Modeling And Control For Smart Materials Based Actuators In High-precision Electronic Manufacture Equipment

Precision electronic assembly is one of the key procedures in the electronic information manufacture. The development of the novel electronic components has been developed to the multiple-pin direction. The research of the theory and technique for the optimization control based on vision is still in the primary stage. The smart materials based actuators have been applied widely because of their excellent properties, such as high precision. Also, how to design the corresponding control approaches to improve the positioning precision of the nano-smart material based actuators has attracted more attention during these years. Therefore, the improvement of the positioning precision of the precision electronic assembly by using smart-material based actuators has been one of the key issues in this field.The idea of the surface mounting technology is to use smart vision detection, positioning algorithms, high precision control algorithms and industrial robot technique achieving fast and precise assembly. With the nano assembly development of the next generation component, the classical template matching for detection and motion deceleration to ensure the terminal mounting head cannot match the high speed and high precision requirements. Therefore, novel smart-materials based sensors and actuators have been paid attention because of their excellent characteristics, such as high precision, fast response speed and large stress, and have been adopted in the high precision of the electronic assembly. With the improvement of the positioning precision, especially the nano-stage positioning application, the hysteresis existing in these actuators limits the improvement of the system performance. How to describe the hysteresis characteristics in the smart materials based actuators and design the related controller mitigating the effects caused by the hysteresis effectively become one of the main tasks of the precision control field.The contents of this dissertation include1. The main portion of the surface mounting technology control system is the servo-controlled positioning system. With the fineness of the lead pin pitch in the IC chip, the positioning precision needs to be more accurate than before. In order to achieve nano positioning precision, it is necessary to construct the related hysteresis model describing the hysteresis properties in the smart materials-based actuators for concerted and precise control.2. The working principle and the related hysteresis characteristics of these smart material based actuators, such as piezoelectric actuators, magnetostrictive actuators and shape memory alloy actuators are analyzed. Due to the multiform of the smart materials, the hysteresis existing in these smart materials actuators have some special properties, for example, except the multi-values, minor loop, saturation property and asymmetric property etc. existing in these smart materials actuators. Addressing this issue, describing the hysteresis accurately becomes one of the main tasks for the smart materials actuators based assembly control.3. The hysteresis models utilized to describe hysteresis characteristics are analyzed. Considering the modeling principle, these models can be roughly classified as operator-based hysteresis model, such Preisach model, Prandtl-Ishlinskii model and KP model, and differential equation-based hysteresis models, such as Backlash-like model and Duhem model.4. Focusing on the saturated hysteresis in the smart materials actuators, a generalized Prandtl-Ishlinskii model is adopted to represent the hysteresis characteristics in the shape memory alloy actuators. Based on the generalized Prandtl-Ishlinskii model, a robust adaptive control approach without construction of the hysteresis inverse is proposed.5. Still focusing on the saturated hysteresis in the smart materials actuators, Duhem model is adopted to describe the saturated hysteresis characteristics in the shape memory alloy actuators. By exploring the property of Duhem hysteresis model, another robust control approach without construction the hysteresis inverse is proposed. The proposed method mitigates the effects caused by the hysteresis effectively and ensures the tracking precision.6. These smart materials based actuators are adopted in the positioning control of servo system experiment stage as the primary application of the smart materials based actuators in the electronic assembly devices.The dissertation is supported by the National Natural Science Foundation of China (No. 60835001, The research on the key vision detection and optimal control oriented to the assembly line), Project of Product-Education-Research Association of Guangdong Province and Ministry of Education(2009A090100027)"Research and industrialization of hight-level full-automatic surface mounting assembly"and by the Fundamental Research Funds for the Central Universities, SCUT under Grant 2009ZZ0005.