ardupilot/libraries/AP_Scripting/applets/Aerobatics/FixedWing/README.md

# Scripted Aerobatics

The lua script "plane_aerobatics.lua" implements scripted aerobatics,
allowing fixed wing aircraft to execute a number of aerobatic
manoeuvres either in AUTO mission or by triggering using pilot commands
using RC switches.

As always, but particularly with scriped aerobatics, test in SITL until 
you understand the function and behaviour of each manouver. You will need 
an appropriate aircraft, and be ready to take manual control if necessary!

## Available Manoeuvres

The following table gives the available manoeuvres. Each manoeuvre has
an ID number which is used in the AUTO mission or in the TRIKn_ID
parameters (described below). The present ground track is used as the track for the trick.
The "Turnaround" column indicates if the manoeuvre results in a course reversal, which impacts how it is used in 
AUTO missions. Once the trick is completed, the mode that was being used at the start of the trick is restored. If the mode is CRUISE, its
track and altitude are reset to the values present when the mode is restored. Tricks in AUTO missions require that they be performed between two waypoints to establish
the ground track.

| ID | Name                     | Arg1   | Arg2        | Arg3       | Arg4       | Turnaround |
| -- | ------------------------ | ------ | ----------  | -------    | ---------- | ---------- |
| 1  | Figure Eight             | radius | bank angle  |            |            | No         |
| 2  | Loop                     | radius | bank angle  | num loops  |            | No         |
| 3  | Horizontal Rectangle     | length | width       | radius     | bank angle | No         |
| 4  | Climbing Circle          | radius | height      | bank angle |            | No         |
| 5  | vertical Box             | length | height      | radius     |            | No         |
| 6  | Immelmann (FastRoll)     | radius |             |            |            | Yes        |
| 7  | Straight Roll            | length | num rolls   |            |            | No         |
| 8  | Rolling Circle           | radius | num rolls   |            |            | No         |
| 9  | Half Cuban Eight         | radius |             |            |            | Yes        |
| 10 | Half Reverse Cuban Eight | radius |             |            |            | Yes        |
| 11 | Cuban Eight              | radius |             |            |            | No         |
| 12 | Humpty Bump              | radius | height      |            |            | Yes        |
| 13 | Straight Flight          | length | bank angle  |            |            | No         |
| 14 | Scale Figure Eight       | radius | bank angle  |            |            | No         |
| 15 | Immelmann Turn           | radius |             |            |            | Yes        |
| 16 | Split-S                  | radius |             |            |            | Yes        |
| 17 | Upline-45                | radius | height gain |            |            | No         |
| 18 | Downline-45              | radius | height loss |            |            | No         |
| 19 | Stall Turn               | radius | height      | direction  |            | Yes        |
| 20 | Procedure Turn           | radius | bank angle  | step-out   |            | Yes        |
| 21 | Derry Turn               | radius | bank angle  |            |            | No         |
| 22 | Two Point Roll           | length |             |            |            | No         |
| 23 | Half Climbing Circle     | radius | height      | bank angle |            | Yes        |
| 24 | Crossbox Humpty          | radius | height      |            |            | Yes        |
| 25 | Laydown Humpty           | radius | height      |            |            | Yes        |

Note: In the script you will find other (specialised) manouvers which do not appear in the 
'command table'. These tend to be specialised manouvers which may expect an inverted entry or 
finish inverted as well - so will not end well if started upright at a low altitude! These 
manouvers are used in some of the schedules defined below. 


## Available Schedules (pre-defined sequences of manouvers)

The following table gives the available pre-defined schedules. Each schedule has
an ID number which is used in the AUTO mission or in the TRIKn_ID
parameters (described below). Entry ground track orientation is maintained throughout the schedule (except for tricks which 
modify it during the trick, like rolling circles and figure eights)

| ID  | Name
| --  | ------------------------
| 200 | Test Suite (dont fly!)
| 201 | NZ Clubman Schedule
| 202 | FAI F3A P-23 (left to right)
| 203 | FAI F3C Scale Example (left to right)
| 204 | AirShow

Note: ID's 202-203 are best flown with a mission start point 150m out from the pilot, with the prior and subsequent mission waypoints in a straight line with the model starting the script flying down wind. ID 201 is best started in the same manner, but the model positioned 100m out from the pilot.

