Nonparametric UWB radar imaging algorithm for moving target using multi-static RPM approach

Ultra-wideband (UWB) pulse radar is promising technology for the imaging sensors of rescue robots operating in disaster scenarios, where optical sensors are not applicable because of dusty air or strong backlighting. An UWB radar imaging algorithm for a target with arbitrary motion has already been proposed. That algorithm is based on a circular approximation of the target boundary, and employs measured distances. Although it obtains an accurate target motion and image with few antennas for some targets, it is hardly applicable to complex target shapes, particularly if targets have specular surfaces or surface edges. As a substantial solution to this problem, this paper proposes an original imaging algorithm for a moving target with arbitrary shape, which is based on normal vector matching on the target surface with multi-static observations. Specifically, this study extends the existing RPM (Range Points Migration) algorithm, which is a super-high-resolution and accurate imaging approach, to the multi-static radar model. Numerical simulations show that our proposed algorithm accomplishes extremely accurate target surface extraction, and motion estimation at the order of 1/100 wavelength, even for a noisy environment.