ACTIVE CONTROL OF SHALLOW, SLACK CABLE USING THE PARAMETRIC CONTROL OF END TENSION

This study presents a practical, fieldable active controller applicabl e to shallow, slack cables. The controller is based upon an underlying theory that does not assume that the inertial forces are negligible i n the direction of the cable chord. The theoretical framework is devel oped, and an experimental verification is presented. The experiments u tilized a TV camera to track a small number of LED targets on the cont rolled cable, a commercial X-Y tracker and a PC to compute the cable's present position and velocity, and a linear actuator to vary the cabl e's tension. A Kalman filter was employed to smooth the position estim ates and provide least-squares estimates of the cable velocity. The st ability limits for the phase and amplitude of the control signal were established. An analytical estimate of the induced damping expected fr om the control algorithm is derived. Experimental measurements of the cable frequency and induced damping compared well with theoretical pre dictions. It is shown that he proposed active control approach is a si mple, reliable, as well as an effective, method for vibration attenuat ion in lightly damped, shallow, slack cables.