Frequency-Based Adaptive PPF Controller for Vibration Reduction of a Helicopter Shell Body

Active vibration control approaches are focused on unwanted vibration that cannot be reduced by passive control devices. However, they are hard to apply to vibration-induced structures, especially aerodynamic structures, which are subjected to variable-frequency disturbances. This work includes a new adaptive positive position feedback (PPF) controller methodology using a traditional compensator and an adaptive compensator responsible for variable-frequency disturbances to investigate the effectiveness of the proposed design. A UH1H helicopter auxiliary cargo door equipped with piezoelectric patches and strain gauges was used in the laboratory environment as an implementation of Technology Readiness Levels 4 and 5 to implement of proposed controller methodology. Some challenges affect the traditional PFF controller performance, and the most important one is that independent vibration can occur on structures distinct from the natural frequencies. For overcoming this, two second-order compensators are used to enhance the controller performance; one targets previously determined natural frequencies by experimental modal analysis, and the other targets dominant frequencies obtained from simultaneous measurement. The suggested controller performance was investigated under operationally obtained vibration excitation, and this methodology provides a significant vibration reduction against variable conditions in the laboratory experiments.