Dynamics Analysis And Hardware Implementation Of An Active Memristive Chaotic System

Memristor has attracted extensive attention from domestic and foreign scholars due to its characteristics of low energy consumption,small scale,synaptic and non-volatile logic storage.As a new electronic basic element,memristor has great application value in many fields such as electronic engineering,chaotic circuit and system etc.,and will a far-reaching impact on the development of electronic circuit theory.Therefore,the research on memristors and memristor-based chaotic systems is an important and significant work.As an important branch of nonlinear science,chaotic circuits and systems have important applications in chaotic image encryption,secure communication,and intelligent systems.Pseudo-random sequences can be generated by chaotic system to provide encryption keys for chaotic secure communications.Chaotic systems based on active memristors have complex dynamic characteristics,which has potential value and practical significance in the field of secure communication.Based on the bistable bi-local active memristor,a composite active memristor is designed in the thesis.The emulator of the memristor is constructed and the characteristic fingerprints of the memristor are obtained.Particularly,the hysteresis loop of the composite active memristor can maintain a symmetrical "8" shape in a large scale frequency range.A memristor-based chaotic circuit is designed,and the corresponding dynamics is described by the 4-D autonomous differential equations.Complex dynamics behaviors,including the stability of the equilibria,chaotic attractors,the symmetry of the attractors,transient chaos,coexisting bifurcation and heterogeneous multi stability are analyzed and explored by Lyapunov exponents,bifurcation diagrams,phase diagrams and Poincare mapping,etc.The numerical analysis found that the system has a class of novel chaotic attractors.Particularly,the attractors can be switched with point attractors as the initial value changes.The results of Multisim simulation are consistent with the numerical analysis results.The physical circuit is built based on the Multisim simulation circuit and the process from numerical theory to the construction of practical system is described in detail.The DSP technology is used to digitize the memristive chaotic system.The chaotic sequence of the system is extracted and tested by NIST,which confirms that the chaotic sequence is random.Therefore,the memristive chaotic system can be used as a pseudo-random signal generator to provide a key for information encryption.The active memristor-based chaotic system has complex dynamic behaviors.Through the analysis and verification of the chaotic system,some valuable results have been obtained,which has certain theoretical and practical significance.