Initiation and dose concentration of HIV control

In this paper, we propose to initiate the HIV therapy based on the Lyapunov exponents of the system. If one of the Lyapunov exponents of the system is positive, then the therapy is initiated, and the control is deactivated vice versa. The dose concentration (when the therapy is initiated) is determined based on a control law in which it is formulated according to the Lyapunov stability criterion. Numerical simulation results show that the controlled viral load is decreasing and all physical constraints of the system, such as the boundedness and the positivity of all state variables and the dose concentration, are satisfied