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docs/en/selfcheck.md

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+# Automatic check
+
+Before flying (especially autonomous), you can use several methods of automatic self-testing of the quadcopter subsystems.
+
+## <span>selfcheck</span>.py
+
+Utility `selfcheck.py` is part of `clever` package, and automatically tests the main aspects of the ROS platform and the PX4. The utility is pre-installed on [the Raspberry Pi image](microsd_images.md).
+
+To initiate it, type in [the Raspberry Pi console](ssh.md):
+
+```(bash)
+rosrun clever selfcheck.py
+```
+
+<img src="../assets/selfcheck.png">
+
+Description of some checks:
+
+* FCU – checking proper connection with the flight controller;
+* IMU – checking correctness of the data from IMU;
+* Local position – presence of the local position of the drone;
+* Velocity estimation – drone velocity estimation (**if this check fails, never take off offline!**);
+* Global position (GPS) — presence of the global position (GPS required);
+* Camera — proper operation of the Raspberry camera.
+
+## commander check
+
+To check the main sub systems of PX4 and the possibility of arming at the moment, you can perform command `commander check` in the MAVLink console.
+
+<img src="../assets/commander-check.png">
+
+When using SITL instead of the MAVLink console, use a terminal with SITL running.