Center of gravity sensing and adjusting load bar, program product, and related methods

• US 8,000,835 B2
• Filed: 05/10/2007
• Issued: 08/16/2011
• Est. Priority Date: 12/01/2006
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Bates, Mark R., Friz, Daniel C.
• Primary Examiner(s): Rodriguez; Saúl J
• Assistant Examiner(s): Vu; Stephen
• Application Number:
  US11/801,510
• Publication Number:
  US 20080131248A1
• Time in Patent Office: 1,559 Days
• Field of Search: 294/81.3, 294/67.21, 294/67.5, 340/685, 254/268, 254/269, 254/273, 254/275, 414/561, 414/138.3, 700/228, 700/229, 700/230
• US Class Current: 700/230
• CPC Class Codes: B66C 1/10 by mechanical means
• CPC Class Codes: B66C 13/04 Auxiliary devices for controlling movements of suspended loads, or preventing cable slack
• CPC Class Codes: B66C 13/08 for depositing loads in desired attitudes or positions
• CPC Class Codes: B66F 9/18 Load gripping or retaining means

Abstract

An apparatus, program product, and related methods for gravity stabilizing a suspended load are provided. The apparatus includes an center of gravity stabilized automated adjusting load bar in communication with a mobile cart which allows an operator to enable automated stabilization of a load. The adjusting load bar includes redundant first and second control and drive systems. A third control system can both monitor sensed data and the movement commands of first and second control systems, and can monitor the resulting physical movements. If a movement command and the resulting movement does not match or if there is an out of tolerance mismatch between movement commands of the first and the second control systems, the third control system can automatically detect this condition and shift into an emergency stop condition.

Claims

1. A method of lifting a load mass with an automated load bar, the method comprising the steps of:

receiving or accessing X and Y axis tilt data for X and Y axes from an associated one or more inclinometers or gyros;

deriving a control signal responsive to the X and Y axis tilt data to drive a pair of DC motors for a mechanical drive unit each associated with a separate one of the X and Y axes to thereby position an adjustable load bar carriage of the mechanical drive unit at a proper juxtaposition with respect to a center of gravity of a combination of the mechanical drive unit, a load mass being stabilized by the mechanical drive unit, and a spreader bar assembly when operatively positioned between the mechanical drive unit and the load mass, to thereby dampen any rotational tendencies and stabilize the mechanical drive unit; and

receiving or accessing current positioning of a plurality of drive screws to calculate a number of rotations of the pair of DC motors necessary to position the adjustable load bar carriage in the proper juxtaposition with the center of gravity.

2. A method of lifting a load mass with an automated load bar, the method Comprising the steps of:

receiving or accessing X and Y axis tilt data for X and Y axes from an associated one or more inclinometers or gyros;

deriving a control signal responsive to the X and Y axis tilt data to drive at least one motor for a mechanical drive unit to thereby position an adjustable load bar carriage of the mechanical drive unit at a proper juxtaposition with respect to a center of gravity of a combination of the mechanical drive unit, a load mass being stabilized by the mechanical drive unit, and a spreader bar assembly when operatively positioned between the mechanical drive unit and the load mass, to thereby dampen any rotational tendencies and stabilize the mechanical drive unit;

receiving or accessing a preselected tilt tolerance for each of the X and Y axes; and

ordering an emergency stop responsive to a tilt of the mechanical drive unit exceeding one or more of the preselected till tolerances.

3. A method of lifting a load mass with an automated load bar, the method comprising the steps of:

receiving or accessing X and Y axis tilt data from an associated one or more inclinometers or gyros;

deriving a control signal responsive to the X and Y axis tilt data to drive at least one motor for a mechanical drive unit to thereby position an adjustable load bar carriage of the mechanical drive unit at a proper juxtaposition with respect to a center of gravity of a combination of the mechanical drive unit, a load mass being stabilized by the mechanical drive unit, and a spreader bar assembly when operatively positioned between the mechanical drive unit and the load mass, to thereby dampen any rotational tendencies and stabilize the mechanical drive unit;

driving the adjustable load bar carriage of the mechanical drive unit simultaneously by each of a first and a second motion controller along a same axis to position the adjustable load bar carriage at the proper juxtaposition with respect to the center of gravity of the combination of the mechanical drive unit, the load mass, and the spreader bar assembly when operatively position therebetween; and

ordering an emergency stop responsive to a mismatch between output instructions of either of the first and second motion controllers, or responsive to a mismatch between an expected and an actual physical orientation of the mechanical drive unit.

