Robustness-tracking control based on sliding mode and H_∞ theory for linear servo system

A robustness-tracking control scheme based on combining H_∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking and robustness of the linear servo system. The sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the command, and the H_∞ robustness controller suppresses the disturbances well within the close loop(including the load and the end effect force of linear motor etc.) and effectively minimizes the chattering of sliding mode control which influences the steady state performance of the system. Simulation results show that this control scheme enhances the track-command-ability and the robustness of the linear servo system, and in addition, it has a strong robustness to parameter variations and resistance disturbances.

Adaptive robust control for four-motor driving servo system with uncertain nonlinearities

A novel adaptive robust control （ARC） is presented for the four-motor driving servo systems with the uncertain nonlinearities and actuation failures, such that the load tracking control is achieved with the proximate optimal-time. By applying the proposed scheme, several control objectives are achieved. First, the nonlinear synchronization algorithm is presented to maintain the velocity synchronization of each motor, which provides fast convergence without chatting. Moreover, the time-varying bias torque is applied to eliminate the effect of backlash and reduce the waste of energy. Then, the ARC is designed to achieve the proximate optimal-time output tracking with the transient performance in L2 norm, where the friction and actuation failures are addressed by the adaptive scheme based on the norm estimation of unknown parameter vector. Finally, the extensive simulated and experimental results validate the effectiveness of the proposed method.

Data-driven Nonparametric Model Adaptive Precision Control for Linear Servo Systems

Nowadays, high-precision motion controls are needed in modern manufacturing industry. A data-driven nonparametric model adaptive control(NMAC) method is proposed in this paper to control the position of a linear servo system. The controller design requires no information about the structure of linear servo system, and it is based on the estimation and forecasting of the pseudo-partial derivatives(PPD) which are estimated according to the voltage input and position output of the linear motor. The characteristics and operational mechanism of the permanent magnet synchronous linear motor(PMSLM) are introduced, and the proposed nonparametric model control strategy has been compared with the classic proportional-integral-derivative(PID) control algorithm. Several real-time experiments on the motion control system incorporating a permanent magnet synchronous linear motor showed that the nonparametric model adaptive control method improved the system s response to disturbances and its position-tracking precision, even for a nonlinear system with incompletely known dynamic characteristics.

LMI Approach to Robust H_∞/H_2 Controller Design with Regional Poles Constraint of a Pump-Motor System

The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the servo system control problem is transferred into the problem of robust performance optimizing under regional poles constrains described by linear matrix inequality （LMI）. These LMIs are easy to solve through the Matlab LMI-toolbox. Simulations indicate that the controller has excellent dynamic, static and disturbance rejection performance, and the control system is robust and has perfect H2 performance to the bounded external torque disturbance.

System construction of a four-side primary permanent-magnet linear motor drive mechanical press

A primary permanent-magnet linear motor (PPMLM) has a robust secondary structure and high force density and is appropriate for direct-drive mechanical press. The structure of a four-side PPMLM drive press is presented based on our previous research. The entire press control system is constructed to realize various flexible forming processes. The control system scheme is determined in accordance with the mathematical model of PPMLM, and active disturbance rejection control is implemented in the servo controller. Field-circuit coupling simulation is applied to estimate the system’s performance. Then, a press prototype with 6 kN nominal force is fabricated, and the hardware platform of the control system is constructed for experimental study. Punch strokes with 0.06 m displacement are implemented at trapezoidal speeds of 0.1 and 0.2 m/s;the dynamic position tracking errors are less than 0.45 and 0.82 mm, respectively. Afterward, continuous reciprocating strokes are performed, and the positioning errors at the bottom dead center are less than 0.015 mm. Complex pulse trajectories are also achieved. The proposed PPMLM drive press exhibits a fast dynamic response and favorable tracking precision and is suitable for various forming processes.

Control of Linear Servo Carts with Integral-Based Disturbance Rejection

This paper describes a system designed for linear servo cart systems that employs an integral-based Linear Active Disturbance Rejection Control(ILADRC)scheme to detect and respond to disturbances.The upgrade in this control technique provides extensive immunity to uncertainties,attenuation,internal disturbances,and external sources of noise.The fundamental technology base of LADRC is Extended State Observer(ESO).LADRC,when combined with Integral action,becomes a hybrid control technique,namely ILADRC.Setpoint tracking is based on Bode’s Ideal Transfer Function(BITF)in this proposed ILADRC technique.This proves to be a very robust and appropriate pole placement scheme.The proposed LSC system has experimented with the hybrid ILADRC technique plotted the results.From the results,it is evident that the proposed ILADRC scheme enhances the robustness of the LSC system with remarkable disturbance rejection.Furthermore,the results of a linear quadratic regulator(LQR)and ILADRC schemes are comparatively analyzed.This analysis deduced the improved performance of ILADRC over the LQR control scheme.

