智能汽车轨迹跟踪MPC-RBF-SMC协同控制策略研究

针对自动驾驶车辆行驶过程中模型失配以及外部环境干扰导致车辆轨迹跟踪环节精确性不高的问题,提出了一种结合车辆运动学模型预测控制(MPC)、径向基(RBF)神经网络和滑模控制(SMC)的轨迹跟踪控制策略。通过建立车辆运动学MPC模型计算当前状态车辆期望横摆角速度,并将其与实际横摆角速度的偏差输入RBF-SMC控制器,利用RBF快速逼近非线性模型的特点,结合滑模控制输出前轮转角,实现车辆的横向轨迹跟踪控制。仿真结果表明,与传统的控制器相比,该方法轨迹跟踪精度显著提高,并在不同行驶工况下表现出较好的鲁棒性。

Asynchronous Learning-Based Output Feedback Sliding Mode Control for Semi-Markov Jump Systems: A Descriptor Approach

This paper presents an asynchronous output-feed-back control strategy of semi-Markovian systems via sliding mode-based learning technique.Compared with most literature results that require exact prior knowledge of system state and mode information,an asynchronous output-feedback sliding sur-face is adopted in the case of incompletely available state and non-synchronization phenomenon.The holonomic dynamics of the sliding mode are characterized by a descriptor system in which the switching surface is regarded as the fast subsystem and the system dynamics are viewed as the slow subsystem.Based upon the co-occurrence of two subsystems,the sufficient stochastic admissibility criterion of the holonomic dynamics is derived by utilizing the characteristics of cumulative distribution functions.Furthermore,a recursive learning controller is formulated to guarantee the reachability of the sliding manifold and realize the chattering reduction of the asynchronous switching and sliding motion.Finally,the proposed theoretical method is substantia-ted through two numerical simulations with the practical contin-uous stirred tank reactor and F-404 aircraft engine model,respectively.

Robust design of sliding mode control for airship trajectory tracking with uncertainty and disturbance estimation

The robotic airship can provide a promising aerostatic platform for many potential applications.These applications require a precise autonomous trajectory tracking control for airship.Airship has a nonlinear and uncertain dynamics.It is prone to wind disturbances that offer a challenge for a trajectory tracking control design.This paper addresses the airship trajectory tracking problem having time varying reference path.A lumped parameter estimation approach under model uncertainties and wind disturbances is opted against distributed parameters.It uses extended Kalman filter(EKF)for uncertainty and disturbance estimation.The estimated parameters are used by sliding mode controller(SMC)for ultimate control of airship trajectory tracking.This comprehensive algorithm,EKF based SMC(ESMC),is used as a robust solution to track airship trajectory.The proposed estimator provides the estimates of wind disturbances as well as model uncertainty due to the mass matrix variations and aerodynamic model inaccuracies.The stability and convergence of the proposed method are investigated using the Lyapunov stability analysis.The simulation results show that the proposed method efficiently tracks the desired trajectory.The method solves the stability,convergence,and chattering problem of SMC under model uncertainties and wind disturbances.

Stabilization of CSTR w ith Self-tuning Sliding Mode Controller Using T-S Fuzzy Linearization

A self-tuning reaching law based sliding mode control(SMC)theory is proposed to stabilize the nonlinear continuous stirred tank reactor(CSTR).T-S fuzzy logic is used to build a global fuzzy state-space linear model.Combing the traits of SMC and CSTR,three fuzzy rules can meet the requirements of controlled system.The self-tuning switch control law which can drive the state variables to the sliding surface as soon as possible is designed to ensure the robustness of uncertain fuzzy system.Lyapunov equation is applied to proving the stability of the sliding surface.The simulations show that the proposed approach can achieve desired performance with less chattering problem.

