Quasi-zero-stiffness vibration isolation joint based on disc springs

To address the low-frequency vibration isolation at the load-bearing and operating ends of robots and thereby enhance precision, this paper proposes a quasi-zero-stiffness (QZS) vibration isolation joint based on disc springs. The joint employs reverse-stacked disc springs to provide low stiffness in the horizontal direction and negative stiffness in the vertical direction. By adjusting the pre-compression of the disc spring s, the stiffness can be actively tuned to achieve ultra-low-frequency vibration isolation. Mathematical models are established to analyse its mechanical properties and vibration isolation performance in various directions. The results show that the joint attains quasi-zero stiffness near the equilibrium position, exhibits excellent vibration isolation performance in multiple directions, and can adapt to different excitations through active control. The proposed structure is compact and offers high load-bearing capacity, making it suitable for a wide range of applications such as high-precision surgical robots and aerospace instruments.