Vibration suppression of a string through cyclic application and removal of constraints

A low-cost high-precision measurement method of string motion

“…Although researchers mostly use electromagnetic pickup [1], electrodynamic method [2] or electric field sensing methods [3][4][5][6][7] in the case of a steel string, these methods cannot be applied to other common string's materials such as gut or nylon. In this case, optical methods should be more appropriate to obtain the string displacement by an optical tracking device [8], by a photoelectric sensor [9] or using a high-speed camera coupled to image processing [10,11] or the string velocity through a laser doppler vibrometer [12]. Another optical method, less intrusive, expensive and cumbersome, consists in catching the shadow of the string by using an integrated opto-sensor [13], a photo-Darlington [14], or an analog position sensing detector [15], as well as an optoswitch system including an infrared emitting diode coupled to a photo-transistor [16].…”