Sensory feedback of the gripping force of an EMG controlled forearm prosthesis
Boosfeld, C.H.; Chang, J.C.; Chen, M.S.; Wang, B.X.
Biomedizinische Technik. Biomedical Engineering 33(7-8): 172-178
1988
ISSN/ISBN: 0013-5585 PMID: 3214668 Document Number: 313198
Most emg-controlled forearm prostheses lack a sensory feedback which conveys information to the wearer about conditions of his artificial limb he cannot visualize, such as the magnitude of the gripping force he exerts upon an item. This information, however, can be helpful and supporting for a smooth and secure articulation, for example while grasping a soft or slippery object. The presented article describes the design of a strain gauge transducer which is incorporated into the hand of a forearm prosthesis and converts the gripping force into an electrical signal. Within an electronic circuit this signal serves as input for a voltage controlled oscillator, i.e. modulates the frequency of the VCO's output. Via a pair of electrodes the skin of the user is stimulated according to the output signal, thus 'informing' him about the magnitude of the gripping force. For adaptation of this signal to the "needs" of each individual amputee, a detailed escription is given on how to adjust the stimulation parameters (frequency, amplitude, repetition rate etc.).