A Geometric Approach to Nonlinear Control of a Research Aircraft

The paper proposes a new method of flight control design using a geometric approach. The flight control design has been done on the nonlinear manifold Special Euclidean Group or SE(3), thereby avoiding the singularity inherent in local representations. Hence, the region of operation is enhanced. The complete nonlinear 6-Degree of Freedom (DOF) model has been considered in controller design. The control approach has been developed for the newly designed scaled-down multi-role research aircraft. The control approach has also been extended to the case of stuck faults in multiple control surfaces. A novel approach has also been proposed to handle stuck faults of control surfaces. Mathematical proof has been given to demonstrate the stability of the dynamics with the proposed controller. Simulation results have been given to demonstrate trimmed flight without faults as well as in the presence of multiple faults. Comparison results with the method existing in the literature is also presented. First, the simulation results have been given when there is no fault in the control surfaces. Then, another simulation result have been presented when two of the control surfaces get stuck at its previous condition. A comparison result with incremental nonlinear dynamic inversion sliding mode control (INDI-SMC) has also been given, and it is shown that the proposed method outperforms INDI-SMC. In the proposed method, the average thrust variation around the mean value is very small i.e. only 0.72 N as compared to INDI-SMC which is 10.8 N. Again, it is also observed that the average variation around mean in linear velocity along the body X-axis is very small i.e only 0.68 m/s in the proposed method as compared to INDI-SMC where it is 1.9 m/s.