Motor

Turnigy Aerodrive SK3 - 4240-740kv Brushless Outrunner Motor

Kv(rpm/v) 740
Weight (g) 195
Max Current(A) 50
Resistance(mh) 13
Max Voltage(V) 19
Power(W) 870
Shaft A (mm) 5
Length B (mm) 48
Diameter C (mm) 42
Can Length (mm) 23
Total Length E (mm) 70

ESC Speed Controller

TURNIGY Plush 60amp Speed Controller

Cont Current: 60A
Burst Current: 80A
BEC Mode: Switching
BEC : 5v / 3A
Input: 5.6v-22v
Weight: 60g
Size: 80x31x14mm
Supported motor speed for all TURNIGY ESCs is;
(Maximum): 210000 RPM (2 poles), 70000 RPM (6 poles), 35000 RPM (12 poles).

Propeller

Folding Carbon Fiber Propeller 13x7 (1pc)

Length (Inch [X]) 13
Pitch (Inch [Y]) 7
Weight 20gram

Spinner

Folding Prop Spinner 43mm / 5.0mm shaft

Prop Mount Bolts: 3.0mm
Weight: 47g

Yoke

Aeronaut Yoke for Turbo and Black 2-Blade Spinners

Aeronaut Yoke 47/8
33-45mm Spinner
Shoulder: 8mm

Blade Stopper

This was supposed to be in our configuration, but we eventually created it ourselves.

Aeronaut Fiberglass Blade Stopper for 2-Blade Folding Spinners (Black, Turbo)

Servo Motors

AeroStar AS-463HB Standard Servo 3.95kg / 0.12sec / 45.5g

Operating Speed: (4.8V) 0.15sec/60°
Operating Speed: (6V) 0.12sec/60°
Stall Torque: (4.8V) 3.25kg.cm
Stall Torque: (6V) 3.95 kg-cm
Dimensions: 40.5X20.3X38mm
Weight: 45.5g
Connector Wire Length: JR 265mm

Batteries

ZIPPY Flightmax 8000mAh 5S1P 30C

Capacity: 8000mAh
Voltage: 5S1P / 5 Cell / 18.5v
Discharge: 30C Constant / 40C Burst
Weight: 1054g (including wire, plug & case)
Dimensions: 170x69x44mm
Balance Plug: JST-XH
Discharge plug: 5.5mm Bullet-connector (without housing)

None of the commands need any dependencies or new installations that are not available in stock Ubuntu.

Commands

To stress the Odroid, I first set the number of CPUs and then ran a bash calculator command that uses lots of CPU.

NUMCPU=$(grep $'^processor\t*:' /proc/cpuinfo |wc -l)

for ((i=0;i<$NUMCPU;i++));do
echo 'scale=100000;pi=4*a(1);0' | bc -l &
done ;\
read stop; \
killall bc

The test will stop executing if any key is pressed.

I used this exact command because it was the only simple one that used all of 4 cores of the Odroid. Using dd, yes, or outputting to terminal would not use the 4 cores.

To check the CPU temperature, run in another terminal:

while(true) do 
cat /sys/class/thermal/thermal_zone0/temp ; sleep 1; done;

The check the processes and the CPU usage:

top

Results

Maximum temperature the CPU reached was 82 degrees Celsius. That cannot melt the ABS plastic which has a melting point of 100 degrees.

MAVProxy can be used to control autopilots by using mavlink commands. As a first step into allowing an Android phone to control the autopilot using the famous applications such as 3DR's Tower wirelessly without the need for any new hardware, I allowed mavproxy to be controller through a Tcp/Udp client.

If you haven't installed Mavproxy yet, here is how to do it.

Through this post, I'll show you how you can modify Mavproxy to run a Tcp/Udp server. If you are not interested in how it is done, and just want the final code, you can find it here on github.

Mavproxy-server usage

To run a TCP server:

        mavproxy.py --tcp=0.0.0.0:5234

To run a UDP server:

        mavproxy.py --udp=0.0.0.0:5234

You can run both TCP and UDP servers simultaneously, but only the UDP server will be able to write mavlink commands. This is not advised.

Steps into getting there

Learn Tcp/Udp programming in Python

Since mavproxy is written in python, then we do have to modify it in python. For starters, to run a UDP server, this snippet of code would open port 4123 on the machine and print whatever is sent to it.

>>> import sys, socket
>>> s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
>>> s.bind(('0.0.0.0', 4123))
>>> while 1:
...     data,addr = s.recvfrom(1024)
...     print data

To run a UDP client, that can be done easily through a linux terminal in bash.

nc 127.0.0.1 4123 -u -v  

And you'd be able to send to the server.

