Localization of a High-speed Mobile Robot Using Global Features

Source ： Proceedings of the 4th International Conference on Autonomous Robots and Agents, Feb 10-12,2009,Wellington,New ZealandAuthors ： SeungKeun Cho 、 TaeKyung Yang 、 MunGyu Choi and JangMyung Lee Speaker ：余俊瑩Advisor ：洪國寶 老師Date ： 99.03.09

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The relative localization : From the known initial position. The absolute localization : From sensors.

By multiplying the mobile robot’s speed with the processing time, which yields an unavoidable error in the localization.

To reduce this error, the processing time should be reduced.

For this new algorithm, one active beacon sensor and the global features of the mobile robot were utilized to reduce the processing time. 3

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(1)iGS system : a localize, beacons, and PC for user.

Localize: The Robot can select a specific beacon that has its own ID and position information during the

navigation by sending a desired beacon code via RF.

Beacons: Beacons receives its own ID from the localizer, it sends back an ultrasonic signal.To measure the distance from the beacon to the localizer using the time of flight (TOF)

PC: Through Bluetooth to draw the movement path of the mobile robot on the screen.

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(2) The distance by multiplying it by the velocity of the ultrasonic signal in the air. In the following equations:

= counter periodcT

dt = circuit delay in ultrasonic signal detection

n:Timer counters:The total ultrasonic signal transit time r:The distance from the active beacon to the localizer

ceTemperatur 24

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The location of the mobile robot, can be obtained as the intersection of the two circles

),( RR yx

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By delays in the ultrasonic wave propagation velocity and the movement of robot

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To accurately estimate the position of the robot, the final estimation can be derived from the intersection point with the distance from the beacon,d .

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High-speed area

Low-speed area

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With this algorithm, the sampling period of the localization wasreduced to half due to the use of only one beacon, and the error from the movement of the mobile robot was reduced.

This scheme also makes stable position estimation possible when only one beacon signal is received by an obstacle or an ultrasonic reflection.

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Thanks your attention