Experimental investigations on the effectiveness of electromagnetic actuator as sensor

The study aims at examining the behaviour of electromagnetic actuator as inductive sensor. The electromagnets are integrated in an alternative Wheatstone bridge and powered with alternative tension. This circuit allows the measurement of the electromagnet inductance variation, and as this variation is a function of the air gap, the displacement can be deduced. The effect of eddy currents is assessed in order to choose the suitable bridge frequency. Finally, a demodulator is used to obtain the tension proportional to the air gap value. The behaviour is assessed experimentally. Experiments are carried out on a simple beam; clamped at one end and simply supported at the other. The displacements could be measured by using four eddy current sensors and the inductive sensor. The inductive sensor displacement and a modal approximation of the four eddy current sensors resulting from impact testing are compared. Analysis of the results obtained predicts an efficient and robust behaviour.