# Development of a Conveyor Cart with Magnetic Levitation Mechanism Based on Multi Control Strategies
## 1 Introduction  
Magnetic levitation technology can transport objects without contacting the ground whereby the system generates high-speed motion and eliminates vibrations. This innovative technology is widely used in various applications such as magnetic levitation trains, magnetic levitation bearings, and high-speed elevators [1, 2]. In many airports, magnetic levitation conveyor cart technology has been widely applied worldwide. The magnetic levitation transport conveyor carts have the advantages of high speed, high efficiency, low noise, and low energy consumption, which can greatly improve the efficiency of baggage transportation [3, 4, 5].  
This paper explores the design of a control system for a magnetic levitation conveyor that utilizes four magnetic levitation units for support. Unlike the conventional magnetic levitation transport systems that typically employ a single magnetic unit, the magnetic levitation conveyor described in this paper features a rectangular transport platform upheld by four magnetic float units. This platform is specifically designed for the transportation of baggage. The entire magnetic levitation conveyor system is suspended from a rail by means of the four magnetic levitation units. These four magnetic float units operate in tandem, marking a distinctive and innovative departure from the conventional magnetic levitation transport systems. The primary objective is to implement the magnetic levitation mechanism into the conveyor system and assess its performance alongside several existing control ideas.  
In this paper, levitation control is performed by several typical feedback control methods used in magnetic levitation control. The different control strategies of the magnetic levitation unit constitute the core part in this paper. For the traditional magnetic levitation system, which is the second order nonlinear system, the original system cannot keep the cart stable. A PD or PID controller must be applied for the system to achieve stability [6]. There are three control strategies which are applied in the magnetic levitation units of the conveyor cart. The three controllers are the basic PID controller, the state feedback controller, and the zero-power controller. A single controller applied in a magnetic unit is common, but the four controllers that work in sync are main target of research in this experiment [7]. The four-unit design enables the magnetic levitation conveyor cart to carry a heavier mass.  
This paper focuses on the mechanical structures and primary components of the magnetic levitation conveyor cart in Section 2. In Section 3, an analysis of the magnetic levitation force process is provided. Section 4 delves into the analysis of the mathematical model of the magnetic levitation unit, along with the design of the PID controller, state feedback controller, and zero-power controller. The experimental results for all controllers, both for single-unit and four-unit configurations, are presented. The concluding Section 5 provides a summary of the findings and outlines future recommendations.