Sub:add crash check page

Author: Hwurzburg

sub/source/docs/crash_check.rst

@@ -0,0 +1,27 @@
+.. _crash_check:
+
+===========
+Crash Check
+===========
+
+Sub includes a crash check which can disarm the motors in cases where the vehicle is likely out of control and has hit something.  This reduces damage to the vehicle and its surroundings, and also reduces the chance of injury to people or creatures nearby.
+
+When will the crash check disarm the motors?
+============================================
+When all the following are true for 2 full seconds:
+
+* The :ref:`FS_CRASH_CHECK<FS_CRASH_CHECK>` = 2 ( A value of "0" disables the check while "1" will send only a warning to the GCS)
+* The vehicle is armed
+* The current flight mode is *not* ACRO or MANUAL
+* The actual lean angle has diverged from the desired lean angle (perhaps input by the pilot) by more than 30 degrees.
+
+What will happen when the crash check fires?
+============================================
+
+* The motors will disarm
+* "Crash: Disarming" will be displayed on the Ground Station
+* A crash event will be written to the dataflash logs (look for EV, 12 in the logs)
+
+How and when should the crash check be disabled?
+================================================
+In general the crash check should be left enabled but if the vehicle is likely to suffer from lean angle errors of over 30 degrees for a second or more it should be disabled.  

sub/source/docs/failsafe-battery.rst

@@ -24,7 +24,7 @@ When the failsafe is triggered:
 
 -  Buzzer will play a loud low-battery alarm
 -  LEDs will flash yellow
--  "Low Battery!" will be displayed on the ground stations HUD (if telemetry is connected)
+-  "Low Battery!" will be displayed on the ground station's HUD (if telemetry is connected)
 
 Then one of the following will happen, depending on :ref:`BATT_FS_LOW_ACT<BATT_FS_LOW_ACT>`:
 

sub/source/docs/failsafe-landing-page.rst

@@ -14,15 +14,11 @@ Sub has a number of failsafe mechanisms to ease vehicle recovery/prevent wanderi
     Radio Failsafe <radio-failsafe>
     Battery Failsafe <failsafe-battery>
     GCS Failsafe <gcs-failsafe>
-    Pilot Control Failsafe <pilot-failsafe>
-    Internal Leak Failsafe<internal-leak>
-    Internal Pressure Failsafe<internal-pressure>
+    Pilot Control Failsafe <pilot-control-failsafe>
+    Internal Leak Failsafe <internal-leak-failsafe>
+    Internal Pressure Failsafe <internal-pressure-failsafe>
+    Internal Temperature Failsafe <internal-temperature-failsafe>
+    EKF Failsafe <ekf-inav-failsafe>
+    Crash Check <crash_check>
+    Independent Watchdog <common-watchdog>
 
-EKF Failsafe <ekf-inav-failsafe>
-Vibration Failsafe <vibration-failsafe>
-Terrain Data Loss Failsafe <terrain-following>
-Crash Check <crash_check>
-
-Internal Pressure <internal-pressure>
-Internal Temp <internal-temp>
-Independent Watchdog <common-watchdog>

sub/source/docs/gcs-failsafe.rst

@@ -20,7 +20,7 @@ The following situations can cause a loss of GCS MAVLink heartbeat, triggering a
 
 What will happen
 ================
-When a GCS failsafe is triggered, the sub can be configured via parameters to do nothing, send the GCS a warning message, disarm, or change to ALTHOLD or SURFACE modes. 
+When a GCS failsafe is triggered, the sub can be configured via parameters to do nothing, attempt to send the GCS a warning message, disarm, or change to ALTHOLD or SURFACE modes. 
 
 If the failsafe clears (i.e. GCS reconnects and MAVLink heartbeat is restored) the sub will remain in its failsafe mode. It will **not** automatically return to the flight mode that was active before the failsafe was triggered, if it was changed.
 

sub/source/docs/internal-leak-failsafe.rst

@@ -10,7 +10,7 @@ For the remainder of this article, the first leak detector's parameters will use
 
 When the failsafe will trigger
 ==============================
-If :ref:`FS_LEAK_ENABLE<FS_LEAK_ENABLE>` is non-zero, then if the detector attached to a logical pin on the autopilot designated by :ref:`LEAK1_PIN<LEAK1_PIN>` is analog (:ref:`LEAK1_TYPE<LEAK1_TYPE>` = "0"), its considered active ("1") if its voltage is > 2.0V. Digital sensors (:ref:`LEAK1_TYPE<LEAK1_TYPE>` = "1") present a logic level. Whether the active level of an analog sensor or the logic level from a digital sensor is taken as "dry" is determined by the :ref:`LEAK1_LOGIC<LEAK1_LOGIC>` parameter.
+If :ref:`FS_LEAK_ENABLE<FS_LEAK_ENABLE>` is non-zero, then if the detector attached to a logical pin on the autopilot designated by :ref:`LEAK1_PIN<LEAK1_PIN>` is analog (:ref:`LEAK1_TYPE<LEAK1_TYPE>` = "0"), it's considered active ("1") if its voltage is > 2.0V. Digital sensors (:ref:`LEAK1_TYPE<LEAK1_TYPE>` = "1") present a logic level. Whether the active level of an analog sensor or the logic level from a digital sensor is taken as "dry" is determined by the :ref:`LEAK1_LOGIC<LEAK1_LOGIC>` parameter.
 
 What will happen
 ================

sub/source/docs/pilot-control-failsafe.rst

@@ -4,7 +4,7 @@
 Pilot Control Failsafe
 ======================
 
-Sub provides a failsafe mechanism in case pilot manual control is lost. Pilot control in Sub is provided by either or both of two ways: via GCS MAVLink RC override messages( stimulated by GCS Joystick) or by the optional RC control link.
+Sub provides a failsafe mechanism in case pilot manual control is lost. Pilot control in Sub is provided by either or both of two ways: via GCS MAVLink RC override or Manual Control messages (stimulated by GCS Joystick) or by the optional RC control link.
 
 When the failsafe will trigger
 ==============================