Ultrasonic Vibration Parameters Estimation using Fuzzy based PID Controller in Digital-PLL

Ultrasonic vibration parameters are estimated using a Fuzzy based Phase locked loop. A quadrature detector based on the modified sliding discrete Fourier transform (SDFT) is employed that acts as a band-pass filter. A damping factor (r) is introduced in the SDFT to ensure the stability of the filter. Complex poles are eliminated by rationalizing the SDFT filter known as the Goertzel algorithm. The quadrature phase of the Goertzel filter is then passed through a low pass filter. The output of the low pass filter contains the vibration information along with noise. To eliminate the noise, a Fuzzy based PID controller is employed. This fuzzy system, when coupled with the PID controller, is able to estimate a wide range of vibrating frequencies. The output of the PID controller is then fed to a bi-quad oscillator that produces variable pulses, which ensures the phase-locking mechanism. This nonlinear Fuzzy based PID controller can replace the tedious manual tuning procedure. Simulation results validate the efficient performance of the proposed PLL in dynamic and noisy environments.