿真,验证了所提出二级电压控制策略的有效性。

基于干扰观测器的多航天器固定时间姿态协同跟踪控制

针对受扰动下的多航天器系统姿态一致性跟踪问题,提出一种基于干扰观测器与固定时间理论的分布式姿态协同控制策略。多航天器系统在空间中易受太阳光压、重力梯度与地磁力等外部干扰影响而导致控制精度下降,此外航天器内部惯量不确定性带来的影响也不可忽视,因此设计一种基于二阶积分滑模的干扰观测器对复合干扰进行快速精确估计,且该观测器无需任何干扰先验信息。利用观测器获得的估计值,结合领导跟随法,提出一种分布式固定时间姿态协同控制器,实现系统固定时间收敛,收敛时间可通过控制参数进行调节。利用Lyapunov函数证明了系统的固定时间稳定性。仿真与对比试验结果表明,干扰观测器能在较快时间内实现对复合干扰准确估计,协同控制器能在固定时间内实现对期望姿态鲁棒跟踪,与自适应有限时间方法相比,该控制策略精度更高、收敛速度更快和燃油消耗更少。

基于深度强化学习微小软排线装配技术的研究

传统机器人控制方法仅限于固定种类和较为规则的来料,通过位置关系完成装配。由于排线的形态变异较大,很难实现抓取和自动化组装,排线的组装成功率和良率较低。针对宽度小于2 mm微小排线装配难题,通过机器3D视觉传感、力觉传感、触觉传感和本体觉传感等多模态融合技术,设计一套基于深度强化学习的微小软排线装配智能控制算法。在此基础上搭建了一组由协作机器人、六维力传感器、3D机器视觉系统组成的实验设备,并在多环境、不确定因素下验证了此方法装配的可行性。基于高精度微小排线的装配要求,通过深度强化学习多模态控制方法大幅提升了可靠性和装配的成功率,相比传统控制方法装配效率提升15%以上。此测试系统的装配精度可达±0.1 mm,装配成功率到达98%以上。

基于多工况模式的复合型悬架平顺性研究

悬架系统作为调控车辆平顺性的核心组件,其性能直接决定了车辆行驶的优劣。针对目前车辆在复杂路面行驶过程中平顺性较差的问题,本文构建了不同于传统悬架的复合型悬架结构,并搭建该悬架的整体系统构架。首先为了探究整车复合型悬架的振动机理,构建整车复合型悬架动力学模型;其次结合驾驶员复杂的行驶需求,构建基于多工况的复合悬架系统控制策略,通过车辆行驶中不同的加权加速度均方根值验证其优化效果,并结合反空气弹簧模型证明了该系统可以减少空气弹簧的磨损;最后,在VI-Grade紧凑型驾驶模拟器中根据所构建的复杂工况进行试验验证,对比有无控制时的车身垂向加速度、侧倾角加速度和俯仰角加速度试验结果。试验结果表明,通过复杂工况中的车辆性能测试,所提出的复合型悬架系统在直线、弯道和制动3种工况下改善性能分别达到了32.26%、23.77%和7.38%,可以有效改善车辆行驶时的平顺性性能,解决了正常行驶下空气弹簧的损耗问题。

摆臂式全向移动机器人双模式轨迹跟踪研究

为了提升室外轮式移动机器人全向机动能力,文中提出一种通过普通轮作为驱动的移动机器人,根据不同动力分配及摆腿转角实现四轮转向(4WS)、斜行和原地转向模式。基于斜行及4WS模式设计了双模式混合控制器,其中,斜行模式采用多点预瞄模糊补偿轨迹跟踪控制,4WS模式采用增量线性时变模型预测控制(ILTV-MPC)。通过试验样机的横、纵向跟踪性能试验得到双模式混合控制器所需的约束条件。采用Simulink∕CarSim联合仿真平台对控制器的有效性进行验证。采用混合控制器的移动机器人底盘在低曲率跟踪时较4WS模式均方根误差相差0.18%,且横摆角与横摆角速度维持不变。结果表明:混合控制器保证全轮转向机器人低曲率跟踪精度的同时提升了其横摆稳定性。