This paper presents a novel methodology for target recognition and reconstruction of rigid body moving targets. Traditional methods such as Synthetic Aperture Radar (SAR) rely on information gathered from multiple sensor locations and complex processing algorithms. Additional processing is often required to mitigate the effects of motion and improve the image resolution. Many of these techniques rely on information external to the target such as target radar signatures and neglect information available from the structure of the target, structural invariance, and kinematics. This revolutionary target reconstruction method incorporates information not traditionally used. As a result, the absolute position of target scattering centers can theoretically be determined with external, high resolution radar range information from three observations of four target scattering centers. Relative motion between the target and the sensor and structural invariance provide additional information for determining position of the target's scattering center, actual scaling, and angular orientation with respect to the sensor for reconstruction and imaging.
This methodology is based on the kinematics of rotational motion resulting from relative movement between the sensor and the target. External range data provides one-dimensional information for determining position in a two-dimensional projection of the scattering centers. The range location of the scattering center, relative to a defined center, is analyzed using rotational motion. Range and target kinematics support the development of a conceptual model. Actual scaling and the target's orientation with respect to the sensor are developed through a series of trigonometric relationships. The resulting three-dimensional coordinates for the scattering centers are then used for target reconstruction and image enhancement.
Spatial reconstruction of a rigid, moving target's scattering centers using one dimensional, high range resolution (HRR) radar remains of high interest to synthetic aperture radar (SAR) processing of moving targets. Innovative range and Doppler equations for a rotating target with constant angular velocity were developed by Fazio, Hong, and Wood and presented at the April 2002 SPIE AeroSense Conference in Orlando, Florida. Further research has produced a method of reconstructing a three-dimensional scattering center model of a moving target with variable angular velocity. The reconstruction algorithm uses the relative ranges from a minimum of five observations of three scattering centers. In-plane rotational motion provides necessary information for positioning the projection of the scattering centers onto the observation (reconstruction) plane; while out-of-rotational-plane target motion is necessary to locate the center above or below the reconstruction plane.
Three-dimensional image reconstruction of moving targets from one-dimensional radar information traditionally has been challenging. Range and Doppler (range rate) measurements of prominent, radar scattering centers are rich with information for image reconstruction. Target kinematics and structural rigidity produce invariant parameters that support mathematical reconstruction solutions. Relating two frames of reference, one based on the radar source and the other on target motion, generate innovative range and Doppler equations. Solutions of these equations provide the basis for determining the three-dimensional location of scattering centers and target image reconstruction.