DIGITAL LINEARIZATION IN A WEIGHING CELL

摘要

A force exerted by a load is determined in a force-measuring device (1) operating under electromagnetic force compensation. The device includes a measurement transducer (18, 118) with a coil (20, 120) movably immersed in a magnet system (19, 119) and a force-transmitting mechanical connection between a load-receiving part (12, 112) and the coil or magnet system. A position sensor (21, 28), also part of the device, determines a displacement of the coil from its settling position relative to the magnet system (19, 119) which occurs when the load is placed on the load-receiving part. An electrical current (24) flowing through the coil generates an electromagnetic force between the coil and the magnet system whereby the coil and the load-receiving part are returned to, and/or held at, the settling position. The magnitude of current and the amount of displacement are used to determine the weight force exerted by the load.

主权项

1. A method for determining a weight force of a load on a force-measuring device operating according to the principle of electromagnetic force compensation, the force measuring device comprising: a measurement transducer, comprising a magnet system and a coil, arranged for movement relative to the magnet system, the coil having a settling position at which the coil resides when all forces acting on the coil are in equilibrium; a load receiving part, arranged to transmit mechanically the weight force exerted thereon to the measurement transducer, through one of the coil and the magnet system; and a first position sensor, arranged to determine an amount of displacement of the coil from the settling position; the method comprising the steps of:
applying a load to the load receiving part, causing the coil to be displaced from the settling position; determining, using the position sensor, an amount by which the coil is displaced from the settling position; applying, to the coil, an electrical current of a magnitude calculated to generate an electromagnetic force sufficient to return the coil to the settling position, the calculation achieved from an input signal to a position-controlling unit; and calculating a weight force exerted by the applied load, using both the magnitude of the electrical current and the amount of the coil displacement.