Automated Hooking

Code and content for autonomously hooking horizontal pegs with a gantry crane. This project builds heavily on previous research. This code was built for ROS1 Melodic, so no promises about it working on other distros.

For other useful bits of information I refer readers to everything I know about the crane system

Software Setup

0 - Get Access to the Computers

You'll need to be able to run commands on the system Computers. Technically plugging in a monitor and keyboard is a viable option, but ssh and vnc are much nicer.

• Connect your laptop to the system LAN via any of the ethernet cables lying around. As long as it eventually makes its way back to the Console Box, you'll be connected.
• Refer to ros_and_simulink_control.pdf "Instruction of how to connect the VNC" for how to set up your network adapter. Unfortunately these instructions only apply to Windows; you may have to do some searching for equivalents on Linux and Mac.
• Refer also to the table of ip's, usernames, and passwords in the same document. Relatedly, DO NOT publicize this repo.
• You can now connect to the Computers in any of a couple ways.
  • The easiest is to use VNC as described in the document (you can also use any other VNC app, such as tightVNC). Note that this connection is nicely visual, but often slow and uncomfortable.
  • You can also ssh into the Computer: ssh [user]@[ip address]. This method only gives you one terminal to use, but is fast and convenient. If you don't want to type in the password every time, you can add your laptop's ssh key to the remote machine. You can also use tmux to effectively get more terminals per ssh connection.
  • If you use vscode, you can use remote explorer to open the remote Computer. This will allow you to navigate the filesystem graphically and use handy vscode editing tools. Any terminals opened in vscode (Ctrl+`, Ctrl+Shift+`) will open on the target Computer.

1 - Install Code on Crane Computer.

In our case this is the rockpi. The Crane Computer must support odrive 4.(something) The (optional for this device) realsense packages do not support raspbian, so be sure to use something beefier than a pi.

• Install this code and the gantry_description package

  cd ~/catkin_ws/src
  git clone https://github.com/Darbeloff/gantry_description
  git clone https://github.com/Darbeloff/automated_hooking
  cd ..
  catkin build
  

• Install optional dependencies. (technically these only need to be installed on the Vision Computer, see setup step 3 for justification)

  sudo apt install ros-melodic-realsense2
  sudo apt install ros-melodic-realsense2-description
  

  cd ~/catkin_ws/src
  git clone https://github.com/AprilRobotics/apriltag
  git clone https://github.com/AprilRobotics/apriltag_ros
  cd ..
  catkin build
  

2 - Install components on the Vision Computer

In our case this is the nvidia jetson. The (required for this device) realsense packages do not support raspbian, so be sure to use something beefier than a pi.

• Install this code and the gantry_description package

  cd ~/catkin_ws/src
  git clone https://github.com/Darbeloff/gantry_description
  git clone https://github.com/Darbeloff/automated_hooking
  cd ..
  catkin build
  

• Install realsense packages

  sudo apt install ros-melodic-realsense2
  sudo apt install ros-melodic-realsense2-description
  

• Install apriltag packages

  cd ~/catkin_ws/src
  git clone https://github.com/AprilRobotics/apriltag
  git clone https://github.com/AprilRobotics/apriltag_ros
  cd ..
  catkin build
  

3 - Allow Crane Computer to roslaunch remotely onto the Vision Computer

This step is technically unnecessary, but it allows running the code with fewer ssh sessions and makes me feel nice.

• Add the Crane Computer's ssh key to the Vision Computer's authorized_hosts file

  • Find the Crane Computer's ssh key: rockpi> cat ~/.ssh/id_*.pub
  • Copy it into the Vision Computer's authorized_hosts file at: jetson> nano ~/.ssh/authorized_hosts

• Add the Vision Computer to the Crane Computer's known_hosts file

  rockpi> ssh -oHostKeyAlgorithms='ssh-rsa' {user}@{vision_computer_ip}

  This should ssh you onto the Vision Computer without prompting you for a password. the -oHostKeyAlgorithms is required because roslaunch only accepts certain types of keys in the known_hosts file; if roslaunching remotely is failing, try deleting known_hosts and trying this part again.

• Ensure the ~/catkin_ws/env_loader.sh file exists on the Vision Computer. This should already exist, unless someone has destroyed it. This file must define all environment variables (ROS_MASTER_URI, ROS_IP specifically) and source any ros workspace files.

Notes:

• As usual, all computers in this system must agree about who is the ROS master; make sure that all computers have the same device set as their ROS_MASTER_URI, and that all have their own ip set as the ROS_IP environment variable. This must also be true in any env_loader.sh files.

Running

1 - Turn on the Crane

Flip the breaker to On. Move the gantry in all directions to ensure it behaves normally. If the crane jitters or doesnt move in a specific direction, this is often due to the Gantry Computer acting up; try unplugging the gantry computer and starting over.

2 - Start Nodes on the Gantry Computer

In our case this is the raspberry pi that lives next to the breaker. More generally, this is the node connected to arduino CAN that drives the gantry.

• Ensure roscore is running

  pi> nohup roscore &

  This command starts a copy of roscore in the background, that will continue running even if this terminal is closed.

• Start the CAN bridge nodes

  Try simply running pi> can_node.

  If this doesnt work, run these three instead:

  pi> sudo ip link set can0 up type can bitrate 500000
  pi> rosrun socketcan_bridge topic_to_socketcan_node can0
  pi> rosrun socketcan_bridge socketcan_to_topic_node can0
  

3 - Start all other nodes (if you did the optional setup steps)

• Start all other nodes from the Crane Computer

  rockpi> roslaunch automated_hooking all_nodes.launch

  Tip: rostopic list and rosnode list are useful for sanity-checking that all nodes did indeed start.

3 - Start all other nodes (if you did NOT do the optional setup steps)

• Start camera nodes on the Camera Computer

  jetson> roslaunch automated_hooking camera.launch

• Start all remaining nodes on the Crane Computer

  rockpi> roslaunch automated_hooking crane.launch

Parts and Manufacture

Parts List

Manufacture is TODO.