Fuzzy logic method for an indirect measure of a physical signal to be monitored, and corresponding measuring device

摘要

The invention relates to a method for an indirect measure, by the application of fuzzy logic rules, of a physical signal (G1) to be monitored which would be difficult to measure by a direct method and which has at least first (PD) and second (PS) significant values, these significant values (PD,PS) splitting said physical signal (G1) to be monitored time-wise into a first operational zone (Z1) corresponding to values below the first significant value (PD), a second operational zone (Z2) corresponding to values between the first (PD) and second (PS) significant values, and a third operational zone (Z3) corresponding to values above the second significant value (PS), only said second operational zone (Z2) being involved by the presence of a periodic index signal related to the physical signal (G1) to be monitored. The measuring method of this invention comprises the steps of:obtaining a derived physical signal (G2) from the physical signal (G1) to be monitored, this derived physical signal (G2) having a similar behavior as said physical signal (G1) to be monitored but trivial influence thereon and being related to said periodic index signal;measuring the value (P) of the derived physical signal (G2) and its variations over time at suitably selected check points (CP1,CP2,CP3,...,CPn);deriving the presence or absence of the periodic index signal by means of a first set (FUZZY1) of fuzzy rules;measuring the second (PS) and first (PD) significant values of the physical signal (G1) to be monitored as start and end values, respectively, of the second operational zone (Z2), namely as values which correspond to the start and end of the detection of the periodic index signal presence.;The invention also relates to an apparatus for an indirect measure, by the application of fuzzy logic rules, of a physical signal (G1) to be monitored which would be difficult to measure by a direct method, of a type which comprises a compressor block (2) having a first input (3) connected to an input actuator block (5), a first output (4) connected to an output transducer block (7), and a second output (14) connected to a detector block (12), the input actuator block (5), output transducer block (7) and detector block (12) being connected to a fuzzy controller (24). The measuring apparatus of this invention further comprises a secondary exhaust block (9) connected to the compressor block (2) and effective to produce a derived physical signal (G2) behaving similar as the physical signal to be monitored (G1) but having a trivial influence thereon, and being related to the periodic index signal. The fuzzy controller (24) of the measuring apparatus according to the invention ultimately measures the first and second significant values (PD,PS) of the physical signal (G1) to be monitored by acting on the derived physical signal (G2).;The indirect measuring method and apparatus of this invention can be applied in particular to the non-invasive reading of blood pressure and heart beat frequency.