Temperature-Insensitive Inclinometer Based on Transmission Line Fabry–Perot Resonators

Inclination Sensor With a Wide Angle Measurement Range Using Half-Wavelength Microstrip Resonator

“…A N inclination sensor or inclinometer is a device to measure an object's position angle change relative to a reference vector in the Earth's gravitational eld or its magnetic eld. Inclination measurement has been increasingly in demand in many applications including, but not limited to, industrial machine alignment, navigation systems in cars and ships, and prediction of natural disasters such as earthquakes [1] [7]. In addition, inclination angle monitoring has a signicant importance in the process of building civil infrastructures such as roads, tunnels, bridges, and buildings.…”

“…An inclination sensor can be mounted on an infrastructure being built or on the moving parts of a robot and the inclination of that part can be monitored or controlled using a processing wireless network connected to the sensor. Dierent types of inclinometers have been reported using electric contact [8], micro-electro-mechanical method [1], electrolytes [2], capacitance method [9], transmission line resonators [3], [4], [7], and ber optics [5], [6], [10] [14]. Most of the ber-optic (FO) inclinometers fall into one of two types: Extrinsic Fabry-Perot Interferometers (EFPI) or Fiber-Bragg-Grating (FBG) sensors.…”

“…In FBG-based inclinometers, the shift in tilt angle causes a variation in strain applied to the FBGs, which in turn shifts the resonance wavelength [6], [10] [13]. Fiberoptic inclinometers typically have low transmission loss, high accuracy and high sensitivity but they are not always an option when the application involves harsh environments where robust construction and durability are also required, as well as having a costly interrogation system [3], [4], [7].…”

“…Coaxial cables oer higher durability compared to optical bers, making them a promising candidate to implement inclinometers. In [3] and [7], coaxial cable inclinometers mimicking optic-ber EFPIs have been explored. In [3], a metal mass block, suspended in proximity to the open end of a hollow coaxial cable in parallel, is used to make a pendulum structure.…”

“…Applying inclination to the pendulum leads to modication in the phase reection coecient at the open end. In [7], a hollow coaxial cable FabryPerot resonator (HCC-FPR) is implemented, using a metal post that shorts the inner conductor and the outer conductor of the HCC as the rst reector, and airwater interface as the second reector. These inclinometers are robust and have a high measurement resolution, but they have a large size and more importantly, a limited angle measurement range.…”