Determining Extrinsic Parameters for Active Stereovision

2009 ◽  
Vol 13 (2) ◽  
pp. 76-79 ◽  
Author(s):  
Huawei Wang ◽  
◽  
De Xu
Keyword(s):  
Least Squares ◽  
Rotational Axis ◽  
The Novel ◽  
Mapping Model ◽  
Least Squares Fitting ◽  
Marquardt Algorithm ◽  
Levenberg Marquardt ◽  
Extrinsic Parameters ◽  
Novel Method ◽  
The Relationship

In the novel method we propose for determining extrinsic parameters for active stereovision, we first map the relationship between rotational and yaw angles based on least squares fitting, then optimize the rotational axis between two cameras using the Levenberg-Marquardt algorithm. Extrinsic parameters are then easily derived for active stereovision based on the mapping model without complex recalibration. The results of experiments confirmed our proposed method's feasibility.

The Nature of Intrinsic Attenuation

2020 ◽  
Author(s):  
Yu-Chang Wu ◽  
Cheng-Ju Wu
Keyword(s):  
Seismic Waves ◽  
Body Waves ◽  
Northwestern Pacific ◽  
The Novel ◽  
Low Velocity ◽  
High Attenuation ◽  
Intrinsic Attenuation ◽  
Novel Method ◽  
The Difference ◽  
The Relationship

<p>Intrinsic attenuation plays an important role in investigating the interior structure of Earth, especially for the Lithosphere-asthenosphere system, the best place to understand the physical mechanics of plate tectonic. The dissipation, the high attenuation of seismic waves in the low-velocity zones, and the frequency dependence are the characteristic of intrinsic attenuation. However, N. Takeuchi, et al. measured the Northwestern Pacific Ocean’s lithosphere-asthenosphere system, and state the attenuation of the asthenosphere is 50 times larger than the attenuation of lithosphere attenuation. The attenuation of the lithosphere shows strong frequency dependency, but the attenuation of the asthenosphere does not. Previous theories of attenuation failed to explain this phenomenon. Here we demonstrate an explicit attenuation formulation to explain the high attenuation of seismic waves in the low-velocity zones and to show the mechanisms of spectral of teleseismic body waves rapidly fall off as frequency bigger than 1 Hz by perturbing the wave equation with the novel method we proposed. The result also indicates that the difference between the attenuation of the lithosphere and asthenosphere is because their attenuation governs by different physics mechanisms and mathematical models. Moreover, we illustrate the explicit formulation of the relationship between apparent t*, wave velocity, and frequency.</p>

Advanced Sensor-Less Control of IPMSM Motor Using Adaptive Neural FOC Approach

2019 ◽  
Vol 894 ◽  
pp. 149-157
Author(s):  
Pham Quoc Khanh ◽  
Ho Pham Huy Anh ◽  
Cao Van Kien
Keyword(s):  
Vector Control ◽  
Electric Vehicle ◽  
Permanent Magnet Synchronous Motor ◽  
The Novel ◽  
Electric Drives ◽  
Speed Regulation ◽  
Marquardt Algorithm ◽  
Levenberg Marquardt ◽  
Speed Range ◽  
Simulation Results

This paper proposes a neural vector control (NN-FOC) for speed regulation of interior-mounted permanent magnet synchronous motor (IPMSM) drive. The weights of proposed neural NN-FOC structure are optimally identified based on the Levenberg-Marquardt algorithm. The novel MTPA approach is applied for IPMSM-based electric vehicle (EV) drive application. The novel neural NN-FOC control is verified in simulation tests and is compared with the traditional PI-FOC vector control. The simulation results prove that the maximum IPMSM speed range available with the new NN-FOC control is significantly improved in comparison with the traditional IPMSM PI-FOC control. As a consequent the proposed neural NN-FOC control can be successfully applied in advanced electric drives, particularly in PMSM-based electric vehicle EV drive application.

scholarly journals An improved magnetometer calibration and compensation method based on Levenberg–Marquardt algorithm for multi-rotor unmanned aerial vehicle

