| Maglev technology is a high-tech integrating in many disciplines such as mechatronics,electromagnetism,linear system theory,automatic control and signal processing.As the core of magnetic levitation technology,levitation control has attracted people's attention.Due to many factors such as high nonlinearity,random uncertainty and time delay exist in magnetic levitation system,hence it is difficult to obtain satisfactory dynamic performance by means of traditional control algorithms.This paper takes the magnetic levitation ball system as the research object.By using a novel control algorithm to realize the stable suspension control of the magnetic levitation ball,a good dynamic performance can be obtained.The main research contents of this paper are as follows:(1)Firstly,the characteristics,composition and working principle of the magnetic levitation ball are introduced,and then the nonlinear model of the magnetic levitation ball is established.Finally,the controllability and observability of the mathematical model are analyzed.The nonlinear processing of the mathematical model of the magnetic levitation ball is carried out from the following two aspects.One is to expand the linearization process at the equilibrium point through the Taylor formula,and the other is to achieve linearization through nonlinear mathematical mapping.Therefore,two different mathematical models of magnetic levitation ball can be obtained.Three different error performance indicators such as IAE,ITAE and RMSE are used for evaluation,so as to solve the problem of poor dynamic performance of the magnetic levitation ball system due to unsatisfactory parameter selection.(2)After the mathematical model of the magnetic levitation ball system is established,the LADRC algorithm will be used to control the suspension of the magnetic levitation ball to improve the anti-interference ability and robustness of the magnetic levitation ball after which suffers external disturbance.Aiming at the problem of difficulty in parameter tuning of controller bandwidth and observer bandwidth in LADRC algorithm,an adaptive real-time optimization and tuning of parameters based on A-LADRC algorithm is proposed.Then compare the anti-interference ability and tracking effects of SMC,LADRC and A-LADRC under different conditions to verify the effectiveness of the parameter tuning strategy.(3)An adaptive radial basis function(A-RBF)suspension control algorithm that does not depend on the exact mathematical model is proposed.The magnetic levitation ball system can obtain good dynamic performance when the large uncertainty existed in magnetic levitation ball system is eliminated through combination between RBFNN and adaptive control.At the same time,Lyapunov is used to verify the design and derivation of the corresponding control law and adaptive law to ensure the convergence of the algorithm.Finally,the effects of the SMC and A-RBF algorithms in different situations are analyzed,and the corresponding simulation and experimental verification are carried out.(4)Finally,the experimental platform of the magnetic levitation ball system is built to verify the two algorithms of A-LADRC and A-RBF under the situation of step,sine and square waves.The experimental results show that the suspension height error under the A-LADRC algorithm is 0.42 mm.On the contrary,since the A-RBF algorithm does not ignore the highorder terms,the suspension height error range is only 0.2mm.Finally,in order to verify the tracking effect of the A-RBF algorithm and the A-LADRC algorithm,sine and square wave follow-up experiments are carried out in turn.The results show that the A-RBF algorithm can make the magnetic levitation ball system obtain better dynamic performance. |
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