Measurement Of Rotational Motion Research Articles

Coherent detection of the rotational Doppler effect measurement based on triple Fourier transform.

In recent years, the rotational Doppler effect (RDE) has been widely used in rotational motion measurement. However, the performance of existing detection systems based on the RDE are generally limited by the drastic reduction of signal-to-noise ratio (SNR) due to the influence of atmospheric turbulence, partial obscuration of the vortex beam (VB) during propagation, and misalignment between the optical axis of VB and the rotational axis of the object, which poses a challenge for practical applications. In this paper, we proposed a coherent detection method of the RDE measurement based on triple Fourier transform. First, the weak RDE signal in backscattered light is amplified by using the balanced homodyne detection method, and the amplified signal still retains the same characteristic of severe broadening in the frequency domain as the original signal. Furthermore, we proposed the triple Fourier transform to extract the broadened RDE frequency shift signal after the coherent amplification. The proposed method significantly improves the SNR of RDE measurement and facilitates the accurate extraction of rotational speed, which helps to further improve the RDE detection range and promote its practical application.

Translational and Rotational Motion Measurement of a Spherical Particle in Hydraulic Collecting

Translational and Rotational Motion Measurement of a Spherical Particle in Hydraulic Collecting

Real-time radial tagging for quantification of left ventricular torsion.

To develop a real-time radial tagging MRI for accurate measurement of rotational motion and twist of the left ventricle (LV). A FLASH-based radial tagging sequence with an undersampled radial reading scheme was developed for both single and double-slice imaging in real-time. The Polar Fourier Transform was used for reconstruction to push the undersampling artifacts out of a reduced FOV. The developed technique was used to image five normal subjects during rest, plus one during both exercise and rest conditions. LV rotational motions were estimated for five consecutive cardiac cycles in all cases. The process was validated using a numerical phantom. The real-time measurement of global rotational motion was compared with those measured from a non-real-time exam using linear regression analysis and the Bland-Altman plot. The real-time acquisition was performed successfully with a temporal resolution of 46.2 ms. Image quality was sufficient for the reproducible calculation of rotation at rest and exercise. The feasibility of double-slice acquisition on human was further studied and a real-time twist of the left ventricle was demonstrated. The difference between LV global rotations from real-time and non-real-time approaches was 0.27 degrees. A significant reverse recoiling, induced by exercise, was reproducibly measured by the technique. A real-time radial tagging MRI technique was developed based on the undersampled radial acquisition and Polar Fourier Transform reconstruction, for accurate measuring of the heart rotational motion and twist. The technique was able to extract a meaningful change of diastolic recoiling under stress test conditions during physical activities (cycling).

Reply to “Comment on ‘Dynamic Tilt Correction Using Direct Rotational Motion Measurements’ by Felix Bernauer, Joachim Wassermann, and Heiner Igel” by Vladimir Graizer

Reply to “Comment on ‘Dynamic Tilt Correction Using Direct Rotational Motion Measurements’ by Felix Bernauer, Joachim Wassermann, and Heiner Igel” by Vladimir Graizer

Gyro-Free Inertial Measurement Unit With Unfettered Accelerometer Array Distribution and for the Object With Position Change in Center of Gravity

Previous gyro-free inertial measurement units (GF-IMU) usually suffered from installation errors induced by mutual placements and mutual sensing directions of accelerometers, and underlying mechanism for eliminating the effect of position change in the center of gravity (PCGC) was not presented clearly. This paper reports a GF-IMU compensating for the effect of PCGC and installation errors by using two parallel mounted accelerometers as a group in designing accelerometer array configuration. The underlying kinematics is first developed and indicates that subtraction of accelerations within a group can remove the effect of PCGC. Nine acceleration subtractions from nine independent groups with irrelevant sensing directions and arbitrary installation distances can determine the square of angular velocity and angular acceleration directly, which does not induce installation errors. Then three configurations fitting different requirements are proposed based on three accelerometer placement rules. The motion quantities at the center of gravity (GC) can also be obtained if mutual installation distance among different groups is known. The validity and performance of schemes are finally verified by SimMechanics simulations. The rotational motion measurement scheme proposed in this paper does not need to know mutual placement information of accelerometers as well as the GC position, which greatly simplifies its installation, and make it possible to develop a convenient product for the rotational motion measurement with only accelerometers.