Novel AC Servo Rotating and Linear Composite Driving Device for Plastic Forming Equipment

The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.

永磁直线同步电机改进预测电流控制

永磁直线同步电机(PMLSM)预测电流控制(PCC)时存在易受参数变化和延迟以及负载扰动影响,为此提出基于二阶超螺旋滑模观测器(STSMO)的改进型PCC。首先,建立包含不确定性的PMLSM动态数学模型。然后,为了补偿参数变化以及延迟的影响,采用二阶STSMO估计下一周期的电流和参数变化造成的扰动电压,估计值用以计算下一周期的给定电压,以提高电流跟踪精确度,通过李雅普诺夫函数证明观测器的稳定性。同时,采用基于改进指数趋近律的自适应滑模控制器(ASMC)对速度进行跟踪,将状态变量和滑模面加入到指数趋近律中,不仅削弱了电流抖振,且进一步提升了系统的鲁棒性。半实物仿真实验结果表明,与传统PCC相比,提出方法能有效地抑制不确定性对系统影响,使系统具有更好的跟踪性能和鲁棒性。

基于扩张状态观测器的永磁直线同步电机改进模型预测电流控制

针对永磁直线同步电机(PMLSM)模型预测电流控制(MPCC)中存在的电流脉动过大、在线计算复杂的问题,提出一种基于扩张状态观测器(ESO)的改进MPCC策略。利用最优电压矢量相角和重新划分后的电压矢量扇区,改进第一电压矢量的选取方式,减小第二电压矢量选择范围,以实现电压矢量的快速选取,进而降低电流脉动。同时,为了提高PMLSM抗负载扰动能力,通过ESO对扰动进行观测,将观测到的扰动转换为电流进行补偿,提高系统的鲁棒性,且补偿电流可起到进一步减小电流脉动的作用。仿真结果表明,所提出的控制方法切实可行,与MPCC相比,基于ESO的改进MPCC系统具有更好的控制性能、更小的电流脉动和较强的鲁棒性能。

光电经纬仪自抗扰控制方法

为提升光电经纬仪在跟踪时的响应速度和抗干扰能力,提出一种基于观测器的自抗扰控制(active disturbance rejection control,ADRC)方法。对所有已知或未知的影响直流电机工作的干扰输入进行在线估计,并通过适当的反馈控制法来补偿这些干扰;通过选取合适的观测器和控制器带宽参数,来实现良好的抗扰控制效果。仿真结果表明:基于观测器的自抗扰控制方法能有效地提高直流电机对外部干扰和内部未知参数变化的鲁棒性,具有工程应用前景。

基于ATSMC的破障武器随动系统控制研究

针对电动缸驱动的车载破障武器随动系统控制问题,提出了一种基于指数收敛的干扰观测器和反正切滑模控制器的方法。研究了电动缸传动时系统具有的非线性增益,推导了电动缸机构的变传动比和变负载力矩的公式。为了对随动系统进行位置和速度控制,根据多项式Terminal滑模控制器的思想,采用等效趋近律的方法,设计了反正切Terminal滑模控制器(ATSMC),其具有全局鲁棒性和有限时间可达的能力;为了对系统内部的不确定性和外部扰动进行观测和补偿,设计了一种基于指数收敛的干扰观测器。对控制系统进行仿真,结果表明,ATSMC具有更好的鲁棒性,提高了随动系统控制精度,缩短了响应时间;基于指数收敛的干扰观测器能较好地补偿系统运行中产生的各种扰动,降低了系统稳态误差。

数控机床伺服驱动系统的多电机同步控制策略

以数控机床伺服驱动系统的多电机同步控制为研究对象,提出了一种基于多交流伺服电机的同步控制策略。此策略将虚拟主轴和偏差耦合的同步控制方式相结合,并加入反向传播神经网络比例积分微分控制以及自适应鲁棒控制。通过搭建Matlab/Simulink仿真平台模拟了系统的运行状态。结果表明,所提同步控制策略具有良好的同步性能和伺服效果,在提高多电机联动系统的控制精度和响应速度、减少摩擦和齿隙的影响以及增强系统鲁棒性方面表现出优越性。

