Brain computer interface (BCI) is an information channel independent of routine brain output ways such as peripheral nerves and muscle organization. As a special human-computer interface mode, it provides a direct communication pathway between the brain and external devices so as to exert control over those devices by ways other than primitive human communication. Controlling over mobile peripheral devices such as intelligent wheelchairs or nursing robots is a very important application of BCI technology in the future. This paper describes the newest progress of the above mentioned technology, analyzes and compares key techniques involved, and forecasts future development in this field.