3-D Active Antenna for contact sensing

This paper discusses a 3-D Active Antenna that can detect the contact location between an insensitive flexible beam and a 3-D environment through the measurement of the rotational compliance of the beam in contact with the environment. The lateral slip, which possibly occurs for the 3-D Active Antenna, overestimates the rotational compliance, and as a result, brings a large sensing error for the localizing contact point. The goal of this paper is to find the contact point under such conditions. In the first step, we push the antenna to the environment. If no lateral slip is detected during this motion, the contact point can be obtained through a similar method used for the 2-D model. If a lateral slip is confirmed, the pushing direction is changed continuously until development of any lateral slip is finally avoided. The authors explore how to detect a lateral slip and how to determine the new pushing direction to avoid it. The authors show an algorithm which can search not only the contact distance but also the normal direction of the environment´s surface, even under the appearance of a lateral slip during the first step. The basic idea is also verified by experiments