气压伺服系统高性能鲁棒控制器的设计

2自由度控制器越来越在伺服控制中显示其优越性。2自由度控制利用反馈控制来保证稳定性,利用前馈保证轨迹跟踪性能。首先辨识得到了气压系统的闭环传递函数。基于闭环系统辨识模型设计了零相位误差前馈控制器(ZPETC),ZPETC将闭环系统带宽拓宽为100 rad/s左右。系统的干扰抑制能力、鲁棒稳定性由控制器中反馈环节保证。设计了基于干扰观测器的内环反馈控制;外环反馈仍为位置反馈环节。与PID控制比较,整个控制器在试验中得到了良好的轨迹跟踪精度。     

电液马达伺服系统积分鲁棒自适应高精度位置控制

电液马达伺服系统中存在各种类型的扰动,包括参数不确定性和不确定非线性,制约着其高精度位置控制。针对电液马达伺服系统高精度位置跟踪控制,考虑系统的黏性摩擦特性以及外干扰等建模不确定性,提出了一种基于鲁棒自适应的电液马达伺服系统高精度位置控制策略。所提出的全状态控制器通过自适应对模型不确定性进行估计及前馈补偿,提高了系统的低速伺服性能;通过自适应对未建模干扰等不确定性的上界进行估计并前馈补偿,提高了系统对外干扰的鲁棒性。所设计的闭环控制器还能保证系统获得渐近跟踪性能,对比仿真验证了其可行性。     

叠堆式压电陶瓷驱动器的复合控制

提出了逆Bouc-Wen前馈控制与反馈控制相结合的复合控制算法,用于改善压电陶瓷驱动器对目标轨迹的跟踪性能。建立了压电陶瓷驱动器的Bouc-Wen迟滞动力学模型,并用粒子群算法(PSO)对该模型的参数进行识别。基于Bouc-Wen迟滞模型,提出了逆Bouc-Wen前馈补偿控制。最后,为消除迟滞模型的不确定性,引入比例积分(PI)反馈控制,并与前馈补偿控制构成复合控制算法。建立了基于dSPACE实时系统的压电陶瓷驱动实验平台,迟滞实验结果表明:压电陶瓷的迟滞误差量几乎为0,线性度高达96.5%;目标轨迹跟踪实验结果表明:复合控制算法的最大跟踪误差为0.180 5μm,均方根(RMS-Root mean square)跟踪误差为0.055 4μm,跟踪精度达到了10-8 m。相比于开环控制、前馈控制及PI反馈控制,提出的复合控制算法能够基本消除压电陶瓷的迟滞非线性,同时具有很好的轨迹跟踪性能。     

Controller design for high-frequency cutting using a piezo-driven microstage

Controller design consists of a feedforward and a feedback controller to support a microstage with flexure hinge structure driven by piezoelectric ceramic actuator for high-frequency nanoscale cutting is developed in this article. The feedforward controller is designed based on a hysteresis dynamic model in order to reduce the nonlinear hysteresis effect of piezoelectric actuator. The position feedback controller is designed based upon an exponentially weighted moving average (EWMA) method embedded in an internal model control (IMC) structure constructing a run-to-run IMC (RtR-IMC) control scheme in order to deal with system bias or modeling inaccuracy. Also, disturbance due to temperature rise will influence actuator's performance, hence an additional compensator is included in the IMC structure. Surfaces dimple micro-machining utilizes piezoelectric-driven microstage for high-speed cutting is selected as an example to investigate system performance. The developed control algorithm is implemented on a DSP-based system to provide 1 kHz operating speed. In experiment, the proposed feedforward and feedback controller is verified to be able to overcome those negative factors efficiently and preserve good positioning accuracy.     

ZERO PHASE ERROR REAL TIME CONTROL FOR FLIGHT SIMULATOR SERVO SYSTEM

Flight simulator is an important device and a typical high performance position servo system used in the hardware-in-the-loop simulation of flight control system. Without using the future desired output, zero phase error controller makes the overall system's frequency response exhibit zero phase shift for all frequencies and a very small gain error at low frequency range can be achieved. A new algorithm to design the feedforward controller is presented, in order to reduce the phase error, the design of proposed feedforward controller uses a modified plant model, which is a closed loop transfer function, through which the system tracking precision performance can be improved greatly. Real-time control results show the effectiveness of the proposed approach in flight simulator servo system.     

