Effect of nonlinear distortions in frequency doublers on angle-measurement errors

1977 ◽  
Vol 20 (3) ◽  
pp. 366-368
Author(s):  
B. N. Ivanov ◽  
Yu. S. Ivanov
Keyword(s):  
Measurement Errors ◽  
Angle Measurement ◽  
Frequency Doublers ◽  
Nonlinear Distortions

scholarly journals Gravity-Based Characterization of Three-Axis Accelerometers in Terms of Intrinsic Accelerometer Parameters

2017 ◽  
Vol 122 ◽  
Author(s):  
Jon Geist ◽  
Muhammad Yaqub Afridi ◽  
Craig D. McGray ◽  
Michael Gaitan
Keyword(s):  
Gravitational Field ◽  
Coordinate System ◽  
Measurement Errors ◽  
Angle Measurement ◽  
Sensitivity Matrix ◽  
Cross Sensitivity ◽  
Measurement Capability ◽  
Intrinsic Parameters ◽  
The Cross ◽  
Alignment Errors

Cross-sensitivity matrices are used to translate the response of three-axis accelerometers into components of acceleration along the axes of a specified coordinate system. For inertial three-axis accelerometers, this coordinate system is often defined by the axes of a gimbal-based instrument that exposes the device to different acceleration inputs as the gimbal is rotated in the local gravitational field. Therefore, the cross-sensitivity matrix for a given three-axis accelerometer is not unique. Instead, it depends upon the orientation of the device when mounted on the gimbal. We define nine intrinsic parameters of three-axis accelerometers and describe how to measure them directly and how to calculate them from independently determined cross-sensitivity matrices. We propose that comparisons of the intrinsic parameters of three axis accelerometers that were calculated from independently determined cross-sensitivity matrices can be useful for comparisons of the cross-sensitivity-matrix measurement capability of different institutions because the intrinsic parameters will separate the accelerator-gimbal alignment differences among the participating institutions from the purely gimbal-related differences, such as gimbal-axis orthogonality errors, z-axis gravitational-field alignment errors, and angle-setting or angle-measurement errors.

scholarly journals Tibial plateau angle: methods of measurement, value, applicability

2017 ◽  
Vol 73 (9) ◽  
pp. 532-537
Author(s):  
Adam Przeworski ◽  
Joanna Głodek ◽  
Zbigniew Adamiak
Keyword(s):  
Measurement Errors ◽  
Tibial Plateau ◽  
Cruciate Ligament ◽  
Clinical Importance ◽  
Angle Measurement ◽  
Radiographic Examination ◽  
Cranial Cruciate Ligament ◽  
Stifle Joint ◽  
Maximum Tolerance ◽  
Cranial Cruciate Ligament Disease

The tibial plateau angle measurement and its applicability have been reviewed based on the literature. The measurement was made on radiographs of the stifle joint with superimposition of the femoral condyles (with maximum tolerance of 2.0-4.0mm). Due to great variation among dog populations (size, breed), mean tibial plateau angles were found to be between 16.9° and 34°, but an excessive angle was described as >35°. An appropriate measurement of the tibial plateau angle can be made at about 108 days of age. The influence on the magnitude of the measured tibial plateau angle were the limb position during radiographic examination, the measurement technique (with modifications) and the experience level of the observer. Differences in magnitudes of the tibial plateau angles in dogs with and without cranial cruciate ligament rupture were not observed. The tibial plateau angle is commonly used in osteotomy of the tibia and its magnitude in order to select the proper surgical technique. The significance of the tibial plateau angle on the aetiopathogenesis of cranial cruciate ligament disease is questionable. Other measurements of the proximal tibia were attained to determine the risk factor of cranial cruciate ligament insufficiency. Knowledge of the tibial plateau angle and factors influencing measurement errors have great clinical importance.

Analyzing plane-angle measurement errors by means of a dynamoelectric angle-to-time interval converter

1974 ◽  
Vol 17 (1) ◽  
pp. 15-19
Author(s):  
S. A. Kialdunozyants ◽  
V. L. Inosov ◽  
V. I. Pronenko
Keyword(s):  
Measurement Errors ◽  
Angle Measurement ◽  
Time Interval ◽  
Plane Angle

A Simple Goniometer for Use Intraoperatively in Total Knee Arthroplasty

2013 ◽  
Vol 7 (1) ◽  
Author(s):  
W. McGann ◽  
J. Peter ◽  
J. M. Currey ◽  
J. M. Buckley ◽  
K. D. Liddle
Keyword(s):  
Total Knee Arthroplasty ◽  
Measurement Error ◽  
Knee Arthroplasty ◽  
Navigation System ◽  
Measurement Errors ◽  
Computer Assisted Surgery ◽  
Angle Measurement ◽  
Lower Limbs ◽  
Computer Assisted ◽  
Total Knee

