Figure 5.

Exhibits a parabolic drag force characteristic depending on the velocity of micro-UFO. The drag force change is less for the [−2, 2] mm/s range, which is the microrobot motion speed. For this reason, the system can be expressed by linear equation, by performing curve fitting at the specified interval. For the equation proposed as $F_{\mathrm{d}}=k{V}_{\mathrm{r}}$, a constant coefficient was found to be $k=7.075\times {10}^{-9}\mathrm{kg}/{\mathrm{s}}^2$. Due to the symmetric structure of the microrobot, the force calculation is preferably shown only for x-axis.