Industrial Robot And A Method For Adjusting A Robot Program

• US 20120143371A1
• Filed: 02/14/2012
• Published: 06/07/2012
• Est. Priority Date: 08/14/2009
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Technology Limited (ABB Ltd.)
• Inventors: Olofsson, Ake, Selnes, Tony
• Granted Patent: US 8,321,054 B2
• Time in Patent Office: Days
• US Class Current: 700/254
• CPC Class Codes: G05B 19/423 Teaching successive positions by walk-through, i.e. the tool head or end effector being grasped and guided directly, with or without servo-assistance, to follow a path
• CPC Class Codes: G05B 2219/35478 Set flexibility of axis in working coordinates, to move real axis manually easily
• CPC Class Codes: G05B 2219/36422 During teaching shut off, disable motor to move arm easy
• CPC Class Codes: G05B 2219/36425 Move manually, touch surface, record position
• CPC Class Codes: G05B 2219/36472 During teaching low servo power, during playback high servo power
• CPC Class Codes: G05B 2219/39054 From teached different attitudes for same point calculate tool tip position
• CPC Class Codes: G05B 2219/45104 Lasrobot, welding robot

Abstract

A method for adjusting a program including program instructions for controlling an industrial robot to carry out work at a plurality of target points on a work object. The robot includes a tool having two arms adapted to clamp the work object and at least one of the arms is arranged movable relative the other arm in an opening and a closing direction, a manipulator adapted to hold the tool or the work object, and a controller controlling the movements of the manipulator and the tool arm and configured to switch between a normal control mode and a compliant control mode in which the manipulator has a reduced stiffness in at least one direction. The method includes moving the manipulator and the tool according to the program instructions until one of the target points is reached.

Claims

1. A method for adjusting a program including program instructions for controlling an industrial robot to carry out work at a plurality of target points on a work object, the robot comprising:

a tool having two arms adapted to clamp the work object and at least one of the arms is arranged movable relative the other arm in an opening and a closing direction,

a manipulator movable about a plurality of axes and adapted to hold the tool or the work object, and

a controller controlling the movements of the manipulator and the movements of the tool arm and configured to switch between a normal control mode and a compliant control mode in which the manipulator has a reduced stiffness in at least one Cartesian direction, characterized in that the method comprises;

moving the manipulator and the tool according to the program instructions until one of the target points is reached,

switching the controller to the compliant control mode so that the manipulator has a reduced stiffness in said opening and closing direction of the tool,

moving the tool arm in the closing direction until the work object is clamped between the tool arms, by that moving the manipulator to the correct position in relation to the work object, and

storing the positions of the axes of the manipulator and the position of the tool when the work object is clamped between the tool arms, and adjusting the program instructions for the movements of the manipulator and the tool at the target point based on the stored positions.

2. The method according to claim 1, wherein the method further comprises:

switching the controller to the normal control mode,

moving the tool arm in the opening direction to a work position at a distance from the work object, and

repeating the steps of claim 1 for the next target point.

3. The method according to claim 1, wherein said tool is a welding gun and each of the arms is provided with a weld electrode.

4. The method according to claim 1, wherein each arm is provided with a tip, and the method comprises determining the distance between the tips when the tool arm is moved in the closing direction, and stopping the movement of the arm when the distance between the tips are equal to or slightly less than the thickness of the work object at the target point.

5. The method according to claim 1, wherein the method further comprises measuring the force on at least one of the tool arms and detecting when the work object is clamped between the tool arms based on the measured force.

6. A computer program product directly loadable into the internal memory of a computer, comprising software for performing a method for adjusting a program including program instructions for controlling an industrial robot to carry out work at a plurality of target points on a work object, the robot comprising:

a tool having two arms adapted to clamp the work object and at least one of the arms is arranged movable relative the other arm in an opening and a closing direction,

a manipulator movable about a plurality of axes and adapted to hold the tool or the work object, and

a controller controlling the movements of the manipulator and the movements of the tool arm and configured to switch between a normal control mode and a compliant control mode in which the manipulator has a reduced stiffness in at least one Cartesian direction, characterized in that the method comprises;

moving the manipulator and the tool according to the program instructions until one of the target points is reached,

switching the controller to the compliant control mode so that the manipulator has a reduced stiffness in said opening and closing direction of the tool,

moving the tool arm in the closing direction until the work object is clamped between the tool arms, by that moving the manipulator to the correct position in relation to the work object, and

storing the positions of the axes of the manipulator and the position of the tool when the work object is clamped between the tool arms, and adjusting the program instructions for the movements of the manipulator and the tool at the target point based on the stored positions.

