Robust adaptive backstepping speed controller design for a series DC motor

A robust adaptive backstepping technique is proposed in this paper to solve the speed-tracking problem of a series DC motor for improving transient response. The parameters of DC motor are considered as unknown and the external disturbances are incorporated into the dynamical model. The proposed controller is designed in such a way that it is adaptive to the unknown parameters of series DC motor and robust to external disturbances. The unknown parameters are estimated through the adaptation laws and the convergences of these adaptation laws are obtained through the negative semi-definiteness of control Lyapunov functions (CLFs). The proposed controller not only provides robustness property against external disturbances but also overcomes the over-parameterization problem which usually appears in some conventional adaptive methods. Finally, the performance of the proposed controller is tested on a MATLAB simulation model. The performance of the proposed scheme is compared with that of an existing backstepping controller where the external disturbances are neglected. Simulation results demonstrate the effectiveness of the proposed controller in terms of rejecting external disturbances.