OCT

Note

This page is under active development.

This package homes the details for the OCT system. This package simulates an OCT imaging system of a blood vessel by using two lidar sensors.

Package Structure

• oct_description

  • config

    contains the rviz config file.

  • launch

    contains the launch file to start the robot_state_publisher for the OCT system.

  • meshes

    contains the mesh files required for the OCT packages.

  • urdf

    contains the URDF files for the OCT system.

• oct_gazebo

  • config

    contains the the rviz config file.

  • launch

    contains the launch file to start gazebo and rviz, adding the oct system.

  • worlds

    contains the world files for gazebo.

• oct_plugin

  contains the gazebo plugin files for OCT sensor

Running the OCT

1. Build the packages colcon build

2. source install/setup.bash

3. Launch rviz and gazebo with the suture tool ros2 launch oct_gazebo oct.launch.xml

4. In rviz, change the fixed frame from world to oct_link

You should see the sensor output in rviz. The vessel in gazebo represents the blood vessel. Each lidar sensor responds to a different part of the vessel - one lidar responds to the smaller cylinder only, while the other response to the larger cylinder only. The size of the “vessel” is large simply for demonstration purposes. This is accomplished by using the visibility_mask available on lidar sensors in conjunction with the visibility_flags available on sdf models with visual elements. Lidar sensors derive from camera sensors and therefore have a visbility_maks even though it is not mentioned in the documentation. The visibility_mask will be bit-wise AND with each visual element’s visibility_flags. If the AND returns nonzero, then the visual is visible to the lidar sensor. For this project, the visibility_flags are set for tissue visual here and nitinol visual here. The visibility_masks are set for tissue lidar sensor here and nitinol lidar sensor here.

NOTE: it is currently not known how close in proximity the camera and sensor can be. This would be helpful to ascertain so as to determine if this method is suitable long-term for simulating the nitinol/tissue proximity to the OCT sensor.

The below shows an example output.

NOTE: the OCT in gazebo is very small, so you’ll need to zoom in above the “vessel” cylinders to see it.

If the “vessel” is moved along its z-axis in Gazebo, there will be either a set of red or blue laser scans in rviz below the OCT sensor (or both if its centered under the OCT sensor since the cylinders composing the “vessel” overlap some at the middle of the vessel). The laser scans in rviz are rendered from the data streamed on the oct_tissue and oct_nitinol ROS topics.

After: ros2 launch oct_gazebo oct.launch.xml

gazebo (showing simulates blood vessel)	rviz