SMC-inspired Control Approach Applied to DC-Motor Drives

A control approach inspired to sliding-mode theory is proposed in this work. The procedure is based on assuming the system steady-state condition as the Sliding Manifold (SM), which becomes a natural domain of attraction for the closed-loop system. The control action - designed through a tracking algorithm based on Lyapunov and Sensitivity theory - drives the system trajectory on the SM until the prefixed equilibrium point is asymptotically reached. While on the SM, the controlled system dynamics results reduced to the zeroth-order and evolves in time imitating the dynamics of a low-order model adopted for generating reference signals. The proposed procedure guarantees all the advantages of higher-order sliding-mode approaches without increasing the information demand due to the derivatives of the SM equations. Moreover, the dynamic behavior of the controlled system results annihilated while in sliding-mode, thus implying the insensitivity of the control action to modeling uncertainties and external disturbances. Finally, a continuous control action is achieved, with no chattering effect. Numerical simulations, carried out considering as a test case the control of a DC-motor, confirm the effectiveness of the proposed approach.