Effect of unmodelled actuator dynamics on feedback linearised systems and a two stage feedback linearisation method

This paper is concerned with the control design of nonlinear systems using feedback linearisation. The paper highlights the destabilisation effect of unmodelled actuator dynamics when applying feedback linearisation. To overcome this difficulty, a two stage feedback linearisation technique is proposed to compensate for actuator dynamics and subse- quently linearise nonlinear systems. A case study of a tri-rotor UAV is used to showcase the benefits of the proposed method in comparison with classical feedback linearisation. The paper is written from a UAV application's point of view, however, the proposed procedure is still valid for any input-affine invertible nonlinear system.