Self-Calibration of Cameras using Affine Correspondences and Known Relative Rotation Angle

2021 ◽  
Author(s):  
Yingjian Yu ◽  
Guan Banglei ◽  
xiangyi sun ◽  
Zhang Li
Keyword(s):  
Rotation Angle ◽  
Relative Rotation ◽  
Self Calibration

Three Kinds of Gear Transmission Nonlinear Dynamics Models

2013 ◽  
Vol 787 ◽  
pp. 765-770
Author(s):  
Li Juan Wu ◽  
Jin Yuan Tang ◽  
Si Yu Chen
Keyword(s):  
Nonlinear Dynamics ◽  
Numerical Simulation ◽  
Time Domain ◽  
Rotation Angle ◽  
Dynamic Responses ◽  
Relative Rotation ◽  
Dissipation Energy ◽  
Motion Equations ◽  
Low Speed ◽  
Dynamics Models

Based on the Lagranges equations, a new nonlinear dynamic gear model is established by introducing two variables of relative rotation angleand mean rotation angle. The motion equations derived with Lagranges equation exhibit nonlinear terms which are absent in the equations derived on Newtons equations. Combining with the numerical simulation, the dynamic responses in time domain and frequency domain are deduced, and it can be concluded that the responses at low speed of three different models are different. However, they are similar at the designed speed without the consideration of dissipation energy. On the contrary, the dynamic responses are similar at low speed and the simplified Newtons equation differs at the designed speed including dissipation energy.

A New Tightening Technique for Threaded Fasteners

1994 ◽  
Vol 116 (2) ◽  
pp. 64-69 ◽  
Author(s):  
M. Hagiwara ◽  
N. Ohashi
Keyword(s):  
Rotation Angle ◽  
High Accuracy ◽  
Experimental Results ◽  
New Technique ◽  
Relative Rotation ◽  
Threaded Fasteners ◽  
Accuracy And Precision ◽  
Different Types ◽  
A New Technique

A new technique for tightening threaded fasteners was proposed aiming to assure the quality and the reliability in the tightening operations. The technique is based on the torque difference and the relative rotation angle in tightening and loosening process, and no preliminary experiment is required. Repeated tightening (and loosening) experiments were performed for different types of lubricant to verify the applicability of this technique. Experimental results show that the preload provided to the joint can be estimated with high accuracy and precision by this technique, and the possibility to boost the reliability of tightening control is confirmed.

Lateral Equivalent Flexural Rigidity for a Top-Hat Stiffened Composite Plate under Pure Bending

2014 ◽  
Vol 1065-1069 ◽  
pp. 1079-1082
Author(s):  
Li Bao Zhu ◽  
Xiang Ming Zhang
Keyword(s):  
Finite Elements ◽  
Analytical Solution ◽  
Analytical Method ◽  
Composite Plate ◽  
Rotation Angle ◽  
Flexural Rigidity ◽  
Analytical Calculation ◽  
Finite Elements Method ◽  
Relative Rotation ◽  
Pure Bending

This paper is concerned with the analytical solution to lateral equivalent flexural rigidity for fiber-reinforced top-hat stiffened composite plate subjected to pure bending. The plate is divided into three parts consist of single-laminate, double-laminate and hat-laminate. After computing equivalent flexural rigidity of the three parts respectively, the overall rigidity is calculated based on the equality of relative rotation angle. An example has been adopted for analytical calculation and then been modeled by finite elements method. A comparison was made to verify the validity of analytical method.

scholarly journals Can relative rotation angle serve as a sensitive predictor for the development of adjacent segment degeneration after single-segment PLIF?

2020 ◽  
Author(s):  
Xiao Liu ◽  
Haonan Liu ◽  
Xiaosong Yang ◽  
Zhongjun Liu ◽  
xiaoguang liu ◽  
...  
Keyword(s):  
Rotation Angle ◽  
Lumbar Fusion ◽  
Measurement Data ◽  
Adjacent Segment Degeneration ◽  
Adjacent Segment ◽  
Relative Rotation ◽  
Significant Difference ◽  
Flexion Extension ◽  
Adjacent Segments ◽  
Adjacent Vertebra

