Force-controlled robot system with visual sensor for performing fitting operation

• US 6,141,863 A
• Filed: 06/24/1998
• Issued: 11/07/2000
• Est. Priority Date: 10/24/1996
• Status: Expired due to Fees

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Ban, Kazunori, Hara, Ryuichi
• Primary Examiner(s): ROSENBAUM, IRENE CUDA
• Application Number:
  US09/091,730
• Time in Patent Office: 867 Days
• Field of Search: 29/407.04, 29/407.08, 29/407.09, 29/407.1, 29/702, 29/709, 29/720, 29/714, 29/718, 901/47
• US Class Current: 29/714
• CPC Class Codes: B25J 19/021 Optical sensing devices
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: B25J 9/1687 Assembly, peg and hole, palletising, straight line, weaving pattern movement
• CPC Class Codes: G05B 2219/37048 Split beam, stripe projection on object, lines detected with cameras
• CPC Class Codes: G05B 2219/39319 Force control, force as reference, active compliance
• CPC Class Codes: G05B 2219/39393 Camera detects projected image, compare with reference image, position end effector
• CPC Class Codes: G05B 2219/39529 Force, torque sensor in wrist, end effector
• CPC Class Codes: G05B 2219/40609 Camera to monitor end effector as well as object to be handled
• CPC Class Codes: Y10T 29/53061 Responsive to work or work-related machine element
• CPC Class Codes: Y10T 29/53078 with means to fasten by frictional fitting
• CPC Class Codes: Y10T 29/53087 with signal, scale, illuminator, or optical viewer

Abstract

A force-controlled robot system with a visual sensor capable of performing a fitting operation automatically with high reliability. A force sensor attached to a wrist portion of a robot detects force in six axis directions for force control, and transmits the results of detection to a robot controller. Position and orientation of a convex portion of a fit-in workpiece held by claws of a robot hand and position and orientation of a concave position of a receiving workpiece positioned by a positioning device are detected by a three-dimensional visual sensor including a structured light unit SU and an image processor in the robot controller, and a robot position to start an inserting action is corrected. Then, the convex portion is inserted into the concave portion under the force control. After the inserting action completes, it is determined whether or not the insertion state of the fit-in workpiece in the receiving workpiece is normal.

Claims

1. A force-controlled robot system for performing an operation of fitting a first workpiece into a second workpiece, comprising:

a robot having a robot hand for holding the first workpiece and a force sensor for detecting force applied to the first workpiece held by said robot hand;

a visual sensor for obtaining image data for obtaining relative position/orientation between said first workpiece and said second workpiece; and

a control means for controlling said robot and said visual sensor, said control means including a fitting action performing means for making said first workpiece held by said robot hand approach said second workpiece and performing a fitting action under force control based on an output from said force sensor, and a correcting means for obtaining workpiece position/orientation data representing the relative position/orientation between said first workpiece and said second workpiece based on image data obtained by said visual sensor, and for correcting position and orientation of said robot based on the obtained workpiece position/orientation data, in advance of said fitting action.

2. A force-controlled robot system according to claim 1, wherein said correcting means obtains said workpiece position/orientation data based on both of image data of said first workpiece and image data of said second workpiece obtained by said visual sensor.

5. A force-controlled robot system according to claim 1 wherein said correcting means corrects position and orientation of said robot based on comparison between said obtained workpiece position/orientation data and workpiece position/orientation data taught in advance to said control means.

6. A force-controlled robot system according to claim 1 wherein said correcting means obtains said workpiece position/orientation data based on at least one of image data of said first workpiece and image data of said second workpiece obtained at a holding state detecting position which is set in the vicinity of a position where said fitting action starts, and corrects position and orientation of said robot at said fitting action starting position.

3. A force-controlled robot system for performing an operation of fitting a first workpiece into a second workpiece, comprising:

a robot having a robot hand for holding the first workpiece and a force sensor for detecting force applied to the first workpiece held by said robot hand;

a visual sensor for obtaining image data for obtaining relative position/orientation between said first workpiece and said second workpiece; and

a control means for controlling said robot and said visual sensor, said control means including a fitting action performing means for making said first workpiece held by said robot hand approach said second workpiece and performing a fitting action under force control based on an output from said force sensor, a correcting means for obtaining workpiece position/orientation data representing the relative position/orientation between said first workpiece and said second workpiece based on image data obtained by said visual sensor and for correcting position and orientation of said robot based on the obtained workpiece position/orientation data in advance of said fitting action, and a discriminating means for obtaining fitting state data representing fitting state of said first workpiece in said second workpiece based on image data of the first and second workpieces obtained by said visual sensor and discriminating whether or not the fitting state is normal based on the obtained fitting state data after completing said fitting action.

4. A force-controlled robot system according to claim 3, wherein said correcting means obtains said workpiece position/orientation data based on both of image data of said first workpiece and image data of said second workpiece obtained by said visual sensor.