## Adding Schedules

Schedules can be added to those above by creating a text file in the /scripts directory or the root directory on the SD card where the plane_aerobatics.lua script is stored.
An example for the "Airshow" schedule is included as trick72.txt and would be executed as TRIK_ID = 72 via switch or in an AUTO mission command. The schedule will display its "name" when started, and as each trick begins the "message" will sent to the GCS to indicate its start.

Note, that the "straight_align" command is not a trick, but rather a command as to when the next trick is to begin. Its parameter is meters from the
schedules initial entry point. Positive numbers are meters away from that point in the entry direction on the ground track, while negative numbers are in the opposite direction on the track line. If the aircraft is already past that point in the desired direction along the track, the trick will begin immediately.

## Loading the script

Put the plane_aerobatics.lua script on your microSD card in the
APM/SCRIPTS directory. You can use MAVFtp to do this.

Then set

 - SCR_ENABLE = 1
 - SCR_HEAP_SIZE = 250000
 - SCR_VM_I_COUNT = 200000

You will need to refresh parameters after setting SCR_ENABLE. Then
reboot to start scripting.

## Aircraft Setup

The aircraft needs to be setup to perform well in ACRO mode. You need
to enable the yaw rate controller by setting:

 - YAW_RATE_ENABLE = 1
 - ACRO_YAW_RATE = 90

The ACRO_YAW_RATE depends on the capabilities of the aircraft, but
around 90 degrees/second is reasonable.

You need to tune the yaw rate controller by flying in AUTOTUNE mode
and moving the rudder stick from side to side until the yaw rate
tuning is reported as being finished. For optimal results, log examination and manual adjustment
of axis tuning will sometimes be required, especially pitch and yaw tuning in order to get precise rolling circles. A future 
video on this optimization will be produced and posted in the ArduPilot YouTube channel.

## Use In AUTO Missions

To use in an AUTO mission you can create waypoint missions containing
NAV_SCRIPT_TIME elements (shown as SCRIPT_TIME in MissionPlanner). These mission items take the following arguments:

 - the command ID from the table above
 - the timeout in seconds
 - up to four arguments as shown in the above table

The aerobatics system will use the location of the previous and next
waypoints to line up the manoeuvre. You need to plan a normal
waypoint just before the location where you want to start the
manoeuvre, then the NAV_SCRIPT_TIME with the trick or schedule ID, a timeout that is long enough to allow the trick or schedule, and then a normal waypoint after the manoeuvre.

## Use with "tricks on a switch"

You can trigger the manoeuvres using RC switches, allowing you to have
up to 11 tricks pre-programmed on your transmitter ready for use in
fixed wing flight. You can trigger the tricks in the following flight
modes:

 - CIRCLE
 - STABILIZE
 - ACRO
 - FBWA
 - FBWB
 - CRUISE
 - LOITER

To setup tricks you need to first set the parameter TRIK_ENABLE to 1.

After setting TRIK_ENABLE, either restart scripting or reboot. Then
set TRIK_COUNT to the number of tricks you want to make available,
with a maximum of 11.

After setting TRIK_COUNT, reboot and refresh parameters. You will find
you will now have 5 parameters per trick.

 - TRIKn_ID
 - TRIKn_ARG1
 - TRIKn_ARG2
 - TRIKn_ARG3
 - TRIKn_ARG4

The ID parameter is the manoeuvre from the above table, and the arguments are the arguments to each manoeuvre.

Note: these parameters, if being loaded from a file, will not be present until scripting is enabled, the the LUA script has been
actually run, since they are created via the script, not the firmware.

Now you need to setup your two control channels. You should have one 3
position switch for activating tricks, and one knob or switch to
select tricks. It is best to use a knob for the trick selector so you can have up to 11 tricks.

Work out which RC input channel you want to use for activation (a 3 position switch) and set

 - RCn_OPTION = 300

Then work out what RC input channel you want to use for selection and set

 - RCn_OPTION = 301

## Flying with tricks

When the activation channel (the one marked with option 300) is in the
middle position then when you move the knob the GCS will display the
currently selected trick.

To activate a trick you move the activation channel to the top
position, and the trick will run.

Moving the activation switch to the bottom position cancels any
running trick and stops the trick system.

Changing flight modes will also cancel any active trick.