7. A computer-readable medium, having a program recorded thereon, where the program is to make a computer perform, when said program is run on the computer, a method for adjusting a program including program instructions for controlling an industrial robot to carry out work at a plurality of target points on a work object, the robot comprising:

a tool having two arms adapted to clamp the work object and at least one of the arms is arranged movable relative the other arm in an opening and a closing direction,

a manipulator movable about a plurality of axes and adapted to hold the tool or the work object, and

a controller controlling the movements of the manipulator and the movements of the tool arm and configured to switch between a normal control mode and a compliant control mode in which the manipulator has a reduced stiffness in at least one Cartesian direction, characterized in that the method comprises;

moving the manipulator and the tool according to the program instructions until one of the target points is reached,

switching the controller to the compliant control mode so that the manipulator has a reduced stiffness in said opening and closing direction of the tool,

moving the tool arm in the closing direction until the work object is clamped between the tool arms, by that moving the manipulator to the correct position in relation to the work object, and

storing the positions of the axes of the manipulator and the position of the tool when the work object is clamped between the tool arms, and adjusting the program instructions for the movements of the manipulator and the tool at the target point based on the stored positions.

8. A method for programming a welding application by adjusting a program including program instructions for controlling an industrial robot to carry out work at a plurality of target points on a work object, the robot comprising:

a tool having two arms adapted to clamp the work object and at least one of the arms is arranged movable relative the other arm in an opening and a closing direction,

a manipulator movable about a plurality of axes and adapted to hold the tool or the work object, and

a controller controlling the movements of the manipulator and the movements of the tool arm and configured to switch between a normal control mode and a compliant control mode in which the manipulator has a reduced stiffness in at least one Cartesian direction, characterized in that the method comprises;

moving the manipulator and the tool according to the program instructions until one of the target points is reached,

switching the controller to the compliant control mode so that the manipulator has a reduced stiffness in said opening and closing direction of the tool,

moving the tool arm in the closing direction until the work object is clamped between the tool arms, by that moving the manipulator to the correct position in relation to the work object, and

storing the positions of the axes of the manipulator and the position of the tool when the work object is clamped between the tool arms, and adjusting the program instructions for the movements of the manipulator and the tool at the target point based on the stored positions.

9. An industrial robot comprising:

a tool having two arms adapted to clamp a work object and at least one of the arms is arranged movable relative the other arm in an opening and a closing direction,

a manipulator movable about a plurality of axes and adapted to hold the tool or the work object, and

a controller controlling the movements of the manipulator and the movements of the tool arm and configured to switch between a normal control mode and a compliant control mode in which the manipulator has a reduced stiffness in at least one Cartesian direction, and the controller is configured to receive a program including program instructions for controlling the robot to carry out work at a plurality of target points on a work object, wherein the robot comprises means for manually stepping through the program and running the instructions in the program one by one thereby causing the manipulator and the tool to move according to the program instructions, characterized in that the robot further comprises a target adjusting module for automatically adjusting the positions of the targets points and the target adjusting module is configured to upon activation switch the controller to the compliant control mode so that the manipulator has a reduced stiffness in said opening and closing direction of the tool, to move the tool arm in the closing direction until the work object is clamped between the tool arms, by that moving the manipulator to the correct position in relation to the work object, and to store the positions of the axes of the manipulator and the position of the tool when the work object is clamped between the tool arms, and to adjust the program instructions for the movements of the manipulator and the tool based on the stored positions.

10. The robot according to claim 9, wherein the target adjusting module is configured to switch the controller back to the normal control mode, and to move the tool arm in the opening direction to a work position at a distance from the work object.

11. The robot according to claim 9, wherein said tool is a welding gun and each of the arms is provided with a weld electrode.

12. The robot according to claim 9, wherein each arm is provided with a tip, and the target adjusting module is configured to determine the distance between the tips when the tool arm is moved in the closing direction, and to stop the movement of the arm when the distance between the tips are equal to or slightly less than the thickness of the work object at the target point.

13. The robot according to claim 9, wherein at least one of the tool arms is provided with a sensor for measuring the force on the arm and the target adjusting module is configured to detect when the work object is clamped between the tool arms based on the measured force.

14. The robot according to claim 9, wherein the robot comprises a portable operator control device for teaching and manually operating the robot, and the portable operator control device is configured to manually step through the program and to run the instructions in the program one by one, and the operator control device is provided with activation means which upon activation of a user starts execution of the target adjusting module.