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Displacement Sensor (displacement + sensor)

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Engineering	100%

Selected Abstracts

Theoretical and experimental study on the fiber optic displacement sensor with two receiving fibers

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2010
Sulaiman Wadi Harun
Abstract The intensity-modulation-based displacement sensor with two receiving fibers is theoretically and experimentally studied. Themathematical model of the proposed sensor is developed and the simulated responses are obtained to be in a good agreement with the experimental results. Compared with the conventional sensor with only one receiving fiber, the proposed sensor has a better linearity range because it has a larger area to receive the reflected light from the target. However, the sensitivity of both sensors is almost similar. Theproposed sensor has the maximum linearity ranges of 2.5 ,m and 0.9 ,m at the back and front slopes, respectively. The linearity ranges are improved by about 44% compared with the conventional sensor. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 373,375, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24900 [source]

Fiber-optic displacement sensor using a multimode bundle fiber

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2008
Moh. Yasin
Abstract A simple fiber optic displacement sensor based on intensity modulation technique is demonstrated using a bundle multimode plastic fiber as a probe. The sensor consists of a light source, a probe, and photodiode detector. The sensor is capable of measuring displacements of mirror ranging from 0.05 to 2.2 mm using a red light source of wavelength 632.8 nm with maximum output power of 1 mW. The sensitivity of the device is found to be 168.8 mV/mm over 0.05,0.35 mm range and ,29.8 mV/mm over 1.05,2.2 mm range. The sensor is highly sensitive at the front slope and very useful for close distance target. The simplicity of the design, high degree of sensitivity, dynamic range and the low cost of the fabrication make it suitable for applications in industries as position control and micro displacement measurement in the hazardous region. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 661,663, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23147 [source]

Kinematic transformations for planar multi-directional pseudodynamic testing

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2009
Oya Mercan
Abstract The pseudodynamic (PSD) test method imposes command displacements to a test structure for a given time step. The measured restoring forces and displaced position achieved in the test structure are then used to integrate the equations of motion to determine the command displacements for the next time step. Multi-directional displacements of the test structure can introduce error in the measured restoring forces and displaced position. The subsequently determined command displacements will not be correct unless the effects of the multi-directional displacements are considered. This paper presents two approaches for correcting kinematic errors in planar multi-directional PSD testing, where the test structure is loaded through a rigid loading block. The first approach, referred to as the incremental kinematic transformation method, employs linear displacement transformations within each time step. The second method, referred to as the total kinematic transformation method, is based on accurate nonlinear displacement transformations. Using three displacement sensors and the trigonometric law of cosines, this second method enables the simultaneous nonlinear equations that express the motion of the loading block to be solved without using iteration. The formulation and example applications for each method are given. Results from numerical simulations and laboratory experiments show that the total transformation method maintains accuracy, while the incremental transformation method may accumulate error if the incremental rotation of the loading block is not small over the time step. A procedure for estimating the incremental error in the incremental kinematic transformation method is presented as a means to predict and possibly control the error. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Pointing control design for a high precision flight telescope using quantitative feedback theory

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10 2001
Anthony E. Bentley
Abstract A pointing control system is developed and tested for a flying gimbaled telescope. The two-axis pointing system is capable of sub-microradian pointing stability and high accuracy in the presence of large host vehicle jitter. The telescope also has high agility , it is capable of a 50° retarget (in both axes simultaneously) in less than 2 s. To achieve the design specifications, high-accuracy, high-resolution, two-speed resolvers were used, resulting in gimbal-angle measurements stable to 1.5 µrad. In addition, on-axis inertial angle displacement sensors were mounted on the telescope to provide host-vehicle jitter cancellation. The inertial angle sensors are accurate to about 100 nrad, but do not measure low-frequency displacements below 2 Hz. The gimbal command signal includes host-vehicle attitude information, which is band-limited. This provides jitter data below 20 Hz, but includes a variable latency between 15 and 25 ms. One of the most challenging aspects of this design was to combine the inertial-angle-sensor data with the less perfect information in the command signal to achieve maximum jitter reduction. The optimum blending of these two signals, along with the feedback compensation were designed using Quantitative Feedback Theory. Copyright © 2001 John Wiley & Sons, Ltd. [source]