Model Predictive Control for underactuated spacecraft equipped with two reaction wheels in the presence of a residual angular momentum

We propose a Nonlinear Model Predictive Control (NMPC) law for an underactuated spacecraft attitude maneuver in the presence of a momentum bias. We assume that a cluster of only two reaction wheels is available and the spacecraft is no longer fully controllable and stabilizable by means of a continuous static feedback. Nonlinear Model Predictive Control is investigated as a possible approach for the derivation of a suitable control system, which allows for full three-axis control, in spite of underactuation, with acceptable closed-loop performance, in the presence of a residual angular momentum and torque saturation. Maneuver convergence is studied and analyzed in two different scenarios: i) a minimum non-zero pointing error at rest condition; ii) a periodic spinning solution which allows a zero pointing error with a residual angular rate. An extensive simulation campaign shows the effectiveness of the proposed NMPC-based control, proofing the viability of the approach.