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Version: QTrobot V2

Quick start with coding on QTrobot

This document guides you through a quick start to coding on the QTrobot using programming languages. If you are looking for graphical programming, please take a look at Quick start with QTrobot studio.

1. Understanding QTrobot architecture​

QTrobot is a high-end research platform with powerful computers and state-of-the-art hardware such as a 3D camera and a far-field microphone array. It comes with two computers: i) QTRP, a Raspberry Pi based computer to control the main hardware and ii) QTPC, which can be an Intel® NUC i5/i7 PC or Nvidia Jetson AGX Orin, to provide more computational power and to accelerate the software development cycle. Both computers run on Ubuntu/Debian Linux operating systems and leverage ROS to offer an easy-to-use yet very flexible software architecture. QTrobot's hardware is easily extendable via USB-C and USB adaptors, for example, to connect an external monitor, keyboard, and mouse. QTrobot also provides a rich set of APIs for several programming languages such as C++, Python, and JavaScript.

As shown in the following diagram, QTrobot consists of two computers, one in the QTrobot's head (QTRP) and the other in its body (QTPC), which are internally connected via an ethernet cable. All of the QTrobot devices such as the display, speakers, microphone, and motors are connected to QTRP, except the 3D camera, which is connected directly to QTPC. The Wi-Fi of the QTRP is used to create the QTrobot hotspot with the same SSID as the robot's serial number (e.g. QTRD000101).

architecture

Both computers are configured to interact in one ROS environment. Upon starting the QTrobot, QTRP runs the roscore and initializes the ROS environment. It also turns on QTPC via wake-on-lan when the ROS environment is up (check under Turn on QTrobot for AI@Edge version). You will also find two USB ports at the back of the QTrobot. In the QTrobot NUC version: one of them is attached to QTRP and the second one (USB-C) is connected to QTPC. This USB-C port can be used to connect a keyboard, mouse, and monitor to QTPC via a USB-C extension hub. In the QTrobot AI@Edge version: one of the USB ports is connected to QTRP and the other to QTPC. To connect a monitor, you need to use the Display Port on the back of the QTrobot.

Notice

QTPC is already configured to work with roscore, which is running on QTRP, and you can access all QTrobot ROS services and topics.

2. Prepare your setup​

There are a few ways of developing code for QTrobot. We strongly recommend that you start developing directly on QTrobot's integrated QTPC. As shown in the following picture, you need to prepare:

 

a keyboard,
  a mouse,
  and a monitor with HDMI/Display Port cable.

rdsetup

Step 1. Connect keyboard/mouse and monitor to QTPC​

Connect the keyboard, mouse, and HDMI monitor to your USB-C extension, then plug it into the USB-C port at the back of QTrobot.

QTrobot AI@Edge version
  • Connect the monitor with the provided Display Port - HDMI cable to the Display Port on the back of the QTrobot.
  • Connect the mouse and the keyboard to the USB port below the Display Port, which is connected to QTPC.

Step 2. Turn on QTrobot​

To power the QTrobot on, simply connect the QTrobot's power supply1. This triggers the power-on process and your QTrobot will be ready in less than a minute. After powering on, you can see that the QTrobot's face is on and the motors are in their home position. If the QTrobot is already connected to the power supply, simply push the power button to turn on the QTrobot.

QTrobot AI@Edge version

To power on QTrobot, plug it in using the provided power supply. To turn it off, press the power button on the back and wait for it to completely shut down. Always unplug QTrobot from the power supply before turning it on again. Note that pressing the power button does not turn on the QTPC (Nvidia Jetson).

Step 3. Wait for QTPC to boot​

After you turn on your QTrobot, it will need some time until your QTPC turns on, because QTRP will turn on QTPC after the ROS environment is up. You will see the Ubuntu desktop of QTPC, which you can use the same way you would use a standard desktop for development.

QTPC
Powering off QTrobot

To power off the QTrobot, simply press the power button on the back of the QTrobot. This will turn off both QTRP and QTPC. Wait long enough for QTrobot to turn off before unplugging it from the power supply: a blue screen shows up and then immediately goes off.

Now you should be all set and ready for coding. However, in most cases you will need access to the internet. So let's follow the next section to connect your QTrobot to your home/office router and the internet.

3. Connect QTrobot to a home network and Internet​

To have access to the internet from all machines (as demonstrated in the following diagram), the Wi-Fi of QTRP should be connected to your home router. The internet from the home router is shared with all other machines (including QTPC) via QTRP. The green arrows show the direction of how the internet is shared between QTRP and QTPC.

