Inverse Design Method of Magnetic Springs With Customized Force–Displacement Relationship Over a Wide Range
Rui Zhou, Zhiwei Huang, Hui Chen, Jiulin Wu, Jixing Che, Xuedong Chen, Wei Jiang
Abstract
Magnetic springs using permanent magnets (PMs) have shown advantages in various fields. For instance, they are integrated into precision positioning actuators for passive gravity compensation, as well as into precision vibration isolators to reduce dynamic stiffness. In this article, an inverse design method of magnetic springs is proposed, which enables to customize the force–displacement relationship by shaping PMs. First, a concept of modulated magnetic spring is introduced, whose stator PMs are nonuniformly magnetized. The modulation method is developed to customize the force–displacement relationship. Second, uniformly magnetized PMs are shaped layer by layer to substitute the modulated PM. This process involves optimizing the size of each layer independently to generate a nearly equivalent force, resulting in a highly manufacturable special-shaped magnetic spring. Three design examples are presented and tested. The first two examples maintain a constant force and a constant negative stiffness, respectively, within 30 mm. The relative errors are only 3.7% and 2.3%, respectively, which are defined as the ratio between the maximum deviation and the mean value. The third example can compensate for the nonlinear force of the subsidiary structures and maintain a constant resultant force in 40 mm with a relative error of 2.9%. This method is confirmed to customize the force–displacement relationship for various applications.