設置消息信息

ROS 消息是結(jié)構。可以直接復制它們以生成新的消息。副本和原始消息都有自己的數(shù)據(jù)。創(chuàng)建一條類型為geometry_msgs/Twist的消息。

twist = rosmessage("geometry_msgs/Twist","DataFormat","struct")

twist = struct with fields:
MessageType: ‘geometry_msgs/Twist’
Linear: [1x1 struct]
Angular: [1x1 struct]

缺省情況下，此消息的數(shù)字字段初始化為0。您可以修改此消息的任何屬性。例如Y等于5。

twist.Linear.Y = 5;

查看消息數(shù)據(jù)以確保您的更改生效

twist.Linear

ans = struct with fields:
MessageType: ‘geometry_msgs/Vector3’
X: 0
Y: 5
Z: 0

一旦用您的數(shù)據(jù)填充了消息，您就可以將其用于發(fā)布者、訂閱者和服務。

參見“與ROS發(fā)布者和訂閱者交換數(shù)據(jù)”和“調(diào)用和提供ROS服務”示例。然后就可以通過publish發(fā)布我們設置的消息信息了

thermometerNode = ros2node("/thermometer");
tempPub = ros2publisher(thermometerNode,"/twist","sensor_msgs/geometry_msgs/Twist");
tempMsgs(10) = twist;    % Pre-allocate message structure array
for iMeasure = 1:10
    % Copy blank message fields
    tempMsgs(iMeasure) = twist;


    % Record sample message
    tempMsgs(iMeasure).Linear.Y = 20+randn*3;


    % Only calculate the variation once sufficient data observed
    if iMeasure >= 5
        tempMsgs(iMeasure).Linear.X= var([tempMsgs(1:iMeasure).Linear.Y]);
    end


    % Pass the data to subscribers
    send(tempPub,tempMsgs(iMeasure))
end
errorbar([tempMsgs.Linear.Y],[tempMsgs.Linear.X])