Abstract:
A 4-DOF microgripper is proposed to achieve micron level position capability. Each finger of the microgripper has 2 DOFs to accomplish the open-close and up-down direction motion, respectively.
The static model using both Euler-Bernoulli method and Timoshenko method is derived. The maximum displacement and accessible force about y and z direction can be calculated by these methods. It is quite similar to the result of the both model. The Euler-Bernoulli method is accurate and simple enough to establish the control system.
The dynamic model based on the Euler-Bernoulli model presents a precise description of the dynamic behavior of the system. This model consists of actuator and sensor equations. Then, the state space model of the system is constructed to control the system. The controller combines the feedforward and feedback control loops. The feedforward controller compensates the hysteresis effect with the Preisach model. The strain self-sensing method was built as the sensor to measure the deflection of the microgripper without using an external sensor.
Finally, the microgripper is integrated into the three-degree-of-freedom micromanipulator to form a micromanipulation system.
中文摘要:
本文提出一具有四個自由度之微夾爪，其每一指可由壓電雙層驅動器而分別作出上下及左右之運動，達到多自由及微米精度之需求。
藉由Euler-Bernoulli及更精確之Timoshenko原理建構出靜態模型，並求得微夾爪之最大位移與最大出力。由結果可得，二者並無太大差別，Euler-Bernoulli模型亦可適用於精密控制方面。
動態模型則包含致動與感測方程式二者可獲得輸入電壓與輸出位移之關係。利用動態模型設計一前饋和回饋混合型控制器以達到微米精度之控制。首先利用 Preisach理論建構壓電致動器之遲滯現象模模型，再經由前饋控制補償遲滯現象。為避免因增加額外的感測器而造成結構與製作上的複雜度，利用壓電致動 器之自感測原理作為感測器，將量得訊號作回授控制。
最後，將此微夾爪整合於微操作器上形成一微操作系統，並實際進行微操作與微組裝之實驗，達到微組裝工廠之目標。