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# Troubleshooting

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 $sudo service avahi-daemon status  You should get something like the following ● avahi-daemon.service - Avahi mDNS/DNS-SD Stack Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled) Active: active (running) since Sun 2017-10-22 00:07:53 CEST; 1 day 3h ago Main PID: 699 (avahi-daemon) Status: "avahi-daemon 0.6.32-rc starting up." CGroup: /system.slice/avahi-daemon.service ├─699 avahi-daemon: running [robot_name_in_avahi.local └─727 avahi-daemon: chroot helpe  Avahi is the module that in Ubuntu implements the mDNS responder. The mDNS responder is responsible for advertising the hostname of the Duckiebot on the network so that everybody else within the same network can run the command ping robot_name.local and reach your Duckiebot. Focus on the line containing the hostname published by the avahi-daemon on the network (i.e., the line that contains robot_name_in_avahi.local). If robot_name_in_avahi matches the robot_name, go to the next Resolution point. If robot_name_in_avahi has the form robot_name-XX, where XX can be any number, modify the file /etc/avahi/avahi-daemon.conf as shown below. Identify the line use-ipv6=yes  and change it to use-ipv6=no  Identify the line #publish-aaaa-on-ipv4=yes  and change it to publish-aaaa-on-ipv4=no  Restart Avahi by running the command duckiebot$ 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 19.2).

Check that the red indicator on the joystick stopped blinking.

The joystick is connected (as shown in Figure 19.4d - 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.

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