Transient Stability Improvement of Power System Using Non-Linear Controllers

This paper presents the design of a non-linear controller to prevent an electric power system losing synchronism after a large sudden fault and to achieve good post fault voltage level. By Direct Feedback Linearization (DFL) technique robust non-linear excitation controller is designed which will achieve stability enhancement and voltage regulation of power system. By utilizing this technique, there is a possibility of selecting various control loops for a particular application problem. This method plays an important role in control system and power system engineering problem where all relevant variables cannot be directly measured. Simulated results carried out on a single machine infinite bus power system model which shows the enhancement of transient stability regardless of the fault and changes in network parameters.

Position Control of Synchronous Motor Drive by Modified Adaptive Two-phase Sliding Mode Controller

A modified adaptive two-phase sliding mode controller for the synchronous motor drive that is highly robust to uncertain- ties and external disturbances is proposed in this paper.The proposed controller uses two-phase sliding mode control (SMC) where the 1st phase mainly controls the system in steady states and disturbed states-it is a smoothing phase.The 2nd phase is used mainly in the case of disturbed states.Also,it is an autotuning phase and uses a simple adaptive algorithm to tune the gain of conventional variable structure control (VSC).The modified controller is useful in position control of a permanent magnet synchronous drive.

Adaptive Fuzzy Sliding Mode Controller for Grid Interface Ocean Wave Energy Conversion

This paper presents a closed-loop vector control structure based on adaptive Fuzzy Logic Sliding Mode Controller (FL-SMC) for a grid-connected Wave Energy Conversion System (WECS) driven Self-Excited Induction Generator (SEIG). The aim of the developed control method is to automatically tune and optimize the scaling factors and the membership functions of the Fuzzy Logic Controllers (FLC) using Multi-Objective Genetic Algorithms (MOGA) and Multi-Objective Particle Swarm Optimization (MOPSO). Two Pulse Width Modulated voltage source PWM converters with a carrier-based Sinusoidal PWM modulation for both Generator- and Grid-side converters have been connected back to back between the generator terminals and utility grid via common DC link. The indirect vector control scheme is implemented to maintain balance between generated power and power supplied to the grid and maintain the terminal voltage of the generator and the DC bus voltage constant for variable rotor speed and load. Simulation study has been carried out using the MATLAB/Simulink environment to verify the robustness of the power electronics converters and the effectiveness of proposed control method under steady state and transient conditions and also machine parameters mismatches. The proposed control scheme has improved the voltage regulation and the transient performance of the wave energy scheme over a wide range of operating conditions.

Sliding-Mode-Based Attitude Tracking Control of Spacecraft Under Reaction Wheel Uncertainties

The attitude tracking operations of an on-orbit spacecraft with degraded performance exhibited by potential actuator uncertainties(including failures and misalignments) can be extraordinarily challenging. Thus, the control law development for the attitude tracking task of spacecraft subject to actuator(namely reaction wheel) uncertainties is addressed in this paper. More specially, the attitude dynamics model of the spacecraft is firstly established under actuator failures and misalignment(without a small angle approximation operation). Then, a new non-singular sliding manifold with fixed time convergence and anti-unwinding properties is proposed, and an adaptive sliding mode control(SMC) strategy is introduced to handle actuator uncertainties, model uncertainties and external disturbances simultaneously. Among this, an explicit misalignment angles range that could be treated herein is offered. Lyapunov-based stability analyses are employed to verify that the reaching phase of the sliding manifold is completed in finite time, and the attitude tracking errors are ensured to converge to a small region of the closest equilibrium point in fixed time once the sliding manifold enters the reaching phase. Finally, the beneficial features of the designed controller are manifested via detailed numerical simulation tests.

