Abstract
A wide dynamic range, high precision, non-contact and large bandwidth angular displacement measurement (ADM) is greatly necessary for the applications such as industrial control and military equipment. This paper proposes a simple and effective ADM method based on Doppler Effect, heterodyne detection and diffuse reflection, which can fulfill these requirements simultaneously. Two beams of parallel light generated by a pair of laser Doppler vibrometers are incident upon the surface of rotational target, then data processing unit acquires the velocity of dual laser incident points on the moving target, and resolves the rotational angular displacement and translation displacement of target through the relationship between dual laser beams dynamically. Several major measurement errors that may affect the ADM accuracy are analyzed. A high precision rotary table is used as an angular displacement standard to verify the measurement range and accuracy, the verification experiment shows that the measurement range is not less than ±10° and the measurement accuracy is 0.0362° based on the method. After using a polynomial error compensation, the measurement accuracy can be promoted to 0.0088°, and this compensation method can be applied to real time measurement.
Highlights
Angular displacement measurement (ADM) plays an important role in fields of industrial application and scientific research
Based on Homodyne interferometry, Doppler Effect and the geometry relationship between the velocity measured by multiple laser beams and the rotational velocity of shaft, the optical geometry and algorithm of laser torsional Doppler vibrometer is proposed[14,15]
All the angular displacement measurement (ADM) methods have their own advantages and disadvantages, but they cannot meet the requirements of high dynamic range, high precision, non-contact and wide bandwidth simultaneously
Summary
Laser Doppler vibrometer (LDV) is a technology for accurate and non-contact measurement of velocity in industrial and metrological applications[22]. It is an instrument utilising Doppler Effect and heterodyne detection[15]. In optic Doppler Effect, light frequency is shifted by instantaneous velocity of the object[23], the intensity of the interference signal is modulated by velocity of the moving target. Where λ is laser wavelength, and v represents velocity of moving target[24] Based on their non-contact nature, LDV do not destroy the structure to be measured. Integral instantaneous angular velocity ω can obtain angular displacement θ of object
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
