基于微分几何的离合器接合过程速度跟踪滑模控制

针对离合器控制系统中存在的非线性、外部干扰和参数不确定问题,提出了基于微分几何的离合器接合过程速度跟踪滑模控制方法。考虑系统参数的不确定性和外界干扰等不确定因素,建立了单个离合器起步动力学模型;基于微分几何的反馈线性化方法,得出系统的控制律;采用基于趋近律的滑模控制方法,设计了存在不确定干扰的离合器控制系统滑模控制器。利用Lyapunov理论对系统的稳定性进行了证明。仿真结果表明该控制器使离合器接合过程的速度跟踪精度高,且鲁棒性好。     

双离合器自动变速器双离合器起步与换档的反馈线性化控制的研究

对理想发动机飞轮转速与理想离合器从动片转速的精确跟踪是提高双离合器式自动变速器(DCT)起步与换档品质的关键。针对DCT在起步与换档时离合器接合过程的仿射非线性动力学模型,利用基于微分几何的反馈线性化方法,将原非线性系统拓扑等价为完全可控型线性化系统并对该线性系统实施PID控制。仿真结果表明:起步与换档时的仿射非线性系统稳定、跟踪性态良好。     

多关节机器人反馈线性化双模糊滑模控制

为了提高多关节机器人轨迹跟踪控制性能,提出了一种反馈线性化双模糊滑模控制方法。该方法在对机器人非线性动力学模型反馈线性化的基础上,设计了一种双模糊滑模控制器。通过设计一个模糊控制器,根据跟踪误差和误差变化率自适应地调整滑模面的斜率,从而加快响应速度。通过设计另一个模糊控制器,根据滑模面自适应地调整滑模控制的切换控制部分,从而减弱抖振。利用李亚普诺夫定理证明了控制系统的稳定性。针对空间三关节机器人进行了仿真实验,结果表明了所提方法的有效性。     

轮式移动焊接机器人输出反馈线性化控制

针对目前基于运动学模型的焊缝跟踪控制已经不能满足焊缝跟踪的高精度要求的问题,以一种后两轮差速驱动的5自由度轮式移动焊接机器人为对象,给出其动力学模型及其输出反馈线性化的过程,并提出一种基于此动力学的轮式移动焊接机器人路径跟踪控制方法。建立轮式移动机器人具有非完整力学系统形式的动力学模型,并推导出对应的状态反馈精确线性化模型。在此线性化模型基础上,考虑机器人动力学模型参数的不确定性,利用滑模变结构控制方法来设计动力学控制规律,选取线性切换函数和指数趋近律,设计滑模变结构控制器。并利用Lyapunov稳定性理论证明系统的稳定性且跟踪误差收敛,满足了移动机器人的轨迹跟踪要求,且具有设计方法简单、鲁棒性强的特点。通过仿真验证所提控制律的有效性和正确性。     

滑模变结构控制在单级倒立摆系统中的应用研究

基于单级倒立摆的线性和非线性模型,分别设计了滑模变结构控制器,并对滑模运动方程的稳定性进行了分析.其中,为求取倒立摆非线性模型的等效控制和滑模运动,进行了单输入仿射非线性系统方面的研究.     

电磁转差式ECHPS系统自适应模糊滑模控制研究

为实现转向系统随车速可变的助力特性,提出了一种电磁转差式商用车电控液压助力转向系统。分析了该系统的基本组成及原理和电磁转差离合器的组成结构,建立了电磁转差离合器的动力学模型和控制模型。针对控制系统存在的不确定性和外界干扰,提出了自适应模糊滑模控制策略,将模糊推理应用于系统参数的整定,以补偿控制系统因自身不确定性和外界干扰所导致的误差。仿真结果表明,所设计的自适应模糊滑模控制具有超调量小、稳态精度好、抗干扰能力强的优点,可实现电磁转差离合器的精确稳定控制。     

基于滑模变结构的陀螺稳定平台非线性解耦控制

为了消除陀螺稳定平台系统中各框架间的非线性耦合影响,设计了一种滑模非线性解耦控制算法.分析了高精度三轴陀螺稳定平台框架间的非线性耦合特性,建立了系统的动力学模型.利用非线性微分几何方法对系统进行了输入输出解耦控制设计,结合模型跟踪滑模变结构控制方法消除了系统解耦控制中的非线性扰动因素.针对滑模控制中的抖动问题,设计了带有边界层的积分滑模控制器,有效减弱了控制器的抖振现象,提高了系统解耦精度.在某型号电视导引头稳定平台系统中测试表明了该解耦控制方法的有效性和可行性.同PID方法和不带边界层的滑模控制方法相比较,该解耦方法的解耦效果明显优于其他两种方法.     

