2021 Volume 70 Issue 11 Pages 816-823
“Magnet-Coil” method using electromagnetic induction was developed to determine the position of a moving object during penetration into sand. The electromotive force generated in a coil was formulated when a magnet in the object passed linearly thought the coil with the three conditions such as “tilt”, “orbit eccentricity” and “tilt and orbit eccentricity” to measure the position and attitude of the object. The experiments were conducted to validate the theoretical formulas. The results of the theoretical formulas under the conditions agreed well with the experimental results. The tilt and orbit eccentricity of the magnet were found to affect independently the electromotive force generated in the coil. The distance between the positions when the electromotive forces became peak and zero was clarified to be dependent on only the orbit eccentricity, independently of the tilt and velocity of the magnet. Therefore, the eccentric position of the magnet can be identified from the distance even if the magnet passes through the coil with the tilt.
