考虑负载扰动的电液转向系统控制研究

针对农机的电液伺服转向系统,为了克服转向力对系统的影响,提高在各种路况下的跟踪精度,设计了一种基于负载力观测器的前馈和最优状态反馈控制复合控制策略。先采用Luenberger观测器对负载力进行在线估计,然后用线性二次型调节器（LQR）得到系统线性最优反馈控制律,最后把观测到的负载力前馈到系统输入来消除负载力的影响,提高伺服系统精度。仿真和试验结果表明,所设计的负载力观测器能迅速地跟踪实际值,基于观测器的前馈和最优状态反馈复合控制策略具有较高的跟踪精度和抗负载干扰能力。     

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。     

Adaptive extended state space predictive control for a kind of nonlinear systems

This paper presents an adaptive nonlinear predictive control design strategy for a kind of nonlinear systems with output feedback coupling and results in the improvement of regulatory capacity for reference tracking, robustness and disturbance rejection. The nonlinear system is first transformed into an equal time-variant system by analyzing the nonlinear part. Then an extended state space predictive controller with a similar structure of a PI optimal regulator and with P-step setpoint feedforward control is designed. Because changes of the system state variables are considered in the objective function, the control performance is superior to conventional state space predictive control designs which only consider the predicted output errors. The proposed method is tested and compared with latest methods in literature. Tracking performance, robustness and disturbance rejection are improved.     

Research on the control systems of a precision linear motor drive device

The model of a precision linear motor drive device (PLMDD) and its control requirements are analyzed. In order to enhance the tracking and anti-disturbance performance of the system, its third-order model is established, and disturbance-observer based input revising feedforward error compensation robust control algorithm, combined with integral-separated proportional integral derivative (PID) control algorithm is proposed. This includes feedback control algorithm and feedforward control algorithm. The feedback controller improves system tracking performance and suppresses load and mechanical disturbance while the feedforward controller compensates phase hysteresis introduced by feedback control. Theoretical analyses, simulations and experiments show that this control method increases the tracking precision of PLMDD from ±5 μm to ±2 μm and dramatically improves its anti-disturbance ability.     

基于参数优化的连铸结晶器振动位移系统 复合控制研究

本文以伺服电机驱动的连铸结晶器振动位移控制系统为研究对象,针对系统工艺控制中要求伺服电机转速单方向、变 角速度转动,同时考虑系统控制器参数的选取大多依靠经验等问题,提出了一种基于前馈控制与参数优化的 PID 反馈控制相结 合的复合跟踪控制策略。 首先,根据伺服电机驱动的连铸结晶器振动位移系统特性,建立了伺服电机输出转速与振动位移之间 的近似数学模型。 其次,针对伺服电机单方向转动工艺约束条件,确定结晶器振动位移系统以转速补偿作为前馈控制器,保证 系统控制器输出大于零. 再次,针对振动位移系统控制器参数大多依靠经验选取的问题,提出采用一种改进的飞蛾火焰优化算 法优化 PID 控制器参数的策略,以实现结晶器振动位移高精度跟踪控制。 最后,通过仿真与实验验证所提方法的有效性,实验 结果表明:优化后的振动位移调整时间缩短了 0. 3 s,振动位移跟踪相对误差减小了 1. 8% 。     

点位控制数控系统的前馈控制器设计及运动轨迹规划

针对点位控制仅对定位精度以及调节时间有所要求的情况 ,本文从零相位误差跟踪算法出发 ,证明了零相位误差跟踪算法在阶跃输入下的无差性 ,并将之用于点位控制前馈控制器设计 ,以提高定位精度和快速性。在此条件下 ,为适应高速加工的需要 ,给出了一种既快速又稳定的运动轨迹。仿真结果表明 ,与传统的控制相比较 ,零相位误差跟踪前馈控制器用于点位控制能显著提高系统的定位快速性与运动平稳性。     

Active vibration control of trim panel using a hybrid controller to regulate sound transmission

This paper presents a method for actively controlling the sound transmission through an aircraft trim panel using a hybrid feedforward/feedback control technique. The method involves measuring the frequency transfer function of the trim panel system and then creating an autoregressive moving average model using frequency domain curve fitting. The control technique is designed to minimize the vibration of a panel that has a limited piston-like motion. The hybrid controller consists of an adaptive feedforward controller that operates in conjunction with a linear quadratic Gaussian feedback controller. The feedback controller increases the damping capacity of the secondary plant to augment the convergence rate of the adaptive feedforward controller. Experimental results indicate that the hybrid controller effectively reduces the vibration of active trim panels and therefore also reduces the sound transmission of the panel.     

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。     

Control and dynamic releasing method of a piezoelectric actuated microgripper

This paper proposes the control and dynamic releasing method of a symmetric microgripper with integrated position sensing. The microgripper adopted in this micromanipulation system is constructed by two L-shaped leverage mechanisms and the fingers of the microgripper is machined much thinner than the gripper body. A combined feedforward/feedback position controller is established to improve the motion accuracy of the microgripper in high frequency. The feedforward controller is established based on rate-dependent inverse Prandtl-Ishlinskii (P–I) hysteresis model. The inertial force generated in dynamic based releasing process is analyzed through MATLAB simulation. Open-loop experimental tests have been performed, and the results indicate the first natural frequency of the microgripper is 730 Hz. Then experiments in high frequency based on the developed combined controller are carried out and the results show the tracking error of a superimposed sinusoidal trajectory with the frequency of 100 Hz, 120 Hz and 130 Hz is 6.4%. Finally, the tiny objects releasing experiments are conducted where the combined controller is used to control the motion amplitude and frequency to achieve inertial force controllable to improve operation accuracy. And the results show that the dynamic releasing strategy is effective.     