Abstract Background: Adjacent segment degeneration (ASD) is a major issue after posterior lumbar interbody fusion (PLIF). Several studies have reported the potential causes of ASD based on radiography. However, the postoperative dynamic changes in the adjacent segments are not clear. This study aimed to determine the effect of PLIF on ASD using a formetric 4D system and to compare the effectiveness of this system with that of traditional radiography for the prediction of ASD. Methods: Eighty-five consecutive patients who underwent PLIF of a single-segmen t were included. The formetric 4Dsystem was used to calculate the relative rotation angle between the fusion segment and the upper and lower adjacent vertebrae preoperatively and at 6, 12 and 24 months postoperatively. The range of motion (ROM) and disc height (DH) of the adjacent segments were measured using radiography preoperatively and at 24 months postoperatively. At the final follow-up, the visual analogue scale (VAS) and Oswestry disability index (ODI) were used to evaluate the surgical outcome. The patients were divided into two groups according to the occurrence of radiographic ASD: the ASD group with progression of degeneration and the N-ASD group without progression of degeneration. The clinical outcomes and measurement data between the two groups were compared and analyzed. Results: The index fusion segments included L2-3 to L5-S1. Preoperatively, the relative rotation angles between the fused segment and the upper and lower adjacent vertebrae were 5.1°±2.2°and 3.3°±2.0°,respectively, and both angles increased significantly at all time-points after surgery ( p <0.05). The angles changed most significantly during L2-3 fusion . Radiographic ASD was noted in 13 of 85 patients (15.3%) at 24 months. There was no significant difference in the DH, ROM, or clinical outcome between the two groups ( p >0.05), while the relative rotation angle with the upper adjacent vertebra was greater in the ASD group than in the N-ASD group ( p <0.05). Conclusion: The relative rotation angle with the adjacent vertebra increased significantly after lumbar fusion surgery. It may be a more sensitive predictor for the development ofradiographic ASD than flexion-extension ROM and DH.

scholarly journals Study of the Error Caused by Camera Movement for the Stereo-Vision System

2021 ◽  
Vol 11 (20) ◽  
pp. 9384
Author(s):  
Yan Liu ◽  
Zhendong Ge ◽  
Yingtao Yuan ◽  
Xin Su ◽  
Xiang Guo ◽  
...  
Keyword(s):  
Stereo Vision ◽  
Measurement Accuracy ◽  
Rotation Angle ◽  
Vision System ◽  
Distance Measurement ◽  
3D Measurement ◽  
Relative Rotation ◽  
Distance Error ◽  
Stereo Vision System ◽  
Coordinate Error

The stereo-vision system plays an increasingly important role in various fields of research and applications. However, inevitable slight movements of cameras under harsh working conditions can significantly influence the 3D measurement accuracy. This paper focuses on the effect of camera movements on the stereo-vision 3D measurement. The camera movements are divided into four categories, viz., identical translations and rotations, relative translation and rotation. The error models of 3D coordinate and distance measurement are established. Experiments were performed to validate the mathematical models. The results show that the 3D coordinate error caused by identical translations increases linearly with the change in the positions of both cameras, but the distance measurement is not affected. For identical rotations, the 3D coordinate error introduced only in the rotating plane is proportional to the rotation angle within 10° while the distance error is zero. For relative translation, both coordinate and distance errors keep linearly increasing with the change in the relative positions. For relative rotation, the relationship between 3D coordinate error and rotation angle can be described as the nonlinear trend similar to a sine-cosine curve. The impact of the relative rotation angle on distance measurement accuracy does not increase monotonically. The relative rotation is the main factor compared to other cases. Even for the occurrence of a rotation angle of 10°, the resultant maximum coordinate error is up to 2000 mm, and the distance error reaches 220%. The results presented are recommended as practice guidelines to reduce the measurement errors.

scholarly journals Mathematical Simulation of the Movement of a Machine Unit of a Saw Cylinder with Distributed Parameters

2020 ◽  
Vol 8 (6) ◽  
pp. 5520-5525
Keyword(s):  
Mathematical Simulation ◽  
Dynamic Characteristics ◽  
Rotation Angle ◽  
Relative Rotation ◽  
Distributed Parameters

Dynamic characteristics of a saw gin are considered as the subsystems with concentrated and distributed parameters. The graphs plotted as a result of studying the machine units made it possible to determine the maximum values of the angle of relative rotation and the rotation angle of the saw cylinder shaft under torsion.

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