近年來，由於「智慧生活」科技的提倡，人臉辨識技術已延伸至人與機器最佳化介面的實現，使得人臉辨識系統廣泛地應用於身份辨識、門禁監控與人機介面等領域；有鑑於此，我們在本論文中提出一個具有即時自動多重人臉辨識與追蹤功能的機器人跟隨系統，主要包括人臉偵測、人臉辨識與人臉追蹤三大程序。
在人臉偵測方面，我們使用AdaBoost分類器進行訓練，並利用一種階層結構來實行偵測；在人臉辨識程序，我們以二維哈爾小波轉換(two-dimensional Haar wavelet transform)取出人臉影像的低頻部份，而在人臉辨識的議題上，我們修改有辨別力的共通向量(discriminative common vectors)的演算法，來建立具有鑑別性的人臉特徵參數模型。最後，我們採用最小歐幾里德距離的決策方式，連續擷取10張人臉影像予以辨識後，投票判斷最有可能的人，並將其辨識結果分成兩大類：主人與陌生人，而機器人會以主人為主要目標進行追蹤；在確定目標物的類別後，進入人臉追蹤程序，於此，我們利用兩階段的粒子濾除器(particle filter)技術來動態追蹤多重人臉。根據人臉在畫面中的位置，對機器人的輪控馬達下達前進、左轉、右轉等指令，並且利用雷射測距儀，來判斷機器人與目標物的距離，進而下達停止或後退的指令，直到機器人跟隨目標物至一個適當的距離。
由實驗結果顯示，我們所提方法的人臉追蹤率在一般的情況下超過 97%，而在人臉產生交錯時的追蹤率可高於 82%，又人臉的辨識率經過統計得知，在一般的情況下，至少達到 93%；此外，對於機器人的整體系統執行效能可達到每秒處理 7 個畫面的速度。這樣的系統效能令人非常滿意並鼓舞我們將此機器人進一步商品化。

More recently, the technique of face recognition has been markedly extended to realize the optimality of human-computer interfaces due to the promotion of “intelligent life.” Face recognition has been broadly applied in many areas, such as biometric identity authentication, entrance guard, and human-computer interface in recent years. In view of the above-mentioned facts, a completely automatic real-time multi-faces recognition and tracking system installed on a person following robot is presented in this thesis, including face detection, face recognition, and face tracking procedures.
As to face detection, the AdaBoost technique is used in our system, and a structure of cascaded classifiers is adopted to detect human faces; in the face recognition procedure, we have captured face images and apply the two-dimensional Haar wavelet transform (2D-HWT) to acquire the low-frequency data of face images. We modify the discriminative common vectors (DCV) algorithm to setup the discriminative models of face features received from different persons. Finally, we utilize the minimum Euclidean distance to measure the similarity of the face image and a candidate person, and decide the most likely person by the majority voting of ten successive recognition results from a face image sequence. Subsequently, the results of recognition will be grouped into two classes: “master” and “stranger.” In our system, the robot will track the master unceasingly; after check the class of targets, our system will go to the face tracking procedure. Herein, we employ a two-level improved particle filter to dynamically locate multiple human faces. According to the position of the human face in an image, we issue a series of commands (moving forward, turning left or turning right) to drive the motors of wheels on a robot, and judge the distance between the robot and a person with the aid of a laser range finder to issue a set of commands (stop or turn backward) until the robot follows to a suitable distance in front of the person.
Experimental results reveal that the face tracking rate is more than 97% in general situations and exceeds 82% when the face occlusion happening. As for the face recognition, the correct rate is over 93% in general situations; besides this, the efficiency of system execution attains 7 frames per second at least in our system. Such system performance is very satisfactory and we are encouraged to commercialize the robot.

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