US Patent 11587251 Determination of relative position of an apparatus

This application describes fixture having a body and a plurality of fiducials with at least one of the fiducials having a first state and a second state and able to move to one of the first state and the second state. The fiducials are arranged such that knowledge of the 3D positions of the fiducials in an observing coordinate system is sufficient to determine a first position and a first orientation of the body in the observing coordinate system.