Periodic tuning: Using mechanical or electrical techniques, the generator's resonant frequency is changed to correspond with surrounding vibrations.• Bandwidth Broadening: Increasing the operating frequency range by using methods such as generator arrays, mechanical stoppers, nonlinear springs (such as magnetic ones), or bi-stable structures.• Tuning Method Classification: Distinguishing between continuous tuning (constant energy consumption for tuning) and intermittent tuning (periodic energy expenditure for tuning)