基于滑模自适应控制的电液位置伺服系统低速性能改善

在低速、超低速运行时,电液伺服系统受到以摩擦力为主的干扰力矩和参数不确定性等扰动,进而影响电液位置伺服系统的低速性能。该研究从低速平稳性和跟踪精度两个角度出发,分析了电液位置伺服系统低速性能的主要影响因素,提出了一种滑模自适应控制方法。并将该方法应用于某硅钢厂电液单辊CPC系统,进行了仿真。研究表明,在考虑系统非线性、扰动及参数不确定性的情况下,该研究的滑模自适应控制方法能够有效地抑制抖振并获得伺服系统的低速平稳、快速跟踪。     

电液位置伺服系统的自适应滑模鲁棒跟踪控制

针对存在参数不确定性的电液位置伺服系统的跟踪控制问题，基于滑模控制理论，提出了一种具有参数自适应能力的自适应滑模控制方法。通过自适应方法，来消除参数不确定性对系统控制性能的影响，进而实现鲁棒控制。基于李雅普诺夫稳定性理论证明了自适应滑模控制系统的渐近稳定性。将该方法应用于某疲劳试验机电液伺服系统的跟踪控制，仿真和实时控制结果证明了该方法的有效性。     

电液力伺服系统自适应抗扰控制研究

考虑到电液伺服系统中存有各种非线性因素、不确定干扰以及参数时变,为了提高干扰下电液力伺服系统的控制精度,以电液伺服振动实验台作为控制对象,构建其非线性模型,同时使用参数自适应率对不定参数进行补偿,并在反演控制器中引入滑模控制以降低系统的干扰敏感性,利用Lyapunov理论保证闭环系统的全局稳定。对设计的控制器进行实验,模拟在有未知外部位置干扰下的力控制,提升系统的稳定性。实验结果证明,此控制方法能够有效地提升电液力伺服系统的抗干扰跟踪性能。     

改进PSO算法优化的电液位置伺服系统滑模控制

针对电液位置伺服系统因参数不确定性、复杂时变性与非线性而导致控制性能不佳的问题,提出了一种基于改进PSO算法的电液位置伺服系统滑模控制方法。建立电液位置伺服系统的误差状态空间方程,通过设计滑模面和控制律推导出滑模控制器结构,利用李雅普诺夫函数验证了控制器的稳定性,采用柯西变异和自适应速度更新策略改进了PSO算法,并把改进后的PSO算法应用至滑模控制器中进行参数优化,基于AMEsim/MATLAB联合仿真研究了几种方法下系统对位置的跟踪情况。结果表明,相比于PSO算法和APSO算法,改进PSO算法寻优性能更好,从而验证了该方法是有效的;通过对比分析,采用改进PSO算法的滑模控制器极大地提高了系统的控制性能,在抑制抖振的同时实现了系统对状态轨迹的快速精确跟踪。通过现场试验研究,验证了所提方法的应用可行性。     

电液位置伺服系统的模糊滑模控制研究

针对电液位置伺服系统的位置跟踪控制问题,在滑模控制理论的基础上,加入模糊控制理论,提出了一种模糊自学习滑模控制方案.通过设计模糊控制器,用模糊输出代替滑模切换控制,将该控制方法应用于电液位置伺服系统的研究中,仿真实验结果表明该控制方案的有效性,跟踪性能良好,能有效削弱抖振.     

直驱泵控电液位置伺服系统模糊滑模控制仿真与实验研究

针对直驱泵控电液位置伺服系统采用普通滑模控制存在高频抖振现象以及跟踪控制性能欠佳的问题,在普通滑模控制的基础上引入模糊控制量来柔化控制信号,从而削弱滑模切换时产生的剧烈抖振,提高电液位置伺服系统控制精度和稳定性。设计了比例切换模糊滑模控制器,实现了利用模糊控制输出项柔化滑模切换控制。采用滑模控制和模糊滑模控制对单位阶跃响应和余弦跟踪特性进行了仿真与实验研究。结果表明:模糊滑模控制能显著提高直驱泵控系统的动态响应速度和稳态控制精度,增强系统的鲁棒性,削弱普通滑模控制存在的高频抖振现象。     

电液伺服力控系统的自适应滑模控制

针对存在不确定性的非线性电液伺服力控系统的跟踪控制问题,基于等价控制的概念,提出了一种自适应滑模控制律综合方法,应用参数自适应的方法,消除不确定性对控制性能的影响,以达到鲁棒跟踪控制的目的。为了证明这种控制器可行性,利用微机实现的该控制器被应用于某疲劳试验机电液伺服系统,实时控制的结果验证了所提方法的有效性。     

