Patent ID: 9018544
Filing Date: 2015-04-28
Classification: G01G,G06Q,G07B

Abstract:
1. A system for weighing a moving parcel, the system comprising: an intake conveyor for moving a parcel at a first speed; an accelerator conveyor disposed adjacent to the intake conveyor and arranged to receive a moving parcel from the intake conveyor means; a primary drive motor configured to provide a substantially constant first torque input to a transmission; a servo motor arranged to provide a variable second torque input to the transmission; and a transmission coupled to the primary drive motor, the servo motor, and the accelerator conveyor for driving the accelerator conveyor; wherein the transmission is configured to sum the first torque and the variable second torque to generate an output torque, and deliver the output torque to drive the accelerator conveyor; further comprising a servo amplifier coupled to the servo motor in a closed loop configuration to drive and maintain the servo motor at a second speed that is different from the first speed so that, in operation, arrival of the parcel on the accelerator conveyor and the consequent change in mass of the accelerator conveyor, causes a perturbation from the second speed, and the servo motor, under control of the servo amplifier, adjusts the variable second torque so as to restore the accelerator conveyor to the second speed; the servo amplifier arranged to acquire motor current or torque data responsive to operation of the servo motor so that the acquired data; and wherein the constant first torque is substantially greater than a maximum range of the variable second torque, thereby utilizing the primary motor to provide most of the torque to drive the accelerator conveyor, while the servo motor and amplifier provide fine grain differential torque sensing; and a processor coupled to access the acquired data and configured to infer a weight of the parcel based on the acquired differential torque sensing data.