Devices are under development for people with sever disabilities and have no motor control. One is a device which allows wheelchair users to control their wheelchair by "sniffing" and another by eye movement. Most people with locked in syndrome or other types of sever paralysis can move their eyes and can sniff. There are two types of wheelchair technologies under development for these severly disabled people.
Several groups are working on eye controlled wheelchairs. For example, the Eye Com corporation is developing the The Eye-Com EC7T™ eye tracking system which uses frame-mounted microcameras to record eyelid and pupil activity and convert that movement to wheelchair steering.
Here is a video from two final year engineering students (Robotics and Biomedical) from Swinburne University (Melbourne, Australia) using eye controlled technology:
The sniffing technology appears to be equally promising.
Developed by Prof. Noam Sobel, electronics engineers Dr. Anton Plotkin and Aharon Weissbrod and research student Lee Sela in the Weizmann Institute’s Neurobiology Department, the new system identifies changes in air pressure inside the nostrils and translates these into electrical signals. The device was tested on healthy volunteers as well as quadriplegics, and the results showed that the method is easily mastered. Users were able to navigate a wheelchair around a complex path or play a computer game with nearly the speed and accuracy of a mouse or joystick.
Watch this video of the wheelchair controlled by sniff technology.