An experimental study on relative displacement sensing using phototransistor array for building structures

Kiyoshi Kanekawa*, Iwao Matsuya, Maya Sato, Ryota Tomishi, Motoichi Takahashi, Satoru Miura, Yasutsugu Suzuki, Tomohiko Hatada, Ryuta Katamura, Yoshihiro Nitta, Takashi Tanii, Shuichi Shoji, Akira Nishitani, Iwao Ohdomari

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


We propose a novel sensor for directly measuring the relative displacement of a building structure. The sensor is composed of a laser light source and a phototransistor (PT) array. The PT array is immobilized on the floor together with a photo scattering plate made of glass, whereas the laser light source is separately immobilized on the ceiling. The photo scattering plate is placed in front of the PT array and distributes the laser beam on the multiple PTs. The relative displacement between the ceiling and the floor is estimated by the distribution of the PT output voltages, and the displacement is estimated with a resolution finer than the interval between the PTs. The accuracy of the relative displacement sensor (RDS) is experimentally assessed by conducting a shaking table test exhibiting several waves from harmonic sinusoidal waves to real seismic waves. We discuss the feasibility of real-time monitoring system utilizing this sensor.

Original languageEnglish
Pages (from-to)251-255
Number of pages5
JournalIEEJ Transactions on Electrical and Electronic Engineering
Issue number2
Publication statusPublished - 2010 Mar


  • Building structure
  • Health monitoring
  • Inter-story displacement measurement
  • Laser
  • Photo scattering
  • Phototransistor
  • Position sensing

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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