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Abstract

The precise location of the needle tip is critical in robot-assisted needle-based percutaneous interventions. An automatic needle tip measuring system based on binocular vision technology with the advantages of non-contact, excellent accuracy and high stability is designed and evaluated. First the measurement requirements of the prostate intervention robot are introduced. A laser interferometer is used as the reference for measuring the position of the needle tip whose relative position variation is described as the needle tip distance in the time domain. The parameters of the binocular cameras are obtained by Zhang’s calibration method. Then a robust needle tip extraction algorithm is specially designed to detect the pixel coordinates of the needle tip without installing the marked points. Once the binocular cameras have completed the stereo matching, the 3D coordinates of the needle tip are estimated. The measurement capability analysis (MCA) is used to evaluate the performance of the proposed system. The accuracy of the system can be controlled within 0.3621 mm. The agreement analysis is conducted by the Bland–Altman analysis, and the Pearson correlation coefficient is 0.999847. The P/T ratio value is 16.42% in the repeatability analysis. The results indicate that the accuracy and stability of the binocular vision needle tip measuring system are adequate to meet the requirement for the needle tip measurement in percutaneous interventions.

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Authors and Affiliations

Yuyang Lin
Yunlai Shi
Jun Zhang
ORCID: ORCID
Fugang Wang
Haichao Sun
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Abstract

When mining coal from the working face, the main roof withstands the overlying strata. The main roof’s first weighting and periodic weighting may cause accidents, such as crushing the working face hydraulic supports. A mechanical model of the main roof was constructed, and the contributing factors of first and periodic weights on the main roof were examined in order to prevent such accidents. The thickness of the main roof was found as the most contributory factor to the main roof’s stability. Therefore, a new directional roof crack (DRC) technique is proposed, which produces directional cracks in the main roof through directional blasting and makes part of it collapse in advance so as to reduce the thickness and relieve the first and periodic weighting. To verify the effectiveness of DRC, the mechanism of DRC was analysed. A mechanical model of the hydraulic support was constructed, and the DRC techniques were tested on-site. Field experiments with a complete set of monitoring schemes showed that, with DRC technology, the roof periodic weighting interval decreased by 35.36%, and the hydraulic support pressure decreased by 17.56%. The theoretical analysis was consistent with the measured results. Therefore, the DRC technology is feasible and effective to ensure mining safety at the working face.
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Authors and Affiliations

Jun Zhang
1
ORCID: ORCID
Jianning Liu
1
ORCID: ORCID
Yajun Wang
2
ORCID: ORCID
Gang Yang
1
ORCID: ORCID
Shilin Hou
1
ORCID: ORCID
Yanjun Wang
3
ORCID: ORCID
Manchao He
1
ORCID: ORCID
Jun Yang
1
ORCID: ORCID

  1. China University of Mining & Technology (Beijing), State Key Laboratory for Geomechanics and Deep Underground Engineering, Beijing 100083, China
  2. School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
  3. ShanXiYinFeng Science & Technology CO. LTD, Taiyuan 030000, China

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