If this worked locally for you, but remotely it didn't, check your firewall settings.

Modify mavproxy's input

Looking through mavproxy's code in mavproxy.py, there is a function called input_loop(). This function waits for user input. We would want to redirect the input from keyboard to the Tcp/Udp server set.

The previous code was:

def input_loop():  
    '''wait for user input'''
    while mpstate.status.exit != True:
        try:
            if mpstate.status.exit != True:
                line = raw_input(mpstate.rl.prompt)
        except EOFError:
            mpstate.status.exit = True
            sys.exit(1)
        mpstate.input_queue.put(line)

If we want a UDP server to listen to input here, recklessly we can modify it as such:

def input_loop():  
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.bind(('0.0.0.0', 4123))
    '''wait for user input'''
    while mpstate.status.exit != True:
        try:
            if mpstate.status.exit != True:
                data,addr = s.recvfrom(1024)
                line = data
                # line = raw_input(mpstate.rl.prompt)
        except EOFError:
            mpstate.status.exit = True
            sys.exit(1)
        mpstate.input_queue.put(line)

Remember to add the socket import.

And that is it. Whatever now is sent through UDP on this port will be run as a command.

Modify mavproxy's output

To read the log, we would also have to send the log back to the UDP client. If we look around, you'd find that writing is done by mpstate.console.writeln(text). console is a TextConsole class that is available in modules/lib/textconsole.py. Looking at its output code:

    def write(self, text, fg='black', bg='white'):
        '''write to the console'''
        if isinstance(text, str):
            sys.stdout.write(text)
        else:
            sys.stdout.write(str(text))
        sys.stdout.flush()

We can add s.sendto(data, address), to be able to send to the client.

You would have to be able to read the socket s there somehow.

Cleaning things up

To clean things up:

1. Create a class for UdpServer and TcpServer. In my project, you can find them under modules/lib.

2. Add parser options in mavproxy.py to read --udp and --tcp options to allow you to run the servers upon will.

3. Put everything where it should be.

Next steps

Now that I can connect and send commands remotely to the autopilot, it is time to be able to use the Android applications to control the autopilot. Maybe someone can add a functionality for mavproxy to understand mavlink packets directly.

The Odroid can be connected to the Pixhawk using a FTDI/USB cable. The FTDI/USB cable can be soldered as proposed here:

The jumper should go into the TELEM2 port on the pixhawk.

My Odroid seems to be unable to give sufficient power to the Pixhawk. The big LED indicator never turns on and it seems to keep on restarting. Make sure you connect another power source if that is the case with you too.

Installing MAVproxy

Now we will install MAVproxy which will allow us to control the pixhawk using mavlink commands.

In my case, my Odroid does not have internet connection due to the fact that it is connected on an ad-hoc network with my laptop. And so I needed to download all the files offline, and send them to the Odroid. You can send the file through SSH or by simply copying them on a USB stick.

Note: For all the following instructions, change the path /root to wherever you'd like to copy your files.

Copying using SSH can be done through scp as follows: `scp -r root@192.168.1.1:

If you do have internet on your Odroid, download MAVproxy directly. Otherwise, download to your laptop and copy to the Odroid. Also, make it publicly accessible:

 cd /root/
 git clone https://github.com/Dronecode/MAVProxy

 ln -s /root/MAVProxy/MAVProxy/mavproxy.py /usr/local/bin/mavproxy
 chmod +x /root/MAVProxy/MAVProxy/mavproxy.py 

Test if MAVproxy is working:

mavproxy --master/dev/ttyUSB0 --baudrate 57600 --aircraft rover

If it worked out for you and you started seeing logs, you are lucky. Proceed to the Running MAVproxy. Else, in my case the output was:

Traceback (most recent call last):
  File "/usr/local/bin/mavproxy", line 12, in <module>
import serial, Queue, select
    ImportError: No module named serial

It seems that I need to install serial module.

Installing python-serial

Two sections here, for internet and non-internet connected Odroids. Make sure that you are using python 2.7 using which python. If you are using python 3, then you would have to add a "3" to all commands and links.

Internet

Just install it directly from apt-get:

sudo apt-get install python-serial

No internet

Download python-serial deb package to your internet connected laptop from:

http://packages.ubuntu.com/trusty/all/python-serial/download

Make sure to download the armhf one.

