This paper presents an agile and robust spacecraft attitude tracking controller using the recently reformulated incremental nonlinear dynamic inversion (INDI). INDI is a combined model- and sensor-based control approach that only requires a control effectiveness model and measurements of the state and some of its derivatives, making a reduced dependency on exact system dynamics knowledge. The reformulated INDI allows a non-cascaded dynamic inversion control in terms of Modified Rodrigues Parameters (MRPs) where scheduling of the time-varying control effectiveness is done analytically. This way, the controller is only sensitive to parametric uncertainty of the augmented spacecraft inertia and its wheelset alignment. Moreover, we draw some parallels to time-delay control (TDC) -more familiar in the robotics community- which have been shown to be equivalent to the incremental formulation of proportional-integral-derivative (PID) control for second order nonlinear systems in controller canonical form. Simulation experiments for this particular problem demonstrate that INDI has similar nominal performance as TDC/PID control, but superior robust performance and stability.

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Dynamics modeling, simulation, and control have been studied extensively for many applications in robotics, aeronautics, underwater vehicles, and aerospace vehicles (spacecraft, launchers, re-entry vehicles). In that context, this thesis is motivated from two research directions; namely, space launchers guidance and control (G&C) for preliminary design studies and spacecraft nonlinear and agile attitude control systems. The research performed in this thesis focuses on two aspects: 1) attitudemotion and control, which is considered to be one of the classical problems in nonlinear and multivariable control systems; 2) incremental nonlinear control, which is a combined model– and sensor–based control approach and has shown promising results in the aerospace community. The high–performance and robustness of incremental nonlinear control comes from the partial dependency removal of an accurate plant model by just requiring a control effectiveness model to estimate the so–called incremental dynamics, while relying on angular acceleration and actuator output measurements. This approach, integrated with nonlinear control methods, are robust to modeling and parametric uncertainties and allows for aggressive motion control. The objective of this thesis is to develop concepts and methods for nonlinear flight and attitude control design aspects within a multi-disciplinary modeling and simulation approach. With this approach, attitude dynamics and control can play a more important role in the outcomes of aerospace vehicle design and therefore should be considered more within the preliminary design studies of these vehicles. The research performed in this thesis can be summarized in the following three main parts...@en