Three-Dimensional Ultrasound Imaging in Air for Parking and Pedestrian Protection

Acoustic imaging has been used in a variety of applications, but its use in air has been limited due to the slow propagation of sound and high attenuation. We address the problem of obstacle detection in a scene using ultrasound imaging with a 2D array under the constraint of a fixed platform. Applications are in the area of autonomous navigation such as a parking car as well as pedestrian detection for pre-crash measures of crash avoidance. The presented system uses a single transmit pulse combined with a beamformer at the receiving array based on a near-field model to obtain 3D images of a scene. Results from experiments conducted in a laboratory demonstrate that it is possible to detect position and edge information from which an object can be reconstructed. Additionally, echo characteristics change with respect to surface texture. Thus, ultrasound arrays can be employed in cars to augment short-range applications.