A projection matrix-based geometric calibration algorithm in CBCT system

2017 ◽  
Author(s):  
Juan Gao ◽  
Yunsong Qi ◽  
Changhui Jiang ◽  
Na Zhang ◽  
Zhanli Hu
Keyword(s):  
Projection Matrix ◽  
Geometric Calibration ◽  
Calibration Algorithm

scholarly journals A Novel Calibration Algorithm for Cable-Driven Parallel Robots with Application to Rehabilitation

2019 ◽  
Vol 9 (11) ◽  
pp. 2182 ◽  
Author(s):  
Han Yuan ◽  
Xianghui You ◽  
Yongqing Zhang ◽  
Wenjing Zhang ◽  
Wenfu Xu
Keyword(s):  
Calibration Method ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Human Robot Interaction ◽  
Automatic Calibration ◽  
Unknown Parameters ◽  
Robot Interaction ◽  
Geometric Calibration ◽  
Rehabilitation Robots ◽  
Calibration Algorithm

Cable-driven parallel robots are suitable candidates for rehabilitation due to their intrinsic flexibility and adaptability, especially considering the safety of human–robot interaction. However, there are still some challenges to apply cable-driven parallel robots to rehabilitation, one of which is the geometric calibration. This paper proposes a new automatic calibration method that is applicable for cable-driven parallel rehabilitation robots. The key point of this method is to establish the mapping between the unknown parameters to be calibrated and the parameters that could be measured by the inner sensors and then use least squares algorithm to find the solutions. Specifically, the unknown parameters herein are the coordinates of the attachment points, and the measured parameters are the lengths of the redundant cables. Simulations are performed on a 3-DOF parallel robot driven by four cables for validation. Results show that the proposed calibration method could precisely find the real coordinate values of the attachment points, with errors less than 10 − 12 mm. Trajectory simulations also indicate that the positioning accuracy of the cable-driven parallel robot (CDPR) could be greatly improved after calibration using the proposed method.

Geometric calibration algorithm of polarization camera using planar patterns

2017 ◽  
Vol 22 (1) ◽  
pp. 55-59 ◽  
Author(s):  
Yujie Wang ◽  
Xiaoping Hu ◽  
Junxiang Lian ◽  
Lilian Zhang ◽  
Xiaofeng He ◽  
...  
Keyword(s):  
Geometric Calibration ◽  
Calibration Algorithm ◽  
Polarization Camera
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