A hybrid strategy for the control of Rotary Inverted Pendulum

In this paper a new control scheme is proposed for the control of Rotary Inverted Pendulum. Rotary Inverted Pendulum is a nonlinear, non-minimum-phase, unstable and underactuated system. Undoubtedly controlling such a system with mentioned specifications to get the desired response is so difficult. Using the proposed hybrid control structure we take advantage of useful properties of both sliding mode controllers and fuzzy logic controllers at the same time. Sliding mode control is a useful nonlinear control method that is robust against uncertainties and parameter variations but it is usually accompanied by a harmful effect called chattering which in turn may arise various problems for the system. Fuzzy logic controllers are multi-purpose controllers that can be designed to improve conventional controllers´ performances. Taking advantage of the proposed hybrid strategy based on the error criterion we succeeded in suppressing the chattering and getting quite a faster response in comparison with the single sliding mode control.