数控机床磁悬浮直线同步电动机混合H_(2)/H_(∞)鲁棒控制器设计

针对数控机床磁悬浮直线同步电动机控制系统,提出混合H_(2)/H_(∞)鲁棒控制。首先,考虑不确定H_(∞)扰动以及端部效应等因素建立数控机床磁悬浮直线同步电动机的数学模型。其次,将鲁棒H_(∞)控制与线性矩阵不等式(linear matrix inequality,LMI)相结合,设计一种基于LMI的鲁棒H_(2)/H_(∞)控制器。再次,为提高系统的动态性能,设计基于LMI的混合鲁棒控制器。最后,仿真H_(2)/H_(∞)结果证明在保证系统鲁棒稳定的前提下,混合鲁棒控制可有效提高系统的收敛速度和响应灵敏度。

永磁交流直线伺服系统的研究

永磁直线同步伺服系统采用直接驱动方式,可构成大行程、高精度、高速度的高性能伺服系统。针对其变速机械易受参数、负载等扰动的影响,提出一种基于扰动观测辱的鲁棒控制方法,利用观测器预测估算出参数的变化和负载的波动等各种噪声,并产生前馈补偿信号输入系统。实验结果表明,该方法能有效地抑制各种扰动影响。

直线电机驱动技术的研究现状与发展

直线电机直接驱动系统具有结构简单、动态响应快、速度和加速度大、精度高、振动和噪声小等一系列优点 ,是各类超高速、精密机床的理想传动方式。本文介绍了直线电机的工作原理与结构类型 ,阐述了直线电机理论分析、设计以及直线伺服驱动系统控制等方面的研究现状与发展趋势 。

基于鲁棒迭代学习的永磁直线电机控制

针对永磁直线电机速度和位置迭代学习跟踪控制中,由测量扰动引起的跟踪误差有界收敛问题,提出一种带有衰减因子的鲁棒迭代学习控制算法。采用λ范数方法分析鲁棒迭代学习控制算法的收敛性,理论结果表明,鲁棒迭代学习控制算法可以保证跟踪误差收敛到零,而P型迭代学习控制算法仅保证直线电机速度和位置的跟踪误差收敛到一个与扰动信号上界有关的域内。仿真结果表明,所提出的鲁棒迭代学习控制算法可以有效抑制测量扰动,获得较好的跟踪性能。带有衰减因子的迭代学习控制方法是一种抑制非重复测量扰动的有效方法。

直线伺服系统的鲁棒保性能控制研究

对具有不确定性的直线电机伺服系统进行鲁棒控制。把一矢量控制的永磁直线电机构成一个三环系统,在速度环和电流环内采用IP速度控制器和状态反馈控制器,以实现电机的高精度快速进给,并抑制外部扰动对系统的影响。为了保证对于所有允许的参数不确定性,系统都具有所期望的性能,采用保性能控制方法设计其最优状态反馈保性能控制器。对电机在两种最恶劣情况下作了仿真实验。结果表明,和传统的方法相比,用该方法设计的直线伺服系统具有性能鲁棒性,当参数变化时,系统具有较好的抗扰性和跟踪性能。

直线电动机伺服系统的鲁棒H_∞控制

对具有时变不确定性的直线电动机伺服系统提出鲁棒H∞ 控制。将时变参数不确定系统的鲁棒H∞ 控制问题 ,转化成一个等价的、不包含任何参数不确定性的线性时不变系统的标准H∞ 控制问题 ;对标准H∞ 控制问题 ,可通过求解代数Riccati矩阵方程的对称正定解求得控制器 ,也就是不确定系统的鲁棒H∞ 控制器。仿真结果表明 ,用该方法设计的直线伺服系统 ,既能保证系统对外部扰动具有良好的抑制作用 ,又能保证对参数不确定性的鲁棒性。

中凸变椭圆活塞加工用高性能直线伺服系统的研究

提出了一种新型的高性能直线伺服电动机的机电系统设计方法，包括硬件及控制系 统，因为本系统采用光栅位移测量方法和DSP高速信号处理器，并相应应用了基于状态观测 器的滑模控制算法，系统的机电动态特性得到很大的提高。这种直线伺服电动机的高性能已 经在试验环境中进行了测试，结果表明系统的总体性能得到很大的提高。

永磁直线同步电动机的自适应学习控制

由于没有传动机构,使永磁直线交流同步电机(PMLSM)控制器设计较为复杂。PMLSM对模型不确定性和外扰更加敏感;推力波动等非线性因素对运动精度影响很大。针对上述问题,用自适应学习方法改善PMLSM的轨迹跟踪性能,并对迭代模式和单次运行模式下算法的收敛性进行了证明,通过实验进行了算法验证。该控制方法基于迭代学习,控制器分为两个部分,通过执行重复任务自适应学习项补偿系统的非线性;另一项用于增强系统的鲁棒性,保证系统在单次运动模式下稳定。实验结果表明,这种控制方法可以有效提高PMLSM轨迹跟踪精度。