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sendFeedback

Send feedback to action client during goal execution

Since R2022a

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Syntax

sendFeedback(server,feedbackMsg)

Description

sendFeedback(server,feedbackMsg) sends the feedback message, feedbackMsg, to the action client that sent the goal currently being executed by the action server, server.

example

Examples

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Open Live Script

This example shows how to create a ROS action server, connect an action client to it, receive goal, and execute it.

Connect to a ROS network. 

rosinit
Launching ROS Core...
..Done in 2.1278 seconds.
Initializing ROS master on http://172.19.136.75:52554.
Initializing global node /matlab_global_node_56708 with NodeURI http://vdi-wd1bgl-223:61999/ and MasterURI http://localhost:52554.

Set up an action server for calculating Fibonacci sequence. Use structures for the ROS message data format. Use fibbonacciExecution function as the callback.

cb = @fibonacciExecution; 
server = rosactionserver("/fibonacci","actionlib_tutorials/Fibonacci",ExecuteGoalFcn=cb,DataFormat="struct")
server = 
  SimpleActionServer with properties:

        ActionName: '/fibonacci'
        ActionType: 'actionlib_tutorials/Fibonacci'
    ExecuteGoalFcn: @fibonacciExecution
        DataFormat: 'struct'

Create action client and send a goal to the server to calculate the Fibonacci sequence up to 10 terms past the first two terms, 0 and 1. Display the result sequence.

client = rosactionclient("/fibonacci","actionlib_tutorials/Fibonacci",DataFormat="struct");
goal = rosmessage(client);
goal.Order = int32(10);
result = sendGoalAndWait(client,goal);
result.Sequence
ans = 12×1 int32 column vector

    0
    1
    1
    2
    3
    5
    8
   13
   21
   34
      ⋮

Shut down ROS network.

rosshutdown;
Shutting down global node /matlab_global_node_56708 with NodeURI http://vdi-wd1bgl-223:61999/ and MasterURI http://localhost:52554.
Shutting down ROS master on http://172.19.136.75:52554.

Warning: Error shutting down the ROS master.

Supporting Functions

The callback function fibbonacciExecution is executed every time the server receives a goal execution request from the client. This function checks if the goal has been preempted, executes the goal and sends feedback to the client during goal execution.

function [result,success] = fibonacciExecution(src,goal,defaultFeedback,defaultResult)

    % Initialize variables
    success = true;
    result = defaultResult;
    feedback = defaultFeedback;
    feedback.Sequence = int32([0 1]);

    for k = 1:goal.Order
        % Check that the client has not canceled or sent a new goal
        if isPreemptRequested(src)
            success = false;
            break
        end

        % Send feedback to the client periodically
        feedback.Sequence(end+1) = feedback.Sequence(end-1) + feedback.Sequence(end);
        sendFeedback(src,feedback)
        
        % Pause to allow time to complete other callbacks (like client feedback)
        pause(0.2)
    end

    if success
        result.Sequence = feedback.Sequence;
    end

end

Input Arguments

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ROS action server, specified as a SimpleActionServer object handle.

Feedback message for action client, specified as a ROS message. The type and format of the feedbackMsg must match the ActionType and DataFormat properties of server, respectively.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2022a

See Also

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