Apparatus for correcting movement path of a robot and a method therefor

• US 6,414,711 B2
• Filed: 04/29/1997
• Issued: 07/02/2002
• Est. Priority Date: 09/06/1995
• Status: Expired due to Term

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Akiyama, Kazuhiko, Arimatsu, Taro
• Primary Examiner(s): Le, Vu
• Assistant Examiner(s): VO, TUNG T
• Application Number:
  US08/836,059
• Publication Number:
  US 20010010539A1
• Time in Patent Office: 1,890 Days
• Field of Search: H04/N.718, H04/N.947, 348/86, 348/87, 348/88, 348/90, 348/94, 348/135, 348/152, 348/153, 348/154, 348/91, 348/92, 348/125, 348/129, 348/130, 356/394, 382/41, 382/106, 382/8, 364/513, 395/94, 318/568.13, 318/568.11, 901/47, 901/3
• US Class Current: 348/86
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 19/4083 Adapting programme, configuration
• CPC Class Codes: G05B 19/42 Recording and playback systems, i.e. in which the programme is recorded from a cycle of operations, e.g. the cycle of operations being manually controlled, after which this record is played back on the same machine
• CPC Class Codes: G05B 2219/36416 Adapt teached position as function of deviation 3-D, 2-D position of end effector, tool
• CPC Class Codes: G05B 2219/37567 3-D vision, stereo vision, with two cameras
• CPC Class Codes: G05B 2219/40589 Recognize shape, contour of tool
• CPC Class Codes: G05B 2219/40611 Camera to monitor endpoint, end effector position
• CPC Class Codes: G05B 2219/45083 Manipulators, robot

Abstract

A tool mounted on the wrist end of a robot is placed in a predetermined photographing position, and the front and side faces of the tool are photographed by cameras to obtain three-dimensional shape data of the tool. The extent of deformation of the tool is detected by comparing the obtained shape data and reference shape data, and a programmed movement path for the robot is corrected depending on the extent of deformation.

Claims

1. An apparatus for correcting a movement path of a robot, comprising:

a camera photographing a tool mounted on a wrist end of the robot, the robot operable in three dimensions;

an image processing apparatus obtaining shape data of the tool by processing images of said tool photographed by said camera and determining an extent of deformation of the tool by comparing the shape data with previously stored reference shape data; and

a robot control apparatus correcting deviation from a taught path of the robot based upon the extent of deformation of the tool determined in accordance with the shape data of the tool obtained by said image processing apparatus and controlling the robot to move along a corrected taught path, wherein the shape of the tool is recognized before starting operation by the robot and the deviation from the taught path attributable to the deformation of the tool is automatically corrected.

2. An apparatus for correcting movement path of a robot according to claim 1, wherein said robot control apparatus controls the robot to move the tool to a predetermined photographing position and transmit information indicating that said photographing position is reached by the tool to said image processing apparatus, while said image processing apparatus commands the camera to photograph said tool on receiving the information from the robot.

3. An apparatus for correcting movement path of a robot according to claim 1, wherein said image processing apparatus obtains three-dimensional shape data of the tool by receiving an image of one side face of the tool photographed by the camera and an image of another side face of the same tool perpendicular to the one side face.

4. An apparatus for correcting movement path of a robot according to claim 1, wherein said taught path is corrected in accordance with the shape data of the tool obtained by said image processing apparatus only when a difference between the tool shape and a reference tool shape obtained as a result of comparison thereof is not smaller than a predetermined value.

5. An apparatus for correcting movement path of a robot according to claim 1, wherein said image processing apparatus includes:

a tool shape recognizing device recognizing a shape of the tool from the images photographed by the camera,

a reference shape data storage device storing reference shape data of said tool, and

an error value computing device computing error values between the tool shape recognized by said tool shape recognizing device and the reference shape data stored in said reference shape data storage device.

6. A movement path correcting method for a robot, comprising:

locating a tool mounted on a wrist end of the robot and a camera for photographing said tool in predetermined relative positions, the robot operable in three dimensions;

fetching and processing images through the camera to obtain shape data of the tool from the processed image data;

comparing the obtained tool shape data with previously stored reference tool shape data to detect an extent of deformation of the tool; and

correcting a deviation from a path of the robot taught by a program in accordance with the result of the detection, wherein the shape of the tool is recognized before starting operation by the robot and the deviation from the taught path attributable to the extent of the deformation of the tool is automatically corrected.

7. A movement path correcting method for a robot according to claim 6, wherein said camera is placed in a fixed position, and said robot is controlled so that the tool is brought to a photographing position for the camera.

8. A movement path correcting method for a robot according to claim 6, wherein said camera photographs the front and side faces of the tool to obtain three-dimensional shape data of the tool from the two image data.