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Connecting different computers via Rosbridge

asked 2016-12-29 23:34:42 -0600

Werewolf_86 gravatar image

Hi,

I was trying to control turtlesim running on my ros computer via another non ros computer. I used the following html file in my non ros computer:

<!DOCTYPE html>
<html>
<head>
<!-- Based on demo found here:
http://wiki.ros.org/roslibjs/Tutorials/BasicRosFunctionality
http://wiki.ros.org/roslibjs/Tutorials/BasicRosFunctionality
-->

<!--
The next two lines bring in the JavaScript files that support rosbridge integration.
-->
<script type="text/javascript" src="http://cdn.robotwebtools.org/EventEmitter2/current/eventemitter2.min.js"></script>

<script type="text/javascript" src="http://cdn.robotwebtools.org/roslibjs/current/roslib.min.js"></script>

<script type="text/javascript" type="text/javascript">

// This function connects to the rosbridge server running on the local computer on port 9090
var rbServer = new ROSLIB.Ros({
    url : 'ws://localhost:9090'
 });

 // This function is called upon the rosbridge connection event
 rbServer.on('connection', function() {
     // Write appropriate message to #feedback div when successfully connected to rosbridge
     var fbDiv = document.getElementById('feedback');
     fbDiv.innerHTML += "<p>Connected to websocket server.</p>";
 });

// This function is called when there is an error attempting to connect to rosbridge
rbServer.on('error', function(error) {
    // Write appropriate message to #feedback div upon error when attempting to connect to rosbridge
    var fbDiv = document.getElementById('feedback');
    fbDiv.innerHTML += "<p>Error connecting to websocket server.</p>";
});

// This function is called when the connection to rosbridge is closed
rbServer.on('close', function() {
    // Write appropriate message to #feedback div upon closing connection to rosbridge
    var fbDiv = document.getElementById('feedback');
    fbDiv.innerHTML += "<p>Connection to websocket server closed.</p>";
 });

// These lines create a topic object as defined by roslibjs
var cmdVelTopic = new ROSLIB.Topic({
    ros : rbServer,
    name : '/turtle1/cmd_vel',
    messageType : 'geometry_msgs/Twist'
});

// These lines create a message that conforms to the structure of the Twist defined in our ROS installation
// It initalizes all properties to zero. They will be set to appropriate values before we publish this message.
var twist = new ROSLIB.Message({
    linear : {
        x : 0.0,
        y : 0.0,
        z : 0.0
    },
    angular : {
        x : 0.0,
        y : 0.0,
        z : 0.0
    }
});

/* This function:
 - retrieves numeric values from the text boxes
 - assigns these values to the appropriate values in the twist message
 - publishes the message to the cmd_vel topic.
 */
function pubMessage() {
    /**
    Set the appropriate values on the twist message object according to values in text boxes
    It seems that turtlesim only uses the x property of the linear object 
    and the z property of the angular object
    **/
    var linearX = 0.0;
    var angularZ = 0.0;

    // get values from text input fields. Note for simplicity we are not validating.
    linearX = 0 + Number(document.getElementById('linearXText').value);
    angularZ = 0 + Number(document.getElementById('angularZText').value);

    // Set the appropriate values on the message object
    twist.linear.x = linearX;
    twist.angular.z = angularZ;

    // Publish the message 
    cmdVelTopic.publish(twist);
}
</script>
</head>

<body>
<form name="ctrlPanel">
<p>Enter positive or negative numeric decimal values in the boxes below</p>
<table>
 <tr><td>Linear X</td><td><input id="linearXText" name="linearXText" type="text" value="1.5"/></td></tr>
 <tr><td>Angular Z</td><td><input ...
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answered 2016-12-30 00:46:33 -0600

Werewolf_86 gravatar image

Hi all,

I found the solution by myself. The IP address to be specified is that of the ros machine, and not the non ros one. So, i simply put the ip address in this line:

url : 'ws://192.168.0.100:9090'

And i could control theturtlesim from non ros computer.

Thanks !

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Asked: 2016-12-29 23:34:42 -0600

Seen: 977 times

Last updated: Dec 30 '16