From 2090f0a1ae14cc438a725889bfba57d41f1fe947 Mon Sep 17 00:00:00 2001
From: sfalexrog <sfalexrog@gmail.com>
Date: Wed, 19 Jun 2019 21:29:41 +0300
Subject: [PATCH] docs: selfcheck.md proofreading

---
 docs/en/selfcheck.md | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/docs/en/selfcheck.md b/docs/en/selfcheck.md
index 95a51952..5ed51db7 100644
--- a/docs/en/selfcheck.md
+++ b/docs/en/selfcheck.md
@@ -1,12 +1,12 @@
 # Automatic check
 
-Before flying (especially autonomous), you can use several methods of automatic self-testing of the quadcopter subsystems.
+It is generally a good idea to perform some checks before flight, especially before an autonomous one. There are several methods of automated self-checks of the drone 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).
+The `selfcheck.py` utility script is part of the `clever` package; it performs automated tests of the main aspects of the ROS platform and 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):
+In order to run it, enter the following command in [the Raspberry Pi console](ssh.md):
 
 ```(bash)
 rosrun clever selfcheck.py
@@ -16,17 +16,20 @@ rosrun clever selfcheck.py
 
 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.
+* FCU – checks for proper connection with the flight controller;
+* IMU – checks whether the data from from IMU is sane;
+* Local position – checks presence of local position data;
+* Velocity estimation – checks whether drone velocity estimation is sane(**Offboard flight is not to be performed if this check fails!**);
+* Global position (GPS) — checks for presence of global position data (GPS module is required for this check);
+* Camera — checks for proper operation of the Raspberry camera.
+* ArUco — checks whether [ArUco](aruco.md) detection is working
+* VPE — checks whether VPE data is published
+* Rangefinder — checks whether [rangefinder](laser.md) data is published
 
 ## 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.
+In order check the main subsystems of PX4 and the possibility of arming at the moment you can run the `commander check` command in the MAVLink console.
 
 <img src="../assets/commander-check.png">
 
-When using SITL instead of the MAVLink console, use a terminal with SITL running.
+If you're running SITL, you should use the terminal where PX4 simulation is running instead of the MAVLink console.