L₁ adaptive output feedback control for underactuated MIMO systems

This paper addresses the problem of output feedback control for underactuated (non-square) MIMO systems with unknown input gain and matched uncertainties. The L₁ adaptive output feedback control architecture in this paper includes a state predictor, an error observer, adaptation laws, and a low-pass filter. It is shown that the proposed control strategy guarantees that the error signals of the closed-loop system are semi-globally bounded. Simulation results are presented to validate the theoretical claims.