电液伺服系统RBF神经网络滑模控制

针对阀控液压缸位置伺服系统非线性导致模型参数确定困难及干扰问题，在分析三阶位置控制的电液控制系统原理及模型的基础上，引入神经网络的RBF 径向基控制模型和自适应滑模算法，同时考虑了非1负反馈参数，建立了基于RBF 神经网络滑模控制的电液伺服控制系统数学模型。通过选取合适的Lyapunov 函数，分析了系统稳定性，解决了参数未定及挠动情况下的电液伺服系统控制器设计问题。仿真结果证明，所设计的控制器使系统的输出对给定信号的跟踪精度高，响应快，具有较强的鲁棒性。     

模拟转台伺服系统的自适应模糊滑模控制研究

利用Stribeck摩擦模型,将自适应控制与模糊滑模控制相结合,提出了自适应模糊滑模控制模型,对模拟转台伺服系统进行了控制。仿真结果表明,自适应模糊滑模控制器能有效抑制摩擦力矩的影响,实现高精度的位置跟踪,鲁棒性好,值得在其他非线性系统中推广使用。     

自学习模糊滑模控制及其在电液伺服系统中的应用

针对一类不确定性非线性系统的跟踪控制问题,应用模糊逻辑系统来逼近滑模的等价控制,提出了一种具有自学习能力的模糊滑模控制方法。通过在线学习,动态地更新模糊控制的规则,使得模糊控制的输出沿使滑模渐近稳定的方向逐步逼近滑模的等价控制,证明了自学习模糊滑模控制系统在李雅普诺夫意义下的渐近稳定。把这种方法应用于电液伺服系统的跟踪控制,仿真和实时控制结果表明:该方法明显优于常规滑模控制并能获得满意的跟踪精度和稳定性。     

Adaptive super-twisting sliding mode observer based robust backstepping sensorless speed control for IPMSM

This paper proposes a higher-order sliding mode observer based robust backstepping control to realize high-performance sensorless speed regulation for the interior permanent magnet synchronous motor (IPMSM). A new robust adaptive super-twisting higher-order sliding mode based observer is proposed to estimate the rotor position. The proposed observer has advantages of sliding chattering reduction and robustness against uncertainties. And, a new robust integral adaptive backstepping control with sliding mode actions is designed to achieve precise speed regulation. The uncertainties with unknown bounds can be stabilized by the sliding mode actions. And both transient and steady performance can be achieved by using the sliding mode and integral actions simultaneously. Then, a sensorless scheme is put forward to by combining the presented observer and the proposed controller. The stability of the observer and controller are verified. Simulation and experiment results validate the proposed approach.     

Suppression of the noise-induced effects in an electrostatic micro-plate using an adaptive back-stepping sliding mode control

In this work, an adaptive backstepping sliding mode control approach is applied through the piezoelectric layer in order to control and to stabilize an electrostatic micro-plate. The mathematical model of the system by taking into account the small fluctuations in the gap considered as bounded noise is carried out. The accuracy of the proposed modal equation is proven using the method of lines. By using both approaches, the effects of noise are presented. It is found that they lead to pull-in instability as well as to random chaos. A suitable backstepping approach to improve the tracking performance is integrated to the adaptive sliding mode control in order to eliminate chattering phenomena and reinforce the robustness of the system in presence of uncertainties and external random disturbances. It is proved that all the variables of the closed-loop system are bounded and the system can follow the given reference signals as close as possible. Numerical simulations are provided to show the effectiveness of proposed controller.     

Adaptive backstepping sliding mode control with fuzzy monitoring strategy for a kind of mechanical system

A novel adaptive backstepping sliding mode control (ABSMC) law with fuzzy monitoring strategy is proposed for the tracking-control of a kind of nonlinear mechanical system. The proposed ABSMC scheme combining the sliding mode control and backstepping technique ensure that the occurrence of the sliding motion in finite-time and the trajectory of tracking-error converge to equilibrium point. To obtain a better perturbation rejection property, an adaptive control law is employed to compensate the lumped perturbation. Furthermore, we introduce fuzzy monitoring strategy to improve adaptive capacity and soften the control signal. The convergence and stability of the proposed control scheme are proved by using Lyaponov′s method. Finally, numerical simulations demonstrate the effectiveness of the proposed control scheme.     

Adaptive backstepping sliding mode control of flexible ball screw drives with time-varying parametric uncertainties and disturbances

This paper presents a method to model and design servo controllers for flexible ball screw drives with dynamic variations. A mathematical model describing the structural flexibility of the ball screw drive containing time-varying uncertainties and disturbances with unknown bounds is proposed. A mode-compensating adaptive backstepping sliding mode controller is designed to suppress the vibration. The time-varying uncertainties and disturbances represented in finite-term Fourier series can be estimated by updating the Fourier coefficients through function approximation technique. Adaptive laws are obtained from Lyapunov approach to guarantee the convergence and stability of the closed loop system. The simulation results indicate that the tracking accuracy is improved considerably with the proposed scheme when the time-varying parametric uncertainties and disturbances exist.     

