低速大范围下压电执行器动态蠕变特性分析与控制方法研究

发布时间：2018-02-13 22:08

本文关键词： 压电执行器动态蠕变蠕变特性建模迟滞特性蠕变特性抑制　出处：《山东大学》2016年博士论文　论文类型：学位论文

【摘要】：压电执行器是由智能材料构成的固态执行器,因具有亚纳米级位移分辨率而得以在超精密定位的场合广泛应用。对压电执行器内在的迟滞、蠕变、振动和漂移四种非线性,研究人员从宏观和微观两个方面进行了深入的工程实验和理论研究,得到了许多建模与控制的有效方法。目前对于迟滞的静态特性(率无关)和动态特性(率相关)的研究已日趋成熟,蠕变的静态特性(稳态段和单台阶)研究也有很好的抑制方法,但蠕变的动态特性(暂态段和多台阶)方面的研究还亟待解决。本文以压电执行器的蠕变特性为研究对象,在证实蠕变现象具有动态变化的基础上,对动态蠕变的特性进行分析和建模,并且研究了动态蠕变的抑制方法。首先研究了压电执行器在低频大范围下的蠕变动态特性,然后根据假说研究了迟滞与蠕变分离点;为了抑制动态蠕变,研究了双向小幅值电压尖峰对动态蠕变的抑制作用,接下来使用模糊PI复合控制器对不同离散化作用下的动态蠕变抑制作用,最后基于压电执行器是本质分数阶对象的特点,研究了分数阶复合控制器对动态蠕变的抑制作用。主要创新点如下:1、证实了低速大范围条件下压电执行器的蠕变动态现象;阐述了动态蠕变的含义;得到了动态蠕变的基本变化规律;改进了 log-type和反比例函数模型并证实了其参数的迟滞性;提出了在低速大范围条件下,蠕变与迟滞分离点假说,并设计了函数模型,证实了其可前推性。2、基于尖峰电压的方向对蠕变抑制的重要影响,通过实验发现了尖峰电压对压电执行器非线性抑制的优化方向;受滑模等智能算法在台阶电压开始处产生的尖峰电压启发,发现了开环条件下尖峰电压幅值的大小、方向以及间隔时间的长短对台阶蠕变的影响规律,即尖峰电压幅值对动态蠕变有非线性影响,存在最优值:发现了尖峰持续时间增长有利于降低尖峰电压幅值。3、结合控制经验设计了模糊PI复合控制器,实现了对率无关迟滞和动态蠕变同时抑制;证实了微分对压电执行器抑制的效果;提出了合理的模糊控制规则;设计直接逆方法作为前馈控制器保证了控制的快速性,并通过实验证实该控制器能够同时有效抑制率无关迟滞和动态蠕变。4、结合压电执行器具有本质分数阶特性和经典PID的优点,设计分数阶复合控制器,解决了其他算法在台阶电压开始处抑制压电执行器非线性时会产生较大幅值尖峰电压的问题;结合迟滞直接逆实现了动态蠕变的抑制,所提复合控制器具有反应速度快,跟踪精度高,对蠕变暂态段的超调电压具有很好的抑制能力。对压电执行器动态蠕变的特性分析与控制研究是对其内在非线性研究的深化,研究结果有助于推动压电执行器在低速大范围下的应用;蠕变与迟滞分离点的研究对压电执行器迟滞与蠕变依时间顺序划分具有重要的理论价值。
[Abstract]:Piezoelectric actuators are solid-state actuators made of smart materials, which are widely used in ultra-precision positioning due to their subnanoscale displacement resolution. The inherent nonlinearity of piezoelectric actuators is hysteresis, creep, vibration and drift. The researchers carried out deep engineering experiments and theoretical studies from both macro and micro aspects. Many effective modeling and control methods have been obtained. At present, the research on static (rate-independent) and dynamic (rate-dependent) characteristics of hysteresis has become more and more mature. The static characteristics of creep (steady state and single step) also have a good suppression method, but the dynamic characteristics of creep (transient and multi-step) still need to be studied urgently. In this paper, the creep characteristics of piezoelectric actuators are taken as the object of study. On the basis of confirming the dynamic change of creep phenomenon, the dynamic creep characteristics are analyzed and modeled, and the suppression method of dynamic creep is studied. Firstly, the creep dynamic characteristics of piezoelectric actuator in a wide range of low frequency range are studied. Then the separation point of hysteresis and creep is studied according to the hypothesis, and in order to suppress dynamic creep, the inhibition of bidirectional small voltage spike on dynamic creep is studied. Then the fuzzy Pi composite controller is used to suppress the dynamic creep under different discretization. Finally, based on the characteristic that piezoelectric actuator is the essential fractional object, The effect of fractional order composite controller on dynamic creep is studied. The main innovations are as follows: 1. The creep dynamic phenomenon of piezoelectric actuator under low speed and large range is confirmed, and the meaning of dynamic creep is expounded. The basic variation law of dynamic creep is obtained, the log-type and inverse proportional function model are improved and the hysteresis of its parameters is confirmed, the hypothesis of separation point between creep and hysteresis is proposed under the condition of low speed and large range, and the function model is designed. Based on the important influence of the direction of peak voltage on creep suppression, the optimized direction of peak voltage for nonlinear suppression of piezoelectric actuator is found through experiments. Inspired by the peak voltage generated at the beginning of step voltage by intelligent algorithms such as sliding mode, the effects of amplitude, direction and interval of peak voltage on step creep under open-loop conditions are found. That is, the amplitude of peak voltage has nonlinear influence on dynamic creep, and there is an optimum value. It is found that the increase of peak duration is beneficial to decrease the amplitude of peak voltage. A fuzzy Pi compound controller is designed based on the control experience. It realizes the simultaneous suppression of rate-independent hysteresis and dynamic creep, verifies the effect of differential suppression on piezoelectric actuators, puts forward reasonable fuzzy control rules, and designs direct inverse methods as feedforward controllers to ensure the control speed. It is proved by experiments that the controller can effectively suppress both rate-independent hysteresis and dynamic creep. Combined with the essential fractional order characteristic of piezoelectric actuator and the advantages of classical PID, a fractional order composite controller is designed. It solves the problem that when the step voltage starts to suppress the nonlinearity of piezoelectric actuator, other algorithms will produce a large amplitude peak voltage, combined with hysteresis direct inverse to achieve the suppression of dynamic creep, the proposed composite controller has fast reaction speed. The tracking accuracy is high and the overshoot voltage of creep transient section can be restrained well. The study of dynamic creep characteristic analysis and control of piezoelectric actuator is the deepening of its intrinsic nonlinear research. The results are helpful to promote the application of piezoelectric actuators in a large range of low speed, and the study of the separation points of creep and hysteresis has important theoretical value for the division of hysteresis and creep according to the time sequence of piezoelectric actuators.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP215

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