基于DSP的AOD炉氧枪直线电机伺服控制系统

在对AOD炉氧枪直线电机伺服控制系统数学模型进行研究的基础上,针对直线电机位置伺服控制系统要求有较好的位置跟踪性能的特点,提出了基于对象模型的位置前馈跟踪控制策略。研制出了基于数字信号处理器DSP的直线电机位置伺服控制系统,即位置环为数字控制,由DSP完成,用于实现位置前馈跟踪控制算法和较高的位置控制精度。实验结果:仿真曲线和实验曲线基本吻合。     

具有迟滞和蠕变特性压电作动器的模糊自适应逆控制方法

针对具有迟滞和蠕变特性的压电作动器非线性模型,提出了一种前馈控制和反馈控制相结合的自适应模糊逆控制方案。在前馈控制器中压电作动器的迟滞和蠕变非线性特性的逆模型由自适应模糊逻辑系统近似;在反馈控制器中比例控制器用来调节压电作动器的输出误差。该方法可以实时补偿压电作动器的迟滞和蠕变特性,减少作动器跟踪误差。仿真计算结果表明了该方法的有效性。     

A novel dual closed-loop control scheme based on repetitive control for grid-connected inverters with an LCL filter

Grid-connected inverters with LCL filters need high steady-state control accuracy, fast dynamic response performance, and strong robustness to guarantee the power quality. However, there are many problems in traditional control strategies that restrict improvements to control system performance, such as poor dynamic performance of traditional single-repetitive control, large ripples, low steady-state accuracy of inverter current feedback based repetitive dual-loop control or grid-current feedback based single-loop proportional-integral control. In this paper, a novel dual closed-loop repetitive control strategy based on grid current feedback is proposed for single-phase grid-connected inverters with LCL filters. The proportional-integral inner loop is stabilized by using an inherent one-beat delay achieved by digital controller. Based on the inner loop system, a detailed design scheme of a repetitive controller is presented, through which direct control of the grid current is realized, the reference is tracked perfectly to a zero phase shift, and high-attenuation gain is achieved in the high frequency range. In particular, the gird-voltage feed forward control and current reference feedforward control are adopted to suppress grid-voltage disturbance and increase dynamic tracking performance. Finally, the simulation and experimental results show that the proposed method has the advantages of high steady-state accuracy, fast dynamic response, and anti-disturbance ability.     

自适应光学系统中倾斜镜的自适应逆控制

为了克服自适应光学系统中倾斜镜的迟滞响应,提高响应的线性度,改善倾斜镜的控制精度,研究了倾斜镜的迟滞非线性效应。提出了一个基于频率相关的Mutified-Prandtl-Ishlinskii(MPI)模型的补偿方法来在线自适应逆补偿倾斜镜的迟滞非线性。结合反馈PID控制构成了自适应逆前馈复合控制方案,其中自适应逆前馈克服了由于频率等因素引起的迟滞曲线变化,反馈PID则改善了整体的控制性能。建立了倾斜镜二阶系统模型来估计倾斜镜系统的输出,解决了MPI模型参考信号的问题,避免了增加额外前馈传感器,保证了光能量的利用率。实验结果表明,倾斜镜系统15 Hz非线性迟滞率由原来的24.28%降为1.17%,线性度提高了约95%,控制精度较传统PID方法提高了约60%。该方法能够有效补偿倾斜镜的迟滞非线性,提高了自适应光学系统中倾斜镜的校正精度。     

惯性稳定平台自适应前馈控制

结合反馈控制提出了一种自适应前馈控制方法来提高惯性稳定平台稳定控制的指令跟踪性能。应用子空间辨识算法,由输入输出数据辨识稳定平台动态模型的状态空间描述;采用频域回路成型方法设计反馈回路控制器,用于抑制外部扰动。应用递推最小二乘(RLS)自适应滤波器构建反馈控制回路逆模型,构造指令信号的全通特性,提高指令跟踪能力。针对不同的指令信号进行跟踪实验,验证了自适应前馈控制方法的有效性。实验结果表明:提出的自适应前馈方法对阶跃指令响应快,超调量可由反馈控制的30%降低至4.5%,对30 Hz正弦信号的响应幅值无衰减,相位滞后由反馈控制的90°降低至54°。得到的结果显著提高了系统的暂态性能,控制性能优于单独的反馈控制回路。     

FEEDFORWARD CONTROL STRATEGIES FOR TRACKING PERFORMANCE IN MACHINE AXES

Three feedforward (FFD) control techniques for position-servo machine axes are compared. All three FFD controllers are used with two different PID feedback (FBK) controllers. The two different FBK controllers have two different closed-loop bandwidths. They are demonstrated using experimental data from a linear motor test system and from simulations. Laboratory results using the linear motor hardware demonstrate that the velocity & acceleration (V&A) FFD controller improves tracking in all case considered, while the other two FFD controllers actually degrade performance in many cases. Through simulation this degradation is attributed to extreme sensitivity to round off errors. This sensitivity is the result of a complex controller that is implemented outside of the feedback loop.     

