Patent ID: 8481871

Claim:
A weighing assembly for an in-line scale comprising: (a) a capstan roller; (b) a capstan motor operative coupled to drive the capstan roller; (c) a pinch roller, positioned opposite the capstan roller and linked to the capstan motor for rotation in synchrony with the capstan roller; (d) a first servo amplifier electronically coupled to the capstan motor and arranged to drive the capstan motor to a selected command speed of rotation, and to acquire torque data from the capstan motor while a moving article is gripped between the capstan roller and the pinch roller; the torque data responsive to accelerating or decelerating the moving article toward the command speed; (e) a tension arm arranged for supporting the pinch roller while allowing free rotation of the pinch roller responsive to the capstan motor, and to enable repositioning the pinch roller; (f) a tension arm motor operatively coupled to the tension arm, wherein the tension arm is arranged to translate torque applied to it by the tension arm motor to reposition the pinch roller relative to the capstan roller, thereby providing a controllable gripping force for gripping the moving article between the pinch roller and the capstan roller; (g) a second servo amplifier electronically coupled to the tension arm motor and arranged to drive the tension arm motor responsive to a torque command input to apply a controllable force to the pinch roller while an article is gripped between the capstan roller and the pinch roller; wherein the second servo amplifier provides a position output signal indicative of a current position of the pinch roller as the article moves between the pinch roller and capstan roller; (h) an active electronic motion damper coupled to the second servo amplifier to modify the torque command input by a damping force responsive to a change in the position output signal so as to suppress oscillation of the tension arm when encountering a change in thickness of the article; and (i) a processor configured for processing the torque data acquired by the first servo amplifier to determine a weight of the article; (j) wherein the processor is further configured to correct the acquired torque data by subtracting the damping force from the acquired torque data.