Pymavlink Ardupilot SITL

• ardupilot SITL

• pamavlink

• Terminal 1

sim_vehicle.py --console

• Terminal 2 (python code)

from pymavlink import mavutil

master = mavutil.mavlink_connection('tcp:127.0.0.1:5762')

# Get some information !
while True:
    try:
        print(master.recv_match().to_dict())
    except:
        pass

• Terminal 3 (netstat -natp)

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:5760            0.0.0.0:*               LISTEN      5976/arducopter 
tcp        0      0 0.0.0.0:5762            0.0.0.0:*               LISTEN      5976/arducopter 
tcp        0      0 0.0.0.0:5763            0.0.0.0:*               LISTEN      5976/arducopter 

python output

{'mavpackettype': 'TIMESYNC', 'ts1': 1854891080001, 'tc1': 0}
{'custom_mode': 0, 'system_status': 3, 'base_mode': 81, 'autopilot': 3, 'mavpackettype': 'HEARTBEAT', 'type': 2, 'mavlink_version': 3}
{'custom_mode': 0, 'system_status': 3, 'base_mode': 81, 'autopilot': 3, 'mavpackettype': 'HEARTBEAT', 'type': 2, 'mavlink_version': 3}
{'custom_mode': 0, 'system_status': 3, 'base_mode': 81, 'autopilot': 3, 'mavpackettype': 'HEARTBEAT', 'type': 2, 'mavlink_version': 3}

PyMavlink and PX4 SITL

python implementation of the MAVLink protocol

SITL and pymavlink setup

• Terminal 1: from PX4 Firmware run

make posix_sitl_default jmavsim

---

Tip: Run SITL without GUI , good performance save resource

source

• Edit this file, which is part of jMAVSim repository, Visualizer3D.java13, and change setVisible(true) to setVisible(false).

# find . -name Visualizer3D.java
vim `find . -name Visualizer3D.java`
# search setVisible(true) //line 175
# change setVisible(true) to setVisible(false)

# compile and run again
make posix_sitl_default jmavsim

---

Now the SITL run without JMavsim GUI

| ___ \ \ \ / /   /   |
| |_/ /  \ V /   / /| |
|  __/   /   \  / /_| |
| |     / /^\ \ \___  |
\_|     \/   \/     |_/

px4 starting.

INFO  [Unknown] Calling startup script: bash etc/init.d-posix/rcS 0

INFO  [simulator] Waiting for initial data on UDP port 14560. Please start the flight simulator to proceed..
 
Init MAVLink
4000000 B/s on udp port 14556 remote port 14550

INFO  [mavlink] mode: Onboard, data rate: 4000000 B/s on udp port 14557 remote port 14540

PyMavlink demo

• use ipython/ python console

from pymavlink import mavutil
master = mavutil.mavlink_connection("udp:127.0.0.1:14540")
#master
# <pymavlink.mavutil.mavudp at 0x7..>
master.recv_match()
_.to_dict()

{'alt': 487971,
 'hdg': 40,
 'lat': 473977416,
 'lon': 85455938,
 'mavpackettype': 'GLOBAL_POSITION_INT',
 'relative_alt': -12,
 'time_boot_ms': 357265,
 'vx': -3,
 'vy': 0,
 'vz': 0}

PX4 SITL Dronekit

• dependencies
• run jmavsim as simulator
• run dronekit sample code

Install dependencies

sudo apt-get install python-jinja2
sudo pip install numpy toml

Download PX4 and build

ROS and gazebo are preinstalled

mkdir px4
cd px4
git clone https://github.com/PX4/Firmware.git
cd Framework
wget https://raw.githubusercontent.com/PX4/Devguide/master/build_scripts/ubuntu_sim_common_deps.sh
source ubuntu_sim_common_deps.sh

#First Build (Using the jMAVSim Simulator)
make posix jmavsim

DroneKit

dronekit

• droneKit
• dronekit-sitl

sudo pip install dronekit

Demo

• Dronekit read data from PX4 SITL
• Run PX4 SITL (simulation)

dronekit sample code

from dronekit import connect, VehicleMode

connection_string = "127.0.0.1:14540"
# Connect to the Vehicle.
print("Connecting to vehicle on: %s" % (connection_string,))
vehicle = connect(connection_string, wait_ready=True)

