scholarly journals Obstacle-based self-calibration techniques for the determination of the permittivity of liquids

2007 ◽  
Vol 5 ◽  
pp. 29-35 ◽  
Author(s):  
I. Rolfes
Keyword(s):  
Industrial Process ◽  
Calibration Procedure ◽  
Microwave Frequencies ◽  
Material Parameters ◽  
Self Calibration ◽  
Calibration Methods ◽  
Measurement Cell ◽  
Calibration Techniques ◽  
Transmission And Reflection

Abstract. In this contribution, different obstacle-based self-calibration techniques for the measurement of the dielectric properties of liquids are investigated at microwave frequencies. The liquid under test is contained inside a waveguide, which is connected to the ports of a vector network analyzer. The permittivity of the liquid is characterized on the basis of the measured scattering parameters. In order to extract the material parameters precisely and to eliminate systematic errors of the setup, calibration measurements have to be performed. For this purpose, different self-calibration methods based on the displacement of an obstacle are considered. The presented methods differ in that way, that either transmission and reflection measurements or purely reflection measurements are performed. All these methods have in common that the material parameters are already calculable within a so-called self-calibration procedure. Thus, a full two-port calibration of the whole setup is not necessary. Furthermore, the methods can be realized effectively in a practical setup having the advantage that a rearrangement of the setup is not needed for the material parameter measurements and that the liquid under investigation can pass continuously through the measurement cell. This might be of interest for the application in an industrial process, enabling the continuous flow of the material while the parameter characterization can take place at the same time.

Parallel Robot Calibration Utilizing Adaptronic Joints

2008 ◽  
Author(s):  
Philipp Last ◽  
Annika Raatz ◽  
Ju¨rgen Hesselbach ◽  
Nenad Pavlovic ◽  
Ralf Keimer
Keyword(s):  
Parallel Robot ◽  
Parallel Robots ◽  
Machine Component ◽  
Robot Calibration ◽  
Geometric Calibration ◽  
Self Calibration ◽  
Mechanical Constraints ◽  
Special Machine ◽  
Calibration Methods ◽  
Calibration Techniques

Model based geometric calibration is well known to be an efficient way to enhance absolute accuracy of robotic systems. Generally its application requires redundant measurements, which are achieved by external metrology equipment in most traditional calibration techniques. However, these methods are usually time-consuming, expensive and inconvenient. Thus, so-called self-calibration methods have achieved attention from researchers, which either use internal sensors or rely on mechanical constraints instead. In this paper a new self-calibration technique is presented for parallel robots which is motivated by the idea of constrained calibration. The new approach utilizes a special machine component called the adaptronic swivel joint in order to achieve the required redundant information. Compared to similar approaches it offers several advantages. The new calibration scheme is described and verified in simulation studies using a RRRRR-structure as an example.

Graph-optimisation-based self-calibration method for IMU/odometer using preintegration theory

2022 ◽  
pp. 1-20
Author(s):  
Shiyu Bai ◽  
Jizhou Lai ◽  
Pin Lyu ◽  
Yiting Cen ◽  
Bingqing Wang ◽  
...  
Keyword(s):  
Inertial Measurement Unit ◽  
Experimental Tests ◽  
Calibration Method ◽  
Measurement Unit ◽  
Integrated Navigation ◽  
Integrated Navigation System ◽  
Self Calibration ◽  
Calibration Methods ◽  
Calibration Accuracy

Determination of calibration parameters is essential for the fusion performance of an inertial measurement unit (IMU) and odometer integrated navigation system. Traditional calibration methods are commonly based on the filter frame, which limits the improvement of the calibration accuracy. This paper proposes a graph-optimisation-based self-calibration method for the IMU/odometer using preintegration theory. Different from existing preintegrations, the complete IMU/odometer preintegration model is derived, which takes into consideration the effects of the scale factor of the odometer, and misalignments in the attitude and position between the IMU and odometer. Then the calibration is implemented by the graph-optimisation method. The KITTI dataset and field experimental tests are carried out to evaluate the effectiveness of the proposed method. The results illustrate that the proposed method outperforms the filter-based calibration method. Meanwhile, the performance of the proposed IMU/odometer preintegration model is optimal compared with the traditional preintegration models.

scholarly journals Reduction of Interference in Observations with the Westerbork Synthesis Radio Telescope

1991 ◽  
Vol 112 ◽  
pp. 249-257
Author(s):  
T.A. Th. Spoelstra
Keyword(s):  
Radio Telescope ◽  
Calibration Procedure ◽  
Software Tools ◽  
Interference Effects ◽  
Astronomical Observations ◽  
Self Calibration ◽  
Calibration Techniques ◽  
Source Structure

ABSTRACTRadio astronomical observations are increasingly affected by man-made interference of various kinds. Sophisticated software tools have to be developed to cope with interference effects in the data. A calibration procedure is described in which the effects of different categories of errors are separated. If this separation can be performed for interference effects.Interference effects remaining in the data are erroneously interpreted as source structure by self-calibration techniques. This is due to the fact that self-calibration alone does not properly take into account this separation. Some results for the Westerbork Synthesis Radio Telescope are given.

