Smart Vibration Isolator Adapts to Payload and Eliminates Resonance

Vibration isolators are critical components in fields such as high-precision manufacturing, aerospace, and sensitive scientific equipment. Traditional isolators, which use springs and dampers, face a trade-off: achieving low-frequency vibration suppression requires low static stiffness, compromising load-bearing capacity. To address this, researchers have explored quasi-zero stiffness (QZS) isolators that combine positive and negative stiffness elements to decouple static and dynamic behaviors.

However, existing QZS isolators are highly sensitive to payload changes and cannot eliminate residual resonant peaks, which can lead to large oscillations and chaotic motion. A research team led by Professor Seunghun Baek at Pusan National University in South Korea has introduced an innovative hybrid control strategy for a QZS isolator that utilizes motor actuation to overcome these challenges.

The modified rhombus-shaped QZS system integrates electric actuators at joints connected to a horizontal spring. These actuators can modulate the spring's pretension and effective initial length, serving as a control parameter. The hybrid control strategy involves two distinct control laws. The first law adjusts the horizontal spring's effective length to adapt the system to varying payloads, maintaining the QZS condition.

The second control law uses the same actuators to continuously adjust the horizontal spring in real time based on the system's state. This generates a counteracting force that stabilizes the payload, effectively eliminating residual resonant peaks even under base vibrations. Prototype experiments validated the strategy, showing successful adaptation to payloads ranging from 1.01–1.21 kg (2.2–2.7 pounds) and complete elimination of ultra-low-frequency resonance under a 1.11 kg (2.4 pounds) payload.