Implementation of algorithm for tracking resonant frequency of acoustic systems

Ultrazvuk ima široke primjene u medicini, kod kirurških i medicinskih instrumenata. Većina tih sustava radi u frekvencijskom pojasu od 20 do 100 kHz. Signal velike snage uzrokuje vibriranje materijala koji se nalazi u sondi koja u kontaktu s tkivom postiže željene učinke. Važno je da signal koji pobuđuje sondu bude na rezonantnoj frekvenciji u svakom trenutku, tako da je pretvorba energije maksimalna. Sustav podliježe raznim varijacijama tijekom rada kao što su samozagrijavanje, promjena opterećenja itd, pa se mijenja njegova rezonantna frekvencija u vremenu. Pobuda sonde frekvencijom koja nije rezonantna rezultira lošijom pretvorbom energije i sustav radi lošije. U radu su analizirani algoritmi za detekciju faze: detekcija faze sklopom XOR, detekcija faze korištenjem FFT algoritma, detekcija faze korištenjem fazno osjetljive demodulacije. Opisan je izbor platforme na kojoj je sustav implementiran. Opisani su algoritmi za praćenje rezonantne frekvencije, hill – climbing i modeliranje vrha parabole estimacijom parametara.Ultrasound is widely used in clinical applications in surgical and medical instruments for biological tissue cutting, ablation and dissection. Most of these systems work in the low frequency range, 20–100 kHz, and at high power, utilising a vibrating metal probe to contact the target tissue and achieve the desired effects. During such high power ultrasound operations, it is critically important to drive the transducer at its resonant frequency, as the highest power conversion is achieved at this point. However, the resonant frequency of an ultrasonic transducer is subject to significant variations during operation, from causes such as self-heating and variations in input power and acoustic loading conditions. This paper analyzes the detection algorithms phases: phase-detection circuit XOR, phase-detection using FFT algorithm, phase-detection using phase sensitive demodulation. The details of the control algorithm hill climbing and estimation based extremum seeking controlare introduced