Rotation Angle Measurement Research Articles

Study of Three-Component FBG Vibration Sensor for Simultaneous Measurement of Vibration, Temperature, and Verticality

To achieve simultaneous measurement of measurand vibration, temperature, and verticality, a three-component fiber Brag grating (TVFBG) vibration sensor is proposed in this paper. Polymer and metal diaphragm sensitization methods are utilized to improve this sensor measurement sensitivity. Project matrix theory is adopted to analyze this sensor. Theoretically,9×9nonsingular measuring coefficient matrix of this TVFBG sensor made up by three3×3measurand coefficient matrixes is established. In order to effectively extract measurand, Hilbert-Huang transform (HHT) is accepted to process this sensor’s center wavelength signals. Calibration experiments are carried out to verify the performance of this TVFBG sensor. Experiment data confirm that this sensor has excellent frequency response and show good linearity at temperature and verticality measurement. Wrist rotation angle measurement experiment is also implemented to further identify this sensor practical value. Through analyzing by HHT, experiment results show that the angle measurement sensitivities of three fiber Brag gratings which are included in this sensor are separately 25.2 pm/°, 38.2 pm/°, and 38.3 pm/°.

An Improved Experimental Technique to Characterize Micro-Diameter Copper Wires in Torsion

The experimental technique was improved with direct measurement of small torque and rotation angle to characterize micro-diameter copper wires in torsion. This method allows precise measurement of torque applied to micro-diameter wires as low as 10−8 N · m with reasonably high resolution. The rotation angle is also able to be directly measured such that the shear strain rate on the wire surface can be easily controlled. This experimental design removes the misalignment issue that has affected previous efforts in micro-diameter wire torsion testing. Using this technique, the copper wires with four different diameters (12, 16, 20, and 30 μm) were characterized in torsion. The normalized torque-rotation results showed insignificant size effects for the copper wires investigated in this study.

Design and Research of Rotational Inverted Pendulum Control System

The work is designed and made as a controlled system of rotational inverted pendulum. Small direct current machine is droved by Single chip microcomputer that it controls the angle of swinging of swinging rod when the rotating arm does reciprocating rotation motion. The MC9S12CXS128 single-chip microcomputer is adopted as the master control chip of control system, the Angle of swinging rod is measured by the incremental encoder, power of the rotary arm controlled part provided by PM35S - 048 direct current machine and the motor drive module as a control system. It can realize measurement and control of the rotation angle of the rotating arm and the swinging angle of swinging rod precisely.

High-precision rotation angle measurement method based on monocular vision.

To accurately measure the attitude angles (pitch, roll, and yaw) of a rigid object that rotates in a space, we propose a high-precision rotation angle measurement method based on monocular vision. This method combines camera self-calibration, multiview geometry, and 3D measurement. This monocular vision measuring system consists of an area scan CCD, a prime lens, and a spots array target, which are fixed on the measured object. We can calculate the rotation angle according to the rebuilt rotating spots array target by using this monocular vision measuring system. The measurement precision of rotation angle can reach 1 arc sec in this paper's experiments. This method has high measurement precision and good stability. Therefore we can widely use this method in machinery manufacturing, engineering measurement, aerospace, and the military.

Soft Matter and Optical Vortices: A Good Match for New Science and Technology

The interaction of soft materials with optical vortices can give rise to exciting new science and technology. In this paper, I will review a few recent examples of research based on such combination. In particular, I will consider the recently demonstrated applications of the liquid crystal “q-plates” to quantum communication without the need to align the reference frames of the communicating parties and to ultra-sensitive measurement of rotation angles, the latter by the new device concept dubbed “photonic gears”. Moreover, I will discuss the observation of nanometric spiral-shaped structures generated by vortex light on the surface of azopolymers.

Intra- and Interobserver Reliability of the Cobb Angle–Vertebral Rotation Angle–Spinous Process Angle for Adolescent Idiopathic Scoliosis