Copy the deb file to your Odroid, and run dpkg -i <file>. All should go well, unless if you don't really have python installed, see the pymavlink section for how to install a package with all its dependencies.

Try to run mavproxy again:

mavproxy --master/dev/ttyUSB0 --baudrate 57600 --aircraft rover

In my case, I needed pymavlink to proceed.

Installing pymavlink

Download mavlink, but before that you must install the dependencies matplotlib.

Internet

Install it using apt-get:

sudo apt-get install python-matplotlib

No internet

If you are unlucky as I am and you have to do an offline installation of matplotlib, create a list of the dependencies URLs:

 apt-get --print-uris --yes install <my_package_name> | grep ^\' | cut -d\' -f2 > matplotlib.list

Copy the list back to your internet-connected computer using SSH or a USB stick and download the required packages by using:

wget --input-file matplotlib.list

Then copy the deb packages back to your Odroid using SSH or a USB stick, and install them using:

dpkg -i *.deb

Installing mavlink

Install mavlink now:

cd mavlink/pymavlink
python setup.py install --user

See the last line of the output:

Installed /root/.local/lib/python2.7/site-packages/pymavlink-1.1.63-py2.7-linux-armv7l.egg

and add the path to PYTHONPATH permanantly. In my case, these were the commands I added to .bashrc:

export PYTHONPATH="${PYTHONPATH}:/root/.local/lib/python2.7/site-packages/"

Now try to run mavproxy again:

mavproxy

Output:

WARNING: You should uninstall ModemManager as it conflicts with APM and Pixhawk
Auto-detected serial ports are:
/dev/ttySAC3
/dev/ttySAC2
/dev/ttySAC1
/dev/ttySAC0
/dev/ttyACM99
Connect 0.0.0.0:14550 source_system=255
Log Directory: 
Telemetry log: mav.tlog
Process Process-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/multiprocessing/process.py", line 258, in _bootstrap
Waiting for heartbeat from 0.0.0.0:14550
MAV>     self.run()
  File "/usr/lib/python2.7/multiprocessing/process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "build/bdist.linux-armv7l/egg/MAVProxy/modules/mavproxy_map/srtm.py", line 128, in createFileListHTTP
    conn.request("GET",self.directory)
  File "/usr/lib/python2.7/httplib.py", line 973, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python2.7/httplib.py", line 1007, in _send_request
    self.endheaders(body)
  File "/usr/lib/python2.7/httplib.py", line 969, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python2.7/httplib.py", line 829, in _send_output
    self.send(msg)
  File "/usr/lib/python2.7/httplib.py", line 791, in send
    self.connect()
  File "/usr/lib/python2.7/httplib.py", line 772, in connect
    self.timeout, self.source_address)
  File "/usr/lib/python2.7/socket.py", line 553, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
gaierror: [Errno -2] Name or service not known

Perfect. Now mavproxy works. Uninstall modemmanager as instructed by using:

sudo apt-get remove modemmanager

Running mavproxy

Check the USB device which your PixHawk is connected to, probably it is ttyUSB0. Run mavproxy then:

root@odroid:~/mavlink/pymavlink# ls /dev/ttyUSB*
/dev/ttyUSB0
root@odroid:~/mavlink/pymavlink# mavproxy --master=/dev/ttyUSB0 --baudrate 57600 --aircraft rover

Connect /dev/ttyUSB0 source_system=255
no script rover/mavinit.scr
Log Directory: rover/logs/2000-01-01/flight3
Telemetry log: rover/logs/2000-01-01/flight3/flight.tlog
Process Process-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/multiprocessing/process.py", line 258, in _bootstrap
Waiting for heartbeat from /dev/ttyUSB0
    self.run()
MAV>   File "/usr/lib/python2.7/multiprocessing/process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "build/bdist.linux-armv7l/egg/MAVProxy/modules/mavproxy_map/srtm.py", line 128, in createFileListHTTP
    conn.request("GET",self.directory)
  File "/usr/lib/python2.7/httplib.py", line 973, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python2.7/httplib.py", line 1007, in _send_request
    self.endheaders(body)
  File "/usr/lib/python2.7/httplib.py", line 969, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python2.7/httplib.py", line 829, in _send_output
    self.send(msg)
  File "/usr/lib/python2.7/httplib.py", line 791, in send
    self.connect()
  File "/usr/lib/python2.7/httplib.py", line 772, in connect
    self.timeout, self.source_address)
  File "/usr/lib/python2.7/socket.py", line 553, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
gaierror: [Errno -2] Name or service not known
online system 1
AUTO> Mode AUTO
fence breach
waypoint 2
GPS lock at 12 meters
APM: ArduRover v2.50 (3da78052)
APM: PX4: b39d9ae4 NuttX: d447403a
APM: PX4v2 002B0035 32334711 31363032

AUTO> Received 403 parameters
Saved 403 parameters to rover/logs/2000-01-01/flight3/mav.parm

Now you can use MAVLINK commands to control your vehicle.
For example you can run:

manual
hold
steer

It would set the autopilot to these modes.

