利用磁性无活塞杆气缸的磁场检测气缸加速度的原理研究

简要介绍磁性无活塞杆气缸的结构以及现今磁性无活塞杆气缸的加速度检测手段;通过对其内部结构和磁场分布的分析研究,提出一种新的检测思想和实施方案,并原理性的推导出气缸加速度的计算公式。     

落锤式压力发生器气动控制系统设计

在进行高压动态标定或模拟各种新型材料冲击载荷试验时,通常采用落锤式试验装置.为了便于落锤式压力发生器使用、操作和实验室布置,对其托锤、挂锤、二次接锤结构进行改进,提出采用一对无杆汽缸进行驱动,设计了气动控制系统,重点研究二次接锤过程动力学特性,建立其数学模型.试验结果表明,设计的气动控制系统响应时间小于0.1 s,能够进行二次托锤的最小落高为30 mm,不仅满足使用要求,而且整体结构紧凑.     

电磁式惯性作动器的结构振动自抗扰控制

针对四边固支板结构振动主动控制中存在的系统模型不准确性和内外干扰等问题,利用惯性作动器提出一种基于自抗扰控制器的主动控制方法,并且研究自抗扰控制器中观测器带宽、PD控制器参数,控制器增益对振动控制性能的影响。首先,建立基于惯性作动器的四边固支板振动控制系统的状态空间模型。然后,利用三阶线性扩张状态观测器估计整个振动控制系统的不确定性和状态变量。此外,从理论上分析自抗扰控制器各参数对振动控制性能的影响,以获得良好的振动控制性能。最后,基于NI-PCIe 6343采集卡搭建了半实物实验平台,并在Matlab/Simulink中desktop real-time下验证了理论分析的准确性与自抗扰控制的有效性。结果表明,自抗扰算法用于振动控制是可行的,当控制器其他参数不变时,可以在一定范围内提升观测器带宽或降低控制器增益可以提升控制效果,调节PD控制器参数对控制效果影响不大。     

A hybrid disturbance rejection control solution for variable valve timing system of gasoline engines

A novel solution for electro-hydraulic variable valve timing (VVT) system of gasoline engines is proposed, based on the concept of active disturbance rejection control (ADRC). Disturbances, such as oil pressure and engine speed variations, are all estimated and mitigated in real-time. A feed-forward controller was added to enhance the performance of the system based on a simple and static first principle model, forming a hybrid disturbance rejection control (HDRC) strategy. HDRC was validated by experimentation and compared with an existing manually tuned proportional-integral (PI) controller. The results show that HDRC provided a faster response and better tolerance of engine speed and oil pressure variations.     

基于自抗扰控制器的感应电机直接转矩控制

异步电机不同转速运行时模型参数会发生较大变化,传统PI调节器不能满足大范围高精度调速的要求:现采用扩展状态观测器(ESO)对控制对象参数变化进行估计,并经过非线性组合方法对模型进行补偿.仿真结果表明:相对于经典PID控制器,基于ADRC的速度调节器对电机不同转速的运行具有较强的适应性,具有更好的动态性能.     

基于压电智能结构状态估计误差补偿的自抗扰振动控制

压电智能结构的模型难以精确建立,且存在外界环境激励干扰和内部参数不确定等问题,从而影响闭环结构的振动控制性能。基于此,将结构的内部干扰和外界激励的影响归结为系统的集总干扰,并利用扩张状态观测器(Extended state observer,ESO)设计不依赖于模型的自抗扰振动控制器。然而当外界扰动激励变化时,扩张状态观测器对扰动和各阶状态的估计不可避免存在偏差,难以保证振动控制的效果。为克服二阶自抗扰策略在振动主动控制中的不足,提出一种基于压电智能板结构的状态估计误差补偿自抗扰振动控制方案。利用状态观测误差信息,对二阶自抗扰控制器进行补偿,从而减小ESO对扰动和各阶状态估计的压力,提高振动控制效果。利用dSPACE实时仿真系统,搭建四面固支压电智能板结构的振动主动试验平台。四种干扰激励的试验结果验证该方法的有效性、实用性和强抗干扰能力。     

Limit cycle analysis of active disturbance rejection control system with two nonlinearities

Introduction of nonlinearities to active disturbance rejection control algorithm might have high control efficiency in some situations, but makes the systems with complex nonlinearity. Limit cycle is a typical phenomenon that can be observed in the nonlinear systems, usually causing failure or danger of the systems. This paper approaches the problem of the existence of limit cycles of a second-order fast tool servo system using active disturbance rejection control algorithm with two fal nonlinearities. A frequency domain approach is presented by using describing function technique and transfer function representation to characterize the nonlinear system. The derivations of the describing functions for fal nonlinearities and treatment of two nonlinearities connected in series are given to facilitate the limit cycles analysis. The effects of the parameters of both the nonlinearity and the controller on the limit cycles are presented, indicating that the limit cycles caused by the nonlinearities can be easily suppressed if the parameters are chosen carefully. Simulations in the time domain are performed to assess the prediction accuracy based on the describing function.     

