Omni-directional vision with a multi-part mirror
This paper presents an omni-directional sensor based on a camera and a mirror generated with a surface of revolution. The requirements the device must fulfill result from its use as the main perception system for the autonomous mobile robots used in F2000
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Abstract. This paper presents an omni-directional sensor based on a camera and a mirror generated with a surface of revolution. The requirements the device must fulfill result from its use as the main perception system for the autonomous mobile robots used in F2000 RoboCup competitions. The more relevant requirements which have been pursued are: 1) range sensing in a quite wide region centered around the robot, with good accuracy; 2) sensing around the robot in a given vertical sector, in order to recognize team-mates and adversaries (all robots have a colored marker above a given height); 3) range sensing in a region very close around the robot, with the highest accuracy, to locate and kick the ball. Such requirements have been fulfilled by the design of a mirror built up of three different parts. Each part is devoted to the fulfillment of one requirement. Concerning the first requirement the approach developed is based on the design of a mirror’s profile capable to optically compensate the image distortion provided by the mirror profiles commonly used in previous literature. This approach resulted to be similar to a previous work by Hicks and Bajcsy, although independently developed by the authors.
Introduction This work has been accomplished in the framework of the Italian participation to RoboCup [3]. For a more detailed introduction to RoboCup see [4]. A robot capable to compete in a F2000 RoboCup match (F2000 is the so called "middle-size" league, i.e. robots with a dimension of about 0.5 m per side) should be able to observe what happens on the playground in order to recognize and localize objects of interest for the game; e.g. robots, ball and goals. For the above-mentioned aims, an omni-directional vision sensor [6] seems appropriate (Fig. 1); actually this kind of sensing has been chosen by many teams participating to previous RoboCup competitions (e.g. [1][5]). An omni-directional vision sensor should satisfy the following constraints: 1. it must be able to observe around the robot, in the horizontal plane; 2. it must be able to observe the markers, which allow to distinguish team-mates from adversaries, independently from the robots position in the playground; this results in a constraint on the observed angular sector, in the vertical plane; 3. it should be able to perceive colors, because the objects can be distinguished by P. Stone, T. Balch, and G. Kraetzschmar (Eds.): RoboCup 2000, LNAI 2019, pp. 179-188, 2001. c Springer-Verlag Berlin Heidelberg 2001
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Fabio M. Marchese and Domenico G. Sorrenti
their colors (with the current rules all the relevant objects have quite different colors); 4. it must be able to locate the ball (direction and distance) with enough accuracy as follows: 4.1 when the ball is in contact or very near to the robot: very good accuracy, in order to properly control the kicking; 4.2 when the ball is within few meters from the robot: good accuracy and constancy of the accuracy in the range in order to control the motion to properly approach the ball itself; 4.3 when the bal
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