Airborne 3D imaging using ultrasound is a promising sensing modality for robotic applications in harsh environments. Over the last decade, several high-performance systems have been proposed in the literature. Most of these sensors use a reduced aperture microphone array, leading to artifacts in the resulting acoustic images. This paper presents a novel in-air ultrasound sensor that incorporates 1024 microphones, in a 32-by- 32 uniform rectangular array, in combination with a distributed embedded hardware design to perform the data acquisition. Using a broadband Minimum Variance Distortionless Response (MVDR) beamformer with Forward-Backward Spatial Smoothing (FB-SS), the sensor is able to create both 2D and 3D ultrasound images of the full-frontal hemisphere with high angular accuracy with up to 70dB main lobe to side lobe ratio. This paper describes both the hardware infrastructure needed to obtain such highly detailed acoustical images, as well as the signal processing chain needed to convert the raw acoustic data into said images. Utilizing this novel high-resolution ultrasound imaging sensor, we wish to investigate the limits of both passive and active airborne ultrasound sensing by utilizing this virtually artifact-free imaging modality.

翻译：利用超声波进行空中三维成像是一种适用于恶劣环境下机器人应用的有前景的感知模态。过去十年中，文献中提出了多种高性能系统。这些传感器大多采用小孔径麦克风阵列，导致生成的声学图像出现伪影。本文提出了一种新型空中超声波传感器，该传感器集成1024个麦克风，构成32×32均匀矩形阵列，并结合分布式嵌入式硬件设计进行数据采集。通过使用具有前向-后向空间平滑的宽带最小方差无失真响应波束形成器，该传感器能够以高达70dB的主瓣与旁瓣比生成全正面半球的高精度二维及三维超声图像。本文详细描述了获取此类高细节声学图像所需的硬件基础设施，以及将原始声学数据转换为上述图像的信号处理流程。利用这一新型高分辨率超声波成像传感器，我们期望通过这种近乎无伪影的成像模态，探索被动与主动空中超声波感知的极限。