# Multi-Unit Coupled Motion Hybrid Generator Based on a Simple Pendulum Structure
## 3 Results and Discussion
### Output Performance of MCM-HG  
This paper systematically investigates the ability of the MCM-HG to harvest wave energy. To simulate real ocean conditions, a six-degree-of-freedom platform was selected as the experimental platform. The typical power generation performance of the device, including open-circuit voltage (V\({}_{\text{OC}}\)), short-circuit current (I\({}_{\text{SC}}\)), and output power, was systematically measured. To avoid mismatch and performance interference between different power generation units, the output paths of the TENG, EMG, and PENG units in the MCM-HG are separated. Their optimal outputs are obtained under their respective external loads. In an MCM-HG, due to the completely symmetrical composition of the device, any one of the same power generation units can be selected for measurement. To better focus on the core research objectives, this paper does not investigate the potential effects of mechanical, electrical, and thermal factors on device output performance. As shown in Figure 3a,b, the V\({}_{\text{OC}}\) and I\({}_{\text{SC}}\) outputs of the S-TENG unit were measured at different angles (6-24\({}^{\circ}\)) and frequencies (0.3-1.1 Hz). The results indicate that, at the same frequency, the V\({}_{\text{OC}}\) increases and then slightly fluctuates around 700 V as the swing angle increases, and the I\({}_{\text{SC}}\) shows a similar trend. When the swing angle is constant, the I\({}_{\text{SC}}\) gradually increases with the increase in swing frequency, while the V\({}_{\text{OC}}\) remains relatively stable. At a swing angle of 18\({}^{\circ}\) and a frequency of 1.1 Hz, the maximum V\({}_{\text{OC}}\) and I\({}_{\text{SC}}\) values are 710 V and 135 \(\mu\)A, respectively. Figure 3c-f show the output performance of the two EMG units, with Figure 3c,d for C-EMG and Figure 3e,f for P-EMG. The V\({}_{\text{OC}}\) and I\({}_{\text{SC}}\) of the EMG units both increase with the angle and then tend to level off, and they increase with the frequency. At a swing angle of 24\({}^{\circ}\) and a frequency of 1.1 Hz, the maximum V\({}_{\text{OC}}\) and I\({}_{\text{SC}}\) values for C-EMG are 4.2 V and 7.5 mA, respectively. For P-EMG, the maximum V\({}_{\text{OC}}\) and I\({}_{\text{SC}}\) values are 3.2 V and 1.4 mA, respectively. At a swing angle of 15\({}^{\circ}\) and a frequency of 0.5 Hz, the maximum output powers of S-TENG, C-EMG, and P-EMG are 9.7 mW, 2.3 mW, and 51.2 \(\mu\)W, respectively, as shown in Figure 3g-i. The electromagnetic interference between EMG and TENG units will be further investigated in subsequent research projects. Figure 3: The output performance of S-TENG, C-EMG, and P-EMG. **(a)** The open-circuit voltage and **(b)** short-circuit current of S-TENG at a frequency of 0.3–1.1 Hz and angle of 6–24\({}^{\circ}\); **(c)** the open-circuitvoltage and (**d**) short-circuit current of C-EMG at a frequency of 0.3-1.1 Hz and angle of 6-24\({}^{\circ}\); (**e**) the open-circuit voltage and (**f**) short-circuit current of P-EMG at a frequency of 0.3-1.1 Hz and angle of 6-24\({}^{\circ}\); the output power of (**g**) S-TENG, (**h**) C-EMG, and (**i**) P-EMG at frequency 0.5 Hz and angle 15\({}^{\circ}\) under different external loads. It is noteworthy that the upper-layer power generation units of the MCM-HG exhibit multi-output characteristics during operation. By utilizing fixed clamps and highly elastic, weakly magnetic silicon steel sheets, the power generation units can produce multiple outputs from a single excitation due to the inertial force causing the steel sheets to swing repeatedly. With the six-degree-of-freedom platform set at a swing angle of 15\({}^{\circ}\), a frequency of 0.5 Hz, and a duration of 30 s, the output performance of the P-TENG and PENG is shown in Figure 4. The results indicate that within one cycle, the P-TENG generates two significant outputs, with maximum values of V\({}_{\rm OC}\), I\({}_{\rm SC}\), and short-circuit transferred charge (Qsc) reaching 61 V, 16 \(\upmu\)A, and 230 nc, respectively, as shown in Figure 4a-c.