The mouthstick is a common and effective assistive aid used by people with spinal cord injuries. It is effective because it is in intimate contact with the human and hence conveys very good tactile information from the environment. It embodies the concept of proprioception as an extension of the body. A headstick can be equally effective, but is an intrusive assistive aid.
This has motivated us to test the effectiveness of our telerobot with a system that works on the same principle . We have designed and implemented a virtual extension of an individual's head movements (much like a mouthstick) using a telerobotic system which we call a virtual headstick (Fig. 1). We use this term because the end effector of the slave robot moves as if it were at the tip of an imaginary extension of the user's head. This is done by simply adding an extra rigid link to the Master robot kinematics and using the positions of the virtual link's tip to command the slave. Also, the forces experienced at the slave are transformed and applied to the user's head by the master in such a way as to make him feel as if he were actually wearing a headstick and directly in contact with the environment.
Advantages of such a system include power amplification, extension of range of motion and better control due to force feedback while maintaining an intuitive interface.