UWB Radar sensor characterization for obstacle detection with application to the smart white cane

L. Ouvry (1) , O. Debicki (1) , Suzanne Lesecq (1) , J Foucault (1)

1 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information

Obstacle detection capability is of great interest in application domains such as navigation of Visually Impaired and Blind people. To perform free-space assessment over the whole person height, range sensors are usually placed on a white cane and their measurements are analyzed to provide feedback about potential harmful obstacles. Thanks to technology progress both at hardware and software levels, integration of such obstacle detection capabilities in a white cane seems conceivable. It is well admitted that ultra-sonic range sensors have limited sensing range (typically < 3 m) and difficulties of operating on highly reflective surfaces [1]. Laser-based solutions can be highly sensitive to ambient natural light and identification of transparent or mirror-like surfaces is difficult. RF Radar range sensor performance is affected by the electromagnetic backscattering characteristics of the obstacle (Radar Cross Section). The electromagnetic response is in general very different from the mechanical response to ultrasound waves or optical response to LiDAR. [2] shows that Ultra-Wide-Band (UWB) radar can be used effectively to detect obstacles under rain, snow, fog and smoke, thus being complementary to LiDAR. Therefore, to overcome limitations of each range sensor technology, Ultra-Sound, UWB RF Radar and LiDAR will be co-integrated in the obstacle detection system the H2020 INSPEX project is targeting (Fig. 1) [3]. This work details the characterization and future enhancements of the UWB RF Radar developed in the course of the project. The complete system should not exceed 200gr in weight and 100cm3 in volume. Ten hours of lifetime in continuous use are expected with an initial target for power consumption smaller than 500mW. The obstacles could move at an unpredictable speed and direction and the system should detect reliably objects moving at a speed of ~1.4 m/s worst case (relative speed between the user and the objects) and be able to detect obstacles up to a distance of 4m. After a static characterization phase of the UWB Radar, measurements were performed in mobility conditions. The Radar is placed on a cart moving linearly towards the obstacle with a colliding trajectory. The relative radial speed is about-0.15m/s. The right drawing in Fig 1 shows the Radar response over time with three snapshots in the speed domain. The top left curve clearly shows the “approaching” obstacle wave-front while the three other curves show how the speed can be exploited in colliding trajectories detection.

Domaines: Sciences de l'ingénieur [physics]; Micro et nanotechnologies/Microélectronique; Traitement du signal et de l'image [eess.SP]

L. Ouvry, O. Debicki, Suzanne Lesecq, J Foucault. UWB Radar sensor characterization for obstacle detection with application to the smart white cane. 12th Smart Systems Integration Conference 2018, Apr 2018, Dresden, Germany. pp.311. ⟨cea-02075781⟩