Extended physiologic taction: design and evaluation of a proportional force feedback system.

In both robot teleoperation and prosthetics, the feeding back of touch information to the human operator in a physiologically compatible manner is an important problem. Most research in feedback systems for prosthetic devices has concentrated on electrotactile or vibrotactile stimulation of the skin. While these techniques can transmit information to the user, the user does not have the same sensation as if he were grasping an object in his natural hand. The present research investigates a third method of stimulation using direct force. In the sense of Simpson's Extended Physiologic Proprioception (EPP), it is called: Extended Physiologic Taction (EPT). The EPT system produces a one-to-one correspondence of touch sensation to user stimulation. The EPT system applies a force on the surface of the skin of the operator proportional to the grip force applied at the terminal device, or applies a vibration to the operator proportional to the vibration at the terminal device. A method of quantifying grip controllability has also been developed. A prototype was built and tested using a myoelectrically-controlled prosthetic terminal device as the remote gripping device. Quantifiable comparisons can be made between different feedback and gripping systems as well as comparisons between artificial terminal devices and the natural hand. Results are reported of improved grip control and of improved ability to manipulate objects when using the EPT system.