# Experiment Investigation of Bistable Vibration Energy Harvesting with Random Wave Environment
## 3 Results
### Vibration by Period Signal  
The results of response vibration displacement and vibration power generation obtained when the signal is vibrated with a periodic signal by a mini shaker are shown in Figures 8-11. Figure 8: Measurement results of response vibration displacement and vibration power generation when vibrating with a period signal 0.3 Hz. (**a**) Results of response vibration displacement. (**b**) Diagram of displacement velocity of vibration of the support. (**c**) Diagram of displacement velocity of vibration of the mass block. Figure 7: Measurement results of response vibration displacement and vibration power generation when vibrating with a random signal. (**a**) Results of response vibration displacement. (**b**) Diagram of displacement velocity of vibration of the support. (**c**) Diagram of displacement velocity of vibration of the mass block. Figure 10: Measurement results of response vibration displacement and vibration power generation when vibrating with a period signal 0.5 Hz. (**a**) Results of response vibration displacement. (**b**) Diagram of displacement velocity of vibration of the support. (**c**) Diagram of displacement velocity of vibration of the mass block. Figure 9: Measurement results of response vibration displacement and vibration power generation when vibrating with a period signal 0.4 Hz. (**a**) Results of response vibration displacement. (**b**) Diagram of displacement velocity of vibration of the support. (**c**) Diagram of displacement velocity of vibration of the mass block. As shown in Figure 8, the response vibration of the mass block oscillates at the same frequency as the support table, and the response vibration displacement of the mass block is a little larger than the support stage, and the vibration of the mass block becomes a little larger than the support stage, and it makes the single steady vibration on the right side of the vibration model can be confirmed. In addition, since the relative motion of the mass block and the support table is small, the voltage of the oscillatory power generation by the piezoelectric element is small, the average voltage value is 0.44 V, and the maximum voltage value is 1.26 V. Figure 8a,b show that the vibration displacement and the speed of the mass block are relatively small. Figure 9 shows a measurement result obtained by the excitation of a periodic signal of 0.4 Hz frequency, it was found that the vibration was clearly more extensive than the vibration displacement at 0.3 Hz. Moreover, the vibration of the periodic response vibration displacement is slightly disturbed, and it is considered that the vibration frequency is likely to approach the natural frequency of the vibration model. However, the response vibration of the mass block remains on the right side of the vibration model, and it is confirmed that a single stable vibration is performed. In addition, since the relative motion of the mass block and the support table became relatively large, the voltage of the oscillatory power generation by the piezoelectric element became a little larger, and the average voltage value was 2.84 V, and the maximum voltage value was 6.86 V. The vibration displacement and the velocity of the mass block are clearly increased by Figure 9a,b, and the vibration is continued to the vibration model's right side. Figures 10 and 11 show the results of measurement in the case where the signal is oscillated with a periodic signal having a frequency of 0.5 Hz and 0.6 Hz, it was found that the vibration displacement was clearly reduced compared with the vibration displacement at 0.4 Hz.