Dynamic Tilt Correction Using Direct Rotational Motion Measurements

AbstractInertial sensors like seismometers or accelerometers are sensitive to tilt motions. In general, from pure acceleration measurements, it is not possible to separate the tilt acceleration from the translational ground acceleration. This can lead to severe misinterpretation of seismograms. Here, we present three different methods that can help solving this problem by correcting translational records for dynamic tilt induced by ground deformation with direct measurements of rotational motions: (1) a simple time-domain method, (2) a frequency-domain method proposed by Crawford and Webb (2000) using a coherence-weighted transfer function between rotation and acceleration, and (3) an adapted frequency-domain method that corrects only those parts of the spectrum with coherence between translational acceleration and rotation angle higher than 0.5. These three methods are discussed in three different experimental settings: (1) a reproducible and precisely known laboratory test using a high-precision tilt table, (2) a synthetic test with a simulated volcanic very-long-period event, and (3) a real data set recorded during the 2018 Mt. Kīlauea caldera collapse. All the three test cases show severe influence of tilt motion on the acceleration measurements. The time-domain method and the adapted frequency-domain method show very similar performance in all three test cases. Those two methods are able to remove the tilt component reliably from the acceleration record.

Anisotropic magnetoresistive sensors for control of additive manufacturing machines

Abstract Magnetic sensors are employed for dimensional measurements by detection of sensor motion relative to a small magnet. This is widely used everywhere in industrial automation, car industry and in many home appliances. The use of magnetic sensors in machines for additive manufacturing improves control and long term reliability by non contact position measurements. Magnetic sensors with linearized characteristic based on the anisotropic magnetoresistance (AMR) effect can replace mechanical switches, while specialized AMR angle sensors are preferred for the measurement of rotational motions. Both are easy to use and can be integrated with help of 3D printed holders at low cost. In this work, appropriate sensors are selected, integrated and discussed regarding magnetic disturbance signals apparent in low-cost 3D printers.

Analysis of forearm rotational motion using biplane fluoroscopic intensity-based 2D–3D matching

Measuring three-dimensional (3D) forearm rotational motion is difficult. We aimed to develop and validate a new method for analyzing 3D forearm rotational motion. We proposed biplane fluoroscopic intensity-based 2D–3D matching, which employs automatic registration processing using the evolutionary optimization strategy. Biplane fluoroscopy was conducted for forearm rotation at 12.5 frames per second along with computed tomography (CT) at one static position. An arm phantom was embedded with eight stainless steel spheres (diameter, 1.5 mm), and forearm rotational motion measurements using the proposed method were compared with those using radiostereometric analysis, which is considered the ground truth. As for the time resolution analysis, we measured radiohumeral joint motion in a patient with posterolateral rotatory instability and compared the 2D–3D matching method with the simulated multiple CT method, which uses CTs at multiple positions and interpolates between the positions. Rotation errors of the radius and ulna between these two methods were 0.31 ± 0.35° and 0.32 ± 0.33°, respectively, translation errors were 0.43 ± 0.35 mm and 0.29 ± 0.25 mm, respectively. Although the 2D–3D method could detect joint dislocation, the multiple CT method could not detect quick motion during joint dislocation. The proposed method enabled high temporal- and spatial-resolution motion analyses with low radiation exposure. Moreover, it enabled the detection of a sudden motion, such as joint dislocation, and may contribute to 3D motion analysis, including joint dislocation, which currently cannot be analyzed using conventional methods.

