Vibration reduction of traffic signal pole by dynamic absorber that generates electrical power

The authors propose an absorber that generates electrical power in order to not only suppress vibration but also get electrical energy when many traffic signal poles are oscillated by wind, traffic turbulence. The absorber consists of a displacement magnifying mechanism by using levers, solenoid coils and rare-earth magnets. It is useful for small deformation between a beam and a column of the traffic pole. Vibration modes of the pole are analyzed by using FEM, and then a small scale model of the traffic pole is built up. The small scale model has 2.7 m high, consists of a steel column and a cantilever beam due to rescale about 1/3 times of a real scale model, and the natural frequency of first mode is arranged to 3.5 Hz. Trial absorber is manufactured and a damping force, which is caused by the coils crossing magnetic field, is adjusted. Dynamic characteristics of the trial absorber are measured by a shaking actuator. In order to confirm vibration reduction and energy conversion, harmonic vibration test of small scale model when the trial absorber is installed is carried out by using a shaking table. The experimental results of the harmonic responses are compared with the calculated results which are derived by FEM. Effect of vibration suppression and efficiency of generating electrical power are evaluated experimentally and numerically.