Disseny i implementació d'un sistema de pesatge digital

For many years the world of weighing has based on using resistive load cells, mainly made of strain gauges in a bridge configuration. This gauges are connected to electronic systems that provide energy to the bridge and convert the voltage output into a digital value proportional to the weight in order to be presented. The main advantage of this system is that the manufacturing cost of the product remains low but on the other side the precision given by the system can be widely improved. This is specifically critical when working with installations with several load cells, that are the typical architectures used to weight vehicles, tanks or goods in pallets as the weight is divided into the different cells connected in parallel. The output signal of the load cells then is converted form the analog voltage to digital value reducing the quality and precision of the system. The rapid evolution of the electronics has conducted to a set of analog-to-digital converters with a very reduced dimensions and very good precision. This in turn allows the weighing systems to include this devices inside the load cell providing a digital output of the cell that avoids the result to be affected by the distance between the load cells and the user display. Also the amount of cells that can be used in a system can be increased, allowing to apply the corrections to each single cell, which in turn improves the precision of the measurement. The objective of this project is to develop a general purpose electronic solution compatible with most of the existing analog load cells in order to improve the performance of the cells, to reduce the interconnection complexity for systems with multiple load cells and to define the adjustment procedure of the digital cell during the manufacturing process. Last but not least, it is important to keep in mind that the price of the electronic solution developed should be cheap in order to keep the price of the whole system in the range of the existing analog load cell systems as a big increase in the price would hinder the commercialization of the resulting product. Desde la invención de la galga extensiométrica el pesaje se realiza mediante células de carga resistivas, formadas con un puente de galgas extesiométricas, conectadas a equipos electrónicos que alimentan el puente y convierten la salida de tensión a un valor digital proporcional al peso para su visualización. De esta forma se pueden fabricar células muy económicas pero con una precisi