Waiting for robot_description to be published on robot_description topic

[Leesanhang]

Hi there, I am currently doing my project on ROS2. Here are some of the hardware I am using:
Mecanum base, esp32-WROOM-32 microcontroller, Cytron MDD10A (Generic 1) motor drivers, A2M8 RPLidar, and a raspberry Pi 4B as the main computer.

I have followed the steps in this page exactly up until the "test_acc" part. One small issue that I did encounter was "test_sensors" part. The values are not changing even when I tilt my robot and so on. (But i guess its fine since the Gyro isn't that important for my project).

The main issue that I've been facing for the past 2 weeks was this:
when I run:
ros2 launch linorobot2_bringup bringup.launch.py
or
ros2 launch linorobot2_bringup bringup.launch.py base_serial_port:=/dev/ttyUSB0 lidar_serial_port:=/dev/ttyUSB1 micro_ros_baudrate:=921600

it gives me this in the terminal:

it just waits infinitely for the robot_description to be published on the robot_description topic.

If it helps, this is my urdf file for my robot:

<?xml version="1.0"?>
<robot xmlns:xacro="http://ros.org/wiki/xacro">
  <xacro:property name="base_length" value="0.49" />
  <xacro:property name="base_width" value="0.39" />
  <xacro:property name="base_height" value="0.06" />
  
  <xacro:property name="wheel_radius" value="0.0723" />
  <xacro:property name="wheel_width" value="0.05" />

  <xacro:property name="laser_pose">
    <origin xyz="-0.0475 0 0.125" rpy="0 0 0"/>
  </xacro:property>
  
  <material name="grey">
        <color rgba="0.5 0.5 0.5 1" />
    </material>

    <material name="blue">
        <color rgba="0 0 0.5 1" />
    </material>
    
    <material name="pink">
        <color rgba="1 0.75 0.8 1" />
    </material>
    
    <!-- base_footprint (projection of base_link on the ground) -->

    <link name="base_footprint"/>
    
    <joint name="base_joint" type="fixed">
        <parent link="base_footprint"/>
        <child link="base_link"/>
        <origin xyz="0 0 0.2" rpy="0 0 0"/>
    </joint>
    
    <!-- base_link and base_scan (required for Nav2) -->

    <link name="base_link">
        <visual>
            <geometry>
                <box size="${base_length} ${base_width} ${base_height}" />
            </geometry>
            <origin xyz="0 0 0" rpy="0 0 0" />
            <material name="blue" />
        </visual>
    </link>
    
    <joint name="base_scan_joint" type="fixed">
        <parent link="base_link"/>
        <child link="base_scan"/>
        <origin xyz="0 0 0.06" rpy="0 0 0"/>
    </joint>
    
    <link name="base_scan">
        <visual>
            <geometry>
                <cylinder radius="0.0375" length="0.04"/>
            </geometry>
            <origin xyz="0 0 0.04" rpy="0 0 0" />
            <material name="pink" />
        </visual>
    </link>
    
    <!-- Wheels (4 mecanum wheels) -->
    
    <joint name="base_left_back_wheel_joint" type="continuous">
        <parent link="base_link"/>
        <child link="left_back_wheel"/>
        <origin xyz="-0.22 0.225 -0.01" rpy="0 0 0"/>
        <axis xyz="0 1 0"/>
    </joint>

    <link name="left_back_wheel">
        <visual>
            <geometry>
                <cylinder radius="${wheel_radius}" length="${wheel_width}"/>
            </geometry>
            <origin xyz="0 0 0" rpy="1.57 0 0" />
            <material name="grey" />
        </visual>
    </link>
    
    <joint name="base_right_back_wheel_joint" type="continuous">
        <parent link="base_link"/>
        <child link="right_back_wheel"/>
        <origin xyz="-0.22 -0.225 -0.01" rpy="0 0 0"/>
        <axis xyz="0 1 0"/>
    </joint>

    <link name="right_back_wheel">
        <visual>
            <geometry>
                <cylinder radius="0.05" length="0.0723"/>
            </geometry>
            <origin xyz="0 0 0" rpy="1.57 0 0" />
            <material name="grey" />
        </visual>
    </link>
    
    <joint name="base_left_front_wheel_joint" type="continuous">
        <parent link="base_link"/>
        <child link="left_front_wheel"/>
        <origin xyz="0.22 0.225 -0.01" rpy="0 0 0"/>
        <axis xyz="0 1 0"/>
    </joint>

    <link name="left_front_wheel">
        <visual>
            <geometry>
                <cylinder radius="0.05" length="0.0723"/>
            </geometry>
            <origin xyz="0 0 0" rpy="1.57 0 0" />
            <material name="grey" />
        </visual>
    </link>
    
    <joint name="base_right_front_wheel_joint" type="continuous">
        <parent link="base_link"/>
        <child link="right_front_wheel"/>
        <origin xyz="0.22 -0.225 -0.01" rpy="0 0 0"/>
        <axis xyz="0 1 0"/>
    </joint>

    <link name="right_front_wheel">
        <visual>
            <geometry>
                <cylinder radius="0.05" length="0.0723"/>
            </geometry>
            <origin xyz="0 0 0" rpy="1.57 0 0" />
            <material name="grey" />
        </visual>
    </link>
    
    
</robot>

Any help to solve this issue is much appreciated, Thank youu!

