Method and apparatus for tracking objects

Abstract

Two spaced bodies, each including at least two independently oriented radiating antennas, are in communication with each other by such means as an electromagnetic field. The first body receives radiation transmitted from the second body and establishes the pointing angles to the second body with respect to the first body coordinate reference frame. The field received by the first body can include information defining the second body's pointing angles to the first body with respect to the second body's coordinate reference frame and the relative roll about their mutually aligned pointing axis. These pointing angles and relative roll are sufficient for determining the orientation of the first body relative to the second body. The second body receives radiation transmitted from the first body and establishes the pointing angles to the first body with respect to the second body. Analogously, radiation received by the second body can include information defining the first body's pointing angles with respect to the first body coordinate reference frame to the second body and the relative roll between their mutually aligned pointing axes. As before, this information is sufficient for the second body to determine its orientation relative to the first body. Distance between the two bodies can be determined by phase-locking techniques, thus providing the capability of a full six-degree-of-freedom measurement system. A third body, known and defined in the coordinate frame of the first body, can be defined at the second body with respect to the frame of the second body. That is, information is transmitted from the first body and received at the second body which establishes a vector from the second body to the third body thus defining the location of the third body at the second body.