Robust adaptive control of uncertain non-linear systems with non-linear parameterisation

Abstract

Many physical systems such as welding processes are typically non-linear and uncertain. To control such systems effectively the control scheme requires to be robust with respect to varying operating conditions. On the basis of robust control Lyapunov function method and adaptive non-linear damping approach, this paper presents a robust adaptive control scheme for uncertain non-linear systems with non-linear parameterisation. With the proposed method, estimation of the unknown parameters of the system and generation of an additional signal are not required. There is only one adaptive parameter no matter how high the order of the system is and how many unknown parameters there are. It is shown that the proposed robust adaptive control scheme guarantees the stability of the closed-loop system in the presence of unknown parameters, disturbances, non-linear uncertainties and unmodelled dynamics. Simulation results illustrate the effectiveness of the proposed robust adaptive controller.