Robotic machining with a flexible manipulator

• US 20060048364A1
• Filed: 09/06/2005
• Published: 03/09/2006
• Est. Priority Date: 09/08/2004
• Status: Active Grant

• Current Assignee: ABB Research Ltd. (ABB Ltd.)
• Original Assignee: ABB Research Ltd. (ABB Ltd.)
• Inventors: Zhang, Hui, Wang, Jianjun, Zhang, George, Gan, ZhongXue
• Granted Patent: US 9,110,456 B2
• Time in Patent Office: Days
• US Class Current: 29/407.80
• CPC Class Codes: B23Q 17/0966 by measuring a force on parts of the machine other than a motor
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: B25J 9/1641 compensation for backlash, friction, compliance, elasticity in the joints
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05B 2219/37319 Derive acceleration, force, torque from current
• CPC Class Codes: G05B 2219/37355 Cutting, milling, machining force
• CPC Class Codes: G05B 2219/42033 Kind of servo controller
• CPC Class Codes: G05B 2219/45068 Cutting robot
• CPC Class Codes: G05B 2219/49079 Control cutting torque, force
• CPC Class Codes: G05B 2219/49082 Maintain constant material removal rate
• CPC Class Codes: G05B 2219/49099 Cutting force, torque
• CPC Class Codes: Y10T 29/49776 Pressure, force, or weight determining
• CPC Class Codes: Y10T 29/53039 with control means energized in response to activator stimulated by condition sensor

Abstract

A robot machining with a flexible manipulator has an end effector which may either hold the tool to perform the machining or the work piece to be machined. A signal representative of a force applied by said tool to said work piece is used to control either the relative motion between the tool and the work piece to give a controlled material removal rate (CMRR) or the relative position between the tool or the work piece to provide deformation compensation or both CMRR and deformation compensation. A force sensor provides the signal for deformation compensation. For CMRR the signal may be obtained from either a force sensor or the current flowing in the motor of the robot'"'"'s spindle. The force sensor can be mounted either on the robot or together with either the tool or work piece adjacent to the robot.

Claims

1. In a system having a robot and a tool for machining a work piece a method for controlling said machining comprising:

obtaining a signal representative of a force applied by said tool to said work piece;

using said signal representative of a force applied by said tool to said work piece to control the relative motion between said work piece and said tool; and

using said signal representative of said force applied by said tool to said work piece to control the relative position between said tool and said work piece.

2. The method of claim 1 further comprising measuring said applied force and generating said signal representative thereof.

3. The method of claim 2 further comprising using a force sensor to measure said applied force.

4. The method of claim 3 further comprising mounting said force sensor either on said robot or together with said tool or work piece adjacent to said robot.

5. The method of claim 1 further comprising mounting a force sensor either on said robot or together with said tool or work piece adjacent to said robot to thereby provide said signal representative of said force applied by said tool to said work piece.

6. In a system having a robot and a tool for machining a work piece a method for controlling said machining comprising:

providing a signal representative of the force applied to said work piece by said tool; and

inferring from said signal representative of said force applied to said work piece by said tool the relative motion between said work piece and said tool.

7. The method of claim 6 further comprising using said signal representative of said force applied by said tool to said work piece to control the relative motion between said tool and said work piece.

8. The method of claim 6 wherein said signal representative of said force applied to said work piece by said tool is provided by a force sensor.

9. The method of claim 6 further comprising mounting a force sensor either on said robot or together with said tool or work piece adjacent to said robot to provide said signal representative of said force applied to said work piece by said tool.

10. The method of claim 6 wherein said robot has a spindle motor and said signal representative of said force applied to said work piece by said tool is provided using the current flowing in said spindle motor.

11. In a system having a robot and a tool for machining a work piece a method for controlling said machining comprising:

generating from a force sensor a signal representative of the force applied to said work piece by said tool; and

using said force sensor signal to control the relative position between said tool and said work piece.

12. The method of claim 11 further comprising mounting said force sensor either on said robot or together with said tool or work piece adjacent to said robot to provide said signal representative of said force applied to said work piece by said tool.

13. An industrial robot comprising:

a robot controller,

an end effector for holding either a tool or a work piece;

means for providing a signal representative of a force applied by said tool to said work piece;

said robot controller responsive to said signal representative of a force applied by said tool to said work piece to control either the relative motion between the work piece and said tool or the relative position between said work piece and said tool or both the relative motion between said work piece and said tool and the relative position between said work piece and said tool.

14. The industrial robot of claim 13 wherein said means for said signal representative of a force applied by said tool to said work piece is a force sensor.

15. The industrial robot of claim 14 wherein said force sensor is mounted either on said robot on robot or together with said tool or work piece adjacent to said robot.

16. The industrial robot of claim 13 wherein said robot controller only controls the relative motion between said tool and said work piece and said means for providing said signal representative of a force applied by said tool to said work piece provides said signal either from a force sensor or current flowing in a spindle motor of said industrial robot.

17. The industrial robot of claim 16 where said signal is provided from only said force sensor and said force sensor is mounted either on said robot or together with said tool or work piece adjacent to said robot.