Preliminary Study of a Millimeter Wave FMCW InSAR for UAS Indoor Navigation

Abstract

Small autonomous unmanned aerial systems (UAS) could be used for indoor inspection in emergency missions, such as damage assessment or the search for survivors in dangerous environments, e.g., power plants, underground railways, mines and industrial warehouses. Two basic functions are required to carry out these tasks, that is autonomous GPS-denied navigation with obstacle detection and high-resolution 3D mapping with moving target detection. State-of-the-art sensors for UAS are very sensitive to environmental conditions and often fail in the case of poor visibility caused by dust, fog, smoke, flames or other factors that are met as nominal mission scenarios when operating indoors. This paper is a preliminary study concerning an innovative radar sensor based on the interferometric Synthetic Aperture Radar (SAR) principle, which has the potential to satisfy stringent requirements set by indoor autonomous operation. An architectural solution based on a frequency-modulated continuous wave (FMCW) scheme is proposed after a detailed analysis of existing compact and lightweight SAR. A preliminary system design is obtained, and the main imaging peculiarities of the novel sensor are discussed, demonstrating that high-resolution, high-quality observation of an assigned control volume can be achieved.

Indoor Operations by FMCW Millimeter Wave SAR Onboard Small UAS: A Simulation Approach

“…Millimeter wave FMCW SAR has been selected in this work. This is because FMCW radars show interesting features for indoor operations [1,[16][17][18][19][20]. Continuous signal means less transmitted peak power because the duty cycle is one.…”

“…Autonomous operations with small Unmanned Aerial Systems (UAS) indoors have been gaining interest in the last years [1]. Examples of these operations are indoor inspection in emergency missions, damage assessment or search for survivors in dangerous environments, and, more in general, dirty, dull, and dangerous activities in GPS-denied and substantially unknown environments.…”

“…Examples of these operations are indoor inspection in emergency missions, damage assessment or search for survivors in dangerous environments, and, more in general, dirty, dull, and dangerous activities in GPS-denied and substantially unknown environments. A Frequency Modulated Continuous Wave (FMCW) Synthetic Aperture Radar (SAR) operating in the millimeter wave represents an interesting solution to stringent time requirements due to autonomous navigation and mapping, size and power requirements, and range of environmental conditions [1,2].…”

“…The objective of present work is to develop a high-fidelity simulator for indoor raw FMCW radar data, assuming as a reference the interferometric SAR sensor proposed in [1]. The simulated data shall be then focused to achieve highresolution SAR measurements.…”

Ultralight Radar for Small and Micro-Uav Navigation

“…Concerning this, it is also necessary to mention that an advantage of radar-based odometry compared with vision-based systems is the direct access to range information that prevents from scale drift phenomena. Currently most of the lightweight radars exploit Frequency Modulated Continuous Wave (FMCW) technology, owing to inherent features of this scheme that allow small and light high range resolution sensors having a limited consumption of energy radar (Scannapieco et al, 2015). Therefore, the model of radar used in this work is a FMCW radar with a single transmitting (Tx) antenna and two receiving (Rx) antennas separated in azimuthal direction.…”