edrone AR drone control library for Erlang

edrone_client.erl implements the standard commands used to control the standard AR drone 2.0 (may work with version 1.0 as well)

In priv directory there is also an Erlang that can be installed on the AR drone 2.0 (not 1.0) it self.

Install Erlang procedure

After attaching the wifi network announced by the drone, start with transfer the erlang archive and the libutil file to the drone, any user (like root) and no password is passed to ftp.

ftp 192.168.1.1
>put arm-unknown-linux-gnueabi-erl.tgz
>put libutil-2.13.so

Then telnet to the target

telnet 192.168.1.1

You will find the archive placed in /data/video, now unpack and install erlang

cd /date/video
tar xzf arm-unknown-linux-gnueabi-erl.tgz
rm  arm-unknown-linux-gnueabi-erl.tgz
mv /data/video/arm-unknown-linux-gnueabi-erl /data/erlang

and the shared object libutil-2.13.so.

mv /data/video/libutil-2.13.so /lib
cd /lib
ln -s libutil-2.13.so libutil.so.1

Install and check for a prompt

cd /data/erlang 
./Install -minimal /data/erlang
/data/erlang/bin/erl

Copy the additional erlang libraries to the drone: sh transfer-libs.sh

This command will ftp edrone.tgz, gpio.tgz, i2c.tgz and uart.tgz to the edrone (192.168.1.1), and then install these packages under /data/erlang/lib

Loading code with distributed erlang

Instead of transfering libraries and files to the drone every time a beam files is changed the erl_prim_loader can be told to told from the development machin instead.

Erlang on the drone is then started like:

erl -loader inet -id drone -hosts 192.168.1.2

To make the drone node a distribute node then give the following arguments

-sname drone -setcookie <cookie>

On the development a node with a bootserver must have been started

erl -kernel start_boot_server true boot_server_slaves '[{192,168,1,1}]'

The boot server node may also be a distributed node by giving the following argument to the command line:

-sname devnode -setcookie <cookie>

Note the argument to boot_server_slaves, for some reason the manual is wrong here and this is the only accepted format. is any string, like a password. This erlang system will list on a tcp port number 555 and and udp port 546.

The flying bit

Connect a Logitech Extreme 3D Pro joystick to a PC connected to the AR Drone WiFi access point.

On the PC, start erlang and fire up the edrone_pilot app:

erl 
application:start(inpevt).
application:start(edrone_pilot).

Telnet to the AR Drone
```
telnet 192.168.1.1
```

Kill the original AR Drone flight control software.

ps | grep program.elf | head -n 1 - | cut -c 1-5 | xargs kill

Start an erlang prompt on the Drone:
```
/data/erlang/bin/erl
```

Start the necessary apps on the drone On the erlang command prompt, enter:

application:start(uart).
application:start(gpio). 
application:start(edrone). 
edrone_control:flat_trim(). 
edrone_control:enable().

Joystick controls

Stick forward
Dip the nose of the drone, making it move forward.
Stick backward
Raise the nose of the drone, making it move backward.
Stick right
Raise the left side of the drone, making it move to its left.
Stick left
Raise the right side of the drone, making it move to its right.
Rotate stick left
Make the drone rotate anti clockwise.
Rotate stick right
Make the drone rotate clockwise.
Throttle (base of the joystick)
Throttles the motors between off and max.
Fire button
Press and hold to disable throttle control and lock altitude at the current level.
Thumb button (left side of stick)
Activate a newly uploaded edrone_control.beam file (through edrone_upgrade.erl).

Demo script (to be simplified)