码垛机器人的幂次指数趋近律变结构控制

为提高码垛机器人的控制精度,并保证系统在存在建模误差及扰动时的鲁棒性,设计了一种基于幂次指数趋近律的变结构控制算法。建立了二连杆机械臂数学模型,分析了三种趋近律的缺点,比较并提出了幂次指数趋近律。提出了使用求解微分方程的办法分三个阶段来研究算法的鲁棒性。分析了有界综合扰动极限值与控制器参数之间的关系。使用新算法得出了机器人在不含扰动时的仿真结果,解出了变结构控制三个阶段的微分方程,得出了机械臂在存有建模误差及扰动时的仿真结果。幂次指数趋近律变结构控制算法提高了码垛机器人的控制精度,在系统存在各种误差及扰动条件下具有极强鲁棒性并依然可以保证很高的控制精度。

基于多目标SMC汽车转向稳定性研究

为提高汽车转向稳定性,针对主动前转向(AFS)系统提出了一种基于可变传动比转向系统(VGRS)的多目标滑模控制(SMC)策略。首先依据AFS系统工作原理,建立了VGRS执行器数学模型,构建了控制器输出转向角与实际前轮转向角之间的关系。然后以双自由度汽车控制模型为基础,运用滑模变结构控制原理,设计了以侧滑角和偏航率为控制变量的滑模控制器,分析了该控制系统的稳定性。最后利用MATLAB和Simulink软件,在仿真平台上分别进行开环和闭环转向稳定性控制的仿真试验,结果表明,与模糊PID策略相比,SMC策略中的侧滑角和偏航率均有所降低,表明SMC策略能有效提高汽车转向稳定性。

基于双环自适应滑模的移动机器人轨迹跟踪控制

为了提升移动机器人轨迹跟踪精度,针对传统双环控制内外环协调性差、抗扰性弱的问题,文章提出双环自适应滑模的控制方法。为消除传统滑模控制(sliding mode control, SMC)方法中的趋近阶段,设计新型时变积分终端滑模控制器以保证系统状态始终位于滑模面,并通过控制器参数调节实现内环姿态误差和外环位置误差的快速收敛;构建基于势垒函数的增益调控方法,保证在扰动上界未知的情况下有效地抑制状态抖振,提高轨迹跟踪系统的抗干扰能力。对所提方法进行的验证分析结果表明,相较于现有的双环控制方法,该文轨迹跟踪控制方法精度更高、鲁棒性更强。

基于前馈+预测LQR的智能车循迹控制器设计

为提升智能车辆循迹性能,基于线性二次调节器(linear quadratic regulator,LQR)理论和滑模理论,提出了一种兼顾横纵向跟踪精度与转向稳定性的横纵向控制器。首先,构建了基于二自由度横向动力学模型的前馈LQR控制器。针对模型线性化后前馈LQR控制器转向稳定性降低的问题,结合恒定转弯率和速度(constant turn rate and velocity,CTRV)模型设计预测控制器,建立了基于实时车速-曲率模糊自适应预测时间的前馈LQR控制器。此外为提升纵向车速跟踪稳定性和跟踪精度,提出了一种基于滑模控制理论的纵向跟踪方法。并进行了联合仿真和硬件在环实验验证。结果表明:文中提出的横纵向控制器有效解决了跟踪精度与稳定性两者难以兼顾的问题,提升了智能车辆循迹性能。

SMC/BMC用低收缩添加剂的研究进展

介绍了SMC/BMC用低收缩添加剂的发展、收缩控制机理研究概况以及发展方向。

SMC/BMC制备中树脂糊的粘度控制

本文研究了在SMC/BMC制作过程中分散剂氧化镁和二异氰酸酯化合物对树脂糊增稠特性的影响,通过树脂糊的粘度变化,考察新型增稠体系的增稠性能和片材的贮存稳定性。本研究对于改进SMC/BMC的成型压力、片材流动、制品质量、模塑料的贮存使用期有一定的指导意义。

基于SMC的飞机仿真器航道罗盘伺服系统研究

建立了飞机仿真器航道罗盘伺服系统数学模型,选择直流电动机作为系统的执行元件,采用滑模控制(SMC)设计位置环控制器,重点讨论了控制参数的选取。仿真和实验结果表明,与直接采用LQR方法设计的控制器相比,结合变结构控制选取的控制器具有较强的鲁棒性能,能够满足系统的快速定位要求。

