# Levitating Control System of Maglev Ruler Based on Active Disturbance Rejection Controller
The T-shaped mover of the TU-type maglev platform has three ends [14]. There are two air gaps between each end and the stator yoke, an upper air gap and a lower air gap [14]. The magnetic flux in the upper and lower air gaps determines the force on the ends where they are located, controlling the levitation height of the ends [14]. The magnetic flux in the air gap can also be divided into two parts, one from the permanent magnet and the other from the levitating control coil [14]. The magnetic flux emitted by the levitating control coil is related to the current of the levitating control coil [14]. Therefore, the magnetic flux emitted by the levitating coil can adjust the size of the air gap flux, thus achieving stable levitation of the T-shaped mover [14]. However, the TU-type maglev platform uses one coil to control the upper and lower air gap fluxes at one end, which cannot solve the simultaneous asynchronous interference in the two air gap fluxes [14]. In addition, due to the use of one control coil to adjust the magnetic flux in the upper and lower air gaps, there is a commutation problem in the current of the control coil [14]. The control coil is an inductance and an energy storage element [14]. During current commutation, there is a transition process, causing the current in the control coil to have a turning point at the commutation point [14]. Therefore, the TU-type maglev platform is equipped with only two levitating control magnetic circuits, making it incapable of independently regulating four air gaps. Furthermore, the current flowing through the levitating control coil of the TU-type maglev platform does not exhibit a linear relationship with time. The MR establishes four levitating control magnetic loops. The magnetic flux of each magnetic loop can be independently controlled, eliminatingthe need for current commutation of the levitating coil, eliminating the inflection point, and allowing independent control of the magnetic flux in each air gap. The working principle of the levitating system of the MR is analyzed, and a mathematical model of the levitating system is established in this paper. The levitating system uses an active disturbance rejection control (ADRC) control algorithm to stabilize the levitation position of the MC while also stabilizing the magnetic field in air gaps. The structure of this paper is as follows: In the second part, this paper analyzes the characteristics of the maglev system of the MR and establishes a mathematical model. In the third part, this paper designs a maglev control system based on ADRC according to the characteristics of the maglev system of the MR and conducts simulation analysis on the maglev control system. In every fourth part, this paper conducts experimental testing on the maglev control system. The organization of this paper is as follows. In Section 2, the characteristics of the maglev system of the MR are analyzed, and a mathematical model is established. In Section 3, according to the characteristics of the maglev system, a levitating control system based on ADRC was designed, and a simulation analysis of the levitating control system was conducted. In Section 4, an experimental test was conducted on the levitating control system. Finally, conclusions are presented in Section 5.