4. A method of lifting a load mass with an automated load bar, the method comprising the steps of:

receiving or accessing X and Y axis tilt data from an associated one or more inclinometers or gyros;

deriving a control signal responsive to the X and Y axis tilt data to drive at least one motor for a mechanical drive unit to thereby position an adjustable load bar carriage of the mechanical drive unit at a proper juxtaposition with respect to a center of gravity of a combination of the mechanical drive unit, a load mass being stabilized by the mechanical drive unit, and a spreader bar assembly when operatively positioned between the mechanical drive unit and the load mass, to thereby dampen any rotational tendencies and stabilize the mechanical drive unit;

providing an XY display screen to display X and Y axis positions of the carriage, and pitch and roll orientation of the mechanical drive unit, and to display commanded X and Y axis movements of the carriage along with respective X and Y axis movement error; and

changing commanded X and Y axis positions of the carriage up to a preset limit by the operator using a joystick responsive to the provision of carriage position information provided on the display screen.

5. The method as defined in claim 4, further comprising the step of changing the commanded pitch and the roll orientation of the mechanical drive unit by the operator using the joystick responsive to the provision of mechanical drive unit orientation information provided on the display screen.

6. The method as defined in claim 5, further comprising the step of wirelessly communicating the position and orientation changes between a mobile cart and a mechanical drive unit controller.

7. The method as defined in claim 6, wherein the mobile cart includes a dead man'"'"'s switch, the method further comprising the steps of:

engaging the dead man'"'"'s switch during execution of all automated carriage positioning operations when the mechanical drive unit is interfaced with the load mass; and

releasing the dead man'"'"'s switch to immediately cease the automated carriage positioning operations.

8. A method of lifting a load mass with an automated load bar, the method comprising the steps of:

acquiring, by a first controller, automated load bar angular position data associated with a first axis from a first angular position sensor and angular position data associated with a second axis from a third angular position sensor;

acquiring, by a second controller, automated load bar angular position data associated with the first axis from a second angular position sensor and angular position data associated with the second axis from a fourth angular position sensor;

processing the automated load bar angular position data from the first and the second angular position sensors to thereby compare first axis angular position data acquired by the first controller with first axis angular position data acquired by the second controller to thereby detect a mismatch between the first axis angular position data acquired by the first controller and the first axis angular position data acquired by the second controller;

processing the automated load bar angular position data from the third and the fourth angular position sensors to thereby compare second axis angular position data acquired by the first controller with second axis angular position data acquired by the second controller to thereby detect a mismatch between the second axis angular position data acquired by the first controller and the second axis angular position data acquired by the second controller; and

disengaging automated load bar lift point correction functions responsive to either detecting a mismatch between the first axis angular position data acquired by the first controller and the first axis angular position data acquired by the second controller being outside a first preselected range, or detecting a mismatch between the second axis angular position data acquired by the first controller and the second axis angular position data acquired by the second controller being outside a second preselected range.

9. The method as defined in claim 8, wherein the second axis is substantially perpendicular to the first axis, the angular position data acquired from the second angular position sensor acquired independent of the data acquired from the first electronic angular sensor, the angular position data acquired from the fourth angular position sensor acquired independent of the data acquired from the third electronic angular sensor.

10. The method as defined in claim 9, wherein the first preselected range is equal to the second preselected range to provide a preset attitude value tolerance in both the first and the second axes.

11. The method as defined in claim 8, further comprising:

acquiring automated load bar angular position data from a fifth electronic angular sensor associated with the first axis and a sixth electronic angular sensor associated with the second axis;

processing the angular position data of the fifth electronic angular sensor by a third controller to thereby compare first axis angular position data acquired by the third controller from the fifth electronic angular sensor with first axis angular position data acquired by one or more of the first and the second controllers to thereby detect a mismatch between the first axis angular position data acquired by the third controller and the first axis angular position data acquired by the first or the second controllers;

processing the angular position data of the sixth electronic angular sensor by the third controller to thereby compare second axis angular position data acquired by the third controller from the sixth electronic angular sensor with second axis angular position data acquired by one or more of the first and the second controllers to thereby detect a mismatch between the second axis angular position data acquired by the third controller and the second axis angular position data acquired by the first or the second controllers; and

disengaging automated load bar lift point correction functions responsive to either detecting a mismatch between the first axis angular position data acquired by the third controller and the first axis angular position data acquired by either the first or the second controllers outside the first preselected range, or detecting a mismatch between the second axis angular position data acquired by the third controller and the second axis angular position data acquired by either the first or the second controllers outside the second preselected range.

