Study of a load cell: calculation of load cell parameters and study of a weighing process

This thesis had two main purposes: the first one was to calculate the elastic constant and the damping factor of the load cell; the second goal was to develop a high speed weighing process, a procedure for achieving a mass estimate within 100 milliseconds with a precision of 0.5%. The work has been conducted during an internship in Nanolever s.r.l., a company which designs industrial weighing systems. Regarding the first goal, the obtained results consist in an elastic constant k = (22741 ± 53)N/m and a damping factor ζ = 0.0107 ± 0.0007. The next part of the project allowed the achievement of mass estimates of a mass sample without all the data points of the settling transient of the load cell. I obtained the results thanks to two methods: firstly, a MATLAB fitting of the graph, then another fitting procedure but with Python. As a complessive final result, for a set of data acquired in 10 milliseconds, Python returned mass estimates with a precision of about 0.5% - 1%, whereas MATLAB presented analogous outcomes with a bit lower precision, ranging from 1% to 2%. By observing the results, a minimum precision of 0.5%, as required, is reached by analising data samples acquired in 50 ms. Moreover, all the time results exceeded the prefixed time limit of 100 ms: Python fitting shown a computing time of about 120 - 140 ms and MATLAB 130 - 160 ms. To conclude, a method for estimating the mass of an object without having all the data points of the settling transient of the load cell has been developed. Unfortunately, to gain the required precision the time limit of 100 ms has been exceeded; however, this fact may lead to future studies which will be able to allow the hoped results with more advanced technology and improved working methods.