Designing an Input-Linearized Adaptive Sliding Mode Coupled Nonlinear Integral Controller

A novel I-controller with antiwindup feature has been proposed as a tangent hyperbolic function of an integral of a sliding function. This has been combined with an input-linearized first-order sliding mode controller (SMC). A practical two-parameter sliding mode with integral controller (SMIC), design thus formulated has been adapted online by minimizing a Lyapunov functional together with constraining the parameter growth by projection operator. Keeping only the I-control live, but not adaptable, small sliding variable together with withholding discontinuous form of SMC has been proposed to eliminate chattering. Both from theoretical standpoint and through numerical simulation, the design is established as convergent. A set up actuated by an electrohydraulic valve-cylinder pair providing angular motion, typical of aircraft wing maneuvering system, has been realized and a real-coded genetic algorithm, together with offline experiments, has yielded the parameters for the system and the initial controller setting. Real-time experiments have clearly shown the SMIC to have tracking accuracy and bandwidth better than those achievable from some existing controllers. The proposed design has yielded chattering-free real-time responses for different external loading and motion demands.