# Development of a Novel Deployable Solar Panel and Mechanism for 6U CubeSat of STEP Cube Lab-II
## 5 Experimental Validation  
### Solar Panel Deployment Test  
To validate the proposed mechanism's stable release function, the deployment tests of the solar panel were executed at an ambient room temperature of 25 \({}^{\circ}\)C with the experimental test setup shown in Figure 10. The qualification model of the P-HRM electrical system illustrated in Figure 6 was electrically connected to a power source for the triggering mechanism and a data acquisition (DAQ) system to determine the solar panel deployment status. In addition, an accelerometer at the center of the solar panel was attached to measure the panel acceleration responses. The solar panel's random equivalent static analysis result showed that at least triple wire winding is required to secure a positive margin with a safety factor of 3, which is not shown here. Thus, to stow the solar panel as it is in launch configuration, triple wire winding was performed as described in the above-mentioned wire-tightening procedure. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Solar Panel** & **1 st Eigenfrequency (Hz)** & **Damping Ratio** \\ \hline Typical PCB panel & 82.6 & 0.036 \\ \hline VMLSA & 110.1 & 0.141 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Free-vibration test results of the solar panels in rigidly mounted condition. Figure 9: Dynamic characteristics investigation results of the solar panels: (**a**) time histories of free-vibration response in rigidly mounted condition and (**b**) acceleration profile under deployment. Figure 11 shows the VMLSA release function test results. The time history of the input voltage in the mechanism and separation signal indicated that the solar panel is released at 0.72 s from the power triggering in the circuit. The solar panel's acceleration response indicates that the complete deployment of the panel took 1.58 s after the release action was completed. The test results validated the release function of the mechanism. As intended in the design, the deployment status of the solar panel was confirmed according to the electric current flow status through the resistor mounted on the resistor PCB using pogo pins and a voltage divider circuit. Figure 11: The solar panel’s deployment test results. Figure 10: The solar panel deployment test setup. The function of the deployment mechanism must be confirmed by conducting at least 10 repeatability checks at room temperature, as several deployment tests are required during the development of CubeSat and testing phases such as run-in and acceptance testing [32]. The mechanism was therefore repeatedly released in the same test configuration as shown in Figure 10. The main objectives of the tests were to verify the repeatability of the mechanism and to identify the release time difference between single and triple wire windings. The release times are shown in Figure 12. The system functioned well in 10 repetitive activations without electrical malfunction on the circuit and no failure on the mounted resistor. However, the release time was noticeably varied in repetitive release tests because of the variable workmanship of applied tension on the knot of the wire. The mechanism's average release time with one, two, and three wire windings in 10 repetitive triggers for each case were 0.77 s, 0.89 s, and 1.1 s, respectively. Thus, P-HRM has adequate repetitive release capability for application in actual space missions. There is no fast release requirement, but it is advantageous to cut the wire as soon as possible after the initiation of burn wire triggering in the mechanism to prevent electrical malfunction in the circuit. Furthermore, [PERSON] et al. [8] performed solar panel release tests as a function of the wire thickness within the qualification temperature range of \(-40\) to \(+60\)\({}^{\circ}\)C. The release time of the panel was slightly higher at low temperatures than that in the high-temperature environment because of the environmental effect on the variation in the heating time of the resistor.