**Table 2.**

*Aileron angle at each wind speed.*

**Figure 17.** *Aileron displacements at applied voltage DC3,200 V.*

**Figure 18.** *Aileron drive speed when there is no wind.*

**Figure 19** shows the operating speed of the aileron. The displacement speed was measured using a laser distance sensor mounted inside the body. At a wind speed of 5 m/s, it took 250 ms to reach the maximum displacement, but at a wind speed of 10 m/s, it took 300 ms. As described above, since the angle change of the aileron can be easily replaced with the voltage change, the feedback control can be easily performed by changing the voltage applied to the DEA using the voltage change.

**185**

**Figure 20.**

*SEM photograph of high-crystal CNT.*

*The Challenge of Controlling a Small Mars Plane DOI: http://dx.doi.org/10.5772/intechopen.95507*

DEA with existing motors for these requirements.

Next is a comparison between the DE and existing motors:

The structural model used this time required a force of 2.6 kg for steering even at a wind speed of 0 m/s. This was a huge loss. It is probable that the maximum aileron angle could not be obtained due to insufficient driving force at a wind speed of 10 m/s. Most of this loss was due to the link mechanism. By increasing the efficiency of the link mechanism, we were able to obtain a maximum displacement of up to 15 m/s even with the same DEA. In the next experiment, we will investigate how much the mechanism can reduce the power consumed by developing a new drive that drives ailerons directly, enabling a simple and practical steering system.

To send a Martian plane to Mars, we need to dramatically reduce the weight of our compact and powerful motors. In addition, a powerful, efficient and responsive motor is essential for long-term flight of the spacecraft on the surface of Mars. Also, the surface temperature of Mars is very low and dust is present. Therefore, the required level of efficiency and responsiveness is very high. In this paper, based on the data obtained in this experiment, we attempted to compare the current level of a

First, we will explain the performance of the DE developed for this experiment: The total weight of the DEA used is 52.8 g, of which 51.8 g is the weight of structures, etc., and the weight of the DEA itself is as small as 0.98 g. This DEA can lift a 4 kgf weight by 2 mm with an applied voltage of 3.3 kV. In order to increase this operating speed, the DE has been strengthened, and the total weight is 0.98 g, which is 98 ms.

From the above data, the power of the DE linear actuator is 0.0074 W per gram. As shown above, the weight including the DE actuator and its associated structure was approximately 53 g. If a similar linear actuator is configured using an existing DC motor of similar weight, the output of the linear actuator is 0.0015 (W). The weight including the DC motor and linear gear is about 95 g. Therefore, the DEA has a working speed per gram that is 4.9 times faster than a linear actuator that uses an existing DC motor. However, in the case of a linear actuator that uses a DC motor, a displacement of 1 mm takes about 200 milliseconds, so the difference in drive time is 9.9 times. In this experiment, we created a DE actuator that can lift a weight of 4 kgf using SWCNT (ZEONANO®-SG101) from Zeon Corporation. However, using high-crystal SWCNTs (extracted in the laboratory of Zeon Corporation under the guidance of Chiba et al.) gives about 1.32 times better results [35]. An SEM photograph of high-crystal CNTs is shown in **Figure 20**. It is estimated that DE motors using this CNT are about 13.1 times better than existing

#### **Figure 19.**

*Aileron's operating speed measured by the laser distance sensor. (a) Wind speed of 5 m/s; (b) Wind speed of 10 m/s.*

### *The Challenge of Controlling a Small Mars Plane DOI: http://dx.doi.org/10.5772/intechopen.95507*

The structural model used this time required a force of 2.6 kg for steering even at a wind speed of 0 m/s. This was a huge loss. It is probable that the maximum aileron angle could not be obtained due to insufficient driving force at a wind speed of 10 m/s. Most of this loss was due to the link mechanism. By increasing the efficiency of the link mechanism, we were able to obtain a maximum displacement of up to 15 m/s even with the same DEA. In the next experiment, we will investigate how much the mechanism can reduce the power consumed by developing a new drive that drives ailerons directly, enabling a simple and practical steering system.

To send a Martian plane to Mars, we need to dramatically reduce the weight of our compact and powerful motors. In addition, a powerful, efficient and responsive motor is essential for long-term flight of the spacecraft on the surface of Mars. Also, the surface temperature of Mars is very low and dust is present. Therefore, the required level of efficiency and responsiveness is very high. In this paper, based on the data obtained in this experiment, we attempted to compare the current level of a DEA with existing motors for these requirements.

