Method and system for load measurement in a crane hoist

• US 6,527,130 B2
• Filed: 02/16/2001
• Issued: 03/04/2003
• Est. Priority Date: 02/16/2001
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Ruddy, Thomas A.
• Primary Examiner(s): Brahan, Thomas J.
• Application Number:
  US09/784,920
• Publication Number:
  US 20020144968A1
• Time in Patent Office: 746 Days
• Field of Search: 212/270, 212/275, 212/278, 340/685, 318/432
• US Class Current: 212/278
• CPC Class Codes: B66C 13/16 Applications of indicating, registering, or weighing devices in crane hooks B66C1/40; in safety gear B66C15/00; weighing-apparatus G01G; remote indicating in general G08
• CPC Class Codes: B66D 1/46 electric

Abstract

The invention provides a load measurement in a crane hoist system. A parameter adaptation process uses a model of the system in order to measure the lifted load. A controller monitors hoist speed and hoist torque feedbacks that are input into the model and processed using a filter, as well as a previously determined load value. The model adapts automatically to determine the weight of the lifted load.

Claims

1. A method for determining the load value of a lifted load in a hoist system, comprising:

determining a speed feedback value from the hoist system;

filtering the speed feedback value using a filter to provide a filtered speed feedback value;

determining a torque feedback value from the hoist system;

filtering the torque feedback value using the filter to provide a filtered torque feedback value;

inputting a previously determined load value;

comparing values, including comparing the speed feedback value, the filtered speed feedback value, the filtered torque feedback value and the previously determined load value to determine an error value; and

determining a measured load value based on the error value.

2. The method according to claim 1, wherein the comparing includes the steps of:

determining the difference between the speed feedback value and the filtered speed feedback value to obtain an adjusted speed value;

determining the difference between the previously determined load value and the filtered torque feedback value to obtain an adjusted torque value; and

determining the difference between the adjusted speed value and the adjusted torque value to determine the error value.

3. The method according to claim 1, the method further including:

determining a loss torque value; and

determining an inertia value; and

wherein the step of comparing values further includes comparing the loss torque value and the inertia value with the speed feedback value, the filtered speed feedback value, the filtered torque feedback value and the previously determined load value.

4. The method according to claim 3, wherein the comparing includes the steps of:

determining the difference between the speed feedback value and the filtered speed feedback value to obtain an adjusted speed value;

determining the difference between the filtered torque feedback value and a summation of the previously determined load value and the loss torque value to obtain a processed torque value;

processing the processed torque value using the inertia value to determine an adjusted torque value; and

determining the difference between the adjusted speed value and the adjusted torque value to determine the error value.

5. The method according to claim 1, wherein the filtered torque feedback value is defined as:

$T_f=\frac{\mathrm{\lambda <br><br>}}{s+\mathrm{\lambda <br><br>}}·<br><br>T<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{where};<br><br>$

T_f=filtered torque feedback value;

T=torque feedback value;

λ

=filter cutoff frequency; and

s=Laplace operator.

6. The method according to claim 1, wherein the filtered speed feedback value is defined as:

${\mathrm{sfb}}_f=\frac{\mathrm{\lambda <br><br>}}{s+\mathrm{\lambda <br><br>}}·<br><br>\mathrm{sfb}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{where};<br><br>$

sfb_f=filtered speed feedback value;

sfb=speed feedback value;

λ

=filter cutoff frequency; and

s=Laplace operator.

7. The method according to claim 1, wherein the filtered torque feedback value is defined as:

$T_f=\frac{\mathrm{\lambda <br><br>}}{s+\mathrm{\lambda <br><br>}}·<br><br>T<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{where};<br><br>$

T_f=filtered torque feedback value;

T=torque feedback value;

λ

=filter cutoff frequency; and

s=Laplace operator

and the filtered speed feedback value is defined as;

${\mathrm{sfb}}_f=\frac{\mathrm{\lambda <br><br>}}{s+\mathrm{\lambda <br><br>}}·<br><br>\mathrm{sfb}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{where};<br><br>$

sfb_f=filtered speed feedback value;

sfb=speed feedback value;

λ

=filter cutoff frequency; and

s=Laplace operator.

