Networking

The Sawyer Research Robot uses ROS to communicate with the user´s Development Workstation. This requires an ethernet network to be established between Sawyer and the Workstation with full bi-directional connectivity. If you have trouble connecting to your Sawyer, see this page for our Recommended Network Setup and other common network debugging steps. 

Contents

• Contents
• Confirm that Sawyer is Running in SDK Mode on the Robot
• Basics
• ROS Naming Conventions
• Network Configuration through a Router
• Direct Network Configuration
• Troubleshooting

Confirm that Sawyer is Running in SDK Mode on the Robot

In order to network with the robot, be sure that the robot is in SDK mode. You can confirm this by booting the robot and seeing this image on the screen:

 
If you boot the robot and it is running Intera please follow these instructions to update the robot.

Basics

These Network Configuration settings are available in the Field Service Menu (FSM).

Basic Requirements

Sawyer must be connected to a development workstation which uses ROS over an ethernet network to communicate bi-directionally.

Important Note: Connect to the robot via the ethernet port on the outside of the Controller. Connecting to the ethernet port inside the Controller door will not work (this is a diagnostic port that is only accessible by Field Service Technicians).

Sawyer's hostname can be configured using the Field Service Menu (FSM) if you do not like the one given out at the factory which matches its serial number.

Network address assignment

Sawyer supports IPV4 addressing for the following network configurations:

• Automatic address assignment (“Automatic” mode)
  • If a DHCP server is present in the network, the DHCP server automatically assigns a network address to the robot, and may (or may not) assign a DNS server for host name resolution.
  • If no DHCP server is present, the robot will use the Autoip protocol to assign itself a link-local address in the 169.254.0.0/16 address block.
  • All assignments in this mode are automatic, and no options can be configured manually.
• Manual address assignment from the Field Service Menu (“Manual” mode)
  • The user must specify a valid IPV4 address for the robot, and may optionally specify a network mask, default gateway address, and DNS server address. All network options are configured manually.

Host name resolution

In all addressing modes, Sawyer provides link-local advertising of the robot’s host name as “<robot name>.local” using the Avahi mDNS service. Computers that are located in the same subnet as the robot and that support mDNS can always resolve the robot’s host name as “<robot name>.local” even if no other host name resolution service is present. Sawyer will also be able to communicate with these computers using their host names.

In “Automatic” addressing mode, Sawyer will be able to resolve external host names only if the network’s DHCP server supplies a DNS server address. If the DHCP server does not provide a DNS server address, Sawyer will only be able to communicate with external computers by their IP addresses.

In “Manual” addressing mode, Sawyer will be able to resolve external host names only if the user specifies a DNS server address (and a default gateway address if computers in a different subnet are involved). If the user does not provide a DNS server address, Sawyer will only be able to communicate with computers by their IP addresses. If the user does not provide a default gateway address, Sawyer will only be able to communicate with computers within the same subnet.

ROS Naming Conventions

Intera robots supports 3 ROS naming conventions. These control how the ROS Master publishes the access information for the individual nodes published by the robot. Regardless of how you connect to the robot, you will need to be able to reach it by the address configured by its ROS naming convention if you want to be able to interact with it. (i.e. if you can reach the robot by its IP, but it is configured with the ROS_HOSTNAME convention and you can't reach it by its hostname, then you will be unable to do meaningful work with the robot)

• ROS_HOSTNAME.local:This publishes the nodes at <robot hostname>.local
  • This is the least versatile, but the most stable configuration, and is our recommended when it is available.
  • This convention only works in a local setup, where your robot and development machine are on the same subnet, but will almost always work in that network configuration.
  • This will only break if
    • A naming conflict is introduced on the local network or
    • You manually change the hostname of the robot.
• ROS_IP:This publishes the nodes at the IP4 Address associated with the robot
  • This is the most versatile naming convention, but also the most fragile.
  • It will work in any network configuration where you have connectivity to the robot, but will break if the IP of the robot changes
• ROS_HOSTNAME:This publishes the nodes at the hostname of the robot.
  • This configuration has medium versatility and stability.
  • It only works if there is a working DNS running on your network, and pointed at the robot.
  • This will only break if
    • A naming conflict is introduced in the network or
    • If the the DNS-resolved hostname of the robot is changed, which can be done by the Server admin, but is unlikely to happen.

Network Configuration through a Router

Recommended Network Configuration

The recommended network configuration is to connect your development workstation and your Sawyer to an all in one SOHO (Small Office/Home Office) router/firewall similar to the Linksys EA-Series routers. This type of router provides DHCP and other networking services, and has the benefit of keeping the network traffic off of your main network. It also allows the development workstation access to internet in particular, the Rethink Robotics github repo for code and documentation.

Router Configuration Diagram

• Sawyer and the user's computer can both be set to "Automatic" addressing mode, which will draw IP information directly from the router.

Sawyer

• Sawyer can be set to use either ROS_IP or ROS_HOSTNAME.local:
  1. ROS_HOSTNAME.local is our recommended ROS naming protocol for the robot in this setup. It is very stable in this network configuration, and would only need to be adjusted if you switch to a separate subnet from the robot.
     • If you can ping <robot hostname>.local, then the network is working correctly
  2. ROS_IP is the most reliable naming method, if you know that the robot is going to keep its .IP. This naming protocol works across all network configurations as long as you have reliable routing to the robot.
     • If you can ping <robot ip> then the network is working correctly.
     • Note: You can set the robot to use a Static IP if you are interested in using this naming convention because you are unsure of your future network configurations, but be sure to talk to your network administrator if you are hooking your router up to a larger network.