12. A method of lifting a load mass with an automated load bar, the method comprising the steps of:

acquiring, by a first controller, mechanical linear actuator position feedback data associated with a first axis for a first mechanical linear drive actuator and position feedback data associated with a second axis for a third mechanical linear drive actuator;

acquiring, by a second controller, mechanical linear actuator position feedback data associated with the first axis for a second mechanical linear drive actuator and position feedback data associated with the second axis for a fourth mechanical linear drive actuator;

processing the mechanical linear actuator position feedback data for first and second mechanical linear actuators to thereby compare mechanical linear actuator position feedback data for the first mechanical linear actuator with the mechanical linear actuator position feedback data for the second linear actuator;

processing the mechanical linear actuator position feedback data for the third and the fourth actuators to thereby compare mechanical linear actuator position feedback data for the third mechanical linear actuator with the mechanical linear actuator position feedback data for the fourth linear actuator; and

disengaging automated load bar lift point correction functions responsive to either detecting a mismatch between mechanical linear actuator position feedback data outside a first preselected range for either of the first and the second mechanical linear actuators, or detecting a mismatch between the mechanical linear actuator position feedback data outside a second preselected range for either of the third and the fourth mechanical linear actuators.

13. The method as defined in claim 12, wherein the position feedback data for the second mechanical linear drive actuator is independent of the position feedback data for the first mechanical linear drive actuator, and wherein the position feedback data for the fourth mechanical linear drive actuator is independent of the position feedback data for the third mechanical linear drive actuator.

14. The method as defined in claim 13,

wherein the first preselected range is equal to the second preselected range to provide a preset load bar attitude value tolerance in both the first and the second axis;

and

wherein the method further comprises the step of selecting one of a plurality of preset attitude values defining the first and the second preselected ranges.

15. A method of lifting a load mass with an automated load bar, the method comprising the steps of:

acquiring automated load bar angular position data from a first electronic angular sensor and a second electronic angular sensor, the angular position data for the second electronic angular sensor acquired independent of the data acquired from the first electronic angular sensor;

processing the angular position data of the first electronic angular sensor by a first controller to thereby drive a first mechanical linear drive actuator; and

processing the angular position data of the second electronic angular sensor by a second controller to thereby drive a second mechanical linear drive actuator, the second mechanical linear drive actuator operating in parallel with the first mechanical linear drive actuator to provide redundant mechanical linear drive control to thereby continuously maintain a substantially level orientation along a first axis during a lift operation.

16. The method as defined in claim 15, further comprising the steps of:

processing position feedback from a position encoder associated with each separate mechanical linear drive to verify that movement of each of said respective mechanical linear drive actuators matches associated controller drive movement commands; and

disengaging automated load bar lift point correction functions responsive to either the first or the second controller detecting a mismatch outside a preselected range between an associated controller drive movement command and the position feedback for either of said respective mechanical linear drive actuators.

17. The method as defined in claim 15, further comprising the steps of:

acquiring automated load bar angular position data from a third electronic angular sensor and a fourth electronic angular sensor, the angular position data for the fourth electronic angular sensor acquired independent of the data acquired from the third electronic angular sensor;

processing the angular position data of the third electronic angular sensor by a first controller to thereby drive a third mechanical linear drive actuator; and

processing the angular position data of the fourth electronic angular sensor by a second controller to thereby drive a fourth mechanical linear drive actuator, the fourth mechanical linear drive actuator operating in parallel with the third mechanical linear drive actuator to provide redundant mechanical linear drive control to thereby continuously maintain a substantially level orientation along a second axis during the lift operation, the combination of the first and second linear drive actuators operating in parallel with each other and the third and fourth linear drive actuators operating in parallel with each other to provide two-axis positioning for automated load bar lift point correction relative to a center of gravity of the load mass being lifted.

18. The method as defined in claim 17, further comprising the steps of:

acquiring automated load bar angular position data from a fifth electronic angular sensor associated with the first axis and a sixth electronic angular sensor associated with the second axis;

processing the angular position data of the fifth electronic angular sensor by a third controller to thereby compare first axis angular position data acquired by the third controller from the fifth electronic angular sensor with first axis angular position data acquired by one or more of the first and the second controllers to thereby detect a mismatch between the first axis angular position data acquired by the third controller and the first axis angular position data acquired by the first or the second controllers;

processing the angular position data of the sixth electronic angular sensor by the third controller to thereby compare second axis angular position data acquired by the third controller from the sixth electronic angular sensor with second axis angular position data acquired by one or more of the first and the second controllers to thereby detect a mismatch between the second axis angular position data acquired by the third controller and the second axis angular position data acquired by the first or the second controllers; and

disengaging automated load bar lift point correction functions responsive to either detecting a mismatch outside a preselected range between the first axis angular position data acquired by the third controller and the first axis angular position data acquired by either the first or the second controllers, or detecting a mismatch outside a preselected range between the second axis angular position data acquired by the third controller and the second axis angular position data acquired by either the first or the second controllers.