How px4 firmware connects to the gazebo in code level?

zyq1993 · December 1, 2016, 1:08pm

I would like to know how the px4 firmware connects to the gazebo simulation in code level. Now I can fly the iris in gazebo through PX4Devguide.
But I would like to know which files the connection process is occurring and the principles of communications between px4 firmware and gazebo. Why drone in gazebo can move?
I have lost in the PX4 firmware code and I haven’t find any relevant information.
can someone help me? Thanks a lot.

dagar · December 1, 2016, 8:32pm

I’m not familiar with this code, but I believe it’s entirely through mavlink.

github.com

PX4/sitl_gazebo/blob/f6a067a4bc75e1dd8b871cd78197f38dea28ea3b/src/gazebo_mavlink_interface.cpp

/*
 * Copyright 2015 Fadri Furrer, ASL, ETH Zurich, Switzerland
 * Copyright 2015 Michael Burri, ASL, ETH Zurich, Switzerland
 * Copyright 2015 Mina Kamel, ASL, ETH Zurich, Switzerland
 * Copyright 2015 Janosch Nikolic, ASL, ETH Zurich, Switzerland
 * Copyright 2015 Markus Achtelik, ASL, ETH Zurich, Switzerland
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0

 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

This file has been truncated. show original

MAVLINK_MSG_ID_HIL_GPS
MAVLINK_MSG_ID_HIL_SENSOR
MAVLINK_MSG_ID_DISTANCE_SENSOR
MAVLINK_MSG_ID_HIL_OPTICAL_FLOW
MAVLINK_MSG_ID_HIL_ACTUATOR_CONTROLS

http://mavlink.org/messages/common

zyq1993 · December 5, 2016, 8:01am

@dagar
The gazebo_mavlink_interface.cpp shows how gazebo receives/sends mavlink messages, but where dose px4 firmware sends/receives mavlink messages from?
When px4 firmware connects a real drone, is the same method to send messages to drone as connectiong to simulation?

dagar · December 5, 2016, 1:35pm

PX4 centralizes mavlink send/receive in the mavlink module here - https://github.com/PX4/Firmware/tree/master/src/modules/mavlink

A bit of an explanation here. http://dev.px4.io/concept-architecture.html

zyq1993 · December 5, 2016, 2:19pm

Oh! You are a very nice person!