# Get some vehicle attributes (state)
print " System status: %s" % vehicle.system_status.state

Run gazebo simulation (without gzclient)

HEADLESS=1 make posix_sitl_default gazebo

Programing NodeMcu with Arduino IDE

1. setup additional board url
2. install board manage
3. set board and port
4. select blink example
5. upload and run

Setup additional board url

file -> preference paste the link into field "Additional Bard Manager URL"

http://arduino.esp8266.com/stable/package_esp8266com_index.json

Install board

Tools -> Board -> Board manager
filter: esp8266

Set board and port

board: NodeMcu 1.0
port: /dev/USB0

Select blink example

File -> Example -> esp8266 -> blink

Upload and run

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, LOW);
  delay(1000);
  digitalWrite(LED_BUILTIN, HIGH);
  delay(2000);
}

GO lang on Ubuntu 16.04

Downloading and installing Go 1.9.1, Setup environment, building a simple Hello World application

Download and setup

curl -O https://storage.googleapis.com/golang/go1.9.1.linux-amd64.tar.gz

tar -xvf go1.9.1.linux-amd64.tar.gz

sudo mv go /usr/local 

Setting path

vim ~./profile
#add as last line
export PATH=$PATH:/usr/local/go/bin

Init

source ~/.profile

Test

mkdir $HOME/gowork
mkdir -p $HOME/gowork/src/hello

Set gopath

export GOPATH=$HOME/gowork

Write hello.go

Note: save under $HOME/gowork/src/hello

package main
import "fmt"
func main() {
     fmt.Printf("hello, world\n")
}

Compile and run 

use run, compile or install

from source folder run
go run hello.go
#or
go build hello.go
./hello

cd $GOPATH
go install hello
#run
$GOPATH/bin/hello

Install and config Go extension on VSCode

This extension uses a set of Go tools to provide the various rich features. These tools are installed in your GOPATH by default

settings

"go.gopath": "/home/user/gowork"

 

 

Reference

Install Go 1.9.1 on Ubuntu 16.04

Hello Arduino and FIRMATA

Firmata is a protocol for communicating with microcontrollers from software on a computer
Like Arduino for example :
In essence it turns your Arduino device into a slave with a simple provided sketch. Then using the python/or any other language you can interface the Arduino via Serial bus and exposed API provided by the Firmata system

1. Install arduino IDE
2. Add dialup group to user `sudo adduser $USER dialout` 
3. Upload Firmata to arduino
1. File -> Examples -> Firmata -> StandardFirmata
4. Install python library
1.  sudo pip install pyfirmata
5. Write some code

code example to turn on output 13 (build-in led)

from pyfirmata import Arduino, util
board = Arduino('/dev/ttyACM0')
board.digital[13].write(1)

Reference

• Firmata protocol
• pyfirmata 

VSCode tips for ROS

Tip1 - Adding a file extension to a language

You can add new file extensions to an existing language with the files.associations setting, for example assign gazebo .world file to XML

"files.associations":{
 ".world": "xml"
}

Tip2 - use code runner to check urdf files

code runner:  Run code snippet or code file for multiple languages

• install 'Code runner' extension into vscode 
• install check_urdf (apt-get install liburdfdom-tools)
• from settings append file extension into code runner mapping
  

"code-runner.executorMapByFileExtension": { 
".urdf": "check_urdf"
} 

Tip3 - use code runner to check xacro files

ROS node xacro in package xacro convert xacro  file to urdf

rosrun xacro xacro <file_name.xacro>

The idea is to run the above command redirect the output to tmp file and then run check_urdf on it.

"files.associations":{
".xacro": "rosrun xacro xacro --inorder $fullFileName > /tmp/tmp.urdf && check_urdf /tmp/tmp.urdf"
}

code runner supported parameters

• $workspaceRoot: The path of the folder opened in VS Code
• $dir: The directory of the code file being run
• $dirWithoutTrailingSlash: The directory of the code file being run without a trailing slash
• $fullFileName: The full name of the code file being run
• $fileName: The base name of the code file being run, that is the file without the directory
• $fileNameWithoutExt: The base name of the code file being run without its extension