**3.2 Preliminary experiment**

First, in order to examine the specifications required to control the actuator used to steer the aileron, a load cell was used to measure the load applied to the actuator part at each steering angle. **Figure 13** shows the measurement system used for load measurement [6].

The load cell used for load measurement was mounted at the DEA mounting position of the main body. The maximum load applied to the load cell is 20 kg, and the analog data output from the load cell is converted to digital data by the 24-bit A/D converter IC (HX-711), and the CPU (ATmega328P). A lithium polymer battery (Li-Po) was used as the power source to minimize the effect of noise on the weak signal output from the load cell. In order to shorten the connection distance, the circuit to the CPU was attached to the fuselage. A personal computer for operation and recording was installed outside the wind tunnel, and it was connected by serial communication.

A laser distance sensor (VL50L0X) was also installed to measure the displacement velocity (**Figure 14**) [6]. Since this laser distance sensor uses I2C for the interface, it is not easily affected by noise and stable measurement is possible. The control was performed by the same CPU (ATmega328P) as the load measurement, and the measurement data was transmitted to the measurement PC by serial communication. Laser distance sensors were installed in the front and rear to observe the movement of ailerons and the DE.

The load was measured by continuously changing the wind speed from 0 m/s to 40 m/s in 5 m/s increments and setting the steering angles to 0, 5, 10, 15, and 20 degrees. When the set wind speed was reached, measurements were taken at each wind speed for about 30 seconds, and the load applied to the actuator section was measured (see **Figure 15**) [6].

In this experiment, it was found that the DEA was loaded with 11.54 kg/f in an environment with a steering angle of 20 degrees and a wind speed of 40 m/s (see **Table 1**). In order to move the aileron through the link mechanism, a force of about 2.6 kgf is required even in the absence of wind. It was found that a force of about 14.14 kg/f is required to steer 20 degrees in an environment with a wind speed of 40 m/s. It was also confirmed that the wings were deformed from the joint with the airframe at a wind speed of 30 m/s or more. Since the experiment was repeated in

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