Camera Calibration for 3D Reconstruction and View Transformation

2011 ◽  
pp. 70-129
Author(s):  
B. J. Lei ◽  
E. A. Hendriks ◽  
Aggelos K. Katsaggelos
Keyword(s):  
3D Reconstruction ◽  
Camera Calibration ◽  
Mathematical Description ◽  
The Self ◽  
Model Reconstruction ◽  
Face Model ◽  
Self Calibration ◽  
Calibration Methods ◽  
View Transformation ◽  
Calibration Techniques

This chapter presents an extensive overview of passive camera calibration techniques. Starting with a detailed introduction and mathematical description of the imaging process of an off-the-shelf camera, it reviews all existing passive calibration approaches with increasing complexity. All algorithms are presented in detail so that they are directly applicable. For completeness, a brief counting about the self-calibration is also provided. In addition, two typical applications are given of passive camera calibration methods for specific problems of face model reconstruction and telepresence and experimentally evaluated. It is expected that this chapter can serve as a standard reference. Researchers in various fields in which passive camera calibration is actively or potentially of interest can use this chapter to identify the appropriate techniques suitable for their applications.

Flame ionization detector response to coeluting hydrocarbons and carbon disulphide and its application to the determination of the sum of C6-C11 alkanes and cycloalkanes in air

1983 ◽  
Vol 48 (3) ◽  
pp. 722-734
Author(s):  
Martin Koval
Keyword(s):  
Carbon Disulphide ◽  
Internal Standard ◽  
Calibration Procedure ◽  
Detector Response ◽  
Column Temperature ◽  
Flame Ionization ◽  
Other Substances ◽  
Flame Ionisation Detector ◽  
Ionisation Detector

The flame ionisation detector response to C6-C11 aliphatic hydrocarbon solutions in carbon disulphide in the concentration range between 1.3-9.5 mg ml-1 retained lineary despite the excess of solvent entering the detector simultaneously with the analyte. Pure carbon disulphide exhibited a small positive detector response which did not interfere in calibration procedure and which, under certain GC conditions, inverted to negative values. This response was not proportional to the injected volume and was strongly influenced by the column temperature and/or bleed. On the basis of these findings, a method compatible with the widely used charcoal tube carbon disulphide desorption procedure was developed and evaluated. It consists of static desorption of the sum of aliphatic alkanes and cycloalkanes from the activated charcoal after which an internal standard is added to the supernatant eluate. The resulting carbon disulphide solution is analysed on a highly polar stationary phase 1,2,3-tris(2-cyanoethoxy)propane where the solvent and the analyte coelute in a single peak, the height of which is practically proportional to the sum of alkanes and cycloalkanes present. This also makes determinations of other substances present in the sample more simple. The field test of the proposed method yielded values comparable in precision and accuracy with a control infrared spectrophotometric method.

scholarly journals Proposed New AV-Type Test-Bed for Accurate and Reliable Fish-Eye Lens Camera Self-Calibration

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2776
Author(s):  
Kang Hyeok Choi ◽  
Changjae Kim
Keyword(s):  
Outer Part ◽  
Calibration Procedure ◽  
Geometric Distortion ◽  
Eye Lens ◽  
Wide Field ◽  
Test Bed ◽  
Self Calibration ◽  
Type Test ◽  
Balanced Distribution ◽  
Fish Eye

The fish-eye lens camera has a wide field of view that makes it effective for various applications and sensor systems. However, it incurs strong geometric distortion in the image due to compressive recording of the outer part of the image. Such distortion must be interpreted accurately through a self-calibration procedure. This paper proposes a new type of test-bed (the AV-type test-bed) that can effect a balanced distribution of image points and a low level of correlation between orientation parameters. The effectiveness of the proposed test-bed in the process of camera self-calibration was verified through the analysis of experimental results from both a simulation and real datasets. In the simulation experiments, the self-calibration procedures were performed using the proposed test-bed, four different projection models, and five different datasets. For all of the cases, the Root Mean Square residuals (RMS-residuals) of the experiments were lower than one-half pixel. The real experiments, meanwhile, were carried out using two different cameras and five different datasets. These results showed high levels of calibration accuracy (i.e., lower than the minimum value of RMS-residuals: 0.39 pixels). Based on the above analyses, we were able to verify the effectiveness of the proposed AV-type test-bed in the process of camera self-calibration.

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