Matsushita prototype robot vacuum
In "Flesh and Machines" by Rodney Brooks (2002), Brooks writes, "All of our robots were based on two fundamental principles: situatedness and embodiment. These two terms can be a little fuzzy at times, but I like to use the following definitions for them:
A situated creature or robot is one that is embedded in the world, and which does not deal with abstract descriptions, but through its sensors with the here and now of the world, which directly influences the behavior of the creature.
An embodied creature or robot is one that has a physical body and experiences the world, at least in part, directly through the influence of the world on that body. A more specialized type of embodiment occurs when the full extent of the creature is contained within that body.
Under these definitions an airline reservation systems is situated but it is not embodied. A robot that mindlessly goes through the same spray painting pattern minute after minute is embodied but not situated."
Brooks goes on to talk about his lab's "Cambrian explosion" (a pun on their location, Cambridge, MA, and the postulated evolutionary event) and how his robots filled various ecological niches within the lab. If you're interested in his approach to building robots, you might learn more about their early robots, e.g., Genghis, Polly and Toto, as well as their more recent humanoid probots such as Cog and Kismet. Brooks' book is also interesting and worth reading for its commentary on such things as the consequences of batteries not keeping up with Moore's law, reflections on ethology and robotics from arctic terns to digger wasps, and a very nice treatment of the philosophical issues concerning machine intelligence.