Chattering-free sliding mode control with unidirectional auxiliary surfaces for miniature helicopters

Purpose: This article proposes a chattering-free sliding mode control scheme with unidirectional auxiliary surfaces (UAS-SMC) for small miniature autonomous helicopters (Trex 250). Design/methodology/approach: The proposed UAS-SMC scheme consists of a nested sequence of rotor dynamics, angular rate, Euler angle, velocity and position loops. Findings: It is demonstrated that the UAS-SMC strategy can eliminate the chattering phenomenon exhibiting in the convenient SMC method and achieve a better approaching speed. Originality/value: The proposed control strategy is implemented on the helicopter and flight tests clearly demonstrate that a much better performance could be achieved, compared with convenient SMC schemes.