Estimation of object location and radius of curvature using ultrasonic sonar

Abstract

Acoustic sensors are very popular in time-of-¯ight (TOF) ranging systems since they are inexpensive and convenient to use. One of the major limitations of these sensors is their low angular resolution which makes object localization dicult. In this paper, an adaptive multisensor con®guration consisting of three transmitter/receiver ultrasonic transducers is introduced to compensate for the low angular resolution of sonar sensors and improve the localization accuracy. With this con®guration, the radius of curvature and location of cylindrical objects are estimated. Two methods of TOF estimation are considered: thresholding and curve-®tting. The bias-variance combinations of these estimators are compared. Theory and simulations are veri®ed by experimental data from a real sonar system. Extended Kalman ®ltering is used to smooth the data. It is shown that curve-®tting method, compared to thresholding method, provides about 30% improvement in the absence of noise and 50% improvement in the presence of noise. Moreover, the adaptive con®guration improves the estimation accuracy by 35±40%. #

Timed Trajectory Generation Combined with an Extended Kalman Filter for a Vision-Based Autonomous Mobile Robot

“…In mobile robotics the EKF has been extensively used e.g., to smooth data from ultrasonic sensors in order to estimate the location of objects [19] or in robotic arms catching a flying ball [20], [21] where a ball is launched towards to the robotic arm, and an EKF is used to track and to predict the position of the ball at each instant of time. EKFs have been also widely spread in the literature addressing target tracking.…”

Research of Long Range Accurate Ranging Technology Based on Ultrasonic Sensor Measurement

“…In reference [9] and reference [10] cross correlation method and phase shift method were combined to estimate the value of TOF, first calculated cross correlation function of the transmit and echo wave through cross correlation method to get the peak position of cross correlation function, and then detected phase shift of the transmit and echo wave through parabolic interpolation and phase shift method to decrease the measurement error of cross correlation method, so that more accurate TOF value was obtained. In reference [8], reference [11] and reference [12] TOF value was estimated by using of parabola fitting method, which was, taking the starting line of ultrasonic echo envelope as part of a parabola, and performing parameter fitting of the starting line on the basis of curve fitting idea to achieve more accurate echo starting position. In reference [13], different techniques and limitations of series of ultrasonic ranging methods were reviewed, and the accuracy and repeatability of the measurements were emphasized.…”

Estimating Vehicle Position Using Few Range Measurements to a Known Curved Surface

“…Similar work has been done by Madhavan and Durrant-Whyte [6] in which they navigate based on points of maximum curvature extracted from observed surfaces. Several other authors including Sekmen [7] have considered the problem of identifying the location and curvature of cylindrical targets from a mobile agent. Kondo and Ura also use curvature in [5] to track features with their AUV remaining at a desired relative heading.…”