For this particular system, it was necessary to add PD feedback across the plant to kill oscillations and a deadzone around the set value to prevent updating of the adaptive parameters when the actual angle approached the commanded angle. In general, the MIT method is not the best implementation of MRAC, particularly with nearly unstable systems.
MRAC design comes in many flavors. Some of the more robust methods include Lyapunov direct and indirect MRAC. These methods are founded of of Lyapunov stability theory. More recent uses of MRAC incorporate other control methodologies such as Fuzzy-MRAC and Variable-Structure MRAC (VS-MRAC).
I hope you enjoyed the introduction to MRAC. If you have any questions or comments feel free to email me at:Keithicus@drexel.edu.