Arc-transversal median algorithm: an approach to increasing ultrasonic sensor accuracy

Keiji Nagatami, Howie Choset, Nicole Lazar

Research output: Contribution to journalConference articlepeer-review

25 Scopus citations


This paper describes a new method for determining range information about a robot's surroundings using low resolution ultrasonic sensors. These sensors emit ultra-sound which bounces off of nearby objects and returns to the sensor. The time-of-flight for the sound to return to the sensor is the distance between the sensor and the object. A sonar arc represents the possible locations of the object. We model these locations with a simple uniform probability distribution on the sonar arc. We then introduce a new method to fuse sonar data to determine the actual obstacle location. This new method is termed the Arc-Transversal Median method because the robot determines the location of an object by intersecting one arc with other arcs whose angle-of-intersection exceeds a threshold and then taking the median of the intersection. The median is a robust estimator that is insensitive to noise because a few stray readings will not affect the median. We show via some simple geometric relationships, that this method can improve the accuracy of the sonar sensor by a specified amount, when certain assumptions were in place. Finally, experimental results on a real mobile robot verify this approach.

Original languageEnglish (US)
Pages (from-to)644-651
Number of pages8
JournalProceedings - IEEE International Conference on Robotics and Automation
StatePublished - 1999
EventProceedings of the 1999 IEEE International Conference on Robotics and Automation, ICRA99 - Detroit, MI, USA
Duration: May 10 1999May 15 1999

All Science Journal Classification (ASJC) codes

  • Software
  • Control and Systems Engineering
  • Artificial Intelligence
  • Electrical and Electronic Engineering


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