Visualization Measurement of Rotational Motion of Pistons and Slippers of A Piston Pump (Preliminary Experiment)

Visualization Measurement of Rotational Motion of Pistons and Slippers of A Piston Pump (Preliminary Experiment)

Advances in 6C seismology: Applications of combined translational and rotational motion measurements in global and exploration seismology

Over the past few decades, the potential of collocated measurements of 6C data (3C of translational and 3C of rotational motion) has been demonstrated in global seismology using high-sensitivity, observatory-based ring laser technology. Proposed applications of 6C seismology range from tomographic reconstruction of near-receiver structure to the reduction of nonuniqueness in seismic source inverse problems. Applications to exploration problems have so far been hampered by the lack of appropriate sensors, but several applications have been proposed and demonstrated with array-derived rotational motion estimates. With the recent availability of, for example, fiber-optic-based high-sensitivity rotational motion sensors, widespread applications of 6C techniques to exploration problems are in sight. Potential applications are based on, for example, the fact that the extended set of combined translational and rotational motion observations enables carrying out array-type processing with single-station recordings such as wavefield separation and surface-wave suppression. Furthermore, measuring the rotational component (curl) of the seismic wavefield enables direct isolation of the S-wave constituents and could significantly improve S-wave exploration. Rotational measurements provide estimates of the spatial wavefield gradient at the free surface that allow carrying out analyses such as local slowness estimation and wavefield reconstruction. Furthermore, rotational motion measurements can help to resolve wavefield infidelity introduced by seismic instruments that are not well-coupled to the ground.

Comparison of direct rotational-motion measurements and array-derived rotations during a 3D seismic-exploration campagin - the Rot3D experiment

Comparison of direct rotational-motion measurements and array-derived rotations during a 3D seismic-exploration campagin - the Rot3D experiment

Investigation of the effectiveness of using an experiment to validate experimental substructure models

Experimental-to-analytical substructuring has been investigated as a way to avoid costly tests and analyses on large systems by experimentally characterizing certain subcomponents and then coupling them to an analytical model for the rest of the structure. Unfortunately, substructuring has sometimes proven difficult to implement because the substructuring calculations can be sensitive to modal truncation and experimental noise and often require the measurement of rotational motions at the interface. These issues have led to decreased confidence in substructuring calculations, causing it to remain underutilized in industry. This work proposes performing a small, inexpensive validation test to give confidence or reveal flaws in an experimentally derived model. This is only meaningful if the error in the validation test is characteristic of the error in an application of interest; this work explores this assumption. The validation test is evaluated in two scenarios which represent substructuring realities. The first scenario investigates measurement errors by applying normally distributed noise to a simple beam structure and evaluating how well the validation test compares to the application of interest. The second scenario simulates substructuring of a complicated engine–generator system with a statically indeterminate connection, where the effect of modal truncation is not easy to anticipate.

Examining ambient noise using colocated measurements of rotational and translational motion

In the past decade, a number of studies have reported the observation of rotational motion associated with seismic events. We report a first observation of rotational motion in the microseismic ambient noise band. A striking feature of rotational motion measurements is that the information about the seismic phase velocity and source back azimuth is contained in the amplitude ratio of a point measurement of rotation rate and transverse acceleration. We investigate the possibility of applying this method to ambient noise measured with a ring laser and a broadband seismometer at the Wettzell Geodetic Observatory in Germany. Using data in the secondary microseismic band, we recover local phase velocities as well as the back azimuth of the strongest noise source for two different time periods. In order to confirm these findings, we additionally compare the results with classical array processing techniques of the Grafenberg array located nearby.

