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压电式微/纳米级高精度定位系统的Noether对称性数值解法

NUMERICAL SOLUTION METHOD OF NOETHER SYMMETRY FOR PIEZOELECTRIC MICRO/NANO LEVEL HIGH-PRECISION POSITIONING SYSTEM

  • 摘要: 迟滞非线性效应会使压电式微/纳米级定位系统产生严重定位误差, 为了减小迟滞非线性的影响, 需要对系统进行动力学建模和非线性行为研究, 并构建控制器补偿迟滞以提高定位精度. 由于存在迟滞、耗散等非保守量, 传统方法寻找系统的Noether对称性非常困难进而导致无法构造系统的对称性解, 从而影响系统的优化设计, 对此本文提出压电式微/纳米级定位系统的Noether对称性数值解法. 以德国Physik Instrumente公司生产的P721.CDQ型Z轴柔性物镜扫描器为研究对象, 根据其结构特点, 从研究系统的能量入手, 得到了系统的Lagrange函数, 并建立了系统的动力学方程. 引入时间、电荷和位移坐标的无限小群变换, 给出压电式微/纳米级定位系统的广义Noether定理, 提出特殊情形的Noether对称性的概念, 在每个采样时间间隔内把系统的输入、迟滞和外力等非保守量均视为阶跃序列, 计算发现了此时系统的广义Noether对称性生成元, 并获得相应的守恒量, 进而构造了特殊情形下对称性解. 在系统的对称性解的基础上, 运用循环控制技术设计了Noether对称性数值解法的计算流程, 并在MATLAB环境下开发了计算程序, 可用于压电式微/纳米级定位系统含迟滞动力学方程的求解. 最后进行了实验验证, 在同样的输入电压的作用下分别比较了采用Noether对称性数值解法、Runge-kutta 四五阶方法和实验测量的系统输出位移响应, 并进行了大规模计算模拟. 结果显示Noether对称性数值解法不仅具有较高的精度而且显著地提升输出响应的计算速度,在涉及大规模计算的场合更具有优势.

     

    Abstract: The hysteresis nonlinear effect can induce significant positioning errors in piezoelectric micro/nano level positioning system. To mitigate the impact of hysteresis nonlinearity, it is essential to perform dynamic modeling and investigate the nonlinear behavior of the system, and build a controller to compensate for hysteresis to enhance positioning accuracy. Due to the presence of non-conservative quantities such as hysteresis and dissipation, it is very difficult for traditional methods to find the Noether symmetry of the system, which leads to the inability to construct symmetry solutions for the system, thereby affecting the optimization design of the system. To address this issue, this paper proposes a Noether symmetry numerical solution method for piezoelectric micro/nano level positioning system. The study focuses on the P721.CDQ Z-axis flexible objective scanner manufactured by Physik Instrumente in Germany. Based on its structural characteristics, the Lagrange function of the system is obtained by studying its energy, and the dynamic equations of the system are established. By introducing the infinitesimal group transformations of time, charge and displacement coordinates, the generalized Noether theorem for piezoelectric micro/nano level positioning system is given. The concept of Noether symmetry for special cases is proposed, where non-conservative variables such as input, hysteresis, and external forces are treated as step sequences within each sampling time interval. The generalized Noether symmetry generators of the system are found, and the corresponding conservation quantities are obtained, leading to the construction of symmetry solutions for these special cases. On the basis of the symmetry solutions of the system, the calculation flow of Noether symmetry numerical solution method is designed by using the loop control technology, and several calculation programs are developed in MATLAB environment, which can be used to solve the hysteresis dynamic equation of piezoelectric micro/nano level positioning system. Finally, experimental verifications are carried out, comparing the output displacement responses under the same input voltage using the Noether symmetry numerical solution method, the Runge-Kutta fourth-fifth order method, and experimental measurements. Large-scale computational simulations are also performed. The results show that the Noether symmetry numerical solution method not only achieves high precision but also significantly improves the calculation speed of output response, which is more advantageous in scenarios involving large-scale computations.

     

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