Active–passive hybrid full-spectrum vibration isolation using tri-stability and cam-roller mechanism

This paper develops a novel active–passive hybrid vibration isolator that realizes absolute-zero-stiffness (AZS) behavior by integrating a tri-stable magnetic spring with a cam-roller mechanism. The tri-stable configuration introduces five equilibrium points, generating a wave-like nonlinear restoring force that is precisely counteracted by a cam-profiled compensation force to achieve AZS. This approach effectively decouples external excitations, enabling full-frequency vibration isolation with enhanced stability and low sensitivity to amplitude variations. To improve robustness against parameter uncertainties and manufacturing errors, a proportional–integral–derivative (PID) feedback loop is incorporated, forming a hybrid control strategy. Theoretical modeling, validated by finite element analysis and static testing, confirms the accuracy of the magnetic force predictions. Dynamic analysis and experimental results confirm that the proposed isolator delivers significantly enhanced isolation performance compared to conventional mono-, bi-, and tri-stable configurations. Under sinusoidal excitation over the tested ultra-low frequency range of 0.1–8 Hz, the proposed isolation method achieves vibration isolation across the entire spectrum, effectively lowering the displacement transmissibility from 16.5 dB and 19 dB in the passive tri-stable mode to –28.7 dB and –39.1 dB, respectively. Notably, the mean power consumption of the proposed control strategy remains below 1.21 W, significantly lower than that of traditional active or hybrid control approaches. Compared to state-of-the-art designs, the isolator offers superior isolation bandwidth, working stroke (10 mm), and normalized load capacity (39.52 N/cm³). Its compact form factor and low power requirement make it highly suitable for precision vibration isolation in automotive, aerospace, and mobile platforms.