This paper presents a new interface for the spinal cord injured person and a control scheme of the robot manipulator with the developed interface. The interface is developed to meet four guidelines: ease of motion for the disabled, ease of wearability, human friendly design and low cost. The system is mainly aimed at C3 and C4 injured people who cannot move below the shoulder.
With an increase in the number of spinal cord injured persons, there is a growing demand for human-friendly interface to control wheelchair, a robot manipulator and a mouse cursor. To meet this need, we have developed a new interface that uses head motion. The interface consists of a laser pointer and a pressure sensor. The laser pointer is installed on the back phone, and the disabled controls the position of the red spot on a white board mounted on the wrist of the manipulator. The USB camera, which is behind the white board, continuously captures the position of the red spot on the white board. The pressure sensor is linked to the person’s mouth through a tube and the pressure is measured by the person’s “sip and puff”. The USB camera and white board are located on a pan-tilt unit that is mounted on the manipulator wrist. The pan-tilt unit is designed so that the white board always faces itself towards the disabled person. The disabled person controls the position of the red spot on the white board and the manipulator changes its position so that the red spot is always centered at the white board. By doing so, 2 DOF motion is controlled by the positioning of the laser pointer and one additional DOF motion is controlled by “sip and puff.” Using this interface, the disable person can effectively control the motion of the manipulator. And to add to voice recognition, the disabled can control the 6 DOF motion, change between several modes and switch on/off the robot or developed interface.
And several scheme of robot control for disabled person are developed. The disabled can control the position of end effector using the interface. And then, after changing mode with voice recognition, the disabled can control the angle of it. For easy control of it, pattern recognition and fuzzy algorithm are used. Pattern recognition is used for distinguishing between general motion of laser pointer and periodic motion of it. So detection of periodic motions, which are up and down motion, right and left motion or a circular motion, causes that movement of end effector changes horizontal, vertical or usual direction. And fuzzy algorithm is applied to change robot velocity. So the robot understands intention of user, robot is controlled on user’s wish speed.