Laser Pump Diffracted-X-Ray-Tracking (Laser-Pump DXT) for Single Molecule Measurement of Rotational Motion in Reaction with Photodissociated ATP

Laser-pump diffracted-X-ray-tracking measurement system has been developed using nanosecond pulse laser at the beamline NW14A, Photon Factory Advanced Ring, KEK, Japan. Generally, diffracted X-ray tracking (DXT) has elucidated rotational motions of single protein molecule in real time [1]. In this work, single protein molecule labeled with gold nanocrystals in reaction with ATP molecule was irradiated by wide-energy band X-ray and nanosecond UV laser pulse. The motion of diffraction spots from gold nanocrystals were tracked in real time. The laser pulse produced the ATP molecules from photodissociation of caged-ATP in solution. The real-time rotational motion of single protein molecule reacting with ATP molecule can be observed using laser pump DXT.Pulse laser system (Powelite8000, Continuum Inc., USA) was synchronized with the diffracted X-ray tracking system. We took 90-120 diffraction images, and time resolution of DXT was from 5 μs/frame to 36 ms/frame. The wavelength, pulse width and laser intensity of single nanosecond laser pulse was 355 nm of third harmonic generation of the Nd:YAG laser, 10 ns and 20 mJ/cm2, respectively. This beamline gave the wideband-energy X-ray in the energy range 13-18 keV using an undulator at a repetition rate of 794 kHz. Delay time of laser pulse in DXT measurement was controlled by delay generator. Laser pulse can be irradiated sample in the arbitrary frames. We compared the motion of diffraction spots from gold nanocrystals attached protein molecule before laser irradiation with that after laser irradiation. The dynamical structural change of protein molecule in capturing ATP molecule will be revealed using laser-pump DXT. The rotational motion of Chaperonin in the presence of ATP is demonstrated as a typical example.[1] H. Shimizu, et al., Cell, 132, 67 (2008).

Is there any reality to the reverse Kapandji operation in the treatment of proximal radioulnar synostosis? Biomechanical measurements

The forearm, wrist and elbow joints in addition to the ligamentous system which holds the two bones together make up a combined joint with complex movement. Within this joint framework, injury at any point can result in profound biomechanical changes leading to functional alterations. Such an alteration is the bony bridge between the radius and ulna which is blocking the rotational movements. Surgical treatment can be instead of the resection of the bridge-callus creating a defect on the radius distally to the synostosis. This leads to a “reverse” Sauve–Kapandji situation and to the disintegration of the bony frame of the forearm. The authors examined the stabilizing effect of the ligamentous system which holds the framework together, with emphasis on the role of the interosseous membrane. Measurements of rotational motion in various stages in the forearm were performed on fresh cadaver forearm preparations in both intact cases and also following the excision of a proximal segment of the radius. The movements were measured and registered using an Instron 8874 biomechanical material testing machine. In addition to registration, both fi xed and mobile digital recording was done. The stabilizing role of the interosseous membrane in supination was only effective when the radius was of normal length. The excision of the radial segment seriously damaged both the rotational motion and the stability of the wrist. DOI: 10.17489/biohun/2010/2/05

Performance Test of a Commercial Rotational Motions Sensor

Abstract The application of rotational motion sensors has only recently proven to give new ways of measuring seismic-wave-field properties when comparing the recorded data with seismograms of collocated traditional seismometers. The data in these test cases were produced using either sophisticated and thus expensive ring laser technology or cumbersome seismic array techniques including some restrictive assumption about the wave field. In this article, we want to test the performance of one of the first medium-priced commercial rotational motion sensor (eentec R 1) by comparing its output with the aforementioned classical array-derived rotational motions. The data set consists of seismic array and rotational motion measurements that were performed during a demolition blast of a 50 m high building in the city of Munich (Germany). In addition to the simple comparison of the outputs, we want to classify the performance of the two methods by comparing derived wave-field properties with the result of classical frequency-wavenumber ( f - k ) array analysis. The results of this experiment demonstrate that, when using an array technique for estimating rotational motions, much effort in site selection, array design, and a priori knowledge of subsurface conditions is needed. It also becomes evident that the performance of an array and its estimated quantities strongly depends on the number of deployed seismic stations. Given the uncertainties in both the array-derived measurements and the rotation sensor transfer function, it is difficult to quantify the accuracy of the rotation sensor data, which indicates the need for further extensive laboratory and field testing.

