Our world is getting older and older (OECD 2009), and therefore there is considerable expectation for more widespread home, medical, and nursing care services to assist not self-sufficient elderly people, both from the physical and psychological points of view. In this context, robots are expected to perform human tasks such as operating equipment designed for humans in dangerous environments, providing personal assistance, social care, cognitive therapy, entertainment, and education (Kozima, Nakagawa et al. 2007). These robots should be capable of a smooth and natural adaptation and interaction with their human partners as well as with the environment. They should also be able to communicate naturally with humans, especially in home and personal assistance applications for elderly and/or handicapped persons. Moreover, these devices should be safe and, more in general, should never have a negative effect on their human partners, neither physical nor emotional.