Rotation Angle Sensor Research Articles

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

A rotational-angle sensor composed of two Fiber Bragg gratings glued axially on a cylindrical can- tilever beam to be bent by the resultant repulsion force of three magnets is designed and proposed for detecting the rotary random position of a rotor. By means of using three different materials on cantilever beams for check- ing each feature's effect on this fiber optic sensor, it has been experimentally confirmed that a nearly identical performance is achieved among them. From these experimental results, a maximum deviation of 1.3 deg is obtained and it is in good agreement with the theoretical prediction. As a whole, the cantilever design exploited in this proposed optical fiber sensor configuration is independent of the intrinsic materials used. This sensor can provide a robust kind of technique for accurately measuring the rotational angle or rotational rate of a rotor in an arbitrary rotational direction for a wide range of industrial applications. © 2015 Society of Photo-Optical Instrumentation

A motor's rotational angle sensor based on fiber Bragg grating

ABSTRACTThis article develops an optical fiber sensor using a fiber Bragg grating (FBG) and a piezo‐electrical transducer (PZT) to measure a motor's rotational angle. By mounting an FBG on a PZT bar, a dynamic strain simulator was constructed. The equivalent voltage produced by the potentiometer caused by the rotational angle of a motor's shaft was applied to the PZT and converted to the dynamic variation of the FBG Bragg wavelength. The motor's rotational angle was attained by measuring the changing value of the wavelength. The experimental results demonstrate that a high sensitivity of 0.459 pm/deg is achieved over a range of 0° to 270°. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1449–1452, 2014

Temperature-Independent Rotational Angle Sensor Based on Fiber Bragg Grating

A novel temperature-insensitive fiber Bragg grating (FBG) rotational angle sensor is presented. The temperature-independent property of the sensor, as well as the adjustability of sensitivity and measurement range by means of altering the dimensions of the sensor, is analyzed both theoretically and experimentally. The experimental results demonstrate that a high sensitivity of 0.743 nm/deg over the range of the rotational angle from -21 to +21 is achieved.

Design of Element Configuration on Magnetic Rotation Angle Sensor with Spin-Valve Film

To reduce the error of a magnetic rotation angle sensor, we investigated the effect of sensor element configuration on the output signal of the sensor by using numerical calculations. The sensor elements were made of spin-valve films with a large shape-induced anisotropy. The magnetization of elements was calculated by minimizing the magnetic energy in a framework of the Stoner–Wohlfarth model. The sensor response was calculated as a function of the relative angle between the spin-valve elements. The error of signals was minimized when the relative angle was 99.5°. It is clear that this configuration is robust against the variation of shape-induced anisotropy.

융착 광섬유 커플러를 이용한 회전 각도 센서

We have proposed and demonstrated a rotation angle sensor based on the stress -optic effect of a fused fiber coupler whose transmission spectrum is altered by the torsional stress. The peak of transmission spectrum was shifted to longer wavelength region with rotation of the coupler. The rotation angle sensor revealed reproducibility and symmetric behavior with respect to the rotation direction. The sensitivity of the sensor was 0.367 [nm/degee].

Characteristics and Improved Design of Piezoresistive Rotation Angle Sensor Integrated in Micromirror Device

The characteristics and design of an improved piezoresistive rotation angle sensor integrated in a micromirror device are described. This study focuses on realizing higher resolution and accuracy in sensing the micromirror rotation angle compared with results reported in previous research. The structural design takes account of stress and temperature distributions. The lower resistance for current enables lock-in detection of rotation angle signals at a frequency higher than the mechanical resonant frequency of the micromirror, and the fluctuation generated by sensing the signal can be minimized. The resolved rotation angle is 0.02° and hysteresis of the signal is less than 4%.

Piezoresistive Rotation Angle Sensor Integrated in Micromirror

A piezoresistive rotation angle sensor is integrated in a micromirror device. The sensor signal is the voltage generated by the shear piezoresistance effect. This sensor has the advantage of being a single element which can be included in a torsion bar. The sensor signal is confirmed to be proportional to the mirror rotation. By taking advantage of the crystal orientation dependence, the sensor can be designed to be sensitive to the mirror rotation and insensitive to the shift motion.

High-temperature operations of rotation angle sensors with spin-valve-type magnetic tunnel junctions

Direction detection of a magnetic field by spin-valve-type magnetic tunnel junction (MTJ) has been investigated at temperatures ranging from room to 150/spl deg/C, concentrating on the magnetic property of the pinned layer. Angular dependencies of resistance curves show that detection errors from cosine curve increase with rising temperatures in MTJ with the IrMn/CoFe pinned layer. Measurements of the magnetization curves of the pinned layer found that detection errors are caused by rotation of the pinned layer magnetization. Direction detection of a magnetic field by MTJ with a IrMn/CoFe/Ru/CoFe of synthetic antiferromagnetic (SyAF) pinned layer, in which magnetizations of two CoFe layers nearly cancel each other, was also investigated. We confirmed that the pinned layer of SyAF structure in MTJ effectively reduces the dependence of detection errors on temperature.

Compensating for Thermal Size Change in Platforms for Gyroscopes and Laser Angle Sensors

Devices are described for compensating the thermal size change in platforms for gyroscopes and laser rotation angle sensors that employ various optical systems. Ways are considered of reducing the measurement errors and improving the resolving power.

Rotation angle sensors based on spin valve structures: A modeling approach

Spin valve systems are widely considered in magnetic rotation angle sensors. We present a simple magnetostatic model to simulate the electrical and magnetic signal of typical spin valve systems as a function of external magnetic field and rotation angle. To match simulation and experiment only a few parameters are needed, which can be determined by a single measurement. Two types of systems are treated and discussed: a simple spin valve and a spin valve with an “artificial antiferromagnet,” often used to enhance the exchange bias. The model shows a very good correspondence of the predictions to the experimental results of the systems investigated. In order to quantitatively compare experiment and model, we introduce a useful concept to quantify the quality of the angle rotation curves: the total harmonic distortion.

Development of Wheelchair with Assistive Power Unit

A wheelchair with an assistive power unit employing a differential gear is now under development. The wheelchair is specially aimed to those who have a little residual power to drive a hand driven wheelchair, but often use a powered wheelchair. People who have C5 or C6 level spinal cord injury or the aged who have lower limb impairment are initially considered. The purpose is to encourage them to keep their residual ability or even to improve it by adjusting the assistive ower. A prototype has been developed and tested on experimental basis. The prototype has one DC servo motor(120W)and the output torque is transmitted to rear wheels through a differential gear, Oldam's shaft couplings and electromagnetic clutches. Applying voltage to the clutches turns the land-driven wheelchair into a powered wheelchair. The control system is utilizing an 8 bit single chip microcomputer and rotation angle sensors. Velocity feedback control is installed in the oftware. In addition to performance tests following the JIS test procedures, 11subjects, hand-driven wheelchair users tried the prototype and found its operation easy and that it is helpful when ascending or descending a slope.