# Improvement of Hexacopter UAVs Attitude Parameters Employing Control and Decision Support Systems
## 4 Laboratory and In Situ Measurement Results and Discussion
### In situ Ground and In-Flight Experiments
#### 4.3.1 Hover Flight  
The purpose of these tests is to ensure, verify and prove the appropriate functioning of the hexacopter in the proposed configuration, both in terms of the structural design and the avionics components, especially the employed flight controller. These tests are divided into two main categories: ground and flight tests. The purpose of the ground test is to ensure that the drone's structure and avionics systems comply with the requirements so that the hexacopter will perform the flight as expected.  
* This test consists of:
* Inspection of the structural integrity of the drone. Each joint of the structural elements is checked and must be well secured to ensure its rigidity.
* Checks of the weight and the drone equilibrium. These checks provide information on the location of the actual centre of gravity in respect to all three axes X, Y and Z. The centre of gravity location affects the performance and stability of the drone in flight.
* Examination of the avionic systems operation: controller, navigation, power supply, video system, telemetry data transmission system and wiring. All data concerning the operating limits of the equipment must be memorized in order to avoid undesirable events such as maximum drone range, maximum operating range of the radio controls, battery capacity, power consumption of the various electronic components, maximum authorized flight altitude and legislative aspects concerning the operation of the drone in certain areas, depending on the geographical layout. In the case of autonomous flight following a preprogrammed route, the flight controller has programmed the flight scenario, the flight parameters and the failsafe measures required in the event of emergencies such as the loss of radio link between the drone and the operator, battery voltage falling close to the critical value and a motor shutdown.
* Test of the motor's operation by simple on/off commands to ensure the rated static performance based on throttle stick position, increasing the speed incrementally up to 10-15% and checking their operation, oscillations, noises, proper propeller rotation directions.
* Telemetry data link tests between the drone and the mission planner ground control station. This ensures the stability of the radio link between the drone and the operator. With the help of the control station, the operator can either plan autonomous flights on preprogrammed routes or intervene in the control of the hexacopter in emergency conditions if the radio control is not used.
* Weather condition checks: wind speed, temperature, precipitation and atmospheric pressure. This is an extremely important step in planning a flight, as there are limitations to operating the hexacopter.  
For the GCS, the mission planner platform was employed, whose main interface is illustrated in Figure 17(a), which also shows the map of the test location. Figure 17(b) depicts the HUD window, which provides valuable data for the operator during flight stage and also during ground operations.  
Figure 19 pictures the test stands, the ground control station and the test location, while Figure 20 encompasses details during the execution of the hexacopter manoeuvres: take-off, climb, hover, descent and landing.  
Images of the drone on the ground and in flight received from the GoPro Hero 4 camera mounted on the hexacopter are illustrated in Figure 21, while Figure 22 represents the mission planner interface with the layout of the hexacopter on the test location map and the video received from the GoPro camera on the built-in dual receiver monitor.