Air-Coupled FMCW Ultrasonic Sensor for High-Resolution 3-D Perception

As seamless object detection and localization are getting important in emerging systems, such as autonomous vehicles, robots, and extended reality devices, numerous 3-D depth sensors have been developed. However, most of those sensors have focused more on far-distance applications, leaving near-field, including less than 50 cm, as a task for a conventional ultrasonic (US) sensor. Even though the conventional US sensor has many advantages, including object detection in near field, it has limited capability on localizing objects and providing 3-D point cloud preventing itself from further applications. In order to overcome these limitations, multi-input–multi-output (MIMO) frequency-modulated continuous wave (FMCW) method is adopted and demonstrated in this letter. Presented computer simulation implies the US 3-D object detection with 2.3 mm depth resolution and 0.6° angular resolution preserving its minimum detection range lower than 5 cm and field of view (FoV) wider than 160°. A novel MIMO US FMCW sensor system composed of commercially available components is implemented and evaluated. For 16 cm ∼ 2 m range, the proposed system shows fair depth and angular resolution (5.5 mm and 2.6°) at low sampling rate (overall 480 kHz). This letter suggests that ultrasound can be a new modality capable of providing near field 3-D point cloud at low system requirement.