Mobile HTS-SQUID NDE system with robot arm and active shielding using fluxgate
✍ Scribed by Y. Hatsukade; K. Yotsugi; S. Tanaka
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 590 KB
- Volume
- 468
- Category
- Article
- ISSN
- 0921-4534
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✦ Synopsis
A robot-arm-based mobile HTS-SQUID NDE system was developed for inspection of advanced structures such as hydrogen fuel cell tanks. In order to realize stable operation of HTS-SQUID exposed in Earth's field and robot arm's noise without flux trapping, flux jumping and unlocking during motion, a new active magnetic shielding (AMS) technique using fluxgate was introduced. The high sensitive fluxgate, which could measure magnetic field of up to several 10 lT, was mounted near an HTS-SQUID gradiometer on the robot arm to measure the ambient noise and feed back its output to a compensation coil, which surrounded both SQUID and fluxgate to cancel the ambient noise around them. The AMS technique successfully enabled the HTS-SQUID gradiometer to be moved at 10 mm/s by the robot arm in unshielded environment without flux trapping, jumping and unlocking. Detection of hidden slots in multi-layer composite-metal structures imitating the fuel cell tank was demonstrated.