3D Robotics Comment by Chris Anderson on May 28, 2011 at 1:52pm

Ralph, APM doesn't support the regular Arduino Mega 2560 board. It uses the custom APM 2560 board. They're also sold as complete kit.

Comment by I Heart Robotics on May 28, 2011 at 2:56pm

Ralph, don't get discouraged, large chunks of the necessary code are already working and I'd be happy to help answer questions you might have. Though email is easier for me.

 

Most of what needs to be done is figuring out how all the parts fit together and make it work with the APM. There are parts of the larger problem that I am already committed to working on, however I am not available to work on integrating the APM until I can dequeue my to do list.

 

MAVLink is really two separate things

  First it is a lightweight communications and marshaling protocol that can run on a microcontroller.

    This is already running on the APM

    and on the ROS side there is a driver that handles generic messages

      http://www.ros.org/wiki/lcm_mavlink_ros

  Second there is a set of commands that can be sent over the protocol to control the MAV

    This is a matter of getting the APM to act on incoming messages

      This should be at least partially done for qground control integration but there is probably

      more work to be done.

      http://qgroundcontrol.org/mavlink/start

    This also requires that ROS is capable of processing and formatting these messages

      AFAIK, this is where most of the work is. You need to figure out how to get the GPS

      position, and etc, from a generic MAVLink message into a properly formatted ROS message.

Also keep in mind that this is an area of open research and there are quite a few groups working on different parts of the problem. The current version of ROS has some issues with robots that operate in 3D, however it is quickly improving.

 

I suspect the easiest way to work on this type of project is to start with a task you want to use ROS/APM for and work backwards to add the necessary functionality.

Comment by Ralph Castain on May 28, 2011 at 3:19pm

Chris: ouch, that was clear as mud. :-(

3D Robotics Comment by Chris Anderson on May 28, 2011 at 5:16pm

Ralph: I'm confused. Can you tell me what path you took to buying the board? I can't find any description, including the product listing itself, that doesn't make it crystal clear that you need the APM board.

Comment by Ralph Castain on May 28, 2011 at 6:40pm

On the DIYDrone store, I followed the Arduino link because the docs all say things are based on Arduino, you need the Arduino IDE, etc. That link takes you to the Arduino Mega 2560 card - nice blue card, matching the color in the picture of the controller on the newbie's page. Of course, it turns out that the picture is showing the blue IMU card, hiding the *red* controller card, but that only became clear after the fact.

So basically I wound up confused because of the emphasis on using Arduino IDE + Arduino hardware, the "Ardu" in APM, etc. - and not realizing that APM doesn't use the Arduino hardware after all. I also found some linkage on the Arduino site, where they mention your name and that there is a connection to APM - hence furthering the notion that somehow Arduino hardware and APM are related.

As a newbie to DIYDrones, it would have helped if the newbie docs and the site overall made it clear that there is a distinction between the Arduino *Pilot* Mega 2560 board and the Arduino Mega 2560 board of the nearly identical name. My impression was that the only difference is that one came with the APM software, and the other didn't....

Comment by Ellison Chan on September 16, 2011 at 8:42am

Correct me if I'm wrong, but currently there is no ground station software that runs in Linux. So, before any ROS integration is going to be useful, I think we will need a Ground Station software that runs in Linux.  Otherwise we'll need a Windows PC to run a ground station, another one to run Linux/ROS.

3D Robotics Comment by Chris Anderson on September 16, 2011 at 8:44am

Ellison, I'm afraid you're mistaken. QGroundControl is native Linux.

Comment by Ellison Chan on September 16, 2011 at 8:53am

Thanks Chris.  I'll try it out.  This helps a lot.  Now, I don't have to keep rebooting my PC.  I'm learning ROS myself, right now, so might use the my APM as the first try at making a first node.

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