Real-Time 3-D Imaging Using an Air-Coupled Ultrasonic Phased-Array

Area of Science:

• Acoustics and Ultrasonics
• Signal Processing
• Robotics and Automation

Background:

• Traditional ultrasonic imaging systems often face limitations in real-time 3D localization, particularly in far-field applications.
• Achieving grating lobe-free beamforming with low-cost transducers requires innovative array configurations and signal processing techniques.

Purpose of the Study:

• To develop and characterize an air-coupled ultrasonic imaging system for 3D real-time localization of multiple objects.
• To enable adaptable imaging parameters for optimizing frame rate or detection range.

Main Methods:

• Utilized a 40-kHz 8x8 phased-array with waveguides to achieve half-wavelength interelement spacing for grating lobe-free beamforming.
• Implemented custom transceiver electronics, a field-programmable gate array (FPGA) system-on-chip, and GPU-accelerated signal processing (CUDA, OpenGL).
• Employed multiple transmit and receive methods, including hemispherical pulse (HP) transmission and dynamic transmit beamforming.

Main Results:

• Demonstrated real-time 3D object localization with a horizontal and vertical field of view of ±80° and a range of 0.5-3 m at 29 frames/s.
• Characterized imaging properties including axial and lateral resolution, field of view, and range of view in an anechoic chamber.
• Provided a comparative analysis of HP and dynamic transmit beamforming methods for different localization scenarios.

Conclusions:

• The developed air-coupled ultrasonic imaging system offers robust 3D real-time localization capabilities with adaptable imaging parameters.
• The system's design, incorporating waveguide-enhanced arrays and advanced signal processing, overcomes limitations of traditional ultrasonic systems.
• This technology holds potential for various applications requiring precise object detection and tracking in diverse environments.