Miniature lightweight digital camera for robotic vision system applications

• US 4,727,471 A
• Filed: 08/29/1985
• Issued: 02/23/1988
• Est. Priority Date: 08/29/1985
• Status: Expired due to Fees

• Current Assignee: SGS-Thomson Microelectronics (STMicroelectronics NV)
• Original Assignee: Rhode Island Board of education (STATE OF RHODE ISLAND)
• Inventors: Collins, Edward A. Jr., Driels, Morris R.
• Primary Examiner(s): Ruggiero, Joseph
• Application Number:
  US06/770,710
• Time in Patent Office: 908 Days
• Field of Search: 364/513, 364/559, 364/560, 364/514, 364/525, 356/2, 356/3, 356/376, 358/88, 358/101, 358/91, 358/92, 358/107, 382/48, 382/46, 382/27, 382/19, 382/8, 250/558, 364/167, 364/191-193, 901/46, 901/47
• US Class Current: 700/66
• CPC Class Codes: B25J 19/023 including video camera means
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G06T 1/0014 Image feed-back for automatic industrial control, e.g. robot with camera robots B25J19/023

Abstract

A robot arm with a vision system affixed thereto. A gripper acquires and object at an acquisition site and carries the object to a target site. During travel the position of the object is determined by the vision system viewing the object in two positions.

Claims

1. A method of determining the location of an object in space said object having at least two identifiable features which includes:

(a) holding the object in a first position;

(b) recording a first image of the object by a vision system;

(c) rotating the object by a predetermined angle about a known axis;

(d) recording a second image of the object by the vision system, the vision system remaining fixed with reference to the rotation of the object from its first to its second position;

(e) determining which feature in the first image corresponds to the same feature in the second image in the image plane;

(f) calculating a vector, V_p, which describes the location of a point in the image plane corresponding to the feature with respect to a known frame of a robot;

which robot has a coordinate system; and

(g) expressing said location as a tool transform.

2. The method of claim 1 which includes:

determining the location of said feature with respect to the robot coordinate system after calculating the vector V_p.

3. The method of claim 1 which includes:

moving the object from an acquisition site to a target site while steps (a)-(g) are executed.

4. The method of claim 1 which includes:

recording the images using binary processing after recording said first and second images.

5. The method of claim 1 which includes:

establishing an inverse camera transform for a first camera;

reading the inverse camera transform from a memory; and

calculating the center of the vision system in reference to its recording the first image subsequent to calculating the vector V_p.

6. The method of claim 5 which includes:

calculating the forward transform of a second camera by manipulation of the appropriate transformation multiplier;

calculating subsequently the center of the vision system in reference to its recording the second image; and

determining the baseline vector V.

7. The method of claim 6 which includes:

determining the length of a ray, a, to an object point from a first image plane;

determining the length of a ray, b, to the object point from a second image plane; and

determining subsequently V_o the object point in space.

8. The method of claim 1 wherein the calculation of the vector V is effected with respect to a third frame of the robot.

9. A robot, having a robot coordinate system, for determining the location of an object in space, said object having at least two identifiable features which comprises:

means to hold the object in a first position;

means to record a first image of the object by a vision system;

means to rotate the object by a predetermined angle about a known axis;

means to record a second image of the object by the vision system, the vision system being fixed with reference to the rotation of the object from its first to its second position;

means to determine which feature in the first image corresponds to the same feature in the secon dimage in the image plane;

means to calculate a vector V_p which describes the location of the point in the image plane corresponding to the feature; and

means to express the feature as a tool transform.

10. The system of claim 9 which comprises:

means to determine the location of the feature with reference to the robot coordinate system.

11. The system of claim 9 which comprises:

means to move the object from an acquisition site to a target site while the object is held and rotated.

12. The system of claim 9 wherein the vision system comprises:

a housing;

a lens secured to the housing;

a sensor secured to the housing in optical communication with the lens, the element adapted to produce a binary image.