# Semi-Active Vibration Control Based on a Smart Exciter with an Optimized Electrical Shunt Circuit
## 4 Experimental Verification of Noise Reduction Potential  
### Experimental Setup  
To verify the vibration reduction effects of the SE and RL-shunt, experiments have been conducted. In the experiment, an exciter Visaton ES 45 S, a panel (400 \(\times\) 700 \(\times\) 7 mm) and a RL-shunt box, produced by the Zentrum fur Angewandte Luftfahrtforschung (ZAL) (Hamburg, Germany), have been used. The dimensions of the panel are not identical to the dimensions described in Section 2. However, to experimentally prove the feasibility of the semi-active vibration control concept in the first step, it has not been necessary to match the parameter of the numerical model. All equipment is shown in Figures 10-12. Figure 10 shows the details of the RL-shunt box.  
Figure 10: The box for different combinations of RL-shunts: (**a**) top, (**b**) right side and (**c**) front.  
Figure 9: Displacement over time of the panel for 9.95 to 10 s: (**a**) without the SE and (**b**) with the SE.  
On the top side (Figure 10a) are the controls, which are more clearly shown in Figure 11. \(L\) and \(R\) are the inductance and resistance in the electrical shunt. Parallel and Series represent the connection types. In this box, 127 different types of inductances and resistances have been implemented. The values for \(R\) may be set to values between 12.216 and 299.8 \(\Omega\), and \(L\) may be set to values between 0.0132 and 2.15 mH. The black and white sockets on the right-hand side (Figure 10b) are for USB connections for programming the device and the power supply. The red and black circles on the front (Figure 10c) are sockets for the exciter, which are not affected by the accessing sequence.  
Additionally, an impulse hammer (B&K type 8206), a microphone, a multi-input-fronted (B&K type 3050 using 5 kHz as the sampling frequency and an integrated digital high-pass filter with 0.7 Hz corner frequency for all inputs) and three accelerometers (B&K type 4508 B) have been used. The coupling positions of the SE and accelerometers (both sides of the panel) and the tapping positions of the hammer are marked on the panel. The positions of these points are shown in Figure 13. Double-sided tape has been used to define the coupling positions for the SE and the accelerometers on both sides of the panel. The impulse hammer, all accelerometers and the microphone have been connected to the frontend.  
Figure 11: The operation interface of the RL-shunt box.  
Figure 12: The experimental equipment: (**a**) smart exciter, (**b**) panel and (**c**) RL-shunt box.  
The panel has been mounted with two pieces of tape. The microphone has been placed at a 1m distance in front of the panel's center. Three accelerometers have been glued to the back of the board, as shown in Figure 14a. Finally, the SE and RL-shunt have been coupled to the front of the panel, as shown in Figure 14b. The SE was coupled at all positions, P1 to P3, successively. Simultaneously, the force of the impulse hammer, the acceleration and the sound pressure have been recorded and saved on the hard disk of the laptop, which has been connected to the frontend module.