Positive nonlinear control of tumor growth using angiogenic inhibition

The input of physiological control systems is positive in almost every case (i.e. it is the concentration of a drug), thus the application of controllers which guarantee positive input is crucial. However, most of the controller design methods can not incorporate the constraint that the input has to be positive. We propose a method based on the dynamic extension of the system that guarantees that the output of the controller is always positive, and design nonlinear controller and observer for the extended system. The extended system is linearized using exact linearization, and path tracking control law is applied to ensure the desired tumor volume regression. The output of the resulting controller is always positive, and achieves the desired tumor regression with low control inputs that are desirable in physiological point of view. The results show that the proposed dynamical extension can be sufficiently used along with exact linearization to control nonlinear dynamic systems with positive inputs. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.