Position Estimation of Slowly Moving Obstacles Using Ultrasonic Sensor Array

We developed an obstacle position estimation system using ultrasonic sensors to obtain short-time and wide-range measurements for low-speed driving. We aligned the transmitter array vertically with the detection plane to create a fan-shaped horizontal beam that covered the target area in a single detection. The receivers are arrayed horizontally to the detection plane to estimate the obstacle's position. Each sensor's measured distance is assumed to have an error distribution, and the product of the probability density distributions of the measured distances is the obstacle's position. The observation results of a person walking at 5 km/h and car moving at 20 km/h using the proposed system are reported in this paper. Even though humans have a lower detection intensity and are more prone to measurement distance errors than automobiles, the proposed system could estimate distances exceeding 10 m within 2 m error in the x-axis direction.