Research On Chaos Suppression Method Of A Class Of Biological Systems Based On Variable Structure Theory

Coronary artery is a muscle vessel that is responsible for delivering oxygen and nutrients to the heart,and its depth affects the health of the heart.A large number of medical studies have shown that the vast majority of cardiovascular disease are associated with the lesion of coronary artery system.Coronary artery disease is clinically manifested as uncontrolled and uncoordinated contraction of the coronary artery system,which is chaotic phenomenon from the perspective of mathematical modeling.Therefore,the analysis and treatment of coronary artery disease can be reduced to the problem of chaos suppression in the coronary system in the field of control science.Firstly,based on the bio-mathematical model of the coronary artery system,the dynamic characteristics of the coronary artery system were analyzed from the aspects of state time domain waveform,phase trajectory and Poincare mapping,and the lumped parameter range of the system in the chaotic region was demonstrated by using bifurcation diagram and information entropy.In this paper,the representative parameters of the coronary artery system model are selected within this parameter range,and then the driving response error system is derived by using this set of parameters.The chaotic synchronization control problem of the coronary artery system is transformed into the stabilization problem of the error system.Secondly,for the problem of chaos suppression in the coronary system,researchers have combined chaos theory with the coronary system and proposed many methods to suppress chaos in the coronary system.Although these control methods can basically achieve the chaos suppression of coronary artery system,the control input is not smooth and has jagged fluctuations.This problem will cause damage to human cardiovascular system in the process of chaos suppression,and seriously affect the control effect of coronary artery chaos suppression.In this paper,a smooth second-order sliding mode algorithm is used to design a chaotic synchronous controllerto achieve smooth and stable control input,reduce the damage to the human cardiovascular system during the control process,and improve the control effect of chaos suppression in the coronary system.For various unknown disturbances in the system,on the basis of the smooth second-order sliding mode controller,the nonlinear disturbance observer and the adaptive method are used to estimate and compensate them respectively,so as to improve the robustness of the smooth second-order sliding mode control system and improve the control effect of chaos suppression in the coronary artery system.Finally,the stability of the proposed control method is analyzed using Lyapunov stability theorem,and the stability of the proposed control method in the process of chaos suppression of the coronary artery system is proved.In addition,this paper uses MATLAB as the platform to verify the design of the control method and compares it with the ordinary super-twisting sliding mode control,which proves the feasibility and effectiveness of the design method in this paper.