Intraoperative range of motion (ROM) assessment can be challenging during total knee arthroplasty (TKA) surgery. As computer assisted surgery is costly and not readily available to many surgeons, we have developed a simple, cost-effective intraoperative device to precisely measure knee flexion and extension. A simple knee goniometer system was constructed consisting of a digital level mounted to a base that rigidly attaches two standard needles. The needles are pushed through the overlying soft tissue of the distal femur. The device is then applied to the proximal tibia, where an angle measurement of the knee is registered. A validation study for this device was conducted on two pairs of intact cadaveric lower limbs at 0 deg, 10 deg, 15 deg, 20 deg, 25 deg, and 30 deg. Two orthopedic surgeons experienced with the system performed three measurements at each angle. Systematic error, defined as the goniometer reading at 0 deg flexion anatomically as determined by the navigation system, ranged from −9.1 deg to 3.0 deg, consistent for each operator on every case. Measurement error, defined as the variability in repeated, fixed angle measurements made with the goniometer, was 1.5 ± 1.0 deg across all surgeons, cases, and prescribed flexion angles. For both surgeons and all imposed flexion angles, measurement errors were below the 4 deg clinical threshold. The simple knee goniometer system generated accurate, repeatable measures of changes in flexion angle intraoperatively with measurement error comparable to errors obtained using the commercial navigation system (1 deg–2 deg). However, the knee goniometer is less complex, less time intensive, and less costly than currently available computer assistive devices. Taken together, our results are very promising for the continued development of this device.

scholarly journals Scanning polarization lidar LOSA-M3: opportunity for research of crystalline particle orientation in the ice clouds

2020 ◽  
Vol 13 (3) ◽  
pp. 1113-1127
Author(s):  
Grigorii P. Kokhanenko ◽  
Yurii S. Balin ◽  
Marina G. Klemasheva ◽  
Sergei V. Nasonov ◽  
Mikhail M. Novoselov ◽  
...  
Keyword(s):  
Tilt Angle ◽  
Measurement Errors ◽  
Polarization State ◽  
Angle Measurement ◽  
Particle Orientation ◽  
Exponential Dependence ◽  
Crystalline Particle ◽  
Ice Cloud ◽  
Horizontal Orientation ◽  
First Results

Abstract. The article describes a scanning polarization lidar, LOSA-M3, developed at the V. E. Zuev Institute of Atmospheric Optics, the Siberian Branch of the Russian Academy of Sciences (IAO SB RAS), as part of the common use center “Atmosphere”. The first results of studying the crystalline particle orientation by means of this lidar are presented herein. The main features of the LOSA-M3 lidar are the following: (1) an automatic scanning device, which allows changing the sensing direction in the upper hemisphere at the speed up to 1.5∘ s−1 with the accuracy of the angle measurement setting of at least 1 arcmin, (2) separation of the polarization components of the received radiation that is carried out directly behind the receiving telescope without installing the elements distorting polarization, such as dichroic mirrors and beam splitters, and (3) continuous alternation of the initial polarization state (linear–circular) from pulse to pulse that makes it possible to evaluate some elements of the scattering matrix. For testing lidar performance several series of measurements of the ice cloud structure in the zenith scan mode were carried out in Tomsk in April–June 2018. The results show that the degree of horizontal orientation of particles can vary significantly in different parts of the cloud. The dependence of signal intensity on the tilt angle reflects the distribution of particle deflection relative to the horizontal plane and is well described by the exponential dependence. The values of the cross-polarized component in most cases show a weak decline of intensity with the angle. However, these variations are smaller than the measurement errors. We can conclude that they are practically independent of the tilt angle. In most cases the scattering intensity at the wavelength of 532 nm has a wider distribution than at 1064 nm.

A new method for absolute calibration of high-sensitivity accelerometers and other graviinertial devices

1994 ◽  
Vol 84 (2) ◽  
pp. 438-443
Author(s):  
Yu. V. Tarbeyev ◽  
Ye. P. Krivtsov ◽  
A. Ye. Sinelnikov ◽  
A. A. Yankovsky
Keyword(s):  
Gravity Field ◽  
Mass Distribution ◽  
Measurement Errors ◽  
High Sensitivity ◽  
Angle Measurement ◽  
Absolute Calibration ◽  
Measuring Instruments ◽  
Gravitational Acceleration ◽  
Measuring Instrument ◽  
Sensing Element

Abstract To investigate the dynamic characteristics of high-sensitivity graviinertial devices (accelerometers, seismometers, and others) it seems advantageous to use for the input signal the gravitational acceleration produced by bodies with a known mass distribution. This eliminates the need for moving the transducer under investigation. Such motion is needed in the inertial acceleration reproduction as well as for inclining a measuring instrument in the Earth's gravity field. Error in measuring the parameters of the transducer motion is determined by the uncertainties of the length- and angle-measuring instruments being used. Particularly, it concerns the angle measurement errors when the gravity field effects have been taken into account. The existing methods for reproducing gravitational acceleration are based on the use of nonuniform fields of simple shape bodies (sphere, cylinder, and the like). These methods require calculation of the corresponding acceleration, taking into account the spatial mass distribution of the instrument sensing element. The commonly employed approximation results in a procedural error of the order of 10% and over. It is proposed to calibrate a measuring instrument using a uniform, flat gravity field of varying direction. The set-up designed to realize this method reproduces varying accelerations over the frequency range 0.01 to 0.3 Hz with amplitude less than 1.3 × 10−7 m/sec2. This enables calibration of seismometers of various types with a higher accuracy.

