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Flight Controller Data Analysis Series Tutorials -- Part 2
5897 0 2017-9-28
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Content:

1.        Flight Controller Data Analysis Series Tutorials – Exporting the Flight Controller Data and Introducing DataViewer
2.        Flight Controller Data Analysis Series Tutorials – Locating the Crash Data
3.        Flight Controller Data Analysis Series Tutorials – Introduction to Coordinate Systems
4.        Flight Controller Data Analysis Series Tutorials – Introduction to Attitude Mode and Crash Cases
5.        Flight Controller Data Analysis Series Tutorials – Stopping Motors by Conducting the Combination Stick Command (CSC)
6.        Flight Controller Data Analysis Series Tutorials – Drone Under Control Crash Cases
7.        Flight Controller Data Analysis Series Tutorials – Compass Interference Cases


2.        Flight Controller Data Analysis Series Tutorials – Locating the Crash Data

Crash data for drones is like the black box data for planes. It records everything that occurred during flight, which helps us to know more about the situations when accidents happen.
One flight controller data record will be generated when the drone is powered on. So, there will be many data records for a drone. The first step for analyzing the drone’s data is to sort out the crash data from multiple flight data records.


Generally, you can locate the crash data by using four indicators: data size, accelerometer value, motor data, and drone’s height.
  • Data Size: Estimate the flight time according to the size of the flight controller data files and delete those data files generated when the drone did not fly.
  • Accelerometer’s Value: The sum of the external forces that the drone undertakes. When the sum of the external forces is 0, the drone in motion continues to move at constant velocity, or the drone remains at rest. If the drone crashes with an obstacle, the sum of external forces will increase significantly in a short period of time and the accelerometer’s value will suddenly change.
  • Motor Data: Motors must be working before the crash and may be obstructed after the crash.
  • Drone’s Height: The drone’s relative height must change after the drone takes off. Mostly, the drone will drop down from air after a crash. The original values along the height curve are close to the altitude of the location where the drone is flying. So, to get the relative height of the drone, the height of the take-off point must be deducted.

Next, we will show you how to analyze the data. Figure 2.1 shows the crash data of a drone.


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Figure 2.1 Crash Data of a Drone


In figure 2.1, the accelerometer curve drops down significantly, indicating that the drone may have crashed. After the crash, the motors stop rotating and the height decreases considerably. With the preceding data, we can locate the crash data and the time when the crash occurred. But we can also see that the accelerometer’s values along the X axis (red line) decrease to negative values and change much more severely than those along the Y axis and Z axis.

In the next passage, we will introduce the meanings of the positive and negative values of each curve. We will also discuss the causes of drone crashes.




2017-9-28
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