JetRacer Inbetriebnahme

Inbetriebnahme des Roboters

Um diesen Schritt durchzuführen muss eine SD-Karte mit einem Jetson Nano Image vorhanden sein, falls dies nicht der Fall ist wird im Abschnitt "[]" erklärt wie das Image auf der SD-Karte installiert werden kann.

Wifi verbinden

• Schließen Sie hier Peripheriegeräte wie z.B. Monitore an, um sich schnell und einfach mit dem WiFi zu verbinden.
• Stecken Sie die SD-Karte in den Jetson Nano ein (der SD-Kartensteckplatz befindet sich auf der Rückseite des Jetson Nano-Moduls).
• Bereiten Sie Maus, Tastatur und Monitor vor und schließen Sie sie an die Jetson Nano-Platine an.
• Schalten Sie den Netzschalter ein, um den Jetson Nano zu starten, und loggen Sie sich ein, nachdem das Display normal leuchtet, wobei der Benutzername und das Passwort "jetson" sind.

• Nachdem erfolgreichen Login können sie das Wifi auswählen und sich verbinden. Vergewissern Sie sich, dass der jetson nano und der PC mit demselben Netzwerk verbunden sind, da sonst die weitere Kommunikation fehlschlägt.

• Nach erfolgreicher Verbindung mit dem WiFi zeigt der OLED-Bildschirm des JetRacer automatisch die IP-Adresse des WiFi an.

Login per Fernzugriff

• In den vorherigen Schritten haben wir den jetson nano und den PC-Host mit demselben WiFi verbunden, und nach dem Neustart bleibt der jetson nano im Allgemeinen mit dem ursprünglichen WiFi verbunden, und die IP bleibt unverändert.
• In den folgenden Vorgängen verwenden wir SSH-Fernanmeldung, um den Roboterknoten zu starten.
• Wenn der jetson nano eingeschaltet wird, zeigt der OLED-Bildschirm des Fahrzeugs die IP-Adresse des zuletzt verbundenen WiFi an. Wenn das WiFi nicht verbunden ist, wird die IP-Adresse des kabelgebundenen Netzwerkanschlusses angezeigt.

MobaXTerm

• Laden sie [[1]] für den SSH-Login herunter.
• Open MobaXterm, click "Session -> SSH", fill in the IP address displayed by the car in the host, and press Enter to open the terminal; the login name and password are jetson.

• It is easy to transfer the files by MobaXterm.

• To transfer files from Windows to Raspberry Pi simply drag the files to the left directory of MobaXterm.
• Similarly, to transfer Raspberry Pi files to Windows, just drag the files in the left directory of MobaXterm to Windows.

NoMachine Login

• Compared with SSH and VNC, you may not know much about Nomachine. Nomachine is a free remote desktop software.
• NoMachine basically covers all major major operating systems, including Windows, Mac, Linux, iOS, Android and Raspberry, etc.
• Install On Jetson Nano

• Download and unzip the Nomachine
• After unzipping, you can copy the ".deb file" to the Jetson Nano by the U disk driver or MobaXterm File Transmission.
• Install command:

sudo dpkg -i nomachine_7.10.1_1_arm64.deb

• Install On the Windows Computer

• Download [[2] and open it to install. After clicking Finish, you also need to restart the computer.

• Verbinden zum Jetson Nano

1. Open NoMachine and enter the IP address of the Jetson Nano. For example 192.168.15.100

• Please refer to the IP address displayed by the OLED on your car or from the ifconfig command.

2. Click Connect to new host 192.168.15.100, enter the name and password of the Jetson Nano, and then click to log in.

• Use the configured image provided by Waveshare. The name and password are jetson.

3. After downloading, there will display the software introduction, just click "ok".

4. Now we can successfully log in to the Jetson Nano.

IP & Hostname

• Open the robot terminal and enter the following command, check the IP and hostname of the Jetson Nano and remember that it will be used for subsequent multi-machine communication.

ifconfig #Get the IP address of the virtual machine
hostname #Get the hostname of the virtual machine

• Enter the command to check the WiFi name that Jetson Nano is connected to, and make the PC also connect to the same WiFi.

iwconfig wlan0 #View WiFi name

Inbetriebnahme Virtuelle Maschine

Virtuelle Maschine installieren

The robot uses the ubuntu virtual machine as the remote control terminal, and it is more convenient and intuitive to control the robot by using various graphical tools of ROS. Here, open the Ubuntu image by VMware. VMware version should be not lower than 16.