Study DesignA reliability analysis of Cobb angle, vertebral rotation (VR), and spinous process angle (SPA) measurements in adolescent idiopathic scoliosis. ObjectiveTo determine the intra- and interobserver reliability of semi-automated digital radiograph measurements. Summary of Background DataCobb angle measurements on posteroanterior radiographs are commonly used to determine the severity of scoliosis. Vertebral rotation helps assess scoliosis 3-dimensionally and has a role in predicting curve progression. Recent studies have shown that the spinous process angle is a useful parameter in assessing scoliosis when using ultrasound imaging. Because the reliability of SPA measurements on radiographs has yet to be determined, it is important to compare the reliability of these 3 parameters (Cobb angle, VR, and SPA) using a computer assisted semi-automated method. MethodsSixty posteroanterior radiographs of patients with adolescent idiopathic scoliosis were obtained and measured twice by 3 observers who were blinded to their previous measurements, using an in-house developed program. Measurements were obtained using a semi-automated method to minimize variability resulting from observer reliability. The intra- and interobserver reliabilities were analyzed using intra-class correlation coefficients (ICCs) as well as Bland–Altman's bias and limits of agreement. ResultsOver 350 (intra) and 90 (inter) sets of curves with an average Cobb angle of 26° ± 9° (range, 10° to 44°) were compared for each parameter. Intra-observer reliabilities for each parameter were excellent (ICC[2,1], .82; 1.00), with mean absolute differences under 3° between most measurements. Interobserver reliability (ICC[2,1], .72; .95) was mostly good to excellent, with mean absolute differences ranging from 2.0° to 5.6°. ConclusionsBoth the intra- and interobserver assessment of the Cobb, VR, and SPA from the semi-automated measurements had clinically acceptable reliability ranges and may be considered for clinical implementation. Additional studies will be conducted to determine the accuracy and sensitivity to change of these scoliosis severity measurements.

Optical Fibre Angle Sensor Used in MEMS

There is a need for displacement and angle measurements in many movable MEMS structures. The use of fibre optical sensors helps to measure micrometre displacements and small rotation angles. Advantages of this type of transducers are their simple design, high precision of processing, low costs and ability of a non-contact measurement. The study shows an analysis of a fibre-optic intensity sensor used for MEMS movable structure rotation angle measurement. An intensity of the light in the photodetector is basically dependent on a distance between a reflecting surface and a head surface of the fibre transmitting arm, and the deflection angle. Experimental tests were made for PMMA 980/1000 plastic fibres, ΘNA=33°. The study shows both analytical and practical results. It proves that calculated and experimental characteristics for the analysed transducers are similar.

Quantifying the Resolution of Single-Molecule Torque Measurements by Allan Variance

Single-molecule manipulation techniques have provided unprecedented insights into the structure, function, interactions, and mechanical properties of biological macromolecules. While many single-molecule manipulation techniques naturally operate in the space of (linear) extension and force, recently a number of techniques have been developed that enable measurements of rotation angle and torque. Examples include the rotor bead tracking assay, the optical torque wrench (OTW), and magnetic torque tweezers (MTT). While systematic analyses of the position and force resolution of single-molecule techniques have attracted considerable attention (see e.g. [1,2]), detailed analysis of the angle and torque resolution is currently lacking.Here, we propose Allan variance as a criterion to systematically quantitate the angle and torque resolution in single-molecule measurements. We apply the Allan variance method to experimental data from our implementations of MTT [3,4,5] and an OTW [6]. Both magnetic and optical torque tweezers can achieve a torque resolution of better or equal to 1 pN⋅nm. We find that our state-of-the-art OTW outperforms MTT for short measurement times. However, for measurement times > 10 s, drift becomes a limiting factor in the OTW and the superior stability of MTT accomplishes higher ultimate torque resolution for long measurement times.In summary, our Allan variance criterion enables to critically assess the torque resolution as a function of measurement time and across different measurement modalities that rely on distinct physical principles. In addition, the Allan variance method provides a tool to optimize the measurement protocol for a given instrument and system.[1] Czerwinski, et al., Opt. Express (2009).[2] Lansdorp & Saleh, Rev. Sci. Instrum. (2012).[3] Lipfert, et al., Nature Methods (2010).[4] Lipfert, Wiggin, et al., Nature Communications (2011).[5] Janssen, Lipfert, et al., Nano Letters (2012).[6] Pedaci, et al. Nature Physics (2010).

非接触式扫描反射镜转角测量系统

A non-contact rotation angle measurement system based on a line laser, and a linear array CCD was established to extent the angle measuring scope of a scanning mirror. The structure and measurement principle of the measurement system were introduced. It calculates the rotational angle of the scanning mirror by the position of the laser spot on the linear CCD and extents the measuring scope by array mirrors with special design. To reduce the alignment requirements, the error was analyzed and a calibration measurement method with polynomial fitting was verified. A series of error sources that affect the measurement accuracy were analyzed and the total errors of the measurement system were calculated. Finally, the related measurement experiment was performed. Experimental results indicate that the measurement system can offer a resolution of 2.5, angular measurement range of 11 , and the precision of angular measurement is up to 3. Obtained results can satisfy the system requirements for non-contact, higher precision and wider measurement ranges.

