MIBE architecture (Motivated Independent BEhavior) is a behavior-based robot architecture developed at Artificial Intelligence and Robotics Lab of Politecnico di Milano by Fabio La Daga and Andrea Bonarini in 1998.
MIBE architecture is based on the assumption that autonomy is grounded on motivation and arises from superimposition of synergetic activities in response to multiple drives.
That is, there are not layers and static hierarchical dependencies between behavioral modules, but each behavior constantly competes with others for taking control of the agent through the top level motivational state from which specific drives originate (via predetermined or reinforcement-learned functions).
While subsumption architecture is built on a predetermined hierarchy of behavioral modules, MIBE architecture consists of a more complex structure, where several behaviors (that always compete for taking control of the robot via the motivational state) can activate and control dynamically an adaptive set of underlying modules, called abilities.
The main issue of MIBE architecture is the difficulty of modeling the optimal boundaries of the state-space by shaping the motivational structure (i.e.: tuning the drive-generation functions or their learning algorithms) so that the autonomous agent performs the best behavior for each robot+environment state (however the same difficulty also concerns the development of autonomous agents based on subsumption architecture, although the static hierarchical dependencies between behavioral modules make them a bit easier to set up).