## 5 Conclusions  
In view of the uncontrollable and underdamping characteristics of the permanent magnet suspension system, the red rail of China, the electromagnetic damping structure is introduced in this paper, a permanent magnet electromagnetic hybrid suspension experiment platform is built, a fuzzy linear active disturbance rejection control method with an air gap deviation integrator is proposed, the stability control of the suspension plat  
Figure 14: Suspension experiment results when the platform is moving. (**a**) Air gap of each suspension unit without control; (**b**) Air gap of each suspension unit under PID control; (**c**) Air gap of each suspension unit under LADRC control; (**d**) Air gap of each suspension unit under Fuzzy-LADRC control.  
form is studied and the following conclusions are obtained through theoretical analysis and experiments:  
(1) Based on the structure analysis of the permanent magnet electromagnetic hybrid suspension platform, the model of the suspension control unit is improved by combining the existing information. The stability, observability and controllability of the system are analyzed, the design of the controller is simplified and the time of parameter tuning of the controller is shortened.  
(2) Combined with a fuzzy control and linear active disturbance rejection control method, the parameters of the state error feedback control theory in linear active disturbance rejection can be self-adjusted considering the actual working conditions of the suspension platform, effectively improving the adaptability and robustness of the system. To solve the problem that in the practical application of linear active disturbance rejection the controlled object cannot be simplified into an integral series system, the air gap deviation integrator is introduced to improve the control accuracy of the system.  
(3) The experiment's results show that compared with linear active disturbance rejection and PID control methods, the proposed fuzzy linear active disturbance rejection control method not only improves the stability, anti-interference and robustness of the system, but also has stronger adaptability when the system is in operation and can better maintain the given suspension state.  
The method proposed in this paper provides good theoretical support for further promoting the engineering application of hybrid suspension technology. It can also be applied to magnetic bearing, UAV control and APT system control of the space optical communication, and has good application prospects.  
Lastly, introducing the integrator into the fuzzy linear active disturbance rejection also leads to integral saturation and can cause a large overshoot and long adjustment time. Therefore, the next stage of research is to optimize the integrator design to achieve the control effect that can not only improve the steady-state accuracy of the system, but also inhibit the integral saturation.  
Conceptualization, J.Y.; data curation, Y.Q. and H.G.; formal analysis, J.Y. and H.G.; investigation, Y.Q.; methodology, Y.Q.; project administration, J.Y.; software, Y.W. and Y.Q.; validation, Y.Q.; writing--original draft preparation, Y.Q.; writing--review and editing, H.G.; All authors have read and agreed to the published version of the manuscript.  
This research was funded by a grant from the National Natural Science Foundation of China (No. 62063009), the cultivation project of the State key Laboratory of Green Development and High-value Utilization of Ionic Rare Earth Resources in Jiangxi Province (No. 20194 AFD44003),and by a grant from the Research Projects of Ganjiang Innovation Academy, Chinese Academy of Sciences. (No. E255J001).  
Not applicable.  
The authors declare no conflict of interest.