Where is the actual URDF the Create3 is using to broadcast tf2 transforms?

[slowrunner]

How are you connecting to your Create 3?

Wi-Fi (ROS 2)

Computer(s) Model(s) and Operating System(s)

No response

Which version of ROS 2 is installed on your computer?

Humble

Which firmware version is installed on your robot?

H.2.3

Which RMW is your robot running?

FastRTPS

Does your robot have an assigned namespace? If so, please share.

No response

Is the robot connected to a network? If so, what is the network type?

Yes: 2.4GHz Home WiFi

Are there multiple Create 3 robots connected to your network?

No

Is multicast enabled?

Yes

What is the Adapter Board's USB/BLE Toggle currently switched to?

Bluetooth (default)

Describe your question.

Where is the URDF the Create3 is actually using to broadcast tf2 transforms?

For the right_wheel, the Create3 broadcasts:

$ ros2 run tf2_ros tf2_echo base_link right_wheel

At time 0.0
- Translation: [0.000, -0.116, 0.036]
- Rotation: in Quaternion [-0.707, 0.000, 0.000, 0.707]
- Rotation: in RPY (radian) [-1.571, 0.000, 0.000]
- Rotation: in RPY (degree) [-90.000, 0.000, 0.000]
- Matrix:
  1.000 -0.000  0.000  0.000
  0.000 -0.000  1.000 -0.116
 -0.000 -1.000 -0.000  0.036
  0.000  0.000  0.000  1.000

Which would be 232mm or 233 if the full precision value is 0.1615. This would seem to match the URDF of create3_sim (distance_between_wheels = 23.3*cm2m divided by 2), and the roughly 233-234mm measurement of my Create3, but not the Create3 docs mechanical drawing which states 235.0 mm.

! BUT the Create3 is also broadcasting the base_link to ir_intensity_right sensor as:

$ ros2 run tf2_ros tf2_echo base_link ir_intensity_right
At time 0.0
- Translation: [0.081, -0.155, 0.052]
- Rotation: in Quaternion [0.000, 0.000, -0.519, 0.855]
- Rotation: in RPY (radian) [0.000, 0.000, -1.092]
- Rotation: in RPY (degree) [0.000, 0.000, -62.567]  <<---
- Matrix:
  0.461  0.888  0.000  0.081
 -0.888  0.461 -0.000 -0.155
 -0.000  0.000  1.000  0.052
  0.000  0.000  0.000  1.000

which I believe says the "ir_intensity_right" sensor is pointed -62.6 degrees CW from the Create3 heading

This value does not match either the mechanical drawing value of -65.3 degrees, nor the create3_sim URDF value of -75 degrees (rpy=[0 0 -1.309] radians).

I understand the create3_sim URDF might have been simplified or perhaps pre-dated the physical robot, but it is the only URDF I have found.

As a related but not critical that I understand:

The turtlebot4 URDF references

  <xacro:include filename="$(find irobot_create_description)/urdf/create3.urdf.xacro" />

but I don't know how to see the path it is using to resolve that include and I don't have a Turtlebot4 to test that further. (I own a Create3 with no intention of turning it into a Turtlebot4lite, just like to understand everything...)

I did sudo apt install irobot-create-* and see that something installed:

/opt/ros/humble/share/irobot_create_description/urdf/create3.urdf.xacro

(not sure which package installed it), which seems to match the create3_sim URDF but not what my Create3 is broadcasting.

Additionally - front_center_left tf2 transform is broadcast as 2.636 degrees CCW from robot heading

$ ros2 run tf2_ros tf2_echo base_link ir_intensity_front_center_left

At time 0.0
- Translation: [0.175, 0.008, 0.052]
- Rotation: in Quaternion [0.000, 0.000, 0.023, 1.000]
- Rotation: in RPY (radian) [0.000, -0.000, 0.046]
- Rotation: in RPY (degree) [0.000, -0.000, 2.636]
- Matrix:
  0.999 -0.046  0.000  0.175
  0.046  0.999  0.000  0.008
  0.000  0.000  1.000  0.052
  0.000  0.000  0.000  1.000

UPDATE all sensors summary:

• IR Intensity Sensor Orientation Angle (yaw from forward 0 deg)

   Sensor              tf2      |Mech Drawing|   URDF
- side_left:           57.3 deg |  65.3  deg |  75.0 deg
- left:                36.0 deg |  38.0  deg |  50.0 deg
- front_left:          19.1 deg |  20.0  deg |  25.0 deg 
- front_center_left:    2.6 deg |   3.0  deg |   0.0 deg (defaulted)
- front_center_right: -13.8 deg | -14.25 deg | -25.0 deg 
- front_right:        -32.3 deg | -34.0  deg | -50.0 deg
_ right:              -62.6 deg | -65.3  deg | -75.0 deg


$ ros2 run tf2_ros tf2_echo base_link ir_intensity_side_left


- Translation: [0.095, 0.147, 0.052]
- Rotation: in Quaternion [0.000, 0.000, 0.479, 0.878]
- Rotation: in RPY (radian) [0.000, -0.000, 1.000]
- Rotation: in RPY (degree) [0.000, -0.000, 57.296]

$ ros2 run tf2_ros tf2_echo base_link ir_intensity_left

- Translation: [0.141, 0.103, 0.052]
- Rotation: in Quaternion [0.000, 0.000, 0.309, 0.951]
- Rotation: in RPY (radian) [0.000, -0.000, 0.629]
- Rotation: in RPY (degree) [0.000, -0.000, 36.039]

$ ros2 run tf2_ros tf2_echo base_link ir_intensity_front_left

- Translation: [0.165, 0.057, 0.052]
- Rotation: in Quaternion [0.000, 0.000, 0.166, 0.986]
- Rotation: in RPY (radian) [0.000, -0.000, 0.333]
- Rotation: in RPY (degree) [0.000, -0.000, 19.079]


$ ros2 run tf2_ros tf2_echo base_link ir_intensity_front_center_left

- Translation: [0.175, 0.008, 0.052]
- Rotation: in Quaternion [0.000, 0.000, 0.023, 1.000]
- Rotation: in RPY (radian) [0.000, -0.000, 0.046]
- Rotation: in RPY (degree) [0.000, -0.000, 2.636]


$ ros2 run tf2_ros tf2_echo base_link ir_intensity_front_center_right

- Translation: [0.170, -0.042, 0.052]
- Rotation: in Quaternion [0.000, 0.000, -0.120, 0.993]
- Rotation: in RPY (radian) [0.000, 0.000, -0.240]
- Rotation: in RPY (degree) [0.000, 0.000, -13.751]


$ ros2 run tf2_ros tf2_echo base_link ir_intensity_front_right

- Translation: [0.148, -0.094, 0.052]
- Rotation: in Quaternion [0.000, 0.000, -0.278, 0.961]
- Rotation: in RPY (radian) [0.000, 0.000, -0.564]
- Rotation: in RPY (degree) [0.000, 0.000, -32.315]


$ ros2 run tf2_ros tf2_echo base_link ir_intensity_right

- Translation: [0.081, -0.155, 0.052]
- Rotation: in Quaternion [0.000, 0.000, -0.519, 0.855]
- Rotation: in RPY (radian) [0.000, 0.000, -1.092]
- Rotation: in RPY (degree) [0.000, 0.000, -62.567]

[slowrunner]

Opened issue to resolve published transforms, mechanical drawing, and create3_robot_descrription

#561 (comment)