Abstract
According to the World Robotics 2011 report [79], up to the end of 2014, more than 14 million service robots will populate the world. A service robot is a robot which operates partially of fully autonomously to provide services useful to the humans [10]. The group of service robots can be further divided into professional service robots, intended to perform service tasks at a professional level, and personal robots, suitable for education, assistance or entertainment tasks at home. Among these, it is of special interest the group of assistive robots, which main purpose is to help elderly and impaired people in their daily life.