This paper develops a functional voice activated wheelchair. Various interfaces to control powered wheelchair are proposed. Since the voice is the most natural communication ways for person, our study pays attention to speech recognition. The user controls the wheelchair by the interactive operation. The wheelchair does not act based on false speech recognition. However, there is a problem that is the wheelchair collides in the wall and obstacle by delaying the voice command. Then, our system applies the collision avoidance function CAF by which wheelchair avoids the wall or obstacle without voice command by using the information of two kinds of sensor. CAF assists the user to control the wheelchair without colliding in the wall or obstacle. The effectiveness of our system was confirmed through the running experiment.