Reliability and Validity of Measurement Using Smartphone-Based Goniometer of Tibial External Rotation Angle in Standing Knee Flexion

The purpose of this study was to assess the intra-rater test-retest reliability of tibial external rotation angle measurement using a smartphone-based photographic goniometer, DrGoniometer (DrG) compared to a three-dimensional motion analysis system (Vicon). The current study showed an interchangeable method using DrG to measure the tibial external rotation angle in standing knee flexion at <TEX>$90^{\circ}$</TEX>. Twelve healthy subjects participated in this study. A rest session was conducted 30 minutes later for within-day reliability and five days later for between-day intra-rater test-retest reliability. To assess the validity of the measurement using DrG, we used a three dimensional motion analysis system as a gold standard to measure the angle of tibial external rotation. Intra-class correlation coefficient (ICC) and the standard error of measurement (SEM) values were used to determine the within- and between- day intra-rater test-retest reliability of using DrG and a three dimensional motion analysis system. To assess validity, Pearson correlation coefficients were used for two measurement techniques. The measurement for tibial external rotation had high intra-rater test-retest reliability of within-day (ICC=.88) and between-day (ICC=.83) reliability using DrG and of within-day (ICC=.93) and between-day (ICC=.77) reliability using a three-dimentional motion analysis system. Tibial external rotation angle measurement using DrG was highly correlated with those of the three-dimensional motion analysis system (r=.86). These results represented that the tibial external rotation angle measurement using DrG showed acceptable reliability and validity compared with the use of three-dimensional motion analysis system.

Measurement of Rotation Angle about Rotating Object Based on Digital Image

One measurement of rotation angle about rotating object was proposed, it can realize precise and non-contact measurement. This measurement was executed as follow: firstly, select one image that it has abundant information, and the object which need rotation was pasted by this image. Secondly, when this object is begin to rotation, use CCD to collect the external images of the object before and after rotation respectively. Lastly, convert these two collected images from Descartes coordinate to polar coordinate, then calculate these two images in polar coordinate with phase correlation. The rotated angle was found by these steps. The result of this measurement experiment shows that this method can measure the rotated angle correctly. So this measurement method is worth to research and apply according to the theory and the experiment.

Comparison of three methods for calculating the Bath Ankylosing Spondylitis Metrology Index in a randomized placebo‐controlled study

To compare 3 methods for calculating the Bath Ankylosing Spondylitis Metrology Index (BASMI) score using patients who participated in the GO-RAISE study. Patients with active ankylosing spondylitis (AS) were randomly assigned in a 1:1.8:1.8 ratio to receive subcutaneous injections of placebo, golimumab 50 mg, or golimumab 100 mg every 4 weeks. Lumbar flexion, tragus-to-wall distance, lumbar side flexion, intermalleolar distance, and cervical rotation angle measurements at baseline, week 14, and week 24 were used to calculate the BASMI 2-step (BASMI(2) ), 10-step (BASMI(10) ), and linear (BASMI(lin) ) scores. BASMI(2) scores were generally lower than BASMI(10) and BASMI(lin) scores, which were nearly identical. Median changes from baseline to week 14 in the combined golimumab group were similar to those in the placebo group when using the BASMI(2) calculation method (0.00 versus 0.00; P = 0.288). The combined golimumab group showed significantly greater improvement from baseline to week 14 than the placebo group when using the BASMI(10) (-0.20 versus 0.00; P = 0.018) and BASMI(lin) (-0.31 versus -0.07; P = 0.015) calculation methods, with the latter showing the greatest difference between golimumab and placebo. Guyatt's effect size was better for the BASMI(lin) and the BASMI(10) versus the BASMI(2) in the combined golimumab group at week 14 (0.58 and 0.53 versus 0.42, respectively) and week 24 (0.76 and 0.69 versus 0.61, respectively), despite the relatively short period to assess changes in spinal mobility. The BASMI(lin) method was the most sensitive to changes in range of motion exhibited by patients with AS who received golimumab.