基于滑模变结构的DCT车辆双离合器起步控制研究

对双离合器式自动变速器(DCT)的结构特点进行分析,利用Matlab/Simmechincs建立起步过程中DCT车辆的物理模型。分析车辆起步时发动机输出转矩和发动机转速的变化规律,实现发动机恒转速起步。根据发动机的输出转矩、离合器传递转矩、离合器滑差率以及车辆的阻力矩建立了滑模控制器,控制输出离合器控制油压。制定双离合器同时接合的起步和l挡单离合器结合起步控制策略,在轻载、中载和重载三种工况下对车辆起步进行仿真,从而验证滑模控制器的正确性,并以离合器结合时间、起步平顺性以及离合器滑模功为评价指标。最后,在轻载工况下,将滑模控制器控制双离合器起步与PID控制双离合器轻载进行仿真对比。仿真结果表明,滑模控制器能够实现DCT车辆平稳起步,并且双离合器起步可以缩短起步时间,可以减少单个离合器滑摩功,有利于提高离合器的寿命。     

悬臂梁非线性振动的压电分阶最优控制

提出非线性的分阶最优控制策略,并将其应用于悬臂梁非线性振动的压电减振控制.建立悬臂梁非线性压电减振系统动力学模型,导出减振系统的非线性动力学运动微分方程.将梁振动挠度和压电驱动器的控制电压同时展开为小参数形式,利用摄动法实现非线性压电控制微分方程的线性化.通过空间解耦,得到状态空间方程.设计非线性分阶控制器,对该减振系统进行分阶最优控制.     

含齿隙伺服系统的反步自适应模糊滑模控制

针对具有齿隙非线性和参数摄动的某机械传动回转位置伺服系统,提出一种基于反演法的自适应模糊滑模控制策略。首先,在两质量系统中,引入近似死区模型,建立含齿隙的系统动力学模型。然后,通过反演法逐步选择Lyapunov函数,结合滑模控制补偿系统中的参数不确定和齿隙非线性。通过模糊推理机制将不连续切换项线性处理,消除传统滑模控制中的抖振现象。对比试验表明,基于反演法的自适应模糊滑模控制较PID控制更能有效削弱大、小齿轮间传递力矩的波动,并具有更高的位置跟踪精度和对系统参数变化的鲁棒性。     

Adaptive fuzzy sliding-mode control for the Ti6Al4V laser alloying process

It is well known that surface alloying quality may vary significantly with respect to process parameter variation. Thus a feedback control system is required to monitor the operating parameters for yielding a good quality control. Since this multi-input and multi-output (MIMO) system has nonlinear coupling and time-varying dynamic characteristics, it is very difficult to establish an accurate process model for designing a model-based controller. Hence an adaptive fuzzy sliding-mode controller (AFSMC) which combines an adaptive rule with fuzzy and sliding-mode control is employed in this study. It has an on-line learning ability for responding to a system’s nonlinear and time-varying behaviours. Two adaptive fuzzy sliding-mode controllers are designed for tuning the laser power and the traverse velocity simultaneously to tackle the absorptivitiy and geometrical variations of the work pieces. The simulation results show that good surface lapping performance is achieved by using this intelligent control strategy.     

Output tracking control of mobile manipulators based on dynamical sliding-mode control

A dynamical sliding-mode controller is devised to track the output of mobile manipulators. During the investigation, firstly a reduced dynamic model considering the dynamics of the driving motor is developed for mobile manipulators. Then, the system is decomposed into four lower-dimensional subsystems by means of diffeomorphism and nonlinear input transformation. Moreover, a design method of the dynamical sliding-mode controller that is applied to the output tracking of mobile manipulators is proposed. The simulation results indicate that the dynamical sliding-mode controller can not only track the given trajectory correctly but also reduce the chattering of sliding-mode control system considerably. __________ Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(6): 29–33 [译自: 华南理工大学学报 (自然科学版)]     

Precision tracking control of a piezoelectric-actuated system

In this paper, precision tracking control of piezoelectric-actuated systems is discussed. In order to obtain precision tracking control, a modified Prandtl–Ishlinskii (MPI) model is used to model the hysteresis nonlinearity. Then, the inverse MPI model is used to reduce the hysteresis nonlinearity, and a sliding-mode controller is used to compensate for the remaining nonlinear uncertainty and disturbances. In general, the piezoelectric-actuated system can be modeled as a linear model coupled with a hysteresis. When the linear model is identified, it is used to design the sliding-mode controller. Finally, this design method is applied to the motion control of a nano-stage, and experimental results are presented to verify the usefulness of this method.     