For help, just type help. You'll get all commands available.

ahrstrim        : do AHRS trim
alias           : command aliases
alt             : show altitude information
arm             : arm motors
attitude        : attitude
auxopt          : select option for aux switches on CH7 and CH8 (ArduCopter only)
bat             : show battery information
calpress        : calibrate pressure sensors
camctrlmsg      : camctrlmsg
cammsg          : cammsg
changealt       : change target altitude
compassmot      : do compass/motor interference calibration
disarm          : disarm motors
fence           : geo-fence management
ground          : do a ground start
guided          : fly to a clicked location on map
gyrocal         : do gyro calibration
land            : auto land
level           : set level on a multicopter
link            : link control
log             : log file handling
magcal          : magcal
mode            : mode change
module          : module commands
motortest       : motortest commands
output          : output control
parachute       : parachute
param           : parameter handling
position        : position
posvel          : posvel
rally           : rally point control
rc              : RC input control
rcbind          : bind RC receiver
reboot          : reboot autopilot
relay           : relay commands
repeat          : repeat a command at regular intervals
reset           : reopen the connection to the MAVLink master
script          : run a script of MAVProxy commands
servo           : servo commands
set             : mavproxy settings
setspeed        : do_change_speed
setup           : go into setup mode
setyaw          : condition_yaw
shell           : run shell command
status          : show status
switch          : flight mode switch control
takeoff         : takeoff
terrain         : terrain control
time            : show autopilot time
tuneopt         : Select option for Tune Pot on Channel 6 (quadcopter only)
up              : adjust pitch trim by up to 5 degrees
velocity        : velocity
version         : show version
watch           : watch a MAVLink pattern
wp              : waypoint management

To exit, Ctrl+C.

Connect

From the client:

1. In order to connect to the ad-hoc connection, first create a shell script file:

   gedit connect.sh
   

   And put the following contents in it:

   #!/bin/sh
   service network-manager stop
   ifconfig wlp2s0 down
   iwconfig wlp2s0 mode ad-hoc
   iwconfig wlp2s0 essid "odroid"
   iwconfig wlp2s0 key 1234567890
   ifconfig wlp2s0 192.168.1.2
   ifconfig wlp2s0 up
   
   
   echo "Connected to ODROID\n"
   
   
   ssh root@192.168.1.1
   

   Where wlp2s0 is my wireless interface. So you must change wlp2s0 and all the variables as you set them up in auto-connect to an ad-hoc connection.

2. Change the execution bit on the file to make it executable:

   chmod +x connect.sh
   

   And run it:

   ./connect.sh
   

   It might not SSH on the first try, try to run it again if it failed.

Disconnect

1. To disconnect the client from the ad-hoc connection, create a shell script file:

   gedit disconnect.sh
   

   And put the following contents in it:

   #!/bin/sh
   iwconfig wlp2s0 mode managed
   service network-manager start
   
   
   echo "Disconnected"
   

2. Change the execution bit on the file to make it executable:

   chmod +x disconnect.sh
   

   And run it:

   ./disconnect.sh
   

   I stop the Network Manager because it might attempt to find a more reliable network which would cause disconnection of the ad-hoc network.

In order to have an ad-hoc connection automatically connected on boot of the OS do the following steps:

1. Edit /etc/network/interfaces, add these lines to the bottom and make sure there is no other configuration for your WiFi interface.

   auto wlan3
   iface wlan3 inet static
     address 192.168.1.1
     netmask 255.255.255.0
     wireless-essid odroid
     wireless-mode ad-hoc
     wireless-key 1234567890
   

2. Edit /etc/NetworkManager/NetworkManager.conf, this should be a template for how to restrict the Network Manager to manage your WiFi interface.

   [main]
   plugins=ifupdown,keyfile,ofono
   dns=dnsmasq
   
   
   [ifupdown]
   managed=false
   
   
   [keyfile]
   unmanaged-devices=mac:00:13:d4:c0:62:db
   

   Where 00:13:d4:c0:62:db is my WiFi interface MAC address.