The authors have been developing new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. In this paper, they focus on the olfactory sensation and facial color that humans use to communicate with each other. Human's olfactory sensation recognizes over thousand different smells. The WE-3RIV (Waseda eye No.3 refined IV) developed can recognize the smell of alcohol, ammonia and cigarette smoke. The olfactory sensor consists of four semiconductor gas sensors. WE-3RIV is able to recognize certain smells within a few seconds of being presented with the smell stimuli by using the sensor output and the rate of changing of output. Further, we developed the facial color expression using red electro-luminescent sheets. By adding the facial color expression, the expressiveness of the robot and its facial expression are improved.

The authors deal with human-like head robots in order to develop new head mechanisms and functions for a humanoid robot that has the ability to communicate naturally with a human by expressing human-like emotion. When humans communicate through auditory or visual sensations, they estimate their mental state through not only the information of each sensation but also their mental model. A robot's mental model consists of a 3D mental space having a pleasantness, and activation and a certainty axes. When the robot senses the stimulus, a mental vector moves in this mental space based on the equations of emotion. We also propose a robot personality which consists of sensing personality and expression personality. Further, we assign and load various sensing personalities.

The authors have been developing anthropomorphic head robots in order to develop a new head mechanisms and functions for a humanoid robot having the ability to communicate naturally with a human by expressing human like emotion. We developed the anthropomorphic head-eye robot "WE-3RIV" (Waseda Eye No.3 Refined IV) which has four sensations and facially expresses emotions in 2000. We have recently added the olfactory sensation and the facial color expression function to its previous model, WE-3RIII, and we improved and rebuilt its artificial psychological model that consists of a 3D mental space having pleasantness, activation and certainty axes. When the robot senses the stimulus, a mental vector moves in the mental space based upon a set of differential equations in the mathematical formulation. We named it "equations of emotion. " We also introduced the robot personality, which consists of the sensing personality and the expression personality. WE-3RIV was realized to express the mental state affected by various stimuli based on the equations of emotion and the robot personality.

The authors have been developing anthropomorphic head-eye robots, in order to elucidate the human vision system from an engineering point of view, and to develop a new head mechanism and function for a humanoid robot having the ability to communicate naturally with a human. We developed the anthropomorphic head-eye robot "WE-3RII" (Waseda Eye No.3 Refined II), with eyes, eyelids, eyebrows, lips, jaw and a neck. The robot has the ability to express an autonomous facial expression using three independent parameters of a psychological model. With the robot, the mechanism of changing eye movement from smooth pursuit eye movement to saccadic, and the control of scanning eye movement like that of a human's can be achieved. The robot is also able to express more human-like motion in pursuing a target by changing its eyeball control parameters, rather than that of WE-3R which we developed in 1996. Therefore, the authors have confirmed that WE-3RII has the ability to realize a pursuing motion in three dimensional space with its autonomous facial expression adapting to the target position and brightness like a human.