Research On Mechanism And Control System Of Robot Head

With the development of the intelligent service robot, the robots with human-robot interaction function are becoming important trends. The human-robot interaction technology based on facial expression recognition and reproduction has been becoming a research highlight, face interaction plays an irreplaceable role in the service robots human-robot interaction. Therefore, the facial expression reproduction is of great importance in intelligence, emotion and humanization of human-robot interaction.The humanoid robot head system with facial expression reproduction functions has been designed and developed. This system was composed with the humanoid robot head body, the image capture devices, the facial expression and organ control system. Through the control system of the head, organs of the head and expression control points reach to the designated position, accurately and quickly,achieve a variety of facial expressions and express the inner emotional state of the robot, in order to make the robot to communicate with human flowly and naturally, through the vivid facial expression of the robot.In this paper,firstly, we describe the movement principle of the human facial expressions and head organs from the perspective of human psychology and anatomy, and propose a design method of the robot head and the facial expressions in accordance with Ekman's Facial Action Coding System (FACS). In the expression reproduction part, we draw 9 facial feature control points achieved facial expressions, according to concepts of the expression characteristics and expression feature points offset, and then we get a method which could form six kinds of basic facial expression based on the theory of emotion spatial distribution.In this research, servo motors are selected as main driver, and crank-rocker mechanism is selected as transmission.The robot head body with 13-DOF has been designed, and includes four motion modules which are the eyes, eyebrows, eyelids, and jaw. we use Catia make three-demensional model of the robot head body, and complete the prototype of the processing and assembly. In the part of control system, ATmega8L is selected as the main control chip.The design of hardware includes power supply, serial communication and 13 PWM controlling circuit. The software will be designed by the ICC AVR development environment based on C language, using the chip's time cournter, interrupt function and the method of the facial expression reproduction, which can output 13 PWM contron signal for achieving six kinds of basic facial expression. Experimental results of organ movement of the robot head and the six kinds of basic facial expressions reproduction demonstrate the system reliability of the head organ action,and the method of facial expressions reproduction which based on the theory of expression feature points offset is available and correct.