Patent ID: 8373078

Claim:
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.