超磁致伸缩致动器的小脑神经网络前馈逆补偿-模糊PID控制

针对超磁致伸缩致动器(GMA)在精密致动控制中存在的迟滞和位移非线性,提出了小脑神经网络(CMAC)前馈逆补偿结合模糊PID控制的新策略。通过小脑神经网络(CMAC)学习获得超磁致伸缩致动器动态逆模型用于对超磁致伸缩致动器迟滞非线性进行补偿;利用模糊PID控制降低小脑神经网络(CMAC)学习时的误差和抑制扰动,提高系统的跟踪控制性能,从而实现超磁致伸缩致动器的精密致动控制。仿真和实验结果表明:所采用的控制策略有效地消除了迟滞非线性的影响,系统的跟踪误差降低到了5%以下,而位移跟踪误差均方差仅为0.58。此外,这种策略的特点是学习和控制同时进行,控制系统能够适应被控对象动态特性的变化,使系统具有较强的鲁棒性,同时也能够有效地抑制外界的干扰,提升系统的自适应控制性能。     

基因测序仪运动平台的高精度定位控制

为了实现对基因测序仪运动平台的高精度定位控制,建立了基因测序仪运动平台控制系统。对该系统所采用的数学建模、模型辨识、控制器设计、输入整形等方法进行研究。根据运动平台动力学方程和永磁同步直线电机电压-推力关系构建了运动平台数学模型,利用频域扫描法在实物实验的基础上辨识出运动平台的模型参数。最后,基于运动平台模型设计了双闭环控制器和前馈控制器组成的复合控制器来保证运动平台的稳定性和高精度,同时根据整个系统的主导极点设计了输入整形器以抑制运动平台的残余振荡。实验结果表明:加入了输入整形的复合控制器将运动平台的稳态重复定位精度从±1.47μm提高到±0.354μm。较传统复合控制器,本文提出的方法能使基因测序仪运动平台更快进入可用重复定位精度范围,并基本满足基因测序仪采集图像时所需的稳定性强、精度高等要求。     

Ultra-precise tracking control of piezoelectric actuators via a fuzzy hysteresis model

In this paper, a novel Takagi-Sugeno (T-S) fuzzy system based model is proposed for hysteresis in piezoelectric actuators. The antecedent and consequent structures of the fuzzy hysteresis model (FHM) can be, respectively, identified on-line through uniform partition approach and recursive least squares (RLS) algorithm. With respect to controller design, the inverse of FHM is used to develop a feedforward controller to cancel out the hysteresis effect. Then a hybrid controller is designed for high-performance tracking. It combines the feedforward controller with a proportional integral differential (PID) controller favourable for stabilization and disturbance compensation. To achieve nanometer-scale tracking precision, the enhanced adaptive hybrid controller is further developed. It uses real-time input and output data to update FHM, thus changing the feedforward controller to suit the on-site hysteresis character of the piezoelectric actuator. Finally, as to 3 cases of 50 Hz sinusoidal, multiple frequency sinusoidal and 50 Hz triangular trajectories tracking, experimental results demonstrate the efficiency of the proposed controllers. Especially, being only 0.35% of the maximum desired displacement, the maximum error of 50 Hz sinusoidal tracking is greatly reduced to 5.8 nm, which clearly shows the ultra-precise nanometer-scale tracking performance of the developed adaptive hybrid controller.     

基于前馈解耦的振动与加载电液混合试验系统力加载跟踪控制研究

针对振动与加载电液混合试验系统力加载跟踪过程中的多余力抑制问题,分析了振动与加载电液混合系统的组成及工作原理,建立了混合系统的动力学模型,并对动力学模型的准确性进行了验证。在此基础上,分析了混合系统加载多余力的产生机理,提出了振动与加载电液混合系统力加载前馈解耦控制算法。搭建了振动与加载电液混合试验台及嵌入式控制系统,利用振动与加载电液混合试验台进行了力加载控制策略的试验研究。结果证明,与传统PI控制器相比,提出的力加载前馈解耦控制算法可以更有效地抑制系统多余力,提高力加载的跟踪精度。     