电磁悬浮系统的改进滑模控制方法

针对电磁悬浮系统存在的非线性、模型不准确性以及复杂运行工况对控制精度的影响,提出一种改进滑模变结构控制策略。通过对电磁悬浮系统进行建模分析设计,基于滑模变结构控制方法的位置外环控制器以及基于PI调节器的电流内环控制器,设计一种分段式变速趋近律,减小悬浮气隙跟踪误差和控制系统抖振,并引入速度状态量来降低控制系统在滑动模态初期过大的趋近速度。仿真和硬件实验结果表明,在采用改进滑模变结构控制策略后,系统的调节时间比传统滑模控制减少了60%,超调量减少了77%,具有更小的稳态误差和抖振,同等干扰情况下具有更强的抗扰动能力。本方法不仅能够有效提高电磁悬浮系统的控制性能,对于其他非线性控制系统也具有较好的参考价值。

基于文本策略和SMCS的海量日志分析方法

现有的海量日志统计分析方法速度慢,且对硬件配置的要求高。为此,提出一种基于文本策略和SMCS的海量日志分析方法。根据文件的软件设计策略,采用日志文件索引方法,将日志文件与日志时间关联,以加快日志提取。SMCS算法采用哈希表、文件归并、堆操作方法对海量日志进行统计分析和内存损耗控制。通过对真实软件进行对比实验,结果表明,该方法的分析速度比传统方法提高4倍。

基于滑模交叉耦合的双永磁电机转速同步控制

为降低双永磁电机在动态过程和扰动情况下的速度同步误差,研究了一种基于电流参考切换和滑模交叉耦合控制的方法。首先,建立了交叉耦合控制下的系统模型,并分析交叉耦合控制的作用机理;通过频域分析证明其能够降低速度同步误差,并给出了交叉耦合控制器参数设计方法;然后,为提升扰动情况下的速度同步误差收敛时间,提出了基于滑模的交叉耦合控制方法;最后,使用电流参考切换解决动态过程中受最大电流限制造成的速度同步性能不佳问题。实验结果表明,基于电流参考切换的滑模交叉耦合控制能够使扰动下速度同步误差收敛更快,同时有效降低动态过程中的速度同步误差。

基于线性扩张状态观测器的挖掘机电液系统滑模控制

无人驾驶挖掘机器人实际工作环境恶劣,为提高铲斗在负载扰动下的轨迹跟踪精度,建立了挖掘机电液系统非线性数学模型,设计了基于线性扩张状态观测器的滑模控制器(Sliding mode controller based on linear extended state observer,SMC-LESO)。根据铲斗油缸活塞杆位移信号,利用设计的线性扩张状态观测器对系统的速度、加速度及负载扰动和不确定因素进行估计,解决了系统参数难以测量的问题。在此基础上,设计了滑模控制器,并证明了该控制器的Lyapunov稳定性。为进一步验证该控制器的有效性,建立了挖掘机电液比例控制系统的联合仿真模型,并与PID控制器、滑模控制器的轨迹跟踪精度进行对比。仿真结果表明,该控制器可以有效抑制扰动,位移跟踪精度高、鲁棒性强。

音圈电机全局自适应非奇异快速终端滑模控制

为了改善音圈电机驱动系统的动态性能,课题组提出了一种全局自适应非奇异快速终端滑模控制策略。在非奇异快速终端滑模控制器的基础上,引入全局滑态因子,改善系统的瞬态响应;同时将自适应控制和非奇异快速终端滑模控制相结合,利用自适应控制可以根据系统的实时状态和外部干扰自动调整参数的特点,来减小扰动、提高系统的鲁棒性和抗干扰性;将控制律中的符号函数改为一种边界层的饱和函数来削弱振动;通过李亚普诺夫稳定性理论证明所提出的控制器的稳定性;最后,将全局自适应非奇异快速终端滑模控制与比例积分微分控制(proportional integral derivative,PID)和滑模控制(sliding mode control,SMC)进行仿真对比。结果表明:与PID控制和滑模控制相比,所提出的全局自适应非奇异快速终端滑模控制提高了系统的动态响应速度和控制精度,有效改善了系统的动态性能。