Frictional Effects in a Low Speed Polar-Axis Solar Tracker

摘要

Sensorless solar tracking involves the low speed tracking of the direction of sunrays across the sky. At such low speeds, frictional effects in the electromechanical drive system of the tracker become amplified, and can significantly affect the accuracy of tracking. This paper models the frictional effects in low speed solar tracking and shows that the frictional effects lead to significant positional error during tracking. Further results show that, a class of controllers derived from strictly positive real (SPR) transfer functions, could be used to eliminate the positional tracking error due to frictional effects.