On the centrality of disturbance rejection in automatic control

In this paper, it is shown that the problem of automatic control is, in essence, that of disturbance rejection, with the notion of disturbance generalized to symbolize the uncertainties, both internal and external to the plant. A novel, unifying concept of disturbance rejector is proposed to compliment the traditional notion of controller. The new controller–rejector pair is shown to be a powerful organizing principle in the realm of automatic control, leading to a Copernican moment where the model-centric design philosophy is replaced by the one that is control–centric in the following sense: the controller is designed for a canonical model and is fixed; the difference between the plant and the canonical model is deemed as disturbance and rejected.     

Generalized proportional integral control for periodic signals under active disturbance rejection approach

Conventional repetitive control has proven to be an effective strategy to reject/track periodic signals with constant frequency; however, it shows poor performance in varying frequency applications. This paper proposes an active disturbance rejection methodology applied to a large class of uncertain flat systems for the tracking and rejection of periodic signals, in which the possibilities of the generalized proportional integral (GPI) observer-based control to address repetitive control problems are studied. In the proposed scheme, model uncertainties and external disturbances are lumped together in a general additive disturbance input that is estimated and rejected on-line. An illustrative case study of mechatronic nature is considered. Experimental results show that the proposed GPI observer-based control successfully rejects periodic disturbances even under varying speed conditions.     

On oscillation reduction in feedback control for processes with an uncertain dead time and internal–external disturbances

This paper aims to find a practical solution to reduce oscillation on the Smith Predictor (SP) based design with the dead time (DT) uncertainty, making it less sensitive to DT change and more effective in disturbance rejection. First, a conditional feedback mechanism is introduced in SP to reduce the amount of oscillation caused by the model inaccuracies in the DT parameter. Then, to address the oscillation caused by the phase lag in traditional PI controller and uncertain dynamics, this conditional SP is combined with active disturbance rejection control (ADRC), assisted by the knowledge of process dynamics. A practical tuning method is provided for the practicing engineers. The proposed approach is validated in extensive simulation studies with different types of plants and in frequency domain analysis. The simulation results show significant improvements in performance robustness and transient response.     

气动恒力控制系统的自抗扰控制

针对磨削和抛光等对恒力控制装置的迫切需求,开展气动恒力控制系统研究。由于气动系统存在比例流量阀死区、气缸摩擦力以及气体可压缩等非线性问题,提出了一种二阶线性PID自抗扰控制器,并加入了死区补偿器。该控制器采用跟踪微分器对输入信号进行过渡,利用扩张状态观测器对非线性参数影响进行估计,并通过线性PID反馈控制律进行补偿,同时引入死区补偿器快速跳过死区范围。试验结果表明,相比传统PID控制和积分型线性自抗扰控制(I-LADRC),线性PID自抗扰控制具有更好的动态响应以及更强的鲁棒性,并且稳态误差小于2 N。     

Linear active disturbance rejection control of underactuated systems: The case of the Furuta pendulum

An Active Disturbance Rejection Control (ADRC) scheme is proposed for a trajectory tracking problem defined on a nonfeedback linearizable Furuta Pendulum example. A desired rest to rest angular position reference trajectory is to be tracked by the horizontal arm while the unactuated vertical pendulum arm stays around its unstable vertical position without falling down during the entire maneuver and long after it concludes. A linear observer-based linear controller of the ADRC type is designed on the basis of the flat tangent linearization of the system around an arbitrary equilibrium. The advantageous combination of flatness and the ADRC method makes it possible to on-line estimate and cancels the undesirable effects of the higher order nonlinearities disregarded by the linearization. These effects are triggered by fast horizontal arm tracking maneuvers driving the pendulum substantially away from the initial equilibrium point. Convincing experimental results, including a comparative test with a sliding mode controller, are presented.     

Active disturbance rejection control: Methodology and theoretical analysis

The methodology of ADRC and the progress of its theoretical analysis are reviewed in the paper. Several breakthroughs for control of nonlinear uncertain systems, made possible by ADRC, are discussed. The key in employing ADRC, which is to accurately determine the “total disturbance” that affects the output of the system, is illuminated. The latest results in theoretical analysis of the ADRC-based control systems are introduced.     

计算机控制气动包装机械定位方法

气动包装机已在国内外广泛推广使用,因为气动包装具有高速、无污染、机构简单、成本低廉等优点。在包装过程中,为实现准确快速定位及精确送料、封口、计量、打印等动作,要求机械控制系统重复精度要高。应用计算机及PCM控制的各类气动包装机械,不但可以实现计算机全自动化控制,并可实现准确定位。