Novel moiré-pattern based tilt sensor for slope movement sensing: Repeatability study

Existing tilt sensors used in slope movement monitoring are capable of detecting tilt along a single plane. Multiple sensors are required to detect tilt along two or more plane. In this work, a preliminary design of a novel tilt sensor based on the moiré concept has been designed and developed for sensing tilt movement in any arbitrary plane. The sensor comprises two circular gratings mounted inside a sealed chamber. One of the gratings is fixed while the other is mounted on a float. The effect of various liquids on the repeatability of the moiré patterns was investigated. The results show that water as the working liquid produces more consistent and repeatable patterns owing to the lower absorption by the foam float.