Personal robots and Robot Technology (RT)-based assistive devices are expected to play a substantial role in our society, largely populated by elders; they will play an active role in joint works and community life with humans. In particular, these robots are expected to play an important role for the assistance of elderly and disabled people during normal activities of daily living (ADLs). To achieve this result, personal robots should be also capable of human-like emotion expressions. In this perspective we developed a whole body bipedal humanoid robot, named KOBIAN, which is also capable to express human-like emotions. In this paper we present the mechanical and modular design of KOBAIN.