UDE based Sliding Mode Control for Octocopter

Octocopter system consists of nonlinear, under-actuated and MIMO dynamics. External disturbances acting on octocopter can affect the flight stability of octocopter. In the presented work, the external disturbances are affecting the altitude and attitude states of multi-rotor system. An uncertainty and disturbance estimator (UDE) based sliding mode control (SMC) strategy is proposed to achieve flight stability for a nonlinear octocopter dynamics operating in the presence of external disturbances. The proposed robust control approach does not require any information such as a priori knowledge of disturbance bound and also addresses the the issue of chattering phenomena, a major concern in SMC design. It is also observed that efficiency of actuators can be increased in the absence of chattering phenomena. Efficacy of the proposed design is shown through simulations and comparison with the SMC based controller design.