B-Pro, AD, RC3, Mechatronics Workshop

• This Repo has been created for Skill's Module for Bartlett AD, UCL. It contains Dynamixel SDK from https://github.com/ROBOTIS-GIT/DynamixelSDK.
• Scripts are modified for robotis ax-12a servos.
• It contains control pipeline from Unity to pi, controlling dynamixel servos via udp protocol.

Prerequisite

• python 3
• dynamixel sdk
• python-osc (python 3)
• unity3d
• pip3

Material

• Raspberry pi
• Robotis Dynamixel AX_12A
• U2D2
• SMPS2Dynamixel
• 12V DC Adaptor
• Micro USB cable
• Micro USB (female) cable (if using pi zero)

Unity

• type address pattern and servoid + "#" + value (eg. "writeGoalPos" and "1#720")

Additional Resources

• Google drive link for wpa_config and linux(desbian)-also available from rasbian website https://drive.google.com/open?id=1oLfMgb-lJGOaOLKiIynS6E6ps8A851XD
• Please check Robotis e-manual for servo data sheet http://emanual.robotis.com/docs/en/dxl/ax/ax-12a/
• You may go through free python tutorials from Code Academy https://www.codecademy.com
• Optitracking tutorial https://www.youtube.com/watch?v=m-OKX8Gaqo0&list=PLdKrdVGpQ5OZSlQDCyYFT-iOo1Qmfzl7Z
• You may found the documentation of optitrack unity plugin at https://v110.wiki.optitrack.com/index.php?title=OptiTrack_Unity_Plugin

Raspberry pi - additional resources for sensors

• accelerometer https://maker.pro/raspberry-pi/tutorial/how-to-connect-tcs34725-rgb-color-sensor-with-raspberry-pi-zero-w
• Pi analog to digital MCP and ADC chips https://pimylifeup.com/raspberry-pi-adc/ https://learn.adafruit.com/raspberry-pi-analog-to-digital-converters/ads1015-slash-ads1115

Linux Terminal Cheat Sheet

• run commands with administrative privileges(run as admin in Windows)

sudo

• used for installing or upgrading packages

apt-get
#or
sudo apt-get install
sudo apt-get upgrade

• ge help

--help

• List all files in the current folder

ls

• Change directory

cd /  # to root directory
cd -  # to previous directory
cd .. # to one up directory
cd ~  # to home directory

• print working directory

pwd

• copy

cp
cp exampleCode.py /home/workshop # would copy the file “exampleCode.py” to the directory “/home/workshop”)

• move

mv
mv exampleCode.py /home/workshop # would move the file “exampleCode.py” to the directory “/home/workshop”

• remove

rmdir # removes an empty directory 
rm -r # removes a directory recursively (!!!try not to use this line!!!)
rm exampleCode.py #delete a single file in current folder
rm -rf home/worshop/ # delete all files in this folder
rmd # permanantly delete file

• make directory

mkdir

• edit script on pi

nano filename
nano exampleCode.py

• to logout from pi

logout

• to see usb connected

lsusb

• to see connected device port address

ls /dev/tty*

Using Git on Pi

• clone a repo

git clone <url>.git

• install git

sudo apt-get install git

• configuring github

git config --global user.name "user_name"

git config --global user.email "email_id"

• initialize git

git init

• git on existing repo (origin)

git remote add origin <repourl>.git

• add files

git add .

• commit changes

git commit -m "short text about changes"

• push changes

git push -u origin master

# if more than one branch
git push -all

• pull changes

git fetch

git stash

git merge origin/master

FTP

• you may also use FTP or SFTP with Cyberduck

In case U2D2 is not recognized

• download Dynamixel Wizard to double check the id and baudrate of servo
• check the port name from device manager(in Windows)
• if not visible in the device manager download ftdi driver
• In Linux

ls /dev/tty* # generally its /dev/ttyUSB0
# or
lsusb # to check how many driver is plugged

In case your laptop can not recieve udp message

• check the Firewall settings in Windows and make a new inbound rule