Therefore, you need to connect the QTRP to your home router's Wi-Fi. To do that, follow these steps:

Step 1. Access QTRP via ssh from QTPC​

From the Ubuntu desktop of QTPC, open a terminal and access QTRP via ssh:

ssh developer@192.168.100.1
# or ssh developer@QTRP

For the password use qtrobot.

Step 2. Configure qt_wlan0_client service​

First, edit the /etc/wpa_supplicant/wpa_supplicant-wlan0.conf file to update ssid and psk accordingly.

cd /etc/wpa_supplicant
sudo nano wpa_supplicant-wlan0.conf

set the ssid (your router ssid) and psk (your router passphrase) of your home router setup:

country=LU
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
    ssid="<your router SSID>"
    psk="<your router passphrase>"         
}

The above format is for connecting to WPA/WPA2 standard WiFi routers, which is the most common configuration of WiFi networks. If your organization's WiFi uses a different configuration, such as PEAP, EAP, or LEAP (which require username/password or certificate-based authentication), please contact your IT department to obtain the correct configuration for wpa_supplicant. Please refer to the wpa_supplicant examples for alternative configuration.

Next, restart the qt_wlan0_client service:

sudo systemctl restart qt_wlan0_client.service
Warning
  • Pay attention that the values for ssid and psk are wrapped with double quotation marks!
  • Pay attention to the <TAB> before ssid and psk!
  • Do not create or change any other files related to wpa_supplicant or systemd network! this may break your QTrobot network setup!
  • Ensure that you are modifying the wpa_supplicant-wlan0.conf file and NOT wpa_supplicant.conf

Step 3. Test and make it permanent​

After following the above steps, your QTrobot should be connected to your home/office network and have access to the Internet (i.e. you should be able to ping www.google.com for example).

ping www.google.com

Disable the qt_wlan0_ap service and enable the qt_wlan0_client service to keep QTrobot internet configuration permanent:

sudo systemctl enable qt_wlan0_client.service
sudo systemctl disable qt_wlan0_ap.service

You are all set! QTRP gets an internet connection from your router and will automatically share it with QTPC and any other devices connected to the QTrobot Wi-Fi hotspot.

Troubleshooting
  • Check if QTrobot is connected to your home/office network. Run the following command on QTRP via ssh: sudo wpa_cli -i wlan0 status. You should see wpa_state=COMPLETED and the correct ssid is reported.
  • Double check that you have entered correct values for ssid and psk in /etc/wpa_supplicant/wpa_supplicant-wlan0.conf!
  • See the status of the qt_wlan0_client service for any typo or misformatted lines in /etc/wpa_supplicant/wpa_supplicant-wlan0.conf. To do that, run the following command on QTRP: sudo systemctl status qt_wlan0_client.service. This should show that the service is running and active. If not, follow the error messages reported by the service.
  • If you are connected to your home/office network (as verified by the previous command) but still do not have access to the internet (e.g. cannot ping Google), please double-check that your home/office network is providing an internet connection!
Additional Networking information

For more information about QTrobot's networking and to learn how to re-enable QTrobot's hotspot, please check Computation and networking.

4. Optional ways of working with QTrobot​

1. Accessing and Programming QTrobot via SSH​

You can access and program QTrobot remotely from your laptop via SSH. To do this, you need to connect to QTPC's terminal using SSH.

SSH to QTrobot in Hotspot Mode (Offline):​

If your QTrobot is not connected to any Wi-Fi network, it will automatically enter hotspot mode. You can connect to its hotspot using the following steps:

  • From your laptop, search for the QTrobot's hotspot Wi-Fi, which is named after its serial number (e.g., QTRD000123).
  • Connect to the hotspot using the password: 11111111.
  • Once connected, you can access the QTPC via SSH (the default SSH password is qtrobot): 
    ssh qtrobot@192.168.100.2
    # enter the password

SSH to QTrobot in Online Mode (Connected to Wi-Fi)​

If your QTrobot is connected to your Wi-Fi network, follow these steps to find its IP address and establish an SSH connection:

  • Find QTrobot's (QTRP) IP Address: You can obtain the IP address of QTRP by either of the following methods:

    • Using ifconfig on QTRP (accessed via QTPC with display and keyboard): first, connect to QTPC using a display and keyboard, then run the ifconfig command on QTRP:

      # From QTPC:
      ssh qtrp ifconfig 
      # look for the ip address of wlan0 interface. e.g:
      # wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
      #     inet 192.168.80.3  netmask 255.255.255.0  broadcast 192.168.80.255

    • Using Ping with QTrobot Serial Number: Alternatively, you can try pinging the robot using its serial number (e.g., QTRD000123):

      # From your computer
      ping QTRD000123.local
      # example: 
      # Pinging QTRD000320.local [192.168.80.3] with 32 bytes of data:
      # Reply from 192.168.80.3: bytes=32 time=5ms TTL=64

      Note: This method may not work on all Wi-Fi networks, depending on your network's configuration.

