Method of recognizing a screw hole and screwing method based on the recognition

• US 6,122,398 A
• Filed: 04/10/1996
• Issued: 09/19/2000
• Est. Priority Date: 04/11/1995
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Okumura, Kazumasa, Itsuzaki, Yoshihiro, Horikami, deceased, Kinji, Yokomae (nee Takano), Misuzu
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Werner, Brian P.
• Application Number:
  US08/632,725
• Time in Patent Office: 1,623 Days
• Field of Search: 382/141, 382/152, 382/153, 382/145, 382/151, 382/147, 382/100, 382/194, 382/204, 382/199, 382/282, 382/286, 382/289, 382/291, 348/86, 348/87, 348/94, 348/95, 250/559.29, 250/559.3, 250/559.33, 250/559.37, 250/559.42, 901/47, 901/46, 73/865.8, 29/407.01, 29/407.04, 29/407.09, 29/407.1, 29/407.05, 29/720, 29/721, 29/525.01, 29/525.11, 81/57.4
• US Class Current: 382/152
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: G06V 10/24 Aligning, centring, orientation detection or correction of the image
• CPC Class Codes: Y10T 29/49769 Using optical instrument [excludes mere human eyeballing]
• CPC Class Codes: Y10T 29/49778 with aligning, guiding, or instruction

Abstract

Deviation between an upper portion and a lower portion of a screw hole is recognized. This is accomplished by imaging holes in respective objects to obtain a contrast image. The position of the hole in the upper object and the lower object is detected. The deviation between the positions is calculated. Screws are tightened sequentially beginning with the hole having the smallest deviation. The rotation angle of the object to be tightened is determined. From this rotation angle, the deviation of other holes is calculated.

Claims

1. A method of recognizing deviation between all upper screw hole in an upper object and a lower screw hole in a lower object, comprising the steps of:

(a) imaging first and second upper holes in the upper object and corresponding first and second lower holes in the lower object to obtain a contrast image;

(b) setting a contour scanning circle of a contrast scanning window substantially equal to the circumference of the first and second upper holes in the upper object;

(c) scanning the contrast image of a portion of the first and second upper holes in the upper object with the contrast scanning window onto plural concentration correlation lines, each concentration line having a portion of concentration measuring points inside the contour scanning circle and outside the contour scanning circle, each measuring point measures a value of image concentration at the respective measuring point, each concentration line is to measure image concentration inside and outside of the contour scanning circle;

(d) calculating the absolute value of the difference between a total measured concentration value of the image concentration inside the contour scanning circle of a correlation line and a total measured concentration value of the image concentration outside the contour scanning circle of a correlation line at every concentration correlation line;

(e) detecting the positions where the absolute values calculated in step (d) is greater than a specified concentration threshold value, as the position of the first and second upper holes in the upper object,

(f) setting the scanning range of the contour scanning circle substantially equal to the circumference of the first and second lower holes in the lower object,

(g) detecting the position of the first and second lower holes in the lower object;

(h) calculating the deviation amount between the position of the first upper hole and first lower hole and between the second upper hole and second lower hole;

(i) calculating the rotation angle of either the upper object or lower object to be tightened to the respective other of the upper object or lower object;

(j) calculating the deviation between the upper screw hole and the lower screw hole based on the calculated deviation amounts and rotation angle; and

(k) inserting and tightening screws sequentially beginning with one of said holes in the upper object having a minimum deviation amount relative to a corresponding one of said holes in the lower object.

2. A method of recognizing deviation between a hole in an upper object and a hole in a lower object which when aligned form a screw hole according to claim 1, wherein futher screw holes are also recognized, further comprising the steps of:

tightening screws sequentially beginning with the screw of the minimum deviation.

3. A method of recognizing deviation between an existing upper screw hole in an upper object and an existing lower screw hole in a lower object comprising the steps of:

(a) obtaining the position of first and second upper holes in the upper object;

(b) obtaining the position of first and second lower holes in the lower object; and

(c) calculating the deviation amount between the positions of the first upper and lower holes and between the positions of the second upper and lower holes;

(d) calculating a rotation angle of one of the upper object or lower object to be tightened relative to the other of the upper object or lower object;

(e) calculating the deviation amount in the existing upper screw hole and the existing lower screw hole based on the calculated deviation amounts and rotation angle; and

(f) inserting and tightening screws sequentially beginning with one of said upper and lower holes of the minimum deviation amount.

4. A method of recognizing deviation between a hole in an upper object and a hole in a lower object which when aligned form at least one screw hole of claim 3, in which steps (a) and (b) include calculating the absolute value of the difference between a total measured concentration value of image concentration inside the contour scanning circle of a concentration correlation line and a total measured concentration value of the image concentration outside the contour scanning circle of the concentration correlation line.

5. A method of inserting a plurality of screws into a plurality of screw hole pairs which include corresponding first upper and lower holes, corresponding second upper and lower holes and corresponding further upper and lower holes contained in upper and lower objects, said method comprising the steps of:

a) detecting the position of said corresponding first upper and lower holes and the position of said corresponding second upper and lower holes;

b) determining deviation and rotation between said first upper and lower holes and said second upper and lower holes;

c) generating a deviation amount function based on deviation and rotation determined in step b);

d) applying said deviation amount function to a position of one of said further upper and lower holes to determine deviation between said further upper hole and said farther lower hole; and

e) inserting said plurality of screws into said plurality of screw hole pairs beginning with which of said first upper and lower holes, said second upper and lower holes and said further upper and lower holes has the least deviation.

6. A method of inserting a plurality of screws into a plurality of screw hole pairs according to claim 5, wherein said correction deviation amount function is based on translation and rotation of one of said upper and lower objects relative to the other of said upper and lower objects.