Multi-camera rigid body pose estimation using higher-order dynamic models

2013 ◽  
Author(s):  
Alec E. Forsman ◽  
David A. Schug ◽  
Anton J. Haug
Keyword(s):  
Rigid Body ◽  
Pose Estimation ◽  
Dynamic Models ◽  
Higher Order ◽  
Body Pose Estimation

Using an Extended Kalman Filter for Rigid Body Pose Estimation

2004 ◽  
Vol 127 (3) ◽  
pp. 475-483 ◽  
Author(s):  
Kjartan Halvorsen ◽  
Torsten Söderström ◽  
Virgil Stokes ◽  
Håkan Lanshammar
Keyword(s):  
Kalman Filter ◽  
Rigid Body ◽  
State Space ◽  
Pose Estimation ◽  
Measurement Errors ◽  
The State ◽  
State Space Models ◽  
Marker Data ◽  
Measurement Function ◽  
Body Pose Estimation

Rigid body pose is commonly represented as the rigid body transformation from one (often reference) pose to another. This is usually computed for each frame of data without any assumptions or restrictions on the temporal change of the pose. The most common algorithm was proposed by Söderkvist and Wedin (1993, “Determining the Movements of the Skeleton Using Well-configured Markers,” J. Biomech., 26, pp. 1473–1477), and implies the assumption that measurement errors are isotropic and homogenous. This paper describes an alternative method based on a state space formulation and the application of an extended Kalman filter (EKF). State space models are formulated, which describe the kinematics of the rigid body. The state vector consists of six generalized coordinates (corresponding to the 6 degrees of freedom), and their first time derivatives. The state space models have linear dynamics, while the measurement function is a nonlinear relation between the state vector and the observations (marker positions). An analytical expression for the linearized measurement function is derived. Tracking the rigid body motion using an EKF enables the use of a priori information on the measurement noise and type of motion to tune the filter. The EKF is time variant, which allows for a natural way of handling temporarily missing marker data. State updates are based on all the information available at each time step, even when data from fewer than three markers are available. Comparison with the method of Söderkvist and Wedin on simulated data showed a considerable improvement in accuracy with the proposed EKF method when marker data was temporarily missing. The proposed method offers an improvement in accuracy of rigid body pose estimation by incorporating knowledge of the characteristics of the movement and the measurement errors. Analytical expressions for the linearized system equations are provided, which eliminate the need for approximate discrete differentiation and which facilitate a fast implementation.

Evaluation of occupational exposure to static magnetic field in MRI sites based on body pose estimation and SMF analytical computation

2018 ◽  
Vol 39 (7) ◽  
pp. 503-515
Author(s):  
Lamia Belguerras ◽  
A.Rahim Kadkhodamohammadi ◽  
Antoine Delmas ◽  
Meysam Miralipoor ◽  
Nicolas Weber ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Occupational Exposure ◽  
Static Magnetic Field ◽  
Pose Estimation ◽  
Analytical Computation ◽  
Body Pose Estimation

New Higher-Order Models for Sandwich Plates with a Flexible Core and their Accuracy Assessment

2019 ◽  
Vol 19 (03) ◽  
pp. 1950024 ◽  
Author(s):  
Ali Tian ◽  
Renchuan Ye ◽  
Peng Ren ◽  
Pengming Jiang ◽  
Zengtao Chen ◽  
...  
Keyword(s):  
Dynamic Models ◽  
Accuracy Assessment ◽  
Order Theory ◽  
Higher Order ◽  
Analytical Models ◽  
Core Material ◽  
Sandwich Plates ◽  
Higher Order Theory ◽  
Flexible Core

Two higher-order analytical models based on a new higher-order theory for sandwich plates with flexible cores are developed considering the effect of the core material density and skin-to-core-stiffness-ratio (SCSR). The main difference between the two models is the role of the flexible core in the dynamic response of sandwich plates with cores of different stiffnesses. Firstly, the governing equations of a simply supported sandwich plate with a flexible core are derived based on the two models, and the analytical solutions are determined by using Navier’s approach. Then, the free vibration, static, dynamic bending and stress field characteristics of the sandwich plates with different SCSRs are investigated. The results obtained by the proposed method are compared with other published results. In particular, an accuracy assessment of the present dynamic models is conducted for different SCSRs. Finally, conclusions on the applicability of the proposed method and other theories on sandwich plates with different SCSRs are drawn.

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