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Modified 2018-06-22 by Andrea Censi

The Raspberry Pi of the Duckiebot is connected to the battery.

The Stepper Motor HAT is connected to the battery.

You have a problem!

I cannot access my Duckiebot via SSH

Modified 2018-06-22 by Andrea Censi

When I run ssh robot_name.local I get the error ssh: Could not resolve hostname robot_name.local.

Make sure that your Duckiebot is ON. Connect it to a monitor, a mouse and a keyboard. Run the command

duckiebot $ sudo service avahi-daemon status

You should get something like the following

● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
   Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
   Active: active (running) since Sun 2017-10-22 00:07:53 CEST; 1 day 3h ago
 Main PID: 699 (avahi-daemon)
   Status: "avahi-daemon 0.6.32-rc starting up."
   CGroup: /system.slice/avahi-daemon.service
           ├─699 avahi-daemon: running [robot_name_in_avahi.local
           └─727 avahi-daemon: chroot helpe

Avahi is the module that in Ubuntu implements the mDNS responder. The mDNS responder is responsible for advertising the hostname of the Duckiebot on the network so that everybody else within the same network can run the command ping robot_name.local and reach your Duckiebot. Focus on the line containing the hostname published by the avahi-daemon on the network (i.e., the line that contains robot_name_in_avahi.local). If robot_name_in_avahi matches the robot_name, go to the next Resolution point. If robot_name_in_avahi has the form robot_name-XX, where XX can be any number, modify the file /etc/avahi/avahi-daemon.conf as shown below.

Identify the line


and change it to


Identify the line


and change it to


Restart Avahi by running the command

duckiebot $ sudo service avahi-daemon restart

The Duckiebot does not move

Modified 2018-06-22 by Andrea Censi

I can SSH into my Duckiebot and run the joystick demo but the joystick does not move the wheels.

Press the button on the side of the battery (Figure 21.2).

Check that the red indicator on the joystick stopped blinking.

Bad joystick status

Bad joystick status

The joystick is connected (as shown in Figure 21.4d - Bad joystick status) but the Duckiebot still does not move.

Make sure that the controller is connected to the Duckiebot and that the OS receives the data from it. Run

duckiebot $ jstest /dev/input/js0

If you receive the error

jstest: No such file or directory

it means that the USB receiver is not connected to the Raspberry Pi or is broken. If the command above shows something like the following

Driver version is 2.1.0.
Joystick (ShanWan PC/PS3/Android) has 8 axes (X, Y, Z, Rz, Gas, Brake, Hat0X, Hat0Y)
and 15 buttons (BtnX, BtnY, BtnZ, BtnTL, BtnTR, BtnTL2, BtnTR2, BtnSelect, BtnStart, BtnMode, BtnThumbL, BtnThumbR, ?, ?, ?).
Testing ... (interrupt to exit)
Axes:  0:     0  1:     0  2:     0  3:     0  4:-32767  5:-32767  6:     0  7:     0 Buttons:  0:off  1:off  2:off  3:off  4:off  5:off  6:off  7:off  8:off  9:off 10:off 11:off 12:off 13:off 14:off

it means that the USB receiver is connected to the Raspberry Pi. Leave the terminal above open and use the joystick to command the Duckiebot. If you observe that the numbers shown in the terminal change according to the commands sent through the joystick than the problem is in ROS. Make sure that the joystick demo is launched. Restart the Duckiebot if needed and try again.

If the numbers do not change while using the joystick then follow this guide at the next Resolution point.

The controller might be connected to another Duckiebot nearby. Turn off the controller, go to a room with no other Duckiebots around and turn the controller back on. Retry.

Because of mathjax bug

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