Network Setup

Indoor Network Setup

To ensure your robot has continuous and reliable network connection, you should use wpa_supplicant if you don’t have a display for the robot.

Here are the steps for setting up wpa_supplicant.

0. First of all, ask for a static ip for your robot in the mrsl network.

1. add wpa_supplicant.conf to /etc/wpa_supplicant/:

   ctrl_interface=/var/run/wpa_supplicant
   ctrl_interface_group=0
   ap_scan=1
   fast_reauth=1
   
   network={
       ssid="mrsl_airrouterhp"
       scan_ssid=1
       key_mgmt=NONE
   }
   

2. modify /etc/network/interfaces so that it looks like:

   auto lo
   iface lo inet loopback
   
   # auto start wlan0 interface
   auto wlan0
   # use static ip for wlan0
   iface wlan0 inet static
   # your desired ip
   address 192.168.129.xyz
   gateway 192.168.129.1
   netmask 255.255.255.0
   wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
   
   auto eth0
   iface eth0 inet static
   address 192.168.1.abc
   netmask 255.255.255.0
   

3. The next time your power on your robot, it will automatically connect to the router you specified in wpa_supplicant.conf. And if will reconnect even if you lose connection temporarily.

4. A sample interfaces file can be found here.

Outdoor Network Setup

For large-scale outdoor experiments, we need ad reliable long-range wifi connection between the robot and the ground station. To this end, we use Ubiquiti wireless products. Both bullet M and PicoStation M are good choices.

We recommend using PicoStation simply because it is easier to strip the case off.

We use Ubiquiti products mainly for its airMax technology, which is designed for outdoors wireless communication.

Below we describe in detail how to setup airMax connection between two Ubiquiti devices. We use a Bullet M in Access Point mode to serve as a ground station and a PicoStation M in Station mode, which can be seen as a client.

Access Point (Ground Station)

1. On your computer, add a new Ethernet connection from Ubuntu Network Manager.

2. In IPv4 Settings tab, change Method to Manual

3. Add an Address, here we use 192.168.1.200, with Netmask 255.255.255.0. You can leave the Gateway and DNS servers empty.

4. Power up the Bullet M and connect to your computer via Ehternet.

5. Make sure you are on the network configuration you just setup. Then open a browser window with the following ip address 192.168.1.20, which is the default address for Bullet M.

6. The default Username and Password are both ubnt.

7. In the first tab left to MAIN, select Enable for airMAX, then click Change and Apply. Notice that all the changes you made will be cancelled if you switch tab without applying those changes.

8. In WIRELESS tab, make the following changes. The rest can be left as default.

   Item	Value
   Wireless Mode	Access Point
   SSID	ubnt (anyname)
   Channel Width	20 MHz (recommended)

9. In NETWORK tab, make the following changes.

   Item	Value
   Network Mode	Bridge
   Management IP address	Static
   IP Address	192.168.1.20
   Netmask	255.255.255.0
   Gateway IP	192.168.1.1

Station (Client)

1. On your robot, make sure your ethernet interface (eth0) is on the same subnet as the Access Point, which should be 192.168.1.abc.

2. Power up the PicoStation M and connect to your robot via Ethernet.

3. Open a browser window with the folloing IP address 192.168.1.20 (default).

4. Again, he default Username and Password are both ubnt.

5. In WIRELESS tab, make the folloing changes. The rest can be left as default.

   Item	Value
   Wireless Mode	Station
   SSID	ubnt (same as AP)
   Channel Width	Auto 20/40 MHz

6. In NETWORK tab, make the following changes. Note that IP Address should be something other than 20 and abc.

   Item	Value
   Network Mode	Bridge
   Management IP address	Static
   IP Address	192.168.1.21
   Netmask	255.255.255.0
   Gateway IP	192.168.1.1

7. In MAIN tab, remember the WLAN0 MAC of this device. Then go back to the Access Point setup page on your computer. In WIRELESS tab, select Enable for MAC ACL and Allow for Policy. And add the above MAC to the list by clicking on ACL….

Now you should have established airMAX connection between the Bullet M and the PicoStation M. In MAIN tab of the Access Point, you will see something like this.

Internet Sharing from Your Computer

Often, it is convenient to have internet access on your robot.

1. Add the following two lines to your ethernet interface in /etc/network/interfaces:

   gateway 192.168.1.200 # IP address of your laptop
   dns-nameservers 192.168.129.1 8.8.8.8  # for internet access
   

2. Put the following function in your .bashrc, then you can enable and disable sharing via sharenet on/off:

   function sharenet()
   {
       if [ $# -eq 0 ]; then
           echo "usage: sharenet <on/off>"
           return 0
       fi
   
       local if_from=wlan0
       local if_to=eth0
       # check command-line commands
       cmd=$1
       case $cmd in
           on )
               sudo su -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
               echo "Enable sharing internet from $if_from to $if_to"
               sudo /sbin/iptables -A FORWARD -i $if_to -o $if_from -j ACCEPT
               sudo /sbin/iptables -A FORWARD -i $if_from -o $if_to -m state --state RELATED,ESTABLISHED -j ACCEPT
               sudo /sbin/iptables -t nat -A POSTROUTING -o $if_from -j MASQUERADE
               ;;
           off )
               sudo su -c "echo 0 > /proc/sys/net/ipv4/ip_forward"
               echo "Disable sharing internet from $if_from to $if_to"
               ;;
           * )
               echo "sharenet: $1: invalid command"
               echo "usage: sharenet <on/off>"
               ;;
       esac
   }