Vibration isolators are a key technology in ultra-precision machining and ultra-precision measurements. The increasing performance requirements of magnetic vibration isolation systems (MVISs) continue to demand improvements in the accuracy on which these devices are modeled. However, a serious constraint exists in designing MVISs, as high stiffnesses will be introduced by nonlinear force-displacement characteristics. The traditional analytic magnetic charge model assumes that the relative magnetic permeability $\mu_r$ = 1, which causes the accuracy of the magnetic analytic model of the MVIS to decrease. To solve this defect, low-stiffness MVISs are designed by using the 3D analytic magnetic charge model while considering the variations of the operating point. The optimized parameters of the MVIS are then obtained by combining the genetic algorithm. The feasibility of the proposed analytical charge method is verified from the results of experimental measurements and finite element methods. The results of this paper provide a powerful tool for the design of a high performance MVIS and provide important support for the ultimate goal of ultra-precision machining and measurements.

A two-dimensional (2D) vector vibration sensor is designed and fabricated by using an optical fiber double-clamped beam with four-core fiber Bragg gratings and a mass block which is glued in the middle of fiber. Vectorial acceleration perpendicular to the fiber can be measured using two mutually orthogonal FBG-pairs in the four-core fiber to obtain the 2D vibrating information. The experimental results show that the sensor possesses a 2D vectorial acceleration sensitivity of 345 pm/g in the flat response region of 5-30 Hz, and it is temperature insensitive, compact, and cascadable. Both resonance frequency and sensitivity can be improved by optimizing the length and weight of the free-fiber. The proposed sensor has the potential applications for dynamic monitoring in oil exploration, seismic exploration, heart rate monitoring.

The magnetic characterization of a spacecraft plays a crucial role in ensuring magnetic cleanliness for various space exploration missions. When conducting the magnetic characterization, environmental noise in traditional magnetic coil facilities (MCFs) can significantly reduce the accuracy of magnetic model predictions by influencing the measured magnetic field data. Therefore, the magnetic characterization of spacecraft equipment in a magnetic shielded room (MSR) is conducted in this article to address the above issue. However, the magnetic field generated by the spacecraft equipment may undergo distortion within the MSR due to the presence of high-permeability materials comprising the shielding structure. Therefore, the magnetic characteristics of spacecraft are expressed using the spherical harmonic method and then decomposed into multipole models, in this article. Subsequently, the method of images is used to present the distribution of image multipoles, and the relationship between the spherical harmonic coefficients of original multipoles and image multipoles is provided. Finally, a spherical harmonic model of spacecraft equipment considering the coupling effect with the MSR is proposed. The validity and accuracy of the proposed magnetic characterization method inside the MSR have been verified through simulations and experiments, respectively.

Vibration substantially degrades machining quality and measurement accuracy in ultra-precision processes, necessitating the implementation of vibration isolators to mitigate these effects. Magnetic vibration isolators represent a promising alternative due to their wide isolation frequency range, low energy consumption, and compatibility with vacuum environments. In designing the quasi-zero stiffness magnetic vibration isolator, the particle swarm optimization algorithm is employed to balance multiple performance indicators. To address the limitations of conventional optimization methods, which excessively prioritize stiffness and fail to encompass the entire performance spectrum of magnetic vibration isolators, this study presents an innovative optimization approach. This novel strategy directly enhances vibration isolation by integrating transmissibility and compliance considerations. Structural parameters for two types of magnetic vibration isolators were established through optimizations utilizing both conventional and innovative techniques. Simulations and experiments demonstrate that isolators developed using the proposed optimization method outperform those designed with conventional strategies, thereby validating the effectiveness of this advancement. The insights presented in this paper illuminate a novel and effective pathway for the conceptualization and refinement of magnetic vibration isolators.