Comparative Study of Different Variants of Sliding mode and Back stepping Nonlinear Controllers for Immunosuppressant Drug Control of Renal Transplant Recipients

Abstract

Kidneys are the most often transplanted organs and renal transplantation is the best treatment for patients experiencing End Stage Renal Disease (ESRD). It is imperative to suppress immune system after renal transplant for appropriate kidney performance, which involves the use of various immunosuppressant drugs. However, this suppression exposes patients in danger of viral infections and can activate latent viruses. Aim is to avoid over-suppression or under suppression and to keep a delicate balance between two. Main concern among renal transplantation recipients is Human Cytomegalovirus (HCMV), which is most prevalent virus. This proposed research aims to design different variants of Sliding Mode Controller (SMC) and Backstepping Controllers for an immunosuppressive drug control which will be used to reduce the transplantation rejection risk and to assure that kidney is working well while viral load is observed to be not a severe threat. The drug dosage is taken as the control input for the 6th order state space model of renal transplant. Serum Creatinine is controlled to assure proper working of kidney as it is a measure of kidney’s performance and concentration of Allospecific CD8+T cells that targets kidney is controlled to prevent patient from HCMV infection. The performance of different controllers will be compared to investigate which one is better and more useful for implementing in different clinical scenarios. To ensure convergence of the system output to the desired reference, Lyapunov Stability Theorem is applied. Many numerical simulations are implemented to examine the efficacy of the proposed control techniques.