Khurram Shahzad, Iftikhar Ahmad, Yasir Islam
Human Immunodeficiency Virus (HIV) is a form of virus responsible for destroying or weakening the immune system and causes Acquired Immune Deficiency Syndrome (AIDS). Immune system finds it difficult to fight against life threatening infections and diseases after the attack of this virus. Researchers have proposed many control algorithms of drug injection under antiretroviral therapy for the treatment of HIV/AIDS. In this paper, an updated mathematical nonlinear model of HIV/AIDS has been considered and four Lyapunov based nonlinear controllers namely; Synergetic, Generic Backstepping, Integral Backstepping and Lyapunov Redesign controllers have been designed. The main purpose of proposing the controllers is to regulate the amount of drug, so that the cells may track their desired reference value. Antiretroviral drug doses together with antigen- specific cytotoxic T-lymphocytes play an active role to eradicate HIV/AIDS by destroying infected CD4 cells and free virus and increasing maximum number of uninfected CD4 cells to an adequate level. The proposed nonlinear controllers can reduce maximum amount of steady state error and have fast convergence time. Lyapunov based theory has been used for the analysis of system global stability. Proposed controllers have been simulated under MATLAB/Simulink and detailed comparative analysis of these controllers has been given to study their behavior.