The measurement of Faraday rotation angle by the frequency spectrum analysis

A novel method for measuring Faraday rotation angle by the frequency spectrum analysis is presented in this paper. The theoretical analysis and the experimental results demonstrate that Faraday rotation angle can be determined by the amplitude ratio of the signal's fundamental frequency to double frequency. A solenoid working on different voltages is used to produce different magnetic fields. The Faraday rotation angles in these magnetic fields have been measured. The linear fitting degree of the voltage and Faraday rotation angle is better than 99%.

A Vision-Based Dynamic Rotational Angle Measurement System for Large Civil Structures

In this paper, we propose a vision-based rotational angle measurement system for large-scale civil structures. Despite the fact that during the last decade several rotation angle measurement systems were introduced, they however often required complex and expensive equipment. Therefore, alternative effective solutions with high resolution are in great demand. The proposed system consists of commercial PCs, commercial camcorders, low-cost frame grabbers, and a wireless LAN router. The calculation of rotation angle is obtained by using image processing techniques with pre-measured calibration parameters. Several laboratory tests were conducted to verify the performance of the proposed system. Compared with the commercial rotation angle measurement, the results of the system showed very good agreement with an error of less than 1.0% in all test cases. Furthermore, several tests were conducted on the five-story modal testing tower with a hybrid mass damper to experimentally verify the feasibility of the proposed system.

Rotation angle measurement based on white-light interferometry with a standard optical flat

We propose a simple white-light interferometric method of measuring a one-dimensional rotation angle with use of an optical plane parallel plate of standard refractive index. The phase change of the interference pattern of the interferometer during the rotation of the flat plate of known refractive index and thickness placed in one of the interferometer's arms is used for determination of the rotation angle. This method has been demonstrated for an accurate angle measurement over the angle range from 0° to 40° within a maximum uncertainty of 0.057°.

Progress in development of two color laser diagnostics for the ITER poloidal polarimeter

Two color laser diagnostics using THz laser sources are under development for a high performance operation of the Large Helical Device and for future fusion devices such as ITER. So far, we have achieved high power laser oscillation lines simultaneously oscillating at 57.2 μm (1.6 W) and 47.7 μm (0.8 W) by using a twin optically-pumped CH3OD laser. And, we confirmed the usefulness of this two color laser operation for two-color laser interferometry in a test stand. For the measurement of the Faraday rotation angle we have developed a photo-elastic modulator (PEM) operating around 50 μm, and performed bench tests of the polarimeter with dual PEMs and demonstrated the feasibility of the polarimeter. The achieved angular resolution is 0.01 degrees with a time resolution of 1 ms, which satisfies diagnostic requirements for q-profile measurements on ITER (0.05 deg. at 10 ms time resolution). In this symposium, recent hardware developments and simultaneous measurements of a phase shift and a rotation angle will be presented.

Faraday Rotation Angle Measurement Based on Conoscopic Interference Pattern in Optical Current Transducer

A new method of measuring the Faraday rotation angle directly in optical current transducer (OCT) is proposed based on conoscopic interference pattern. The concept of conoscopic interference and isogyres is illustrated. The relationship between the isogyres angle Φ and the polarized plane rotation angle θcaused by the polarizer rotation is deduced to 2 θ= Φ. This rule can be used to measure the Faraday rotation angle in OCT according to the Faraday magneto-optic effect when a linear polarized light beam passing through a crystal and current magnetic field acting on it at the same time, the polarized plane will be rotated and the angle of isogyre will be changed. An experiment is designed to demonstrate the relationship between the coil current and the isogyre angle. CCD camera are used to capture the conoscopic interference pattern to measure the current of coils, the angle of isogyre is calculated by image processing technology. The measuring range is 18 times of traditional OCT. This experiment proves the relationship between the isogyres angle Φ and the polarized plane rotation angle θ, and the linear relationship between the current and the isogyre angle is realized.

Nanomanufacturing of radial grating patterns by nanoimprint with a silicon mould for rotational angle measurement of micro gears

Micro gear is one of interesting micro machine elements for micro mechanisms in the next generation. In order to measure the rotational motions of meshing micro gears, a grating disk of a micro rotary encoder should be developed. For measurement of rotational accuracy of micro gears, it is necessary to utilise a pair of micro rotary encoders whose diameters are smaller than the reference diameter of micro gears to be measured to avoid the interference between the encoder and the rotational shaft. The focus of this article is to develop and manufacture radial grating patterns for such grating disks of micro rotary encoders. The designed grating disk has a diameter less than 1 mm and the number of gratings is up to 10,000, whose inner half pitch is corresponding to about 50 nm. It was manufactured with nanoimprint technique with a silicon master mould which is developed by EB writer and lithography technique. The radial grating patterns were successfully achieved homogeneously. The accuracy of the pitch and the line width are investigated and height of line and space is measured by AFM. It is found that it is possible to realise grating disks of a micro rotary encoder.

