Design of Minimum Phase Digital FIR Notch Filter for Real-Time Hybrid Simulation

Resonance in actuator dynamics poses critical instability and control challenges, particularly in real-time hybrid simulations (RTHSs). During rapid control, unintended resonance can induce instability, thereby compromising the accuracy of the experimental outcomes. Servo-hydraulic actuators—implemented in RTHS for their robust actuation capabilities—are inherently prone to oscillations resulting from the oil-column compressions, leading to contamination in the measurements with resonant frequencies. Traditionally, mitigating this issue required extensive tuning of control parameters, which demanded significant time and effort. To resolve the above-mentioned control challenges, a novel design method for a minimum phase finite impulse response notch (MPFN) filter is proposed. The performance of the MPFN filter in resonance suppression is thoroughly validated through numerical simulations, RTHS using an electromagnetic linear actuator, and experimental applications with servo-hydraulic actuators. The results demonstrate that the proposed MPFN filter not only eliminates the need for exhaustive control parameter tuning but also enhances experimental performance across all tested conditions, ensuring improved stability and accuracy in a wide range of experimental settings.

Summary

• Development of a minimum phase digital FIR notch (MPFN) filter that can effectively suppress the vibration at the given frequency, while minimizing the time delay.
• Experimental validation of the proposed MPFN filter by conducting RTHS using an electromagnetic linear motor that mimics the oil-column resonance of a typical servo-hydraulic actuator.
• Further experimental validation of the proposed MPFN filter by conducting RTHS with a friction pendulum (FP) bearing by using servo-hydraulic actuators.
• The MPFN filter was validated to be effective in reducing the oil-column resonance, enhancing the stability and accuracy of RTHS results.