# A UAV Wind Field Perception System Inspired by Biological Perception
## 4 Discussion  
### Analysis of the Attack Angle's Lateral Features  
After the experiments of the angle, we find that under various sideslip angle, the angle of attack sensor's measurement accuracy will be impacted. We assess the angle of attack sensor's measurement capabilities under various sideslip angle (lateral) and the angle of attack sensor's measurement features under various sideslip angle conditions in the airborne state (Figure 14). The values measured by the angle of attack sensor are mostly steady (in the red region) within the short range of sideslip angle (\(-\)8-8\({}^{\circ}\)), and the data swings between (\(-\)0.3-0.3\({}^{\circ}\)), however there is a certain fixed inaccuracy. The angle of attack measurement value is low when the sideslip angle is negative and high when the sideslip angle is positive, although the absolute error values are all within 0.5\({}^{\circ}\). Therefore, error correction can increase data accuracy during the range. However, in the case of sideslip angles above 8\({}^{\circ}\), the measurement error of the angle of attack significantly increases. As a result, we must either increase the system's accuracy over a wider range of sideslip angle or apply particular changes to the attack angle data above 8\({}^{\circ}\) sideslip angles.  
From the flight data and the wind data, we found that when the direction of the airflow gradually changes from downward to upward, the flying height of the drone decreased slowly, that is, the rate of descent becomes smaller. When the rising air velocity in the middle period of the above figure was large, the altitude of the drone changed slightly, even it maintained a level flight.  
Figure 12: Vertical wind speed (blue) and UAV climb rate (red); flight altitude change (bottom).  
Figure 13: Horizontal wind compass chart.  
Some problems and deficiencies were also found in the research. However, due to the limitation of objective conditions, such as time and personal ability, some research content in the paper still needs to be discussed and explored in depth. Based on the current research content, the following points are proposed:  
(a) Further research on airborne sensors. Further analysis and research will be carried out, including the error source and error characteristics of the airspeed gauge. It is expected that research be conducted on the working principle of the sensor and the data correction algorithm, etc., and improvements to the measurement accuracy and robustness of the airspeed gauge through these studies are also expected;  
(b) In the wind tunnel experiment, it was found that the measurement accuracy of the airflow sensor under the condition of an angle of attack above 10\({}^{\circ}\) is disturbed, so the system layout needs to be further optimized to meet the measurement requirements of a wider range;  
(c) There is a lot of noise and many outliers in the wind field information measured during the actual flight. How to process the data to obtain more real and reliable wind field information is also an important research topic. In the current experiment process, there is a lack of professional regional wind field measurement equipment to obtain the wind field data in the experimental airspace. Therefore, the current wind field data collected by drones cannot be compared with the standard measurement values. In the follow up research, it is expected to obtain professional regional wind field measurement equipment. The reference value of the measurement equipment is compared and analyzed, and the current system measurement performance is improved and enhanced.