Implementation of a hyperspectral integrated vision system combining radar technology and single-pixel optical principle for unmanned ground vehicles (UGV)

During the last decades the radio detecting and ranging (RADAR) technology underwent an evolution transiting from the linear-frequency-modulated (LFM) systems developed in the 1970s, up to the orthogonal frequency-division multiplexing (OFDM) systems developed in the early 2000s. In mid 2010s, systems were proposed that combined the radar principle with optical solutions developed for imaging and ranging tasks following a hyperspectral embedded systems approach. The idea was to profit on the one side from the possibility offered by RADAR systems to work in harsh environments using emitted radio waves and detect mainly metal objects placed far away (hundreds of meters or even kilometers) from the detection system with positioning spatial resolutions in tens of centimeters, even if there are non-metallic barriers such as e.g. walls in between; and expand this possibility by using optical systems (e.g. light detecting and ranging –LIDAR- systems), using visible light active illumination, capable of generating 2D and 3D images of objects placed at much smaller distances from the detector, but allowing for much higher spatial resolutions (in the millimeter range). To reduce the atmospheric absorption of the emitted active illumination and increase the emitted optical power allowed for these systems that can correctly function even in harsh environments, we propose shifting the active illumination wavelengths from the visible range to the near infra-red (NIR) range, e.g. to 1550 nm. Lacking affordable image sensors fabricated in InGaAs technology, capable of detecting NIR radiation, in this paper we propose a hyperspectral imaging system using a very low power consuming single commercially available InGaAs photodiode to generate 2D images using the single-pixel imaging (SPI) approach based on compressive sensing (CS) and an array of NIR light emitting LEDs, combined with an 80 GHz millimeter band RADAR. The system is conceived to deliver a maximum radar range of 150 m with a maximum spatial resolution of ≤ 5 cm and a RADAR cross-section (RCS) of 10 – 50 m², combined with an optical system capable of generating 24 fps video streams based on SPI generated images yielding a maximum ranging depth of 10 m with a spatial resolution of < 1 cm. The proposed system will be used in unmanned ground vehicle (UGV) applications enabling decision making in continuous time. The power consumption, dimensions and weight of the hyperspectral ranging system will be adjusted to the UGV targeted applications.