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。     

Design of PID controllers in double feedback loops for SISO systems with set-point filters

A PID controller is widely used to control industrial processes that are mostly open loop stable or unstable. Selection of proper feedback structure and controller tuning helps to improve the performance of the loop. In this paper a double-feedback loop/method is used to achieve stability and better performance of the process. The internal feedback is used for stabilizing the process and the outer loop is used for good setpoint tracking. An internal model controller (IMC) based PID method is used for tuning the outer loop controller. Autotuning based on relay feedback or the Ziegler-Nichols method can be used for tuning an inner loop controller. A tuning parameter (λ) that is used to tune IMC-PID is used as a time constant of a setpoint filter that is used for reducing the peak overshoot. The method has been tested successfully on many low order processes.     

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。     

基于反馈与前馈的二自由度电液振动台复合控制

为提高电液位置伺服系统控制精度,以电液振动台为控制对象,针对电液伺服系统液压固有频率较低、阻尼比较小等特点,提出一种三状态反馈控制与前馈逆模型控制相结合的二自由度复合控制策略。利用加速度反馈和速度反馈分别提高位置闭环系统的液压动力机构的阻尼比和液压固有频率,以保证系统在稳定条件下拓展系统工作频率范围;前馈逆模型控制能够改善实验系统的动态响应特性,进一步拓展系统频宽,提高电液振动台波形复现精度。实验结果验证了提出的二自由度控制策略的有效性。     

高频响比例阀非线性补偿控制策略

为了解决单向电磁铁比例阀的非线性特性对系统位置控制精度和动态响应速度的问题,设计了不严格依赖于精确数学模型且具有较好控制精度的非线性补偿策略。基于系统的位置反馈偏差和偏差的变化率,提出了速度和加速度反馈的补偿思想,同时引入了前馈校正提高比例流量阀的跟踪精度。在AMESim仿真平台上验证了非线性补偿策略的有效性。结果表明:非线性补偿算法的引入,消除了比例阀存在的滞后性和不稳定性,提高了高频率下的响应速度和跟踪精度。     

阀控非对称缸非线性系统高精度位置跟踪鲁棒控制研究

针对阀控非对称缸电液位置伺服系统的非线性和不确定因素,采用试验方法建立了等效的线性不确定模型,并在理论线性化模型的基础上确定了抗负载干扰指标,设计了定量反馈(QFT)鲁棒控制器。在发现相位误差较大的情况下,采用零相差跟踪控制器代替前置滤波器,并用设计的零相移低通滤波器来抑制零相差跟踪控制器的高频增益。试验结果证明:改进后的定量反馈控制能够获得更高的曲线跟踪精度。     

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.     

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.     

A study on tracking error based on mechatronics model of a 5-DOF hybrid spray-painting robot

Industrial robots suffer from difficulties in predicting and guaranteeing tracking performance due to the complex dynamic behavior and inaccurate mechatronics model. This study investigates the tracking error and motion accuracy improvement based on a mechatronics model of a 5-degree of freedom hybrid spray-painting robot. The dynamic model of the robot is derived by using Lagrange equation, and an identification method is presented to identify the torque coefficient and joint friction synchronously. An accurate mechatronics model is established after the theoretical dynamic modeling and friction identification. The tracking error generation mechanism of the robot control system is studied, and its analytical equation is derived on the basis of a transfer function. A multichannel feedforward controller is synthesized to reduce the tracking error from different sources. The effectiveness of the proposed method in improving tracking accuracy is verified by physical experiments.

     

Position tracking control with load-sensing for energy-saving valve-controlled cylinder system

This paper deals with the issue of position tracking control with load-sensing for a valve-controlled cylinder system using speed-controlled fixed displacement pump. This is achieved by incorporating a sliding-function based feedforward controller with a feedback control system. The whole feedback control system is composed of a pair of interconnected subsystems, that is, a valve-controlled cylinder system and a load-sensing control system. Experiments show that sliding-mode-based position tracking control in the load sensing control system can accomplish significant reduction in the input energy to a pump compared to a conventional valve-controlled cylinder system, while exhibiting the same position tracking control accuracy.     

变量泵源阀控系统的前馈自适应控制方法

变量泵源导致系统开环增益下降和动态变化,传统的反馈控制和串联校正很难使此类系统跟踪精度达到要求应用复合控制方法,可以对开环增益变化进行有效补偿,提高跟踪控制精度。运用MCS-96系列单片机技术、反馈控制、前馈控制和自适应控制原理,开发设计了数字控制器,实现了对系统的前馈自适应数字控制。试验研究结果表明,前馈自适应控制是实现变量泵源阀控系统高精度跟踪控制的有效方法。