Sensorless Active Suppression of Transverse Vibration of Flexible Plate

In rolling processes, flexible steel sheet is supported by rollers and is bound to produce structural vibration. This vibration can cause severe problem to surface finish and affect the quality of the product. To overcome this problem, active vibration control has been proposed. This usually requires both sensors and actuators. The location of sensors and actuators play a very important role in active vibration control. Moreover, a reliable sensor can be very expensive. This paper proposes a self-sensing vibration control using a push-pull type electromagnet to control the transverse vibration of the steel plate. The construction of the electromagnet has two types of coils, namely the bias coil and the control coil. Vibration displacement is estimated by using the mutual inductance change between the bias and the control coils. The estimated signal is proportional to the gap displacement. The proportional and derivative signal of which is fedback to the control coil to control the transverse vibration of the steel sheet. The proposed method is applied to a simple test rig to confirm the capability of the device. The results obtained are showing high possibility for reducing the sheet steel vibration.