A real-time processing system for dual-channel six-degree-of-freedom grating ruler based on FPGA

Ningning Shi; Shengtong Wang; Gaopeng Xue; Mengfang Liu; Yaodong Han; Junhao Zhu; Kai Ni; Xiaohao Wang; Xinghui Li

doi:10.1117/12.2602239

9 October 2021 A real-time processing system for dual-channel six-degree-of-freedom grating ruler based on FPGA

Ningning Shi, Shengtong Wang, Gaopeng Xue, Mengfang Liu, Yaodong Han, Junhao Zhu, Kai Ni, Xiaohao Wang, Xinghui Li

Proceedings Volume 11895, Optical Design and Testing XI; 1189518 (2021) https://doi.org/10.1117/12.2602239
Event: SPIE/COS Photonics Asia, 2021, Nantong, JS, China

Conference Poster

Abstract

Six-degree-of-freedom (6-DOF) grating encoders have a wide prospect of application. Aiming at the requirement of real-time detection of 6-DOF grating encoders, this study designs and builds a real-time calculation system platform based on field-programmable gate array (FPGA). We realized a real-time parallel calculation of 16-path displacement signal and 24-path angular displacement signal, respectively. Specifically, the optical interference signals, generated by the translation and rotation of the motion stages, are firstly shaped by the front-end analog circuit. We further sampled the front-end analog circuit into an FPGA through a analog-to-digital convertor (ADC) for the realization of the digital filtering, amplitude normalization, phase correction, and phase-information calculation. Thus, the calculated signals on the 6-DOF motions can be displayed in real time. The established system was evaluated with the experimental parameters in terms of the translation with a 50 μm/s moving speed and an 18 mm stroke and the rotation with a frequency of 0.5 Hz, a step length of 100 micro-rad, and within a reciprocating rotation of 24 s. Finally, a linear-displacement error of <1 nm and an angle displacement error of <0.9 micro-rad were achieved, respectively. Furthermore, the system delay of <15 ms is obtained, exhibiting a high performance for the real-time measurement and high integration in the practical application.

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Ningning Shi, Shengtong Wang, Gaopeng Xue, Mengfang Liu, Yaodong Han, Junhao Zhu, Kai Ni, Xiaohao Wang, and Xinghui Li "A real-time processing system for dual-channel six-degree-of-freedom grating ruler based on FPGA", Proc. SPIE 11895, Optical Design and Testing XI, 1189518 (9 October 2021); https://doi.org/10.1117/12.2602239

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