高精度气动同步系统研究

发布时间：2018-02-14 13:41

本文关键词： 气动伺服位置控制运动轨迹跟踪控制同步控制自适应鲁棒控制交叉耦合死区补偿 LuGre模型摩擦力补偿　出处：《浙江大学》2013年博士论文　论文类型：学位论文

【摘要】：因为具有功率-质量比大、清洁、结构简单、易维护等优点,气动同步技术在机器人、工业自动化和医疗机械等领域具有广泛的应用前景。但是气动系统具有很多不利于精确控制的弱点,如强非线性、参数时变性和模型不确定性等,如何提高气动位置伺服系统的轨迹跟踪控制性能和如何实现多执行元件同步控制仍是当前气动技术研究的一个重要方向。本论文以一个双气缸的气动同步系统为研究对象,以实现单缸的高精度运动轨迹跟踪控制和双缸的精确位置同步控制为研究目标,利用理论分析和实验相结合的方法,从建立精确描述系统特性的非线性模型入手,深入的研究了气动伺服位置控制策略和气动同步控制方法。为实现气缸的高精度运动轨迹跟踪控制,本论文首先基于LuGre模型对气缸摩擦力进行了补偿,并提出了一种含死区补偿的自适应鲁棒控制策略。该控制器采用双观测器来估计摩擦力内状态,通过在线最小二乘参数估计来减小模型中参数不确定性,并利用非线性鲁棒控制来抑制参数估计误差、未建模动态和干扰的影响,从而保证一定的鲁棒瞬态性能和高的稳态跟踪精度。由于使用了标准投影映射技术,参数自适应律与非线性鲁棒控制器两个部分可以独立进行设计。鉴于系统模型中的不确定性是非匹配的,采用了反步法来设计非线性鲁棒控制器。此外,由于控制器能在线辨识阀的死区参数并对死区进行补偿,算法的可移植性好。在此基础上,将交叉耦合思想与直接/间接集成自适应鲁棒控制结合起来,提出一种基于交叉耦合方法的自适应鲁棒气动同步控制策略,实现了双缸的精确位置同步控制。本论文共分六章,现将各章内容分述如下：第一章,详细介绍了气动伺服位置控制的研究现状,指出提高气缸的轨迹跟踪控制性能仍是当前气动技术研究的一个重要方向；简述了气动同步控制的研究背景和研究现状；最后概述了本课题的研究意义、研究难点以及主要研究内容。第二章,描述了气动同步系统实验装置的硬件组成；研究了气体通过控制阀阀口的流动、气缸两腔内气体的热力过程和气缸的摩擦力特性等问题,建立了气动同步系统的非线性模型,为控制器设计做好准备；通过参数辨识,获得了控制阀阀口开度与控制电压的关系以及缸内空气与气缸内壁间的热传导率；为满足高精度气动伺服位置控制时基于模型的摩擦力补偿需要,建立了气缸的LuGre动态摩擦模型并对其中参数进行了辨识。第三章,给出气动同步系统某一轴的非线性状态空间模型,并分析系统的控制难点,归纳出为实现气缸的高精度运动轨迹跟踪控制,所采用的控制方法必须考虑模型中参数不确定性和不确定非线性的影响。首先为气动位置伺服系统设计一个鲁棒自适应控制器和一个确定性鲁棒控制器,通过分析二者的优点和研究如何将它们有机结合,提出了一种气动位置伺服系统的自适应鲁棒运动轨迹跟踪控制策略。它采用在线参数的自适应调节减小模型参数不确定性,同时通过鲁棒控制律抑制不确定非线性的影响,从而达到较好的动态性能和较高的稳态跟踪精度。实验证明,自适应鲁棒控制器是有效的,控制性能高于文献中已有的研究成果,且对系统参数变化和干扰具有较强的性能鲁棒性。第四章,在上一章研究的自适应鲁棒控制器基础上,通过引入一个动态补偿型快速自适应项,设计了直接／间接集成自适应鲁棒控制器,提高了系统瞬态跟踪性能；针对比例方向控制阀存在显著的死区且不同阀的死区特性差异较大的情况,提出一种含死区补偿的直接／间接集成自适应鲁棒控制器,在线辨识阀的死区参数并通过构造死区逆对死区进行补偿,提高了算法的可移植性；为进一步提高气缸低速运行时的轨迹跟踪控制精度,研究了基于LuGre模型的气缸摩擦力补偿方法以及如何将该补偿方法与直接／间接集成自适应鲁棒控制方法结合起来。最后,通过实验证明了上述气动位置伺服系统的高精度运动轨迹跟踪控制策略的有效性。跟踪幅值为0.125m、频率为0.5Hz正弦轨迹时,最大稳态跟踪误差为1.32mm,平均稳态跟踪误差为0.68mm,瞬态过程最大跟踪误差为1.61mm；跟踪低速正弦轨迹时,最大稳态跟踪误差为0.59mm,平均稳态跟踪误差为0.21mm。第五章,提出一种基于交叉耦合方法的自适应鲁棒气动同步控制策略,既保证多气缸精确同步又不影响系统中每一气缸的轨迹跟踪控制精度,基本思想是：将同步误差反馈至每个轴控制器的输入端与轨迹跟踪误差组成一个新的称为耦合误差的变量,为每个轴分别设计直接/间接集成自适应鲁棒控制器使耦合误差收敛,实现轨迹跟踪误差和同步误差同时收敛。给出了控制器的详细设计步骤,并以双气缸同步为例,通过实验证明控制器的有效性和性能鲁棒性。跟踪幅值为0.125m、频率为0.5Hz的正弦期望轨迹时,最大同步误差为1.25mm左右,平均同步误差为0.67mm左右。第六章,对本论文的主要工作、研究结论和创新点进行了总结,并对未来的研究工作进行了展望。
[Abstract]:Because has the power to mass ratio is large, clean, simple structure, easy maintenance, pneumatic synchronization technology in robot, and has wide application prospect in industrial automation fields and medical machinery. But the pneumatic system has many not conducive to precise control weaknesses, such as strong nonlinear, time-varying parameters and model uncertainty so, how to improve the pneumatic position servo system of tracking control performance and how to realize multi actuator synchronization control is the pneumatic technology research is an important direction. In this paper, a double cylinder pneumatic synchronization system as the research object, the exact location of the trajectory in order to achieve high precision tracking control of single cylinder and double cylinder synchronous control as the research object, using the method of combination of theoretical analysis and experiment, starting from the nonlinear model accurately describes system characteristics, in-depth study of the pneumatic servo position The control strategy and the pneumatic synchronous control method are used.
To realize high precision trajectory tracking control of the pneumatic cylinder, this paper based on the LuGre model is used to compensate the friction of the cylinder, this paper proposes an adaptive robust control strategy with dead time compensation. The controller adopts double observer to estimate the friction within the state, through the least squares estimation in line parameters to reduce the model parameter uncertainty, and by using the nonlinear robust control to suppress the influence of parameter estimation error, unmodeled dynamics and disturbances, so as to ensure a robust transient performance and high tracking precision. Due to the use of the standard projection mapping technique, adaptive parameters and nonlinear robust controller of two parts to be designed. In view of the uncertainty in the system model is non matching, using the backstepping method to design nonlinear robust controller. In addition, the controller can on-line identification of valve dead zone The parameters and dead time compensation algorithm, the portability is good. On this basis, the cross coupling theory and integrated direct / indirect adaptive robust control combined, proposes an adaptive robust method of dynamic gas cross coupling synchronous control strategy based on the realized precise position of double cylinder synchronous control.
This paper is divided into six chapters, and the contents of each chapter are described as follows:
The first chapter introduces the research status of pneumatic servo position control, points out that improving the tracking performance of the pneumatic technology is still an important direction in the research of the cylinder trajectory; introduces the research background and research status of pneumatic synchronization control; finally summarizes the significance of the research topic, research difficulties and main research contents.
The second chapter describes the pneumatic synchronization system hardware composition; the gas control valve through the valve port flow, friction characteristics on the thermal process and the cylinder cylinder two chamber gas, to establish the nonlinear model of pneumatic synchronization system, meter ready for the controller design; obtained by parameter identification. Control valve opening and the relationship between the control voltage and the heat conduction in the air cylinder and the inner wall of the cylinder between the rate; in order to meet the high precision pneumatic servo position control based on friction compensation model, established the LuGre dynamic friction model of the cylinder and the parameters are identified.
The third chapter to the dynamic nonlinear state space model of a shaft synchronization system and control system of air, difficulty, summed up the tracking trajectory to achieve high-precision cylinder control, the control methods must be taken into account in the model parameter uncertainty and uncertainty nonlinear. The first is to design a robust the adaptive controller and a robust controller of pneumatic position servo system, through the analysis of the two advantages and study how the organic combination of them, this paper presents a robust adaptive trajectory of a pneumatic position servo system. It adopts the adaptive tracking control strategy online parameter adjustment to reduce the uncertainty of model parameters, the robust control law inhibition of uncertain nonlinear effect, steady state so as to achieve good dynamic performance and high tracking accuracy. The experimental results show that the robust adaptive controller It is effective. The control performance is higher than the existing research results in the literature, and it has strong performance robustness for system parameters change and interference.
The fourth chapter, the adaptive robust controller based on the research in the last chapter, by introducing a fast adaptive dynamic compensation, the design of integrated direct / indirect adaptive robust controller, improve system transient tracking performance; the proportional directional control valve of the valve dead zone and significantly different dead zone with different characteristics, put forward direct / indirect adaptive robust controller is integrated with a dead time compensation, dead time on-line parameter identification of valve and through the construction of dead zone compensation for dead time, improves the portability; tracking control precision for the further improving of the cylinder during low-speed operation trajectory of cylinder friction compensation method based on LuGre model and how will the compensation method and integrated direct / indirect adaptive robust control methods together. Finally, through the experiment proved that the pneumatic The effectiveness of trajectory tracking control strategy of high precision servo system tracking. The amplitude of 0.125m, frequency of 0.5Hz sinusoidal trajectory, the maximum tracking error is 1.32mm, the average tracking error is 0.68mm, the transient maximum tracking error is 1.61mm; low speed tracking sinusoidal trajectory, the maximum tracking error is 0.59mm, the average the tracking error is 0.21mm.
The fifth chapter, this paper proposes an adaptive robust method of dynamic gas cross coupling synchronous control strategy based on multi cylinder ensures accurate synchronization and does not affect the control precision of each cylinder of the tracking system, the basic idea is: the synchronization error feedback to each axis of the input end of the controller and trajectory tracking error to form a new call for the coupling error of variables for each axis integrated direct / indirect adaptive robust controller so that the coupling error convergence design respectively, realize trajectory tracking error and synchronization error and convergence. The detailed design procedure of controller is given, and the double cylinder synchronization as an example, through effective and robust performance controller. Experiments show that the amplitude of tracking 0.125m, the frequency of sinusoidal trajectory 0.5Hz, maximum synchronization error is about 1.25mm, the average synchronization error is about 0.67mm.
In the sixth chapter, the main work of this paper, the research conclusions and the innovation points are summarized, and the future research work is prospected.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH138;TP273

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