  • SSH into QTPC: Once you have the IP address for QTRP (e.g., 192.168.80.3), you can SSH into QTPC using the following command (the default SSH password is qtrobot):

    ssh -o UserKnownHostsFile=/dev/null -J developer@192.168.80.3 qtrobot@qtpc
    # enter the password

    Alternative Method: If you prefer, you can first SSH into QTRP, then connect to QTPC:

    ssh developer@192.168.80.3
    # enter the password
    su qtrobot
    # enter the password
    ssh qtpc

2. Programming QTrobot from your computer via ROS​

You can program QTrobot directly from your computer using ROS. To do this, ensure that ROS is installed on your system. If you haven't installed ROS yet, please follow the official installation instructions. Next, follow these instructions to set up your ROS environment:

Setup your ROS environment​

Clone the QTrobot Software repository.

cd ~/; git clone https://github.com/luxai-qtrobot/software.git

Copy the headers folder (or make a link in your Catkin source workspace) and build the messages:

cd ~/catkin_ws/src
ln -s ~/software/headers ./
cd ~/catkin_ws
catkin_make

Next, you'll need to configure your ROS environment to connect to QTrobot. Follow these steps:

Connect to QTrobot's Wi-Fi:

  • If QTrobot is offline, connect to its Wi-Fi hotspot.
  • If QTrobot is online, connect to the same Wi-Fi network that QTrobot is connected to.

Find Your IP Address:

  • Open a terminal on your laptop and run the following command to retrieve your IP address: 
    ifconfig
  • Look for the inet address under the Wi-Fi interface (e.g., 192.168.4.25): 
    wifi0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.4.25  netmask 255.255.255.0  broadcast 10.42.0.255
        ...

Configure ROS Environment variables:

  • Edit the ~/.bash_aliases file on your computer and add the following lines. Replace ROS_IP with the IP address you retrieved in the previous step, and set ROS_MASTER_URI to your QTrobot's serial number. 
    source /opt/ros/noetic/setup.bash
    source ~/catkin_ws/devel/setup.bash

    ## QTrobot
    export ROS_IP=<your PC IP address>                        # e.g. 192.168.4.25
    export ROS_MASTER_URI=http://<your QTrobot serial>:11311  # e.g. http://QTRD000100.local:11311
  • To apply these changes, run the following command: 
    source ~/.bash_aliases

Test your setup​

To verify the connection, you can list all ROS topics running on QTrobot by executing the following command:

rostopic list

If everything is configured correctly, you should see an output similar to the one below:

/rosout    
/qt_robot/audio/play
/qt_robot/behavior/talkAudio
/qt_robot/emotion/show
/qt_robot/gesture/play
/qt_robot/head_position/command
/qt_robot/joints/state
...

You can also test the connection by calling one of QTrobot's ROS interfaces, for example:

rosservice call /qt_robot/speech/say "message: 'Hello.'"

If successful, QTrobot will say "Hello."

Troubleshooting​

If you experience issues such as delayed responses when calling rosservice from your laptop while connected to QTrobot's hotspot (Offline Mode), follow these steps:

  • Add the following line to the /etc/hosts file on your laptop:

    192.168.4.1  <your QTrobot serial>  # e.g. QTRD000100.local

If you encounter delays when calling rosservice while QTrobot is connected to an external Wi-Fi network (Online mode), follow these steps:

  • First, find the QTrobot's IP address by connecting to QTPC and running:

    ifconfig wlan0

  • Then, add the QTrobot's IP address to the /etc/hosts file on your laptop:

    192.168.3.193  <your QTrobot serial>  # e.g. QTRD000100.local

If you face issues such as errors communicating with services or reading topics running on QTPC (e.g., "ERROR: Unable to communicate with service..."), follow these steps:

  • Find your laptop’s Wi-Fi interface name by running:

    ifconfig -a  # e.g., wlan0

  • Add the following route on your laptop to communicate with the services:

    sudo ip route add 192.168.100.0/24 via <your QTrobot IP> dev <Wi-Fi interface name>
    # e.g., sudo ip route add 192.168.100.0/24 via 192.168.3.193 dev wlan0
All done 😉

Congratulations! You are all set and ready to start programming with QTrobot. Now you can follow plenty of exciting tutorials.

Footnotes​

  1. Only use the provided power supply with your QTrobot. ↩