8. The method according to claim 7, wherein the Laplace operator represents information from at least one previous measured load value determination.

9. The method of claim 1, further including comparing the measured load value to a threshold value to determine a slack cable condition.

10. The method of claim 1, further including comparing the measured load value to a threshold overload value to determine an overload condition.

11. The method of claim 1, further including comparing the measured load value to a threshold value to determine a snagged load condition.

12. The method of claim 1, wherein the step of determining a measured load value based on the error value is performed using an adjustable gain.

13. A method for determining the load value of a lifted load in a hoist system, comprising:

determining a speed feedback value from the hoist system;

processing the speed feedback value including using a filter to filter the speed feedback value to provide a filtered speed feedback value, the processing further including comparing the filtered speed feedback value with the speed feedback value to provide an acceleration value;

determining a torque feedback value from the hoist system;

determining a loss torque value and an inertia value from the hoist system;

inputting a previously determined load value;

processing the torque feedback value including using the filter to provide a filtered torque feedback value, the processing further including adjusting the filtered torque feedback value using the loss torque value, the previously determined load value, and the inertia value to determine an adjusted filtered torque feedback value;

comparing the acceleration value with the adjusted filtered torque feedback value to determine an error value; and

determining a measured load value based on the error value.

14. The method according to claim 13, wherein the filter includes a Laplace operator that represents information from at least one previous speed feedback value determination.

15. The method of claim 13, further including comparing the measured load value to a threshold value to determine a slack cable condition.

16. The method of claim 13, further including comparing the measured load value to a threshold overload value to determine an overload condition.

17. The method of claim 13, further including comparing the measured load value to a threshold value to determine a snagged load condition.

18. The method of claim 13 wherein determining the measured load value based on the error value includes:

determining a measured load torque value; and

converting the measured load torque value to the measured load value.

19. The method of claim 18, wherein determining the measured load torque value based on the error value includes using an integrator to convert the error value to the measured torque value.

20. The method of claim 13, further including the step of associating the measured load value to a speed reference scale factor, the speed reference scale factor controlling the speed at which the load is lifted.

21. The method of claim 20, wherein the step of associating the measured load value to a speed reference scale factor is performed using a speed versus load curve.

22. A hoist system for determining the load value of a lifted load in a hoist system, comprising:

means for determining a speed feedback value from the hoist system;

means for filtering the speed feedback value using a filter to provide a filtered speed feedback value;

means for determining a torque feedback value from the hoist system;

means for filtering the torque feedback value using the filter to provide a filtered torque feedback value;

means for inputting a previously determined load value;

means for comparing values, including comparing the speed feedback value, the filtered speed feedback value, the filtered torque feedback value and the previously determined load value to determine an error value; and

means for determining a measured load value based on the error value.

23. The hoist system according to claim 22, wherein the means for comparing:

determines the difference between the speed feedback value and the filtered speed feedback value to obtain an adjusted speed value;

determines the difference between the previously determined load value and the filtered torque feedback value to obtain an adjusted torque value; and

determines the difference between the adjusted speed value and the adjusted torque value to determine the error value.

24. The hoist system according to claim 22, the method further including:

means for determining a loss torque value; and

means for determining an inertia value; and

wherein the means for comparing compares the loss torque value and the inertia value with the speed feedback value, the filtered speed feedback value, the filtered torque feedback value and the previously determined load value.

25. The hoist system according to claim 22, wherein means for determining the filtered torque feedback value uses the relationship:

$T_f=\frac{\mathrm{\lambda <br><br>}}{s+\mathrm{\lambda <br><br>}}·<br><br>T<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{where};<br><br>$

T_f=filtered torque feedback value;

T=torque feedback value;

λ

=filter cutoff frequency; and

s=Laplace operator.

