odestcj's profile - activity

I understand. Thanks for your kind explanation. That said, I think ros-users was better for facilitating this type of discussion at the cost of search-ability and larger email inbox.

Procópio, your comment seems overly strict and pedantic. I appreciated Felix's follow up questions and learned something from it. If we cannot have discussions and follow up on answers.ros.org, maybe such discussions should move back to ros-users.

Regarding rosbridge, is your concern about ASCII parsing due to performance or implementation?

I would think there are a number of existing libraries for JSON parsing. A quick google search yielded a few options:

• http://www.mathworks.com/matlabcentral/fileexchange/20565
• http://www.cs.sunysb.edu/~kyamagu/software/json/

Regarding performance, it is obvious that a binary version of rosbridge would bring a big improvement. We have not done this in order to keep the protocol open and separate from a specific implementation. However, contributions to better support binary and compressed data in rosbridge would be very welcome.

I cannot say for sure why you are getting an error. I can say that this command worked for me:

con.publish('/cmd_vel', {"linear":{"x":1.0,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}});

in the context of this tutorial:

http://www.rosbridge.org/doku.php?id=tutorials:ardrone&s[]=drone

Thanks for working through this issue. A clarification is in order: it is highly recommended to use rosbridge v2 for the current distribution of ROS. rosbridge v1 is the best option for diamondback and electric, v2 for fuerte, groovy, ...

Nice! This is great to see. I will have to give this a try soon.

I assume a page can display 4 different image streams by including 4 img tags to the appropriate topics, which might look something like: "img src="http://localhost:8080/stream?topic=/robot/cameraN">"

I have not tried this yet for 4 image streams, but it should be easy to test.

rosbridge could be used for this purpose:

http://www.youtube.com/watch?v=L-4TuNBiIRc

although multimaster maybe a better option for a ROS-to-ROS connection.

Jon Mace and I had several discussions about whether to include raw sockets along with websockets for v2. Jon had convincing arguments to just stick with websockets for now:

1. rosbridge v1 tried to detect when an incoming connection was a raw socket or a websocket, causing additional (unnecessary) complexity for the server. The v2 design assumes a rosbridge port can be open with either form of socket, but not both.
2. rosbridge_library (in v2) can be wrapped to use a raw socket. The default v2 server essentially wraps around this library
3. Jon posited that creating a raw socket version of rosbridge v2 would be "trivial". We would welcome addition of a raw socket version of the v2 server to the stack

Although this response is a bit late, I hope it is helpful.

I am not yet familiar with "ros_bundle.min.js". However, I can answer this issue using "ros.js", found under "rosbridge_clients" in the release version of rosbridge_suite. Using this ros.js, I used the following example page to control both turtlebots and AR.Drones:

https://dl.dropbox.com/u/14391589/tutorial/rosbridge_ardrone/drone_browser_teleop.html

In this case, the connection is created as follows:

var con = new Bridge("ws://localhost:9090");

Addressing point 1, publishing command velocity for moving forward is done as follows:

con.publish('/cmd_vel', {"linear":{"x":1.0,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}});

In Chrome, you should be able to inspect the actual websocket frame that is sent using the development tools (regardless of which ros.js you are using). I found this description of inspecting websocket traffic useful:

http://blog.kaazing.com/2012/05/09/inspecting-websocket-traffic-with-chrome-developer-tools/

I haven't tried subscribing to pose yet, so I will pass on speculating about the second issue.

The maintainers of irobot_create_2_1 are no longer actively updating this package. I would recommend looking at the turtlebot_driver in the turtlebot stack for interfacing with the Create. If there is larger interest in using irobot_create_2_1, I can take a look at addressing this issue over the next few weeks.

ardrone_brown is now deprecated. I have been using the ardrone_autonomy fork, and it seems to work well.

I also recommend using mjpeg_server to view images through browsers.

I would recommend looking at Russell Toris' nav2Djs as an example:

https://github.com/RobotWebTools/nav2djs

Also, rosbridge_suite is temporarily moving to github under robotwebtools. Please feel free to post issues and pull requests.