• Download [VMware 16]
• Click to download the configured Ubuntu virtual machine image file below; if you want to configure the Ubuntu ROS system by yourself, you can refer to the advanced tutorial. It is recommended to use our configured image for the first time to avoid various problems when configuring the image yourself.
• Download [Ubuntu VM Image]
• Install and run the VMware software, click "File -> Open -> Open the downloaded <Ubuntu JetRacer.vmx>", click "Start this virtual machine" and log in, where the username and password are: jetson.

IP & Hostname

Open the terminal or press Ctrl+Alt+t, enter the following commands to obtain the IP address and hostname of the virtual machine, and remember, the subsequent multi-machine communication will use 【Note: At this time, we need to ensure that the PC and jetson nano is connected to the same WiFi. The Ubuntu image file and PC we configured are in bridge network mode, under the same WiFi, and the virtual machine and jetson nano is in the same network segment.】

ifconfig # Gibt die IP-Adresse der virtuellen Maschine aus
hostname # Gibt den Hostnamen der virtuellen Maschine aus

VM Programm wechseln

• In der obigen Anleitung wird erklärt wo man das Image für den Ubuntu Controller herunterladen kann, und wie man dieses dann im Programm VMware Workstation in Betrieb nimmt. Da dies allerdings nur für einen Monat kostenlos getestet werden kann, sollte besser das kostenlose Oracle VM Virtualbox Programm genutzt werden. Dieses kann hier heruntergeladen werden. Allerdings muss damit es genutzt werden kann, das Image zu einem anderen Datei Typen, von .vmx auf .vdi, konvertiert werden. Diese Konvertierung kann in folgenden zwei Schritten durchgeführt werden:

• Zuerst muss in der Testversion von VMware das .vmx File ausgewählt und dann über das Menü zu einem .ovf File exportiert werden.
• Danach kann man in Oracle Virtualbox das .ovf File importieren und es wird automatisch zu einem .vdi File konvertiert welches dann benutzt werden kann.

Kommunikation Zwischen den Systemen

Einleitung

• Before configuring multi-machine communication, you need to understand the following three systems:
• PC host: It is generally our commonly used computer, and the system is generally Windows system, which is mainly used to remotely log in to jetson nano via SSH to start the robot control node.
• Ubuntu virtual machine: The Ubuntu system virtual machine installed by VMware software on our PC host mainly realizes ROS graphical display and remote control of the robot, which is more intuitive and convenient.
• jetson nano robot: This is our JetRacer. It adopts jetson nano as the main control and is also an ubuntu system. It is mainly used to realize various nodes such as robot cameras, lidar, and chassis control.
• jetson nano robot installs the ROS robot system and sets it as the host. The Ubuntu virtual machine is also installed in the ROS robot system and set as a slave machine.
• We need to ensure that the above three systems are connected to the same LAN, and the IP addresses are on the same network segment, otherwise normal communication cannot be performed.
• In the following tutorials, the default virtual machine refers to the Ubuntu virtual machine, and the robot refers to the jetson nano robot.

Variablen setzen

• In the previous tutorial, we supported the IP address and hostname of the robot and virtual machine. If you are not sure, you can run the following command to check.

ifconfig       #Get the IP address of the virtual machine
hostname       #Get the hostname of the virtual machine

• Using our image, the robot hostname is nano-4gb-jp451, and the virtual machine hostname is ubuntu.
• We need to add environment variables to the robot and the virtual machine respectively and set the robot as the host. The virtual machine is set as a slave.
• The environment variables have been added using the image we have configured and do not need to be added again; this step is what you need to add when you configure the image yourself.

• ROS_MASTER_URI changes to point to the ROS host, running the roscore master node independently.
• ROS_HOSTNAME variable is the current ROS hostname.

