Active damping of a vibrating string

This paper investigates the active damping of the vertical and horizontal transverse modes of a rigidly-terminated vibrating guitar string. After describing the characteristics of various actuators and sensors, we motivate the choice of collocated electromagnetic actuators and a multi-axis piezoelectric bridge sensor. Next, we introduce a state-space model that emulates the behavior of the string, and we explain the theory behind band pass filter control and PID control as applied to a vibrating string. Finally, we discuss the experimental results and implications of applying these control methods. In particular, we consider the difference between damping the energy in only one transverse axis, versus damping the energy in both the vertical and horizontal transverse axes simultaneously.