The Analysis of Turntable Error and Arithmetic Design for North-Finder Based on Rate Biased RLG

2011 ◽  
Vol 383-390 ◽  
pp. 6313-6318 ◽  
Author(s):  
Yan Zhang ◽  
Ju Liang Cao ◽  
Wen Qi Wu ◽  
Guo Chang Hu
Keyword(s):  
Measurement Error ◽  
Measurement Errors ◽  
Ring Laser ◽  
Angle Measurement ◽  
Laser Gyro ◽  
The North ◽  
The Stability

Currently, the continuous rotary north-finder is widely discussed for its outstanding performance. However, few researches on the influence of turntable error to the continuous rotary north-finding algorithm can be found. Turntable errors, such as the stability of rotate speed, the periodic angle measurement error and the discrete angle measurement error, are studied for the north-finder based on rate biased RLG (ring laser gyro). Two north-finding algorithms are designed, which can restrain the influence of angle measurement errors and the stability of rotate speed separately. Finally, simulation and experiments are performed to verify the algorithms.

scholarly journals Scanning Polarization Lidar LOSA-M3: Opportunity for Research of Crystalline Particle Orientation in the Clouds of Upper Layers

2019 ◽  
Author(s):  
Grigorii P. Kokhanenko ◽  
Yurii S. Balin ◽  
Marina G. Klemasheva ◽  
Sergei V. Nasonov ◽  
Mikhail M. Novoselov ◽  
...  
Keyword(s):  
Tilt Angle ◽  
Measurement Errors ◽  
Polarization State ◽  
Angle Measurement ◽  
Particle Orientation ◽  
Exponential Dependence ◽  
Ice Cloud ◽  
Horizontal Orientation ◽  
First Results ◽  
Academy Of Sciences

Abstract. The article describes a scanning polarization lidar LOSA-M3, developed at the Institute of Atmospheric Optics, the Siberian Branch of Russian Academy of Sciences (IAO SB RAS). The first results of studying the crystalline particles orientation by means of this lidar are presented herein. The main features of LOSA-M3 lidar are the following: 1) an automatic scanning device, which allows to change the sounding direction in the upper hemisphere at the speed up to 1.5 degrees per second with the accuracy of angle measurement setting at least 1 arc minute; 2) separation of polarization components of the received radiation is carried out directly behind the receiving telescope, without installing the elements distorting polarization, such as dichroic mirrors and beamsplitters; and 3) continuous alternation of the initial polarization state (linear - circular) from pulse to pulse that makes it possible to evaluate some elements of the scattering matrix. Several series of measurements of the ice cloud structure of the upper layers in the zenith scan mode were carried out in Tomsk in April-October 2018. The results show that the degree of horizontal orientation of particles can vary significantly in different parts of the cloud. The dependence of signal intensity on the tilt angle reflects the distribution of particle deflection relative to the horizontal plane, and is well described by the exponential dependence. The values of cross-polarized component in most cases show a weak decline of intensity with the angle. However, these variations are smaller than the measurement errors. We can conclude that it is practically independent of the tilt angle. In most cases the scattering intensity at the wavelength of 532 nm has a wider distribution than at 1064 nm.

scholarly journals Development and Evaluation of an Adaptive Multi-DOF Finger with Mechanical-Sensor Integrated for Prosthetic Hand

Micromachines ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 33
Author(s):  
Changcheng Wu ◽  
Tianci Song ◽  
Zilong Wu ◽  
Qingqing Cao ◽  
Fei Fei ◽  
...  
Keyword(s):  
Measurement Errors ◽  
Joint Angle ◽  
Angle Measurement ◽  
Human Hand ◽  
Prosthetic Hand ◽  
Finger Joints ◽  
Adaptive Motion ◽  
Distal Interphalangeal ◽  
Measurement Principle ◽  
Mechanical Sensor

To realize the adaptive grasping of objects with diverse shapes and to capture the joint angles of the finger, a multi degree of freedom (DOF) adaptive finger for prosthetic hand is proposed in this paper. The fingers are designed with three joints. The maximum rotation angle of the finger joints is 90°. The angle at which the finger joints bend can be captured. Firstly, the prototype design, forward kinematics and force analysis of phalanges are described in detail. In order to achieve an adaptive motion pattern similar to that of the human hand, this paper investigates the optimization of the torsion spring stiffness coefficient so that the metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, and distal interphalangeal (DIP) joints of the bionic finger meet a motion ratio of approximately 3:3:1. Then, in order to realize the joint angle measurement in the process of grasping an object, the mechanical-sensor integrated finger joint is designed, and the composition, angle measurement principle and measurement circuit are introduced in detail. Finally, joint angle measurement, movement law evaluation and object grasping experiments are performed to verify the validity of the designed finger. The experimental results show that the root-mean-square (RMS) of the DIP, PIP and MCP angle measurement errors are 0.36°, 0.59° and 0.32°, respectively. The designed finger is able to grasp objects with different shapes stably.

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