An enhanced tracking control of marine surface vessels based on adaptive integral sliding mode control and disturbance observer

In this paper, a new control methodology is developed to enhance the tracking performance of fully actuated surface vessels based on an integrating between an adaptive integral sliding mode control (AISMC) and a disturbance observer (DO). First, an integral sliding mode control (ISMC), in which the backstepping control technique is used as the nominal controller, is designed for the system. The major features, i.e., benefits and drawbacks, of the ISMC are discussed thoroughly. Then, to enhance the tracking performance of the system, an adaptive technique and a new disturbance observer based on sliding mode technique are developed and integrated into the ISMC. The stability of the closed-loop system is proved based on Lyapunov criteria. Computer simulation is performed to illustrate the tracking performance of the proposed controller and compare with the existing controllers for the tracking control of a surface vessel. The simulation results demonstrate the superior performance of the proposed strategy.     

On decentralized adaptive full-order sliding mode control of multiple UAVs

In this study, a novel decentralized adaptive full-order sliding mode control framework is proposed for the robust synchronized formation motion of multiple unmanned aerial vehicles (UAVs) subject to system uncertainty. First, a full-order sliding mode surface in a decentralized manner is designed to incorporate both the individual position tracking error and the synchronized formation error while the UAV group is engaged in building a certain desired geometric pattern in three dimensional space. Second, a decentralized virtual plant controller is constructed which allows the embedded low-pass filter to attain the chattering free property of the sliding mode controller. In addition, robust adaptive technique is integrated in the decentralized chattering free sliding control design in order to handle unknown bounded uncertainties, without requirements for assuming a priori knowledge of bounds on the system uncertainties as stated in conventional chattering free control methods. Subsequently, system robustness as well as stability of the decentralized full-order sliding mode control of multiple UAVs is synthesized. Numerical simulation results illustrate the effectiveness of the proposed control framework to achieve robust 3D formation flight of the multi-UAV system.     

Parametric adaptive estimation and backstepping control of electro-hydraulic actuator with decayed memory filter

Some unknown parameter estimation of electro-hydraulic system (EHS) should be considered in hydraulic controller design due to many parameter uncertainties in practice. In this study, a parametric adaptive backstepping control method is proposed to improve the dynamic behavior of EHS under parametric uncertainties and unknown disturbance (i.e., hydraulic parameters and external load). The unknown parameters of EHS model are estimated by the parametric adaptive estimation law. Then the recursive backstepping controller is designed by Lyapunov technique to realize the displacement control of EHS. To avoid explosion of virtual control in traditional backstepping, a decayed memory filter is presented to re-estimate the virtual control and the dynamic external load. The effectiveness of the proposed controller has been demonstrated by comparison with the controller without adaptive and filter estimation. The comparative experimental results in critical working conditions indicate the proposed approach can achieve better dynamic performance on the motion control of Two-DOF robotic arm.     

Disturbance observer-based backstepping sliding mode fault-tolerant control for the hydro-turbine governing system with dead-zone input

This paper investigates a backstepping sliding mode fault-tolerant tracking control problem for a hydro-turbine governing system with consideration of external disturbances, actuator faults and dead-zone input. To reduce the effects of the unknown random disturbances, the nonlinear disturbance observer is designed to identify and estimate the disturbance term. To drastically decrease the complexity of stability functions selection and controller design, the recursive processes of the backstepping technique are employed. Additionally, based on the nonlinear disturbance observer and the backstepping technique, the sliding mode fault-tolerant tracking control approach is developed for the hydro-turbine governing system (HTGS). The stability of HTGS is rigorously demonstrated through Lyapunov analysis which is capable to satisfy a tracking control performance. Finally, comprehensive simulation results are presented to illustrate the effectiveness and superiority of the proposed control scheme.     

Integral backstepping sliding mode control for underactuated systems: Swing-up and stabilization of the Cart–Pendulum System

In this paper an integral backstepping sliding mode controller is proposed for controlling underactuated systems. A feedback control law is designed based on backstepping algorithm and a sliding surface is introduced in the final stage of the algorithm. The backstepping algorithm makes the controller immune to matched and mismatched uncertainties and the sliding mode control provides robustness. The proposed controller ensures asymptotic stability. The effectiveness of the proposed controller is compared against a coupled sliding mode controller for swing-up and stabilization of the Cart–Pendulum System. Simulation results show that the proposed integral backstepping sliding mode controller is able to reject both matched and mismatched uncertainties with a chattering free control law, while utilizing less control effort than the sliding mode controller.