ROS2, MATLAB, GAZEBO.

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Robson Cardoso 2024-4-15

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https://ww2.mathworks.cn/matlabcentral/answers/2107201-ros2-matlab-gazebo

回答： Sanchari 2024-7-11，7:07

I’m using ros2/Matlab and need the tranformations in a chart. How could I do that.

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Robson Cardoso 2024-4-15

on a chart in Matlab

Jaswanth 2024-6-12

Can you explain the specific workflow/use case you are looking to implement?

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Answer 1

Sanchari 2024-7-11，7:07

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https://ww2.mathworks.cn/matlabcentral/answers/2107201-ros2-matlab-gazebo#answer_1484193

在 MATLAB Online 中打开

Hello Robson,

I'm assuming that the need is to visualize transformations in a chart using ROS 2 and MATLAB. Below is a overview of the steps to be taken:

Set Up ROS 2 in MATLAB: Ensure that the necessary ROS 2 setup is present in MATLAB.
Subscribe to TF Messages: Subscribe to the transformation messages (usually "/tf" or "/tf_static" topics) to receive transformation data.
Extract Transformation Data: Extract the transformation data from the received messages.
Plot the Transformations: Use MATLAB plotting functions to visualize the transformations in a chart.

Below is a detailed step-by-step guide and example code to achieve this:

Step 1. Set Up ROS 2 in MATLAB: Make sure that the ROS Toolbox is installed and set up for ROS 2. Please check the setup using below code:

ros2 node list;

Step 2. Create a ROS 2 Node and Subscriber: Create a ROS 2 node and a subscriber for the transformation topic.

% Create a ROS 2 node
node = ros2node("/matlab_node");
% Create a subscriber for the '/tf' topic
tfSub = ros2subscriber(node, '/tf', 'geometry_msgs/TransformStamped', @tfCallback);
% Create a subscriber for the /tf_static topic (if needed)
tfStaticSub = ros2subscriber(node, '/tf_static', 'geometry_msgs/TransformStamped', @tfCallback);

Step 3. Callback Function to Handle Transform Messages: Define a callback function to handle the transformation messages and store the data.

% Initialize a global variable to store transformations
global tfData;
tfData = [];
% Callback function to handle /tf messages
function tfCallback(~, msg)
global tfData;
% Extract the transformation data
tf = msg.transforms;
for i = 1:length(tf)
    % Extract translation
    trans = tf(i).transform.translation;
    x = trans.x;
    y = trans.y;
    z = trans.z;
    
    % Extract rotation (quaternion)
    rot = tf(i).transform.rotation;
    qx = rot.x;
    qy = rot.y;
    qz = rot.z;
    qw = rot.w;
    
    % Store the transformation data
    tfData = [tfData; x, y, z, qx, qy, qz, qw];
end
end

Step 4. Plot the Transformations: Use MATLAB plotting functions to visualize the transformations.

% Plot the transformations
figure;
hold on;
grid on;
xlabel('X');
ylabel('Y');
zlabel('Z');
title('Transformations');
% Plot in a loop to continuously update the chart
while true
    global tfData;
    
    if ~isempty(tfData)
        % Extract translation data
        x = tfData(:, 1);
        y = tfData(:, 2);
        z = tfData(:, 3);
        
        % Plot the translation data
        scatter3(x, y, z, 'filled');
        
        % Clear the data to avoid re-plotting
        tfData = [];
    end
    
    drawnow;
    pause(0.1); % Adjust the pause duration as needed
end

By following these steps, you can subscribe to transformation messages in ROS 2, extract the transformation data, and visualize it in a chart using MATLAB.

Please refer the following links for more details on: