Method of detecting seam characteristic points

A method of detecting seam characteristic points of an object while sealing is performed by a robot equipped with a sensor, said method being characterized by comprising the steps of:

• measuring a distance to an arbitrary cross section of an object with the sensor;
• converting data obtained through said measurement into coordinate data of a series of distance points arranged in a predetermined order;
• calculating a statistic value regarding the distance between paired adjacent distance points among said series of distant points;
• obtaining a threshold level for judging discontinuity, based on said statistic value;
• comparing the distance between paired adjacent distance points with said discontinuity threshold level so as to detect a pair of adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level;
• counting the number of detected pairs, each pair including two adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level;
• when the total number of the counted pairs is one, obtaining, as a seam characteristic point, the center point between the detected pair of distance points separated from each other by a distance equal to or greater than said threshold level;
• and
• when the total number of the counted pairs is equal to or greater than two, obtaining, as a seam characteristic candidate point, the center point between each detected pair of distance points and calculating the center of gravity of said seam characteristic candidate points as a seam characteristic point.

A method of detecting seam characteristic points of an object, characterized by comprising the steps of:

• measuring a distance to an arbitrary cross section of an object with a sensor;
• converting data obtained through said measurement into coordinate data of a series of distance points arranged in a predetermined order;
• calculating a statistic value regarding the distance between paired adjacent distance points among said series of distant points;
• obtaining a threshold level for judging discontinuity, based on said statistic value;
• comparing the distance between paired adjacent distance points with said discontinuity threshold level so as to detect a pair of adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level;
• and
• obtaining the coordinates of a seam characteristic point of the object from the detected pair of adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level,
• wherein when a pair of distance points separated from each other by a distance equal to or greater than said threshold level is not detected, a preset model representing a curved shape is compared with the coordinate data of a series of distance points so as to determine a bend point and the coordinates of the bend point are used as the position of a seam characteristic point.

A method of detecting seam characteristic points of an object, characterized by comprising the steps of:

• measuring a distance to an arbitrary cross section of an object with a sensor;
• converting data obtained through said measurement into coordinate data of a series of distance points arranged in a predetermined order;
• calculating a statistic value regarding the distance between paired adjacent distance points among said series of distant points;
• obtaining a threshold level for judging discontinuity, based on said statistic value;
• comparing the distance between paired adjacent distance points with said discontinuity threshold level so as to detect a pair of adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level;
• and
• obtaining the coordinates of a seam characteristic point of the object from the detected pair of adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level,
• wherein said sensor is caused to follow an arbitrary cross section in the vicinity of a seam characteristic point of an object so as to successively calculate seam characteristic points, and when the position of a seam characteristic point is separated from a predicted position of the seem characteristic point, which is obtained from the positions of seam characteristic points previously measured, by a distance equal to or greater than a preset distance, it is judged that calculation cannot be performed.

A method of detecting seam characteristic points of an object, characterized by comprising the steps of:

• measuring a distance to an arbitrary cross section of an object with a sensor;
• converting data obtained through said measurement into coordinate data of a series of distance points arranged in a predetermined order;
• calculating a statistic value regarding the distance between paired adjacent distance points among said series of distant points;
• obtaining a threshold level for judging discontinuity, based on said statistic value;
• comparing the distance between paired adjacent distance points with said discontinuity threshold level so as to detect a pair of adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level;
• and
• obtaining the coordinates of a seam characteristic point of the object from the detected pair of adjacent distance points which are separated from each other by a distance equal to or greater than said threshold level,
• wherein there are further provided:
• first means for causing said sensor to follow an arbitrary cross section in the vicinity of a seam characteristic point of the object so as to successively calculate seam characteristic points, and for setting a range for processing coordinate data of a series of distance points such that a seam characteristic point obtained from coordinate data of a series of distance points which was measured at a previous time becomes the center of said range;
• and
• second means for setting the width of said range for processing based on the number of times of continuous successful detection of seam characteristic points previously obtained.