First, we will explain the performance of the DE developed for this experiment: The total weight of the DEA used is 52.8 g, of which 51.8 g is the weight of struc-

tures, etc., and the weight of the DEA itself is as small as 0.98 g. This DEA can lift a 4 kgf weight by 2 mm with an applied voltage of 3.3 kV. In order to increase this operating speed, the DE has been strengthened, and the total weight is 0.98 g, which is 98 ms. Next is a comparison between the DE and existing motors:

From the above data, the power of the DE linear actuator is 0.0074 W per gram. As shown above, the weight including the DE actuator and its associated structure was approximately 53 g. If a similar linear actuator is configured using an existing DC motor of similar weight, the output of the linear actuator is 0.0015 (W). The weight including the DC motor and linear gear is about 95 g. Therefore, the DEA has a working speed per gram that is 4.9 times faster than a linear actuator that uses an existing DC motor. However, in the case of a linear actuator that uses a DC motor, a displacement of 1 mm takes about 200 milliseconds, so the difference in drive time is 9.9 times. In this experiment, we created a DE actuator that can lift a weight of 4 kgf using SWCNT (ZEONANO®-SG101) from Zeon Corporation. However, using high-crystal SWCNTs (extracted in the laboratory of Zeon Corporation under the guidance of Chiba et al.) gives about 1.32 times better results [35]. An SEM photograph of high-crystal CNTs is shown in **Figure 20**. It is estimated that DE motors using this CNT are about 13.1 times better than existing

**Figure 20.** *SEM photograph of high-crystal CNT.*

motors. When using metal CNTs, it is estimated to be twice as high as SWCNTs with high crystallinity. It is expected to be about 27.5 times that of existing motors.

In order to explain in more detail the good response of the DE obtained in this research, we compared it with the existing servo motor (which shows better performance than the model airplane used for radio control). The reason we chose the servo motor is that it can be controlled more accurately. The specifications of the servo motor that can obtain the same level of output as the DEA unit used this time are "servo motor (GWS): weight 41 g, torque 4.1 kg/cm, running speed: 270 ms /60 degrees". In contrast, the DEA used this time weighs 36 g (when four cartridges are built in), is about 13% lighter than the servo motor, and has a drive speed of 98 ms/2 mm, so it can be driven at higher speeds.

Based on the data obtained, the power consumption of the DE will be explained as follows. The power consumption during driving was measured with a voltage/current monitor of a high-voltage power supply installed outdoors. The wind speed was 5 m/s, the applied voltage was 3.2 kV, and the power consumption was 0.29 W. The current at this time was as small as 0.09 mA, and there was almost no voltage drop or heat generation due to the wiring cable. As mentioned above, one of the features of the DEA is that it consumes less current and can contribute to the weight reduction of the wiring cable, that is, the weight reduction of the main body. The power consumption during driving was measured with a voltage/current monitor of a high-voltage power supply installed outdoors. The wind speed was 10 m/s, the applied voltage was 3.2 kV, and the power consumption was 0.29 W. The current at this time was as small as 0.09 mA, and there was almost no voltage drop or heat generation due to the wiring cable. One of the features of the DEA is that it consumes less current. It can also contribute to the reduction of wiring cables and reduce the weight of the aircraft.

Considering the manufacturing cost of a DE, the weight of the DE including reinforcement is 0.96 g, which is cheaper and lighter than the price of a general existing motor with the same output. The SWCNT used as the electrode material for the DE in this experiment has started being mass produced at ZEON, so it costs about 1,000 yen (\$ 9.6) per gram. Also, since the amount used is about 0.1 g, it is 100 yen (9 cents). The 3 M acrylic used for the elastomer is 20 yen per gram, so even if 1 g is used, it costs 120 yen (\$ 1.15), which is cheap enough. Also, as mentioned above, the DEA itself is sufficiently lightweight and compact, which is a great advantage when mounted on a rocket.

When the DE is actually transported to Mars, it passes through outer space, so the effects of cosmic rays cannot be ignored. Next year, we plan to conduct a DE exposure test at the International Space Station (ISS: see **Figure 7**) and observe its effects.

Finally, we will explain the further improvement of the DE. As shown in **Figure 4**, we succeeded in launching a weight of 8 kg with a DE of 0.15 g. Using this, it will probably be able to move smoothly even in the wind with a higher speed. In this experiment, SWCNT (SG101) was also used, but it has been found also that the use of highly crystallized SWCNTs further improves drive speed and output. Even if the above link mechanism is not improved significantly, wind experiments of 25 m/s or more can be performed. In addition, new acrylics are currently being synthesized by Chiba et al. These acrylics can be used at −40°C to 150°C and may be able to handle even the harsh temperatures found on Mars. Also, due to the sufficient withstand voltage of the film, the control unit of the Mars probe will be developed mainly using this elastomer.
