System and method for load measuring by motor torque

1. A method for calculating a weight of a material in a bucket of an excavating machine, wherein, in response to rotation of a shaft of a hoist motor, the bucket moves in a substantially vertical direction, the method comprising:

determining a first relationship, wherein the first relationship associates values of static friction with values of bucket position;

determining a second relationship, wherein the second relationship associates values of dynamic friction with values of bucket position;

determining a value of hoist torque of the hoist motor;

determining a specific bucket position;

determining whether the bucket is stationary;

upon determining that the bucket is stationary:

determining, based on the first relationship, a specific value of static friction associated with the specific bucket position;

determining, based at least in part on the specific value of static friction, a value of dynamic torque of the hoist motor;

calculating a value of load torque of the hoist motor by subtracting the value of the dynamic torque of the hoist motor from the value of the hoist torque of the hoist motor; and

calculating the weight of the material based at least in part on the load torque of the hoist motor; and

upon determining that the bucket is not stationary:

determining, based on the second relationship, a specific value of dynamic friction associated with the specific bucket position;

determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor;

calculating a value of load torque of the hoist motor by subtracting the value of the dynamic torque of the hoist motor from the value of the hoist torque of the hoist motor; and

calculating the weight of the material based at least in part on the load torque of the hoist motor.

2. The method of claim 1 , further comprising:

upon determining that the bucket is stationary, determining an acceleration of the bucket;

wherein determining, based at least in part on the specific value of static friction, a value of dynamic torque of the hoist motor is further based at least in part on the acceleration of the bucket.

3. The method of claim 1 , further comprising:

upon determining that the bucket is not stationary, determining a speed of the bucket;

wherein determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor is further based at least in part on the speed of the bucket.

4. The method of claim 1 , further comprising:

upon determining that the bucket is not stationary, determining an acceleration of the bucket;

wherein determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor is further based at least in part on the acceleration of the bucket.

5. The method of claim 1 , further comprising:

wirelessly transmitting the calculated weight of the material to an information device.

6. The method of claim 1 , further comprising:

receiving a value of a maximum weight;

comparing the calculated weight of the material to the value of the maximum weight; and

upon determining that the calculated weight of the material does not exceed the value of the maximum weight, transferring the material to a mine haul truck.

7. The method of claim 1 , wherein the excavating machine is an electric mining shovel.

8. A computer readable medium storing computer program instructions for calculating a weight of a material in a bucket of an excavating machine, wherein, in response to rotation of a shaft of a hoist motor, the bucket moves in a substantially vertical direction, wherein the computer program instructions, when executed by a processor, cause the processor to perform a method comprising:

determining a first relationship, wherein the first relationship associates values of static friction with values of bucket position;

determining a second relationship, wherein the second relationship associates values of dynamic friction with values of bucket position;

determining a value of hoist torque of the hoist motor;

determining a specific bucket position;

determining whether the bucket is stationary;

upon determining that the bucket is stationary:

determining, based on the first relationship, a specific value of static friction associated with the specific bucket position;

determining, based at least in part on the specific value of static friction, a value of dynamic torque of the hoist motor;

calculating a value of load torque of the hoist motor by subtracting the value of the dynamic torque of the hoist motor from the value of the hoist torque of the hoist motor; and

calculating the weight of the material based at least in part on the load torque of the hoist motor; and

upon determining that the bucket is not stationary:

determining, based on the second relationship, a specific value of dynamic friction associated with the specific bucket position;

determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor;

calculating a value of load torque of the hoist motor by subtracting the value of the dynamic torque of the hoist motor from the value of the hoist torque of the hoist motor; and

calculating the weight of the material based at least in part on the load torque of the hoist motor.

9. The computer readable medium of claim 8 , wherein the method further comprises:

upon determining that the bucket is stationary, determining an acceleration of the bucket;

wherein determining, based at least in part on the specific value of static friction, a value of dynamic torque of the hoist motor is further based at least in part on the acceleration of the bucket.

10. The computer readable medium of claim 8 , wherein the method further comprises:

upon determining that the bucket is not stationary, determining a speed of the bucket;

wherein determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor is further based at least in part on the speed of the bucket.

11. The computer readable medium of claim 8 , wherein the method further comprises:

upon determining that the bucket is not stationary, determining an acceleration of the bucket;

wherein determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor is further based at least in part on the acceleration of the bucket.

12. The computer readable medium of claim 8 , wherein the method further comprises:

wirelessly transmitting the calculated weight of the material to an information device.

13. The computer readable medium of claim 8 , wherein the method further comprises:

receiving a value of a maximum weight;

comparing the calculated weight of the material to the value of the maximum weight; and

upon determining that the calculated weight of the material does not exceed the value of the maximum weight, transferring the material to a mine haul truck.

14. A system for calculating a weight of a material in a bucket of an excavating machine, wherein, in response to rotation of a shaft of a hoist motor, the bucket moves in a substantially vertical direction, the system comprising:

means for determining a first relationship, wherein the first relationship associates values of static friction with values of bucket position;

means for determining a second relationship, wherein the second relationship associates values of dynamic friction with values of bucket position;

means for determining a value of hoist torque of the hoist motor;

means for determining a specific bucket position;

means for determining whether the bucket is stationary;

means for, upon determining that the bucket is stationary:

determining, based on the first relationship, a specific value of static friction associated with the specific bucket position;

determining, based at least in part on the specific value of static friction, a value of dynamic torque of the hoist motor;

calculating a value of load torque of the hoist motor by subtracting the value of the dynamic torque of the hoist motor from the value of the hoist torque of the hoist motor; and

calculating the weight of the material based at least in part on the load torque of the hoist motor; and

means for, upon determining that the bucket is not stationary:

determining, based on the second relationship, a specific value of dynamic friction associated with the specific bucket position;

determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor;

calculating a value of load torque of the hoist motor by subtracting the value of the dynamic torque of the hoist motor from the value of the hoist torque of the hoist motor; and

calculating the weight of the material based at least in part on the load torque of the hoist motor.

15. The system of claim 14 , further comprising:

means for, upon determining that the bucket is stationary, determining an acceleration of the bucket;

wherein:

the means for determining, based at least in part on the specific value of static friction, a value of dynamic torque of the hoist motor comprises means for determining, based at least in part on the specific value of static friction and based at least in part on the acceleration of the bucket, the value of dynamic torque of the bucket.

16. The system of claim 14 , further comprising:

means for, upon determining that the bucket is not stationary, determining a speed of the bucket;

wherein:

the means for determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor comprises means for determining, based at least in part on the specific value of dynamic friction and based at least in part on the speed of the bucket, the value of dynamic torque of the hoist motor.

17. The system of claim 14 , further comprising:

means for, upon determining that the bucket is not stationary, determining an acceleration of the bucket;

wherein:

the means for determining, based at least in part on the specific value of dynamic friction, a value of dynamic torque of the hoist motor comprises means for determining, based at least in part on the specific value of dynamic friction and based at least in part on the acceleration of the bucket, the value of dynamic torque of the hoist motor.

18. The system of claim 14 , further comprising:

means for wirelessly transmitting the calculated weight of the material to an information device.

19. The system of claim 14 , further comprising:

means for receiving a value of a maximum weight;

means for comparing the calculated weight of the material to the value of the maximum weight; and

means for, upon determining that the calculated weight of the material does not exceed the value of the maximum weight, transferring the material to a mine haul truck.

20. The system of claim 14 , wherein the excavating machine is an electric mining shovel.