1202 床画像追跡における高精度な回転運動の計測(ロボティクス・メカトロニクスV)

1202 床画像追跡における高精度な回転運動の計測(ロボティクス・メカトロニクスV)

Sagittal plane segmental motion of the cervical spine. A new precision measurement protocol and normal motion data of healthy adults

Objective. (1) Precise documentation of sagittal plane segmental rotational and posteroanterior translational motion of segments C0/C1–C6/C7 of the human cervical spine from lateral radiographic views. (2) Compilation of a database describing normal motion. (3) Comparison of individual motion patterns with the normal database. Design. Descriptive study based on computer-aided measurements from lateral radiographic views taken in flexion and extension. Background. Previous studies concentrated on segmental rotational motion of the cervical spine. Normal data for translational motion were not available. Description of cervical spine motion patterns thus remained incomplete. Methods. Based on computer-aided measurements from lateral radiographic views taken in flexion and extension, a new protocol determines rotational and translational motion for all segments (C0/C1–C6/C7) imaged on the radiographic views. Measured results are corrected for radiographic magnification and variation in stature; they are virtually uninfluenced by radiographic distortion and patient alignment errors. A database describing normal motion was compiled from 137 sets of lateral views of healthy adults taken in active flexion and extension. A specimen study as well as inter- and intra-observer studies quantify measurement errors. Results. The error study demonstrated the error (SD) of a rotational motion measurement to amount to slightly less than 2°. The error (SD) of a translational motion measurement amounts to less than 5% of vertebral depth; for a vertebra of 15 mm depth this corresponds to 0.7 mm. A normal database for rotational and translational motion was compiled. There was a linear relation between rotational and translational motion. This finding agrees qualitatively with results from previous studies; quantitative comparisons are not possible due to divergent definitions for translational motion. The relation between rotation and translation can be employed in individual cases to predict translational motion, in dependence on the rotation actually performed. A comparison of the rotational motion with the normal database and the difference between predicted and actual translational motion allow segmental hypo-, normal or hypermobility to be quantified. Conclusions. The new protocol measures segmental motion with high precision and corrects for radiographic distortion, variation in stature and alignment errors of patients. Thus, archive studies using existing radiographs are feasible. Relevance Flexion–extension radiographs of the cervical spine are performed to explore potential damage to the bony or ligamentous structure resulting in abnormal, segmental motion patterns. Determining rotational motion gives only an incomplete picture. The new protocol allows for precise quantification of translational motion and classification of segments as hypo- or hypermobile by comparison with normal motion data.

Molecular mobility in the cytoplasm of lettuce radicles correlates with longevity

AbstractMolecular mobility is hypothesised to be a key factor influencing storage stability of seeds because it may control the rate of deteriorative reactions responsible for reduced shelf life. The relationship between the longevity of lettuce seeds and the molecular mobility was investigated in the cytoplasm of lettuce radicles. Longevity of lettuce seeds was predicted using the viability equation of Ellis and Roberts, and the molecular mobility was determined by saturation transfer electron paramagnetic resonance spectroscopy measurements of rotational motion of a polar spin probe inserted into the cytoplasm. Increasing the temperature resulted in faster rotational motion and shorter longevity. There was a linear relationship between the logarithms of rotational motion and estimated seed longevity for temperatures above 5°C. Below 5°C, there was a deviation from linearity. Based on the hypothesis that the molecular mobility in the cytoplasm determines the rate of detrimental reactions, seed longevity at sub-zero temperatures was predicted by extrapolation of the rotational motion using the linear relationship. Predictions of longevity at sub-zero temperatures based on rotational motion indicated longer survival times than those based on the viability equation. A kinetic approach to ageing using molecular mobility measurements is expected to improve our understanding of seed storage stability and might eventually lead to realistic predictions of longevity at low temperatures.

加速度センサとジャイロセンサを用いた屈曲動作計測

加速度センサとジャイロセンサを用いた屈曲動作計測