Study on Control of Facial Expressions of Face Robot and Their Informatic Characterisitics

(1)该人脸机器人由头架结构、18个面部肌肉FMA驱动器、硅橡胶面部皮肤、眼睛、嘴、鼻子和颈部结构组成，具有18个自由度来模仿人脸运动。人脸机器人的尺寸比正常人脸大20%。根据心理学中动作单元的种类和强度，确定了表达6种基本面部表情的面部组件的运动，并建立了面部表情的控制算法。(2)对机器人显示的6种基本面部表情进行了视觉测试，除“恐惧”表情外，其余表情的正确率均在90%左右。(3)为实现人脸表情的实时运动，研制了一种小型气缸活塞式驱动器，并将其中的18个驱动器应用于人脸机器人，通过对每个驱动器进行反馈控制，建立了控制算法，实现了人脸机器人的实时表情运动。(4)利用晶片机系统和2个CCD摄像机，成功地实现了眼睛、眉毛和嘴巴运动的实时测量。一次动态面部图像测量所需的时间约为100 ms，对于我们动态识别面部表情来说足够短。(5)将由Transputer系统获得的动态人脸图像数据应用于典型表情训练的神经网络，并进行了人脸机器人表情识别性能的评估，获得了较高的识别率（约80%）。(6)未来的工作将是研究人与人脸机器人之间的心理信息交换的交互特性，利用面部表情。

(1) The face robot consitutes of a head-frame structure, 18 facial muscle FMA actuators, silicone-rubber face skin, eyes, mouth, nose and neck structure and has 18 degree-of-freedom to mimic the movement of human face motion. The size of the face robot is 20% larger tahn that of normal human face. The motion of face components for expressiong 6 basic facial expressions are determined according to the kind and strength of Action Units used in psychology and control algorithm for the facial expressions has been established.(2) The 6 basic facial expressions displayd on the face robot were evaluated by visual test and obtained about 90% correct expression except for "Fear" expression.(3) Small size air-cylinder-piston type actuator was developed for real-time motion of facial expression and 18 of this actuators were implemented into the face robot and control algorithm was established by using a feedback control in each actuator for realizing a real-time motion of facial expressions on the face robot.(4) By using the transputer system and 2 CCD cameras, the real-time measurement of motions in eyes, eye brows and mouth was successfully performed. The time needed for one dynamic facial image measurement was about 100 ms which is sufficently short for our dynamic recognition of facial expressions.(5) The dynamic facial image data obtained by the transputer system were applied to the neural network trained by typical facial expressions and recognition tests were undertaken to evaluate the performance of facial expressions of the face robot and obtained a rather high rate (about 80% correct ratio).(6) Some of future works will be to investigate the interactive characteristics of psychological information exchange between human and face robot by using facial expressions.