경추 및 흉추부 스트레칭 운동과 근력강화 운동프로그램이 머리전방자세에 미치는 효과

본 연구는 경추 및 흉추부 스트레칭과 근력강화 운동프로그램이 머리전방자세에 미치는 효과를 알아보고자 연구하였다. 머리전방자세를 갖고 있는 일반인 32명을 대상자로 자세교육과 운동프로그램을 적용한 실험군 16명과 자세교육만을 받은 대조군 16명을 대상으로 시행하였다. 두 개척추각(CVA:Craniovertebral Angle)과 두개회전각(CRA:Cranial Rotation Angle)을 X-ray로 검사하고, PACS(Picture Archiving and Communications System) <TEX>${\pi}view^{TM}$</TEX> 각도를 측정하였다. 연구결과 실험군은 두개척추각과 두개회전각이 통계적으로 유의한 차이가 있었다. 그러나 대조군은 두개회전각에서만 유의한 차이가 있었다. 또한, 실험 전 그룹 간 차이는 없었으나 실험 후 그룹 간 비교에서는 통계적으로 유의한 차이가 있었다. 이 연구에서는 경, 흉추부 스트레칭 및 근력강화 운동프로그램이 연구대상자들의 머리전방자세를 감소시키는 척추자세정렬을 향상시킬 수 있었다. 이 연구 결과들은 자세증진 치료들에 있어서 향후 발전되는 운동프로 그램을 위해 기초자료가 될 수 있다. This study was to find out the effect of cervical and thoracic stretching and strengthening exercise program on forward head posture. 32 adults had forward head posture were selected as the subjects for the study. The training program of the exercise group(n=16) consist of postural education with exercise program, subjects in the control group(n=16) participated in a postural education only. Postural measurements of Craniovertebral Angle(CVA) and Cranial Rotation Angle(CRA) were obtained from the using x-ray and PACS(Picture Archiving and Communications System) <TEX>${\pi}view^{TM}$</TEX>. The results were compared with change of CVA and CRA exercise group were significant(p<.05) compared to the control group. However CRA of contol group was significant(P<.05). Also, there were no significant difference(p>.05) between groups on any pre-test measure. however there were significant difference(p<.05) between groups on CVA and CRA post-test measure. This study showed that cervical and thoracic stretching and strengthening exercise program can improve spinal posture alignment for decreasing forward head posture in subjects. These results can be fundamental data for further development of exercise program in interventions of postural improvement.

Evaluation of external rotation angle of the knee using an external rotation measuring-scale

ObjectiveTo report a novel measurement of external rotation angles of the knee with our self-designed external rotation measuring-scale in comparison of the dial test.MethodsBetween November 2009 and May 2010, 20 patients with injury to the posterolateral corner (PLC) of the knee were diagnosed and treated at our department. They were 15 men and 5 women, aged from 20 to 41 years (average,32. 9 years) . Their PLC injuries were diagnosed on the basis of case history, physical examination, stress X-ray and MRI. The interval between injury to surgery averaged 309 days (from 7 days to 10 years) . Their external rotation angles of the knee were measured by both the dial test and our self-designed external rotation measuring-scale to compare the 2 methods in terms of accuracy, time consumed, and operators needed. ResultsThere was no significant difference between the mean side-to-side difference by the external rotation measuring-scale (8.6° ± 6. 6°) and that by the dial test (8.2° ± 7.7°) ( t =0. 940, P =0. 370) . But the coefficient of variation by our external rotation measuring-scale (0. 77) was smaller than that by the dial test (0. 94) . The time consumed and operators needed by our external rotation measuring-scale (26. 1 ± 3.9 seconds and 2 persons) were significantly less than those by the dial test (131.9 ± 12. 7 seconds and 3 persons) ( t =- 69. 393, P ＜ 0. 001 ).ConclusionIn measurement of external rotation angles of the knee,our self-designed external rotation measuring-scale can be as accurate as the dial test, but better than the latter in coefficient of variation, time and manpower needed. Key words: Knee joint; Rotation; Wounds and injuries; Exercise test