2020 ◽  
Vol 53 (3-4) ◽  
pp. 276-286
Author(s):  
Helong Wu ◽  
Xinbiao Pei ◽  
Jihui Li ◽  
Huibin Gao ◽  
Yue Bai
Keyword(s):  
Least Squares ◽  
Unmanned Aerial Vehicle ◽  
Optimal Estimation ◽  
Calibration Model ◽  
Marquardt Algorithm ◽  
Levenberg Marquardt ◽  
Magnetometer Data ◽  
Aerial Vehicle ◽  
Magnetometer Calibration ◽  
Yaw Angle

In order to improvethe yaw angle accuracy of multi-rotor unmanned aerial vehicle and meet the requirement of autonomous flight, a new calibration and compensation method for magnetometer based on Levenberg–Marquardt algorithm is proposed in this paper. A novel mathematical calibration model with clear physical meaning is established. “Hard iron” error and “Soft iron” error of magnetometer which affect the yaw accuracy of unmanned aerial vehicle are compensated. Initially, Levenberg–Marquardt algorithm is applied to the process of sphere fitting for the original magnetometer data; the optimal estimation of sphere radius and initial “Hard iron” error are obtained. Then, the ellipsoid fitting is performed, and the optimal estimation of “Hard iron” error and “Soft iron” error are obtained. Finally, the calibration parameters are used to compensate for the magnetometer’s output during unmanned aerial vehicle flight. Traditional ellipsoid fitting based on least squares algorithm is taken as reference to prove the effectiveness of the proposed algorithm. Semi-physical simulation experiment proves that the proposed magnetometer calibration method significantly enhances the accuracy of magnetometer. Static test shows that the yaw angle error is reduced from 1.2° to 0.4° when using the proposed calibration model to calibrate magnetometers. In dynamic tests, the sensor MTi’s output is used as reference. The data fusion of magnetometer compensated by the proposed new calibration model based on Levenberg–Marquardt algorithm can accurately track the desired attitude angle. Experimental results indicate that the accuracy of magnetometer in the yaw angle estimation has been greatly enhanced. In the process of attitude estimated, the compensation magnetometer data given by this new method have faster convergence speed, higher accuracy, and better performance than the compensation magnetometer data given by traditional ellipsoid fitting based on least squares algorithm.

Heat Absorbing Rate in Laser Drilling of YG8 Alloy

2010 ◽  
Vol 97-101 ◽  
pp. 4164-4167
Author(s):  
Xu Yue Wang ◽  
Wen Ji Xu ◽  
Lian Ji Wang ◽  
Jun Wang ◽  
Yan De Liang
Keyword(s):  
Laser Beam ◽  
Laser System ◽  
Laser Drilling ◽  
The Novel ◽  
Spatial Mode ◽  
Drilling Temperature ◽  
Research Outcome ◽  
Novel Method ◽  
Relationship Of ◽  
The Relationship

Based on a principle of laser drilling size and the roundness copied with respect of laser spatial mode, heat absorbing rate for laser drilling of YG8 is presented in theory and application. The mathematical models are then developed. The relationship of heat absorbing rate compared to the original absorbing rate is thus derived that is A = T +A0. It shows that heat absorbing rate to laser beam increases linearly with drilling temperature. The research outcome is used to optimize preheating process in which the novel method improves laser drilling precision from 0.03mm of primitive laser system to 0.01mm under the condition of heat absorbing.

scholarly journals Spherical Harmonics for Surface Parametrisation and Remeshing

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Caitlin R. Nortje ◽  
Wil O. C. Ward ◽  
Bartosz P. Neuman ◽  
Li Bai
Keyword(s):  
Least Squares ◽  
Spherical Harmonics ◽  
Basis Functions ◽  
Surface Mesh ◽  
Polygonal Meshes ◽  
Least Squares Fitting ◽  
Novel Method ◽  
Tikhonov Regularisation

This paper proposes a novel method for parametrisation and remeshing incomplete and irregular polygonal meshes. Spherical harmonics basis functions are used for parametrisation. This involves least squares fitting of spherical harmonics basis functions to the surface mesh. Tikhonov regularisation is then used to improve the parametrisation before remeshing the surface. Experiments show that the proposed techniques are effective for parametrising and remeshing polygonal meshes.

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