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mavlink / mavros

MAVLink to ROS gateway with proxy for Ground Control Station
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Stupid question for the purpose of mavros #261

Closed ymkim92 closed 9 years ago

ymkim92 commented 9 years ago

Hi,

I cannot understand why you use the mavros. Just for using convenient monitoring and control tool of ROS such as rqt and rostopic? Can you share the purposes with me?

vooon commented 9 years ago

Because ROS is great for robotic application development, thats why. In confirmation here is one example: PX4 SITL built as a bunch ROS nodes.

ymkim92 commented 9 years ago

Thanks a lot! I have one more stupid question. If ROS is great for robotic application development, why are PX4 and APM working on MAVLink? I think ground control station such as mission planner and mavproxy is great! Is that all?

vooon commented 9 years ago

Probably because ROS require linux computer, while APM initially uses 16 MIPS AVR8? Also, do not confuse a framework with telemetry protocol.

PX4 uses MAVLink as a telemetry and command protocol, internally they use ORB that similar to ROS topics (thats why they easily use ROS topics in SITL).

ymkim92 commented 9 years ago

I want to use ROS as the framework of my own drone (both H/W and S/W) and MAVLink as telemetry protocol. To do that, can I use mavros? I am working on my own hardware that is a combination of ARM CPU and ATMega 2560. Can you give some hint?

vooon commented 9 years ago

For what purposes you wants atmega? I think better use STM32 or even run AP software on CPU (see erle-brain project).

Mavros node desined to speak with FCU and provide transparent link for GCS software. So in general it not fit if you wants provide ROS-AP <-> MAVLink GCS.

But if unload all standard plugins and replace by yours you could use fcu_url as gcs. Or better use gcs_bridge node for creating link and use to and from topics to send/receive messages. Pro: you may run multiple gcs links Con: additional network io if you want only one, require node for mavlink message processing

Third way: use libmavconn in your mavlink message processing node Pro: no extra net io, no external node Con: number of gcs links limited by your software. Note: current libmavconn has limitation on links count (16) per one process (defined in mavlink c-lib).

ymkim92 commented 9 years ago

In my hardware structure, ATMega takes charge in controlling of IMU, PWM, and GPIO and Arm CPU computes navigation algorithm. But I did not design this structure so I am not sure this is good or not. Thank you very much for your advice.