基于改进前馈逆补偿的电液加载试验系统力跟踪控制研究

针对电液加载试验系统力加载跟踪控制问题，分析了电液加载系统的组成及工作原理，建立了系统动力学模型，并对动力学模型的准确性进行了验证。在此基础上，首先使用了速度反馈补偿控制器抑制外部干扰，其次利用递推增广最小二乘法(Recursive Extended Least Square，RELS)及零相差跟踪技术(Zero Phase Error Tracking，ZPET)设计出系统逆模型，进行前馈逆补偿控制，然后考虑速度反馈存在的微分问题，设计了内模控制器，最后利用电液加载试验台进行了力加载控制策略的试验研究。试验结果证明，与传统PI控制器相比，提出的改进前馈逆补偿力加载控制算法可以更有效地抑制系统外部干扰，提高力加载的跟踪精度。     

SVD-based Preisach hysteresis identification and composite control of piezo actuators

In this paper, the singular value decomposition (SVD) based identification and compensation of the hysteretic phenomenon in piezo actuators are addressed using a Preisach model. First, this paper presents an SVD-based least squares algorithm and a revision approach of the identification through updating the SVD. With the identified parameters and a log of the memory curve, a Preisach-based inversion compensator is constructed which is complemented with a feedback controller to address the inevitable and residual modeling errors. Experimental results are furnished for both the identification and compensation approaches. The Preisach-based feedforward controller significantly improves the tracking performance and reduces the root-mean-square (RMS) tracking error of a PID controller by 76.7% and 89% at 1 Hz and 25 Hz, respectively. With the proposed composite controller, the percent-RMS errors at 1 Hz and 25 Hz are reduced to 0.035% and 0.31%, respectively.     

气动干扰下的Hex-Rotor无人飞行器控制器及其飞行实验

分析了气流扰动、翼间干扰等因素对飞行中的无人飞行器的控制精度和效果产生的影响,并给出了相应的解决方法。建立了Hex-Rotor飞行器的动力学模型,分析了升力因子不确定性导致飞行器控制效果下降的影响因素。设计了反演滑模控制器来控制飞行器的空间六自由度运动,同时考虑升力因子的不确定性采用超螺旋非线性观测器观测各个旋翼的升力因子来克服气动干扰的影响。通过原型机验证了提出的方法,结果显示:Hex-Rotor飞行器在气动干扰较大的外部环境中飞行时,水平位移跟踪误差不超过±4.5m,高度误差不超过±2.5m,姿态角度误差保持在±2°内,较大地增强了飞行器的抗扰能力。结果表明:采用本文的方法可以有效地估计各个旋翼的升力因子,从而提高Hex-Rotor飞行器的控制精度和效果。     

一种双轴直驱平台新型同步渐近跟踪控制设计

针对双轴直驱平台伺服系统中存在同步进给的问题,提出一种交叉耦合迭代学习控制器与自适应加加速度控制器相结合的新型同步控制方法。首先,构建同步误差,利用交叉耦合控制器解决双轴的耦合问题;设计自适应PD型学习律减小同步误差,实现双轴协调同步。采用模型前馈控制补偿系统的参数不确定性,提高系统的响应速度。自适应加加速度控制器抑制系统中外部扰动、摩擦力等不确定性因素,实现系统的渐近跟踪控制。加加速度积分后形成反馈控制律,保证了控制信号的稳定性和连续性。设计自适应更新律,使鲁棒增益实现指数收敛并削弱测量噪声对系统的影响,增强系统的鲁棒性。系统实验结果表明,该方法能够明显地提高系统的同步性能,改善双轴直驱平台伺服系统的控制精度。     

周视扫描成像系统的转台转速高精度控制

为实现基于转台的像移补偿型周视扫描成像系统的高分辨率稳定成像,提出了一种复合控制算法对永磁同步电机驱动的扫描转台进行转速跟踪控制。根据转台的载荷特点及电机的数学模型,建立了包含机械参数不确定性和快变转矩扰动的单采样率控制系统模型;采用快速非奇异终端滑模和扩张高增益观测器复合控制实现了转速跟踪控制;采用快速非奇异终端滑模实现了最大转矩电流比控制;最后,分析并验证了基于上述复合算法的转速跟踪控制性能。实验表明:在转台转速设定为120 r/min或240 r/min时,采用该复合算法的转速跟踪误差均小于0.1%。与PI控制、快速非奇异终端滑模控制及线性滑模+观测器控制相比,采用该复合算法的转台转速响应具有无超调、抗扰动性能更强、跟踪精度更高的优点,能保证所述周视成像系统获得清晰稳定的周视全景图像。