A novel zero delay low pass filter: Application to precision positioning systems

Area of Science:

• Signal Processing
• Control Systems Engineering

Background:

• Linear filters often introduce significant phase lag, limiting their use in precision applications.
• Existing nonlinear filters may not offer optimal performance across diverse noise profiles.

Purpose of the Study:

• To develop a nonlinear low-pass filter with substantially reduced phase lag.
• To enhance filter performance using a saturation function for improved signal fidelity.

Main Methods:

• Analytical derivation of gain and phase responses using a modified describing function.
• Numerical simulations to evaluate filter efficiency and performance.
• Validation in a precision motion control system simulation.

Main Results:

• The proposed filter exhibits near 0dB gain in the pass-band and -40dB/dec noise attenuation.
• Phase lag is reduced by three times compared to a 2nd order Butterworth filter.
• Superior performance over linear and other nonlinear filters for white, blue, and purple noise.

Conclusions:

• The nonlinear low-pass filter effectively minimizes phase lag while maintaining high noise attenuation.
• The saturation function enhances performance, making it suitable for precision control systems.
• A tuning guideline is provided for practical implementation based on noise characteristics.