Machine to dispense coffee-based beverages, and corresponding dispensing method and program

Machine to dispense liquid coffee comprising a circuit provided with at least:

• a pump configured to feed a controlled quantity of water under pressure, a heating device configured to heat the water supplied by said pump, an extraction chamber located downstream of said heating device and configured to contain a desired quantity of coffee powder, and a dispensing valve of the proportional type and selectively adjustable to control the dispensing flow of said liquid coffee exiting from said extraction chamber, and wherein said machine comprises sensors configured to detect at least one functioning parameter of said circuit, a user interface with which a user can select one of a plurality of liquid coffee recipes, and a memorization device to memorize a list of characteristic extraction curves of the liquid coffee, each associated with one of said recipes, wherein said sensors are configured to detect, repeatedly during the dispensing time, said at least one functioning parameter of said circuit, and wherein said machine comprises a control and command unit configured to implement:
• a non-linear mathematical model with coupled variables, configured to mathematically describe the functioning of said circuit,
• a processing and filtering algorithm configured to receive said at least one functioning parameter detected by said sensor, and to determine, repeatedly during the dispensing time and on the basis of said mathematical model, a plurality of system variables suitable to describe the behavior of said circuit over time,
• a non-linear control algorithm configured to compare and identify, repeatedly during the dispensing time, a deviation between said system variables and said characteristic extraction curve selected and to supply, on exit, repeatedly during the dispensing time, command signals at least of said pump, said heating device and said dispensing valve.