An Adjustable Low-Frequency Vibration Isolation Stewart Platform Based On Electromagnetic Negative Stiffness

With the continuously increasing requirements for vibration isolation in multiple degrees-of-freedom(DOFs), the negative stiffness(NS) passive Stewart platform with simple, reliable structure and good vibration isolation capability have become a concern. However, it has the disadvantage of unadjustable stiffness, which limits its application prospects. An adjustable electromagnetic negative stiffness (AENS) Stewart platform is proposed in this paper. It can realize good stiffness match conveniently and has high vibration isolation performance in all 6 DOFs. Firstly, this paper introduces the structural composition of the system. Then, the kinematics model is constructed by the vector method, the dynamic model is constructed by the second Lagrange equation, and the multi-DOFs transmissibility rate matrix is given. Finally, the performance of AENS Stewart platform are verified through experiments. The experimental results show that it can reduce the natural frequency from 3.94 Hz to 2.69 Hz, 7.69 Hz to 5.17 Hz, 9.5 Hz to 6.35 Hz, and 9.5 Hz to 6.35 Hz in the X(Y), Z, alpha(beta), and gamma DOFs, respectively. Convenient stiffness matching and good low-frequency vibration isolation in multi-DOFs make AENS platform have great application potential.