• 【The editor can be nano or vim, just choose one of them according to your preference.】

sudo apt install nano  #install nano editor

Roboter

• On the robot side, add the following text at the end of the ~/.bashrc file, and replace nano-4gb-jp451 if the actual hostname is another name.

sudo nano ~/.bashrc
Add at the end:
export ROS_MASTER_URI=http://nano-4gb-jp451:11311 #Set the robot as the host
export ROS_HOSTNAME=nano-4gb-jp451
After the addition is complete, run the following command to take effect:
source ~/.bashrc

Virtuelle Maschine

• On the virtual machine side, add the following text at the end of the ~/.bashrc file, ROS_MASTER_URI is set to point to the robot as the host, and ROS_HOSTNAME is set to the virtual machine hostname.

sudo nano ~/.bashrc
Add at the end:
export ROS_MASTER_URI=http://nano-4gb-jp451:11311     #Point to the robot host
export ROS_HOSTNAME=ubuntu
After the addition is complete, run the following command to take effect:
source ~/.bashrc

Hostdatei bearbeiten

• Under normal circumstances, after adding environment variables, ROS should be able to communicate normally online. If there are multiple devices with the same name in the LAN, there may be problems such as failure to connect normally or to view topics but not receive topic information. At this point, you need to add hosts to specify the address.
• We need to add honst file settings to the robot and the virtual machine respectively. Please fill in the following settings according to your actual IP address and hostname.

Roboter

• Open the terminal on the robot and enter the following command, add the IP address and hostname of the Ubuntu virtual machine to the /etc/hosts file of jetson nano, the password is jetson.

sudo nano /etc/hosts    

• As shown in the figure below, modify the line below 127.0.1.1 nano-4gb-jp451.localdimain nano-4gb-jp451 to the IP address and hostname of the Ubuntu virtual machine 【if this line is commented out, you need to uncomment.】

• After changing, press Ctrl + x, exit by y, enter, and save it to exit.

Virtuelle Maschine

• Open the terminal on the virtual machine and enter the following command to open the /etc/hosts file and add the robot IP address.

sudo nano /etc/hosts    

• As shown in the figure below, change the line below 127.0.1.1 ubuntu to the IP and hostname of jetson nano. If this line is commented out, it needs to be uncommented.

• After modification, press Ctrl+x, exit y, press Enter, save changes, and exit.

Kommunikation überprüfen

• Connect the robot to open the terminal by SSH, and enter the following command to start the robot master node.

roscore        #Start the robot master node

【The following roslaunch command will also automatically start the master node, but the purpose of starting the master node alone here is to keep connected to the virtual machine all the time, otherwise the master node will be automatically closed when the chassis node is closed, resulting in the virtual machine being disconnected.】

• Open the Ubuntu virtual machine terminal, and enter the following command in the terminal.

rostopic list

• The following normally shows that the two nodes are likely to be able to communicate normally online.

• The robot side saves the startup state of the master node and does not close it. Open a new terminal to run the example receiving node.

rosrun rospy_tutorials listener

• Run the following command on the virtual machine side to start the example sending node.

rosrun rospy_tutorials talker

• After the virtual machine sends the program. The robot side will receive the sent data.

Bevorzugtes Netzwerk

• In der obigen Anleitung ist beschrieben wie man die Verbindung zwischen der Virtuellen Maschine und dem Roboter aufbaut. Wichtig zu beachten ist hierbei das beide Parteien im gleichen WLAN sein müssen.
• Im Labor bedeutet dies, das der PC am besten per LAN Kabel mit dem Router für das "Autonome Systeme" Netzwerk verbunden ist. Und außerdem der Roboter per WLAN mit demselben Netzwerk verbunden ist.
• Ebenfalls ist zu beachten das sich die auf beiden Seiten im /etc/hosts File eingetragenen IP Adressen ändern können, jenachdem welche Geräte mit dem Netzwerk noch verbunden sind. Nach dem Hochfahren der beiden Systeme sollten, mit dem ifconfig Befehl, die aktuellen IP Adressen gecheckt, und falls nötig im File geändert, werden.