Positioning of a Photovoltaic Device on a Real Two-Dimensional Plane in Optical Wireless Power Transmission by Means of Infrared Differential Absorption Imaging

In optical wireless power transmission (OWPT), detection and positioning of the photovoltaic device (PV) in real space is essential before power transmission. One of the candidates for the robust detection of PVs is differential absorption imaging, which has been proposed by the authors. In this method, raw images are captured using absorbable (lambda ON) and non-absorbable (lambda OFF) wavelengths of the PV. Then, the PV is detected from the differential image of these. In this report, the positioning of a PV on a real two-dimensional plane was investigated by means of this differential imaging. Primarily, stereo imagery was utilized for positioning. Non-stereo positioning was also investigated, in which the azimuth angle (direction) was estimated from the position of the PV in the differential image, and ranging was performed using its apparent size. There are diffuse and non-diffuse (specular) options for the lambda OFF reflection of the rear surface of the PV. Positioning accuracy was measured with regard to this characteristic as well as the attitude angle. Especially for a PV with specular characteristics, even though its positioning accuracy was affected by its attitude angle, the accuracy could be improved by increasing the irradiation light power. On the other hand, direction determination was stable for a wide angular range of attitudes.