US 5,617,335 A · System for and method of recognizating and tracking target mark

Abstract

A system for and a method of recognizing and tracking a target mark with a video camera is disclosed. The system includes a target mark (10) disposed on an object (1) and composed of a black circle and a white triangle mounted centrally on the black circle and three-dimensionally shifted from the black circle, a video camera (20) for imaging the target mark (10), a robot (30) supporting the video camera (20) and movable in directions with six degrees of freedom, an image processor (40) for processing image data of the target mark which is produced by the video camera (20), a shift calculating unit (50) for detecting a shift of the target mark (10) from projected histogram information of the target mark (10) which is produced by the image processor (40), and a robot controller (60) for controlling movement of the robot depending on the shift to enable the video camera (20) to track the target mark (10). The system is capable of tracking the target mark (20) attached to the object (1) on a real-time basis. Mark recognizing apparatus capable of accurately recognizing target marks of other shapes is also disclosed.

Claims20

Dependent claims

A target mark attitude detecting method of detecting the attitude of a target mark to detect the attitude of an object about the direction of a camera based on an image produced by the camera of a target mark which is composed of at least a triangle of a particular shape, comprising the steps of:

determining projected histograms in X and Y directions of the image of the triangle of said target mark;
determining the positions of the centers of gravity in the X and Y directions of the image of the triangle of said target mark in said projected histograms;
determining maximum histogram values and X- and Y-axis values in said projected histograms;
determining which of classified and preset attitude patterns the attitude of the triangle of said target mark belongs to based on the positions of the centers of gravity, the maximum histogram values, the X- and Y-axis values, and known geometrical data of said target mark;
and
calculating the attitude of the triangle of the target mark in the determined attitude pattern about the direction of the camera.

3 more elements

A position and attitude measuring apparatus for measuring the position and the attitude of an object based on an image of a target mark, comprising:

a target mark disposed on a particular flat surface of an object and composed of a circle and a central point thereof;
a camera for imaging said target mark to generate an image of the circle and the central point thereof;
feature extracting means for extracting feature points required to measure the position and attitude of said object, from the image of said target mark;
and
calculating means for calculating the position and attitude of said target mark in an object space according to projective geometrical calculations on said feature points.

2 more elements

A distance and attitude measuring apparatus for measuring the distance up to and the attitude of an object, comprising:

first through fourth disk-shaped marks mounted on an object and having respective centers of gravity positioned on one plane, at least one of said disk-shaped marks having a radius different from the radii of the other disk-shaped marks, said centers of gravity of said first through fourth disk-shaped marks being positioned on a first plane;
fifth and sixth disk-shaped marks disposed on a second plane which is different from said first plane;
imaging means for imaging the first through sixth disk-shaped marks;
first center-of-gravity calculating means for calculating the positions of the centers of gravity of said third and fourth disk-shaped marks based on image data of said third through sixth disk-shaped marks which are outputted by said imaging means, and projecting said fifth and sixth disk-shaped marks toward said imaging means to calculate the positions of the centers of gravity in respective projected figures on said first plane;
second center-of-gravity calculating means for calculating the positions of the centers of gravity of the disk-shaped marks based on image data of said first through fourth disk-shaped marks which are outputted by said imaging means;
and
calculating means for solving a four-point perspective problem to calculate the distance up to and the attitude of the object based on the four positions of the centers of gravity calculated by said first or second center-of-gravity calculating means.

4 more elements

Dependencies are inferred from the claim text.

System for and method of recognizating and tracking target mark

Life of this patent

System for and method of recognizating and tracking target mark

Life of this patent

Abstract

Claims20