26. The hoist system according to claim 22, wherein the means for determining the filtered speed feedback value uses the relationship:

${\mathrm{sfb}}_f=\frac{\mathrm{\lambda <br><br>}}{s+\mathrm{\lambda <br><br>}}·<br><br>\mathrm{sfb}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{where};<br><br>$

sfb_f=filtered speed feedback value;

sfb=speed feedback value;

λ

=filter cutoff frequency; and

s=Laplace operator.

27. A hoist system for determining the load value of a lifted load in a hoist system, comprising:

means for determining a speed feedback value from the hoist system;

means for processing the speed feedback value including using a filter to filter the speed feedback value to provide a filtered speed feedback value, the processing further including comparing the filtered speed feedback value with the speed feedback value to provide an acceleration value;

means for determining a torque feedback value from the hoist system;

means for determining a loss torque value and an inertia value from the hoist system;

means for inputting a previously determined load value;

means for processing the torque feedback value including using the filter to provide a filtered torque feedback value, the processing further including adjusting the filtered torque feedback value using the loss torque value, the previously determined load value, and the inertia value to determine an adjusted filtered torque feedback value;

means for comparing the acceleration value with the adjusted filtered torque feedback value to determine an error value; and

means for determining a measured load value based on the error value.

28. The hoist system according to claim 27, wherein the filter includes a Laplace operator that represents information from at least one previous speed feedback value determination.

29. The hoist system according to claim 27, further including means for comparing the measured load value to a threshold load value to determine a slack cable condition, wherein the means for comparing terminates operation of the hoist system if the threshold load value is exceeded.

30. The hoist system according to claim 27, further including means for comparing the measured load value to a threshold overload value to determine an overload condition, wherein the means for comparing terminates operation of the hoist system if the threshold overload load value is exceeded.

31. The hoist system according to claim 27, further including means for comparing the measured load value to a threshold value to determine a snagged load condition, wherein the means for comparing terminates operation of the hoist system if the threshold value is exceeded.

32. A hoist system for controlling the hoist of a load, the hoist system comprising:

a hoist mechanical system that includes a cable, the cable attachable to the load;

an adjustable speed drive, the adjustable speed drive operationally connected to the hoist mechanical system;

a load measurement portion in communication with the adjustable speed drive, the adjustable speed drive communicating torque feedback and speed feedback to the load measurement portion, wherein;

the load measurement portion filters the torque feedback and speed feedback using a filter to generate filtered torque feedback and the filtered speed feedback; and

the load measurement portion processes the filtered torque feedback and the filtered speed feedback using a previously determined load measurement, the load measurement portion outputting a load value signal to control the speed of a hoist based on the load value signal.

33. The hoist system according to claim 32, wherein the system further includes a speed-load portion;

and

the load measurement portion outputting the load value signal to the speed-load portion; and

the speed-load portion outputting a speed reference scale factor to the adjustable speed drive.

34. The hoist system according to claim 32, wherein the filter is a first order filter in the Laplace domain.

35. A hoist system for controlling the hoist of a load, the hoist system comprising:

a hoist mechanical system that includes a cable and a motor, the cable attachable to the load and controllable by the motor;

an adjustable speed drive, the adjustable speed drive operationally connected to the motor so as to control the motor;

a load measurement portion in communication with the adjustable speed drive, the adjustable speed drive communicating torque feedback, speed feedback, and brake status to the load measurement portion, the load measurement portion obtaining a loss torque value and an inertia value of the hoist mechanical system, wherein;

the load measurement portion filters the torque feedback and speed feedback using a filter to generate filtered torque feedback and the filtered speed feedback; and

the load measurement portion processes the filtered torque feedback and the filtered speed feedback using a previously determined load measurement, the loss torque value and the inertia value of the hoist mechanical system, the load measurement portion outputting a load value signal to control the speed of a hoist based on the load value signal.