Consideration of control effector dynamics and saturations in an extended indi approach

This paper proposes an extension of the conventional Incremental Nonlinear Dynamic Inversion (INDI) approach, which enhances the inherent advantages by consideration of control effector dynamics and saturations. The inversion law is derived from a continuous system point of view and presents the resulting system in an intuitive way. First and second order control effectors including absolute and rate saturations can be taken into account in the proposed approach and enable a physically transparent way of designing pseudo control loop and outer loops. The proposed approach is first derived in general and then applied to a simple example system. Lastly, results of a real test flight of the proposed algorithm on a VTOL transition drone are presented. The proposed extension reduces cross couplings in different channels in the presence of control effectors with dissimilar bandwidhts and system orders, and furthermore enables an intuitive way of outer loop gain design. In case of redundant control effectors or "over-actuation", the control effectors are utilized depending on their bandwidth. The algorithm gives promising results and is focus of future research.