Automated work piece center of mass identification system and method for same

Patent metadata

Field	Value
Publication number	US-9897507-B2
Application number	US-201514689125-A
Country	US
Kind code	B2
Filing date	Apr 17, 2015
Priority date	Apr 17, 2015
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

A method and system for identifying a work piece center of mass includes coupling a work piece to a manipulator assembly. The manipulator assembly includes a force and torque sensor. The work piece is positioned in at least two different orientations relative to a gravity vector with the manipulator assembly. The at least two different orientations include at least first and second orientations. In the first orientation the force and torque sensor measures a first torque and at least a first force associated with the work piece in the first orientation. In the second orientation the force and torque sensor measures a second torque associated with the work piece in the second orientation. The work piece center of mass is identified according to at least the measured first and second torques and at least the first force.

First claim

What is claimed is:

1. A method for automatically identifying a work piece center of mass comprising:
coupling a work piece to a manipulator assembly, the manipulator assembly includes a force and torque sensor configured to measure force and torque transmitted from the work piece to the manipulator assembly;
positioning the work piece in at least two different orientations relative to a gravity vector with the manipulator assembly; the at least two different orientations include at least first and second orientations, wherein
in the first orientation the force and torque sensor measures a first torque and at least a first force associated with the work piece in the first orientation; and
in the second orientation the force and torque sensor measures a second torque associated with the work piece in the second orientation; and

identifying the work piece center of mass according to at least the measured first and second torques and at least the first force.

2. The method of claim 1 , wherein the manipulator assembly includes a manipulator arm, and
positioning the work piece in at least two different orientations with the manipulator assembly includes positioning the work piece with the manipulator arm.

3. The method of claim 2 comprising coupling an effector assembly including the force and torque sensor with the manipulator arm, and wherein coupling the work piece to the manipulator assembly includes coupling the effector assembly with the work piece.

4. The method of claim 1 , wherein positioning the work piece in at least two different orientations includes positioning the work piece in three or more different orientations, the three or more different orientations including the first and second orientations and a third orientation,
in the third orientation the force and torque sensor measures a third torque associated with the work piece in the third orientation, and
identifying the work piece center of mass includes identifying the work piece center of mass according to at least the measured first, second and third torques and at least the first force.

5. The method of claim 1 , wherein positioning the work piece in at least two different orientations is included with moving the work piece between first and second pieces of equipment in one or more of an assembly line or a testing line with the manipulator assembly.

6. The method of claim 1 comprising reconfiguring the work piece into a second configuration with a work piece second center of mass, and
repeating positioning of the work piece in at least two different orientations with the work piece in the second configuration to measure first and second updated torques and at least one updated force, and
identifying the work piece second center of mass according to least the measured first and second updated torques and the at least one updated force.

7. The method of claim 1 , wherein positioning the work piece in at least two different orientations includes positioning relative to first, second and third axes:
positioning the work piece in the first orientation with a zero moment around the first axis to align the work piece center of mass with one of the second or third axes; and
positioning the work piece in the second orientation with a zero moment around the second axis to align the work piece center of mass with one of the first or third axes different from the second axis.

8. The method of claim 7 , wherein in the first orientation measuring the first torque and at least the first force includes:
measuring a weight with the force and torque sensor,
measuring the first torque around one of the third or second axes unaligned with the work piece center of mass, and
wherein in the second orientation measuring the second torque includes measuring the second torque around one of the third or first axes unaligned with the work piece center of mass.

9. The method of claim 8 , wherein identifying the work piece center of mass includes:
determining a first location of the work piece center of mass along the first axis based on the measured first torque and the measured weight,
determining a second location of the work piece center of mass along the second axis based on the measured second torque and the measured weight, and
indexing the work piece center of mass according to the determined first and second locations.

10. The method of claim 1 , wherein in the second orientation the force and torque sensor measures the second torque and a second force, and
identifying the work piece center of mass according to at least the measured first and second torques and at least the first force includes identifying the work piece center of mass according to at least the measured first and second torques and at least the first and second forces.

11. A system configured for manipulation of a work piece and determination of a work piece center of mass comprising:
a manipulator assembly, the manipulator assembly including a work piece interface configured to grasp and hold a work piece while the manipulator assembly moves the work piece into at least two different orientations;
a force and torque sensor coupled with the manipulator assembly, the force and torque sensor configured to measure force and torque transmitted from the work piece to the manipulator assembly; and
a center of mass determination module in communication with the manipulator assembly and the force and torque sensor, the center of mass determination module includes:
a manipulation element, the manipulation element configured to move the manipulator assembly and the work piece into the at least two different orientations relative to a gravity vector,
a force and torque measurement element configured to measure the force and torque of the work piece at each of the at least two different orientations with the force and torque sensors, and
an identification element in communication with the force and torque measurement element, the identification element configured to identify the work piece center of mass according to force and torque measurements conducted with the work piece at the at least two different orientations.

12. The system of claim 11 , wherein the manipulator assembly includes a manipulator arm.

13. The system of claim 12 , wherein the manipulator assembly includes at least one effector assembly configured for coupling with the manipulator arm, and the at least one effector assembly includes the force and torque sensor.

14. The system of claim 13 , wherein the effector assembly transitions between at least two effector configurations:
in a first configuration the manipulator arm is coupled with the effector assemblya manipulator interface of the effector assembly, and
in a second configuration the effector assembly coupled with the manipulator ami is coupled with the work piece at a work piece interface of the effector assembly with a mechanical latch of the effector assembly.

15. The system of claim 14 , wherein the mechanical latch includes pneumatic operated fasteners.

16. The system of claim 13 , wherein the effector assembly includes a data and power link in communication with the center of mass determination module, the data and power link configured to provide power and data communication between the force and torque sensor and the center of mass determination module.

17. The system of claim 12 , wherein the manipulator assembly includes a plurality of effector assemblies selectively coupled with the manipulator arm, each of the effector assemblies including respective force and torque sensors, the respective force a

Assignees

• Raytheon Co

Inventors

• Vulcano Anthony R

Classifications

• G01M1/122 Primary

  Determining position of centre of gravity · CPC title

• B25J11/00

  Manipulators not otherwise provided for · CPC title

• Y10S901/44

  inspection · CPC title

• B25J13/085

  Force or torque sensors (B25J13/082, B25J13/084 take precedence) · CPC title