31 December 2008 A robust control scheme of nanopositioning driven by ultrasonic motor
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Proceedings Volume 7130, Fourth International Symposium on Precision Mechanical Measurements; 71301O (2008) https://doi.org/10.1117/12.819598
Event: Fourth International Symposium on Precision Mechanical Measurements, 2008, Anhui, China
Abstract
An innovative nanopositioning control system is proposed in this paper. A commercial ultrasonic motor (Nanomotion Co. model HR4) is employed to generate 3-mode motions of different scales. A multi-scale positioning control scheme can thus been developed by integrating the 3 driving modes. A new displacement sensor LDGI (Linear Diffraction Grating Interferometer) is developed and served as the displacement feedback. The uncertainty of LDGI system has been proved less than 10nm in 15mm. By phase subdivision technique the resolution of LDGI can be interpolated to 0.25nm. With this hardware system a software-based controller is developed. A self-tuning module, called Back Propagation Neural Network (BPNN), is added to a PID control loop. This self-tuning PID controller shows more robust than conventional ones, especially when some unpredictable disturbance occurs. Experiments show that this system is able to reach the steady state in 2 seconds without notable overshoot or vibration and hold the position for a long time with the positioning error less than 3nm. When some disturbances occur the system can build a new steady state in 2 seconds.
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Fang Cheng, Kuang-Chao Fan, Ye-tai Fei, "A robust control scheme of nanopositioning driven by ultrasonic motor", Proc. SPIE 7130, Fourth International Symposium on Precision Mechanical Measurements, 71301O (31 December 2008); doi: 10.1117/12.819598; https://doi.org/10.1117/12.819598
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