“…Existing sensors for a gesture recognition of movements of hands and arms include ultrasound [ 9 , 10 , 11 , 12 ], camera based vision [ 13 , 14 , 15 , 16 , 17 ], and radar [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Ultrasonic sensors have the advantage of relatively low price, but they have short detection distance.…”