滑模模糊控制算法在液压机器人控制中的应用

Pb-211液压机器人腰部是一个非线性液压伺服控制系统，常规PID控制算法很难在不出现超调情况下满足控制系统快速性的要求。针对这种情况以及液压系统参数时变等特点，在常规滑模控制算法的基础上，引入模糊控制技术，采用滑模模糊控制策略进行控制器设计。仿真结果表明，滑模模糊控制算法能够在不出现超调情况下显著提高系统的响应速度，满足系统响应速度和控制精度的要求，而且对正弦干扰具有较强的鲁棒性。     

A novel auto-tuning PID control mechanism for nonlinear systems

In this paper, a novel Runge–Kutta (RK) discretization-based model-predictive auto-tuning proportional-integral-derivative controller (RK-PID) is introduced for the control of continuous-time nonlinear systems. The parameters of the PID controller are tuned using RK model of the system through prediction error-square minimization where the predicted information of tracking error provides an enhanced tuning of the parameters. Based on the model-predictive control (MPC) approach, the proposed mechanism provides necessary PID parameter adaptations while generating additive correction terms to assist the initially inadequate PID controller. Efficiency of the proposed mechanism has been tested on two experimental real-time systems: an unstable single-input single-output (SISO) nonlinear magnetic-levitation system and a nonlinear multi-input multi-output (MIMO) liquid-level system. RK-PID has been compared to standard PID, standard nonlinear MPC (NMPC), RK-MPC and conventional sliding-mode control (SMC) methods in terms of control performance, robustness, computational complexity and design issue. The proposed mechanism exhibits acceptable tuning and control performance with very small steady-state tracking errors, and provides very short settling time for parameter convergence.     

A novel sliding-mode control of induction motor using space vector modulation technique

This paper presents a novel sliding-mode control method for torque control of induction motors. The control principle is based on sliding-mode control combined with space vector modulation technique. The sliding-mode control contributes to the robustness of induction motor drives, and the space vector modulation improves the torque, flux, and current steady-state performance by reducing the ripple. The Lyapunov direct method is used to ensure the reaching and sustaining of sliding mode and stability of the control system. The performance of the proposed system is compared with those of conventional sliding-mode controller and classical PI controller. Finally, computer simulation results show that the proposed control scheme provides robust dynamic characteristics with low torque ripple.     

Analysis and control of micro-cantilever in dynamic mode AFM

The dynamic behavior of micro-cantilever-sample system in atomic force microscopy (AFM) in tapping operational mode is studied. Micro-cantilever is modeled by single-mode approximation and subjected to sinusoidal force input. The interaction between tip and sample is modeled by Lennard–Jones potential. Using this dynamic model, the phase portrait of the system is obtained for a range of cantilever-sample distance, and the effect of cantilever parameters on predictability of the system is discussed. Then the nonlinear behavior of the cantilever-sample system is controlled by a robust sliding-mode controller. System output is designed to track the sinusoidal stimulation of the cantilever base under sample surface perturbation during scanning process. Results of SMC are simulated in MATLAB and compared to a stability that has been proved by PID controller which shows better controller effort and less cantilever tip position accuracy.     

Robust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines

Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme.     

Anti-lock brake system control for buses based on fuzzy logic and a sliding-mode observer

In this paper, an anti-lock brake system (ABS) for commercial buses is proposed based on a fuzzy-logic controller and a sliding-mode observer of the vehicle speed. The brake controller generates pulse width modulated (PWM) control inputs to the solenoid valve of each brake, as a function of the estimated wheel slip ratio. PWM control inputs at the brakes significantly reduce chattering in the brake system compared with conventional on-off control inputs. The sliding-mode observer estimates the vehicle speed with measurements of wheel speed, which is then used to compute the wheel slip ratio. The effectiveness of the proposed control algorithm is validated by a series of computer simulations of bus driving, where the 14-DOF bus model is used.     

基于滤波器的漂浮基空间机器人协调运动的滑模控制

本文讨论了载体位置无控、姿态受控情况下,空间机器人姿态、关节协调运动的滑模控制问题。首先,由系统动量守恒关系和拉格朗日第二类方法,建立了漂浮基空间机器人的系统动力学方程。以此为基础,在滑模控制器输出端加入低通滤波器,设计了漂浮基空间机器人载体姿态与机械臂各关节协调运动的控制方案。此控制方案可有效地滤除滑模控制器输出的高频振动信号,减少了空间机器人在运动过程中引起的振动。最后,数值仿真的结果,证实了该控制方案的有效性。