Determining angular velocities of fast rotating objects based on motion blur to control an optomechanical derotator

PAMM ◽  
2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Bettina Altmann ◽  
Christian Pape ◽  
Eduard Reithmeier
Keyword(s):  
Motion Blur ◽  
Angular Velocities ◽  
Fast Rotating ◽  
Rotating Objects

scholarly journals INTEGRATION OF IMAGE-DERIVED AND POS-DERIVED FEATURES FOR IMAGE BLUR DETECTION

2016 ◽  
Vol XLI-B1 ◽  
pp. 1051-1055 ◽  
Author(s):  
Tee-Ann Teo ◽  
Kai-Zhi Zhan
Keyword(s):  
Feature Extraction ◽  
Image Features ◽  
Motion Blur ◽  
Support Vector ◽  
Svm Classifier ◽  
Image Detection ◽  
Blur Detection ◽  
Angular Velocities ◽  
Image Blur ◽  
Position And Orientation

The image quality plays an important role for Unmanned Aerial Vehicle (UAV)’s applications. The small fixed wings UAV is suffering from the image blur due to the crosswind and the turbulence. Position and Orientation System (POS), which provides the position and orientation information, is installed onto an UAV to enable acquisition of UAV trajectory. It can be used to calculate the positional and angular velocities when the camera shutter is open. This study proposes a POS-assisted method to detect the blur image. The major steps include feature extraction, blur image detection and verification. In feature extraction, this study extracts different features from images and POS. The image-derived features include mean and standard deviation of image gradient. For POS-derived features, we modify the traditional degree-of-linear-blur (blinear) method to degree-of-motion-blur (bmotion) based on the collinear condition equations and POS parameters. Besides, POS parameters such as positional and angular velocities are also adopted as POS-derived features. In blur detection, this study uses Support Vector Machines (SVM) classifier and extracted features (i.e. image information, POS data, blinear and bmotion) to separate blur and sharp UAV images. The experiment utilizes SenseFly eBee UAV system. The number of image is 129. In blur image detection, we use the proposed degree-of-motion-blur and other image features to classify the blur image and sharp images. The classification result shows that the overall accuracy using image features is only 56%. The integration of image-derived and POS-derived features have improved the overall accuracy from 56% to 76% in blur detection. Besides, this study indicates that the performance of the proposed degree-of-motion-blur is better than the traditional degree-of-linear-blur.

scholarly journals Asteroseismology of fast-rotating stars: the example of α Ophiuchi

2013 ◽  
Vol 9 (S301) ◽  
pp. 455-456 ◽  
Author(s):  
Giovanni M. Mirouh ◽  
Daniel R. Reese ◽  
Francisco Espinosa Lara ◽  
Jérôme Ballot ◽  
Michel Rieutord
Keyword(s):  
Rotating Stars ◽  
Early Type ◽  
Oscillation Spectrum ◽  
Mode Identification ◽  
Fundamental Parameters ◽  
Complex Oscillation ◽  
Angular Velocities ◽  
Clear Identification ◽  
Early Type Stars ◽  
Fast Rotating

AbstractMany early-type stars have been measured with high angular velocities. In such stars, mode identification is difficult as the effects of fast and differential rotation are not well known. Using fundamental parameters measured by interferometry, the ESTER structure code and the TOP oscillation code, we investigate the oscillation spectrum of α Ophiuchi, for which observations by the MOST satellite found 57 oscillations frequencies. Results do not show a clear identification of the modes and highlight the difficulties of asteroseismology for such stars with a very complex oscillation spectrum.

scholarly journals Optical Pulsations from Isolated Neutron Stars

2011 ◽  
Vol 7 (S285) ◽  
pp. 369-371
Author(s):  
Roberto P. Mignani
Keyword(s):  
Neutron Stars ◽  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Fast Rotating ◽  
Rotating Objects

AbstractBecause they are fast rotating objects, isolated neutron stars (INS) are obvious targets for high-time-resolution observations. With the number of optical/UV/IR INSs detections now at 24, timing observations become increasingly important in INS astrophysics.

Measurement uncertainty of non-incremental, non-contact, in-situ shape measurements

2017 ◽  
Vol 84 (6) ◽  
Author(s):  
Micha Sebastian Schuster ◽  
Robert Kuschmierz ◽  
Jürgen Czarske
Keyword(s):  
Measurement Uncertainty ◽  
Optical Measurement ◽  
Distance Measurement ◽  
Shape Measurement ◽  
Measurement Systems ◽  
Sensor Position ◽  
The Mean ◽  
Fast Rotating ◽  
Rotating Objects

AbstractOptical measurement systems work fast and non-contact and can achieve sub-micron precision. Thus they appear to be well suited for in-situ shape measurement of fast rotating objects such as cutting processes in metal working lathes. Most optical measurement systems, however, allow an axial position measurement only. In order to retrieve the shape of the object from a distance measurement, the distance between the sensor and the centre of the object has to be known. Otherwise, deviations of this distance, for instance due to temperature effects or vibrations, will result in a measurement deviation. In order to allow an absolute shape measurement, which is independent of the sensor position, the mean radius of the rotating object can be retrieved from the object's circumferential velocity. The laser Doppler distance sensor with phase evaluation (P-LDD sensor) allows a simultaneous velocity and distance measurement with high temporal resolution. Thus, the P-LDD sensor allows to measure the mean radius as well as the spatially resolved deviation of the radius independently of the sensor position. In order to quantify the achievable measurement uncertainty, and especially the influence of the temperature the measurement uncertainty budget is derived and considers random as well as systematic errors. It is shown that the P-LDD sensor allows an absolute, three-dimensional shape measurement of fast rotating objects with sub-micron uncertainty. The systematic measurement uncertainty of the absolute shape due to the temperature amounts to only 200 nm/K. Thus the P-LDD sensor is not dependent on temperature-controlled laboratories but can be employed directly in the production process (in-situ or in-process).

scholarly journals The Mathematical Model for the Tippe Top Inversion

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
R. Usubamatov ◽  
M. Bergander ◽  
S. Kapayeva
Keyword(s):  
Classical Mechanics ◽  
Support Surface ◽  
Gyroscopic Effect ◽  
Complex Design ◽  
Tippe Top ◽  
Angular Velocities ◽  
Gyroscopic Effects ◽  
The Mathematical Model ◽  
Spinning Disc ◽  
Rotating Objects

The dynamics of rotating objects is an area of classical mechanics that has many unsolved problems. Among these problems are the gyroscopic effects manifested by the spinning objects of different forms. One of them is the Tippe top designed as the truncated sphere which is fitted with a short, cylindrical rod for rotation. The unexplainable gyroscopic effect of the Tippe top is manifested by its inversion towards the support surface. Researchers tried to describe this gyroscopic effect for two centuries, but all modelings were on the level of assumptions. It is natural because the Tippe top has a more complex design than the simple spinning disc, which gyroscopic effects did not have an analytical solution until recent time. The latest research, in the area of gyroscopic effects, reveals the action of the system of several interrelated inertial torques on any spinning object. The gyroscopic inertial torques are generated by their rotating mass. These inertial torques and the variable ratio of the angular velocities of the spinning object around axes of rotations constitute the fundamental principles of gyroscope theory. These physical principles of dynamics of rotating objects enable to description and compute of any gyroscopic effects and also the Tippe top inversion.

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