Random Rotary Position Sensor Based on Fiber Bragg Gratings

Abstract

In this paper a new rotary position sensing structure based on a pair of fiber Bragg gratings (FBGs) is experimentally demonstrated with capability of detecting rotating angle of a rotor which is rotated in arbitrary direction or rotated in the same direction infinitely. Moreover, owing to its miniature size, this structure can also be used for small rotary apparatus as a tiny rotating position sensor. The operation mechanism is mainly based on the difference between the wavelength shifts of two FBGs respectively due to the axial strain caused by bending the cantilever towards the angular direction corresponding to the rotating position of rotary shaft. A deviation of 1.1 degrees for rotary angle detecting is obtained.

Fiber anemometer for simultaneously measuring wind speed and wind direction

“…According to Equations , the relationship between the grating wavelength shift Δ λ B and the applied strain ε can be simplified as follows: where and denotes the strain‐optic coefficient of the fiber. For a typical fused‐silica fiber, the value of P e is approximately 0.22.…”

Development of a robust rotational-angle optical fiber sensor using different-material cantilevers

“…6 An axial cantilever beam has one end adhered and fixed at the center of the left-hand side in the aluminum cylinder and the other free end is mounted by a magnet. 6 Two sets of magnet residing on the disc and the free-end of the cantilever beam not only repel each other but also produce the resultant magnetic repulsion to bend the thin cantilever beam. 2.…”

“…2. 6 The relationship between the shift of the Bragg wavelength of FBG (Δλ B ∕λ B ) and the axial strain ε applied to a fiber grating is 2 Two FBGs are axially bound on the cantilever beam separated from each other by a quarter of the circumference as shown in Fig.…”

“…For current commercial products, one of the most common types of rotary sensors is based on electronics used in Ref. [4][5][6] Montanini et al have demonstrated that the tangential strain can be measured by sensing the two fiber Bragg grating (FBG) structured rotary position of a rotor attached to the central end of an approximated Archimedes spiral. Because the electronic signals are subject to the noises, this disadvantage for measuring inaccuracy can be overcome by exploiting the fiber sensors based on optical signals.…”

“…Because the electronic signals are subject to the noises, this disadvantage for measuring inaccuracy can be overcome by exploiting the fiber sensors based on optical signals. 6 One critical design factor for this sensor to exhibit a noticeably nice sensing performance is attributed to the material of the cantilever beam. 2,3 Regarding the rotary position sensors exploited in various design mechanisms, there are several different structures made up of fiber gratings which have already been published.…”