Autonomous navigation initially followed the so called sense-plan-act scheme (SPA) [Albus91], that work with a model of the environment. SPA has some well known drawbacks like strong dependence on a correct model of the environment and high latency. Reactive control architectures [Brooks86], instead, create simple behaviours by coupling sensor readings and actions and complex ones by combining several basic behaviours running concurrently. Reactive behaviours are fast, quite robust against sensor errors and noise and can easily adapt to changes in hardware or tasks. Yet, emergent behaviours are unpredictable, not necessarily efficient and prone to fall into local traps. Hybrid schemes like the well known 3T control architecture [Bonasso97] solve the aforementioned problems by combining both reactive and deliberative paradigms to achieve the best possible performance.