A complete characterization and solution to the microphone position self-calibration problem

2013 ◽  
Author(s):  
Yubin Kuang ◽  
Simon Burgess ◽  
Anna Torstensson ◽  
Kalle Astrom
Keyword(s):  
Complete Characterization ◽  
Self Calibration ◽  
Calibration Problem

scholarly journals Online IMU Self-Calibration for Visual-Inertial Systems

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1624 ◽  
Author(s):  
Yao Xiao ◽  
Xiaogang Ruan ◽  
Jie Chai ◽  
Xiaoping Zhang ◽  
Xiaoqing Zhu
Keyword(s):  
Inertial Sensor ◽  
Low Cost ◽  
Optimization Methods ◽  
Calibration Method ◽  
Measurement Unit ◽  
Intrinsic Parameters ◽  
Self Calibration ◽  
Calibration Problem ◽  
System States ◽  
Inertial Systems

Low-cost microelectro mechanical systems (MEMS)-based inertial measurement unit (IMU) measurements are usually affected by inaccurate scale factors, axis misalignments, and g-sensitivity errors. These errors may significantly influence the performance of visual-inertial methods. In this paper, we propose an online IMU self-calibration method for visual-inertial systems equipped with a low-cost inertial sensor. The goal of our method is to concurrently perform 3D pose estimation and online IMU calibration based on optimization methods in unknown environments without any external equipment. To achieve this goal, we firstly develop a novel preintegration method that can handle the IMU intrinsic parameters error propagation. Then, we frame IMU calibration problem into general factors so that we can easily integrate the factors into the current graph-based visual-inertial frameworks and jointly optimize the IMU intrinsic parameters as well as the system states in a big bundle. We evaluate the proposed method with a publicly available dataset. Experimental results verify that the proposed approach is able to accurately calibrate all the considered parameters in real time, leading to significant improvement of estimation precision of visual-inertial system (VINS) compared with the estimation results with offline precalibrated IMU measurements.

Solving the global photometric self-calibration problem in LSST

2010 ◽  
Author(s):  
R. Lynne Jones ◽  
Nikhil Padmanabhan ◽  
Zeljko Ivezic ◽  
Timothy Axelrod ◽  
James Bartlett ◽  
...  
Keyword(s):  
Self Calibration ◽  
Calibration Problem

scholarly journals Self-Calibration for the General Cable-Driven Serial Manipulator with Multi-Segment Cables

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 444
Author(s):  
Ya’nan Lou ◽  
Haoyu Lin ◽  
Pengkun Quan ◽  
Dongbo Wei ◽  
Shichun Di
Keyword(s):  
Motion Control ◽  
Tracking Error ◽  
Motion Controller ◽  
Self Calibration ◽  
Calibration Problem ◽  
Before And After ◽  
Calibration Algorithm ◽  
Complete Set ◽  
Control Accuracy ◽  
Calibration Parameters

This paper focuses on the kinematic calibration problem for the general cable-driven serial manipulator (CDSM) with multi-segment cables to improve its motion control accuracy. Firstly, to fully describe the calibration parameters of cables, links, joint positions, and the transmission system, this paper proposes a new cable routing description method named cable-routing configuration struct (CRCS), which provides a complete set of parameters to be calibrated for the proposed self-calibration algorithm. Then, a self-calibration algorithm for CDSM with motor incremental encoders is proposed, which can calibrate the robot at one time only using sufficient measured motor and joint positions. Its premise, the initial cable length, needs to be calibrated. Finally, the parameters of a three-DOF (degree of freedom) six-cable CDSM were described using the CRCS description method, and a comparative experiment was carried out on the same motion controller using the parameters before and after calibration. The experiment results of trajectory tracking error showed that the calibration parameters obtained by the proposed calibration algorithm can significantly improve the motion control accuracy of the three-DOF six-cable CDSM. This verified the correctness and effectiveness of the proposed calibration algorithm.

Diffraction contrast of dislocations in icosahedral quasicrystals

1990 ◽  
Vol 48 (4) ◽  
pp. 454-455
Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Complete Characterization ◽  
Extinction Condition ◽  
Burgers Vector ◽  
Diffraction Contrast ◽  
Lattice Geometry ◽  
Reference Space ◽  
Icosahedral Quasicrystals ◽  
The One

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.

443: Can Self-Calibration Prevent Urethral Stricture Recurrence Following Direct Visual Internal Urethrotomy?

2005 ◽  
Vol 173 (4S) ◽  
pp. 121-121
Author(s):  
Hari Siva Gurunadha Rao Tunuguntla ◽  
P.V.L.N. Murthy ◽  
K. Sasidharan
Keyword(s):  
Urethral Stricture ◽  
Internal Urethrotomy ◽  
Self Calibration ◽  
Stricture Recurrence
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