SMARTPHONE USER TESTS FOR USER CENTERED DESIGN

摘要

THESE LAST DECADES SOME NEW INFORMATION AND COMMUNICATION TECHNOLOGIES BECOME POORLY ADAPTED TO ELDERLY, WITH THE INCREASE IN LIFE EXPECTANCY. IN PARTICULAR, THIS IS THE CASE OF DEVICES WITH SMALL SIZE AS SMARTPHONES FOR INSTANCE. IN THIS CONTEXT, IN ORDER TO PREDICT AND IMPROVE THE ACCESSIBILITY OF PEOPLE WITH LIMITED FOREARM MOTOR CAPACITY THIS PAPER DEALS WITH THE STUDY OF INTERACTION MODALITIES BASED ON EMG (ELECTROMYOGRAPHY) FOR HUMAN-COMPUTER INTERACTION, FOR A MORE TOLERANT INTERACTION IN THE FACE OF VAGUENESS OF THE GESTURE. FOR THIS PURPOSE SERIES OF TESTS FOR FINGER ACTIVITY ESTIMATION WERE PERFORMED ACCORDING TO AN APPROPRIATED BIO-MEDICAL PROTOCOL WHILE MANIPULATING A SMARTPHONE IN TWO CASES: WITH AND WITHOUT ERGONOMIC STRAP USED. THE EMG SIGNALS OF THE THREE MOST INVOLVED MUSCLES OF THE THUMB ARE RECORDED AND ANALYZED. THE RESULTS SHOW THAT: I). THE FINGER’S EMG SIGNALS FOR THESE MUSCLES ARE INTERDEPENDENT, II). THE RELATIONSHIPS BETWEEN POSITIONS OF TOUCH, FOR THREE LAYOUTS DOTS DISPOSED ON THE SMART PHONE SCREEN, AND APPLIED FORCE ARE NO LINEAR. USING LINEAR REGRESSION ANALYSIS THE QUANTITATIVE RELATIONSHIPS BETWEEN FORCE AND FINGERS’ DISPLACEMENTS HAVE BEEN EXTRACTED. BY COMPARING FORCE-DISPLACEMENT RELATIONSHIPS, IT IS OBSERVED THAT THE THUMB INDUCES LESS ACTIVATING FORCE THAN THE OTHER FINGERS. IT WAS ALSO FOUND THAT THE RELIEF OF THE FINGER MUSCLES INVOLVED IN THE GRIPPING OF THE SMARTPHONE ALLOWS TO REDUCE THE MUSCULAR ACTIVITY OF THE THUMB AND THUS TO DELAY THE APPEARANCE OF MUSCULOSKELETAL DISORDERS.