On a new contact sensing strategy for dynamic active antenna

This paper discusses a new sensing strategy for the dynamic active antenna which can detect the contact point between an insensitive flexible beam and an object through the estimation of the oscillation frequency in contact with the object. The strategy is composed of two steps. In the first step, the fundamental and the second order natural frequencies of the beam in contact with the object are evaluated by utilizing an extended Kalman filter. Then by using the mapping diagram from those two frequencies into the contact point, we can uniquely obtain the contact point. We show that the use of the fundamental and the second order natural frequencies is sufficient for localizing the contact point