Dev Machine

• In this network configuration, you will want to have your intera.sh script point to either:
  1. ROS_IP = "<your development machine's IPV4 Address>"
     • Verify connectivity by attempting to ping <your development machine's IPV4 Address>
  2. ROS_HOSTNAME = "<your development machine's hostname>.local"
     • Verify connectivity attempting to ping <your development machine's hostname>.local

Connect Directly to Corporate or University Network

Another viable networking configuration is to connect Sawyer directly to your corporate or university network. Here you need to make sure that a DHCP server is available, and that your name server can resolve Sawyer's hostname to an IP address.

You can set Sawyer to use either "Automatic" addressing or a static IP configuration in this configuration.

Note: If you want to set a static IP, you will need to talk to your network administrator to get an appropriate IP for you to assign, in order to avoid network collisions.

Sawyer

In this network configuration, you can use either ROS_IP or ROS_HOSTNAME ROS naming conventions

• In this setup, we recommend using the ROS_HOSTNAME convention. This will rely on your DNS and on not having someone else register a duplicate of your hostname (so pick a unique one), but will be very stable in this network configuration.
  • If you can ping <robot hostname> then the network is working.
• As mentioned in the previous section, ROS_IP is the most versatile ROS naming convention that works across the most network configurations, but is susceptible to automatic IP changes when a lease is exceeded.
  • If you can ping <robot IP> then the network is working.

Dev Machine

• In this network configuration, you will want to have your intera.sh script point to either:
  1. ROS_IP = "<your development machine's IPV4 Address>"
     • Verify connectivity by attempting to ping <your development machine's IPV4 Address>
  2. ROS_HOSTNAME = "<your development machine's hostname>"
     • Verify connectivity by attempting to ping <your development machine's hostname>

Direct Network Configuration

If you do not have a DHCP server or other networking infrastructure, or would just prefer to connect your development workstation directly to Sawyer, you can do so using the following network configuration and steps.

Switch Configuration Diagram

Robot

In this setup, you will need to set your robot to use "Automatic" addressing, and can choose between ROS_IP and ROS_HOSTNAME.local for your ROS naming convention.

1. ROS_HOSTNAME.local is our recommended ROS naming protocol for the robot in this setup. It is very stable in this network configuration, and would only need to be adjusted if you switch to a separate subnet from the robot.
   • If you can ping <robot hostname>.local, then the network is working correctly
2. ROS_IP is the most reliable naming method, if you know that the robot is going to keep its .IP. This naming protocol works across all network configurations as long as you have reliable routing to the robot.
   • If you can ping <robot ip> then the network is working correctly.
   • Note: You can set the robot to use a Static IP if you are interested in using this naming convention because you are unsure of your future network configurations, but be sure to talk to your network administrator if you are hooking your router up to a larger network.

Dev Machine

• In this network configuration, you will want to have your intera.sh script point to either:
  1. ROS_IP = "<your development machine's IPV4 Address>"
     • Verify connectivity by attempting to ping <your development machine's IPV4 Address>
  2. ROS_HOSTNAME = "<your development machine's hostname>.local"
     • Verify connectivity by attempting to ping <your development machine's hostname>.local

Avahi Configuration Steps

These steps assume your ethernet connection to the robot is on enx8ca. Your network device will likely have a different name, or simply be eth0. Follow the below steps to find it:

• Shutdown Sawyer and disconnect ethernet cable.
• Connect the laptop/workstation to Sawyer using a Category-5 ethernet cable.
• Power up Sawyer.
• Disable firewall on laptop if necessary:

    $ sudo ufw disable

• Turn off the Ubuntu Network-Manager to prevent interference:
• Go to the Networking Icon drop-down menu in the top-right of the Desktop.
• Make sure 'Enable Networking' is unchecked (if checked, select the option in the menu to disable)
• Find your ethernet device via ifconfig

 $ ifconfig -a
  
    enx8ca Link encap:Ethernet
    ...
    ...
    lo     Link encap:Local Loopback
    ...
    ...
    wlp2s0    Link encap:Ethernet

Ignore any Loopback or "wlp" wireless devices. On Ubuntu 14.04 and earlier, this usually defaulted to "eth0". In 16.04 and later these devices typically have names that start with "en" followed by a bunch of letters and numbers. For example, my USB-ethernet dongle reads "enx8ca", but yours will likely be different (or just "eth0").

In the following steps, replace "enx8ca" with your ethernet device.

• Check status of enx8ca:

$ ifconfig enx8ca

You should not see any IP addresses under 'inet'.

• Use Avahi to designate an IP address to "enx8ca" (do not close the terminal after running avahi-autoipd):

$ sudo avahi-autoipd enx8ca

• Make sure an IP address is successfully claimed. eg:

Found user 'avahi-autoipd' (UID 104) and group 'avahi-autoipd' (GID 111).
Successfully called chroot().
Successfully dropped root privileges.
Starting with address 169.254.8.16
Callout BIND, address 169.254.8.16 on interface enx8ca
Successfully claimed IP address 169.254.8.16

Keep this Terminal running in the background.

• Open a New Terminal to continue.
• Find the local hostname of the robot by running avahi-browse:

$ avahi-browse -a -r

Note: The default local hostname of the robot is the Serial Number followed by ".local". Ex: "011303P0017.local"

Troubleshooting

See the ROS Network Setup Guide for common ROS network issues and helpful debugging steps to check your base ROS connectivity.