## 6 Test Results and Discussion  
In the first test, the experimental setup was carried out under case 2 of the incident waveform. Tests were conducted in two cases of added inertia, \(I_{0}\) and \(I_{1}\), as shown in Figure 9. The test results were obtained and plotted in Figure 10. As shown in Figure 10, the mathematical model was validated by a good agreement with the measured data. Here, the elevation of the floating buoy was measured by a cable sensor (Me. Floating ele) and compared with the simulation results from Equation (16) (Si. Float ele) on the top floor. Since the floating buoy elevations are the results of the hydrodynamic behavior, these values are different from the wave elevations. The generator speed and the resistive torque were also plotted and compared on the middle floor and bottom floor, respectively. As shown, on the middle floor, the corresponding speed of the generator is measured by an encoder device (Me. Speed). The simulation results (Si. Speed) are calculated by solving Equation (17) (Si. Speed). The Si. Speed is taken from solving differential Equation (16). Therefore, there is some disturbance in the initial state. However, the simulation results can reach a steady state in about 10 s. On the bottom floor, the resistive torque from the generator was measured by a torque transducer (Me. Torque) and compared with the simulation results obtained by solving Equation (19) (Si. Torque). While both test sets showed some discrepancies between the model predictions and the measured data, particularly at peak values, most measured values (buoy elevation, speed, and induced torque) exhibited good agreement with the model. These discrepancies might stem from limitations in the mechanical structure's precision or nonlinearities in the actual wave-structure interaction. Notably, the measured torque exhibited some instability, possibly due to these nonlinearities, friction within the system, or imprecise mechanical parts. However, the average measured torque still aligned well with the model. In the second test, the experiment setup is used to investigate the performance of the WEC under different cases of incident waves, as shown in Table 2. For each experimental case, three added inertias shown in Table 3 were adjusted by controlling the stepper motor. The test results are plotted in Figures 11-13. Figure 11 shows the floating buoy elevation, torque, speed, and energy driving the generator simulator in case 1 of the test. The tests were carried out under different cases of the inertia supplementary. First, the elevations of the floating buoy are measured and plotted in 20 s operating time. The rest results indicated that 20 s is enough time to reach a steady state. Then, the speeds of the generator simulator are presented under different added inertia levels. Next, the induced torques are shown in the figure. Finally, the generated energy is obtained by integrating the product of the generated torque and speed over the operating time. The mean wave power transmitting on the floating buoy is  
Figure 10: Model validation under two cases of tests: (**a**) comparison between simulation and measurement results for \(I_{0}=0\); (**b**) comparison between simulation and measurement results for \(I_{1}=88.5\) kg\(\cdot\)m\({}^{2}\). obtained by using linear wave theory. The experimental results indicate that the generated energy increases in cases with increased added inertia. The same experiments were carried out in case 2 and case 3, and the test results are shown in Figures 12 and 13, respectively. As shown in these figures, the added inertia has a significant influence on the performance of the WEC. According to linear wave theory, the added inertia brings the natural frequency of PTO close to the incident wave frequency (resonance behavior). Therefore, the floating elevation and speed are increased, and the generated energy is also increased. However, due to mechanical structure limitation, the added inertia is bounded in \(I_{3}\). Figure 11: Results in case 1.