[Leesanhang]

Update: When I run:
ros2 launch linorobot2_bringup bringup.launch.py base_serial_port:=/dev/ttyUSB0 lidar_serial_port:=/dev/ttyUSB1 micro_ros_baudrate:=921600
command, only /parameter_events and /rosout topics show up when I run ros2 topic list.

I also did try to unplug and plug my esp32, and it only publishes up until "running" instead of "logger setup".

[hippo5329]

1. Both esp32 and lidar use the same device names as /dev/ttyUSBx, 0 or 1. It is very easy to mixed up. Disconnect the lidar first. Only the esp32 is connected.
2. Please run the micro-ROS agent connection test. https://github.com/hippo5329/linorobot2_hardware/wiki#esp32-with-micro-ros-serial-transport
3. imu is not enabled by default in esp32_config.h. Which imu do you use? You will need to uncomment the line, eg, #define USE_MPU6050_IMU. You should see the i2cdetect. https://github.com/hippo5329/linorobot2_hardware/wiki#i2cdetect-debug-message . And the imu reading in test_sensors should change as you move. You should also see the /imu/data topic changing in step 2.
4. gyro is important. Ekf filter will fuse the wheel odometry and yaw from imu.
5. You should install the linorobot2 with "a2", which is for rplidar a2. eg. bash install_linorobot2.bash 2wd a2
6. You will need the by-path names to specify which serial port is esp32 and lidar. https://github.com/hippo5329/linorobot2_hardware/wiki#esp32-with-serial-transport-and-ld19-lidar
7. In the bring up messages, you should see many messages from "micro ros agent", "joint state publisher", "robot state publisher" and rplidar. In your photo, the micro-ros agent is not connected yet and the lidar did not start.

[hippo5329]

https://github.com/hippo5329/linorobot2_hardware/wiki#esp32-with-serial-transport-and-lidar-on-the-robot-computer

[hippo5329]

I added more details on micro-ros agent connection test and bringup launch. Please check the wiki.

[Leesanhang]

Hi again, I am quite new to ROS so there are quite a few things that I am still unfamiliar with. For the past day, I have been trying to do step 2 and this is the output I am getting.

The open device errors are due to me unplugging the esp and plugging it back in.

I didn't face this problem before I started the changes at https://github.com/hippo5329/linorobot2_hardware/wiki#custom-configuration-file---recommended
If it helps, after running
pio run -e esp32 -t upload
The blue LED on the esp blinks 3 times.

I am quite unsure on how to proceed now.

[hippo5329]

No worries. I am new to ROS2 and I keep learning, too.
Please follow my suggested work flow. In another directory, clone my fork again. Follow this,
https://github.com/hippo5329/linorobot2_hardware/wiki#install-firmware-source
Do not change the source. Build, upload and test connection.
https://github.com/hippo5329/linorobot2_hardware/wiki#esp32-with-micro-ros-serial-transport

[hippo5329]

The access mode of ttyUSB0 might be wrong. You might miss the step,

Install PlatformIO udev rules.

curl -fsSL https://raw.githubusercontent.com/platformio/platformio-core/develop/platformio/assets/system/99-platformio-udev.rules | sudo tee /etc/udev/rules.d/99-platformio-udev.rules
sudo service udev restart
sudo usermod -a -G dialout $USER
sudo usermod -a -G plugdev $USER

Then unplug and plug esp32.

$ ls /dev/ttyU* -l
crw-rw-rw- 1 root dialout 188, 0 May 29 15:22 /dev/ttyUSB0

[Leesanhang]

So, I've tried doing everything from scratch again and I've passed the connection test here: https://github.com/hippo5329/linorobot2_hardware/wiki#esp32-with-micro-ros-serial-transport

And now, I am currently doing step 3 in your earlier comment: https://github.com/hippo5329/linorobot2_hardware/issues/15#issuecomment-2133987557

This is the output I am getting:

(I've tried changing the baudrate because I've encountered similar problems in earlier projects related to Arduino.)

Is there any way I can complete this project without implementing the IMU?

Edit: I tried to skip to https://github.com/hippo5329/linorobot2_hardware/wiki#test-the-motors-and-encoders and the same thing is happening. Random characters are appearing. I actually had no issues with particular part running earlier.

Edit 2: Now that I'm doing the connection test again after doing the steps from https://github.com/hippo5329/linorobot2_hardware/wiki#custom-configuration-file---recommended , the same issue from earlier is happening.

[hippo5329]

Good. Please tell me which IMU you use. And show me the configuration of your IMU. The micro-ROS middle ware is running on the serial. So you will see random chars because the communication is binary, not ascii code. Keep the baud rate at 921600. You will need to press reset button on the esp32 to see the messages right after boot.

[hippo5329]

You should run the test_sensors. There is no micro-ros protocol in test_sensors. Press reset button on the esp32 to see the boot message.

[Leesanhang]

I am using an MPU6050. My IMU is connected to an Arduino 5V and GND for the time being, and the SDA and SCL are connected to pins 21 and 22 of my ESP respectively.

[hippo5329]

Why Arduino? Connect 5V to 5V on esp32 module.

[hippo5329]

Connect 5V of MPU6050 to 5V on esp32. Connect gnd of MPU6050 to gnd on esp32.

[Leesanhang]

Sorry but I dont actually have a 5V pin on my ESP. I am using this dev board: https://i0.wp.com/circuits4you.com/wp-content/uploads/2018/12/ESP32-Pinout.jpg?resize=604%2C373&ssl=1

[hippo5329]

Please check with a multimeter the Vin of esp32. If you see 5-4.5V, then use the Vin. Otherwise use 3.3V output of esp32.