Virtual sensors are a software that, given the available information, estimates product properties or process conditions using mathematical models. These mathematical models use other physical sensor readings to calculate the estimated property or condition. The sensors learn to interpret the relationships between the different variables and observes readings from different instruments. Virtual sensors are useful in conditions where properties or states such as shelf aging time, humidity tests, tensile strength measures cannot be measured by physical sensors. They are also faster than physical sensors in providing information between readings.