Example: VTOL Transitions
This example shows how you can use the SDK Action class to transition between VTOL copter and fixed-wing modes (and back).
Running the Example
The example must be run against a VTOL aircraft (simulated or otherwise). Otherwise the example is built and run in the standard way.
Instructions for running the Gazebo simulator for a standard VTOL can be found here: PX4 Development Guide > Gazebo Simulation. jMAVSim does not support VTOL simulation.
The example terminal output for a debug build of the SDK should be similar to that shown below (a release build will omit the "Debug" messages):
$ ./transition_vtol_fixed_wing udp://:14540
Waiting to discover system...
[10:24:42|Info ] New system on: 127.0.0.1:14557 (udp_connection.cpp:210)
[10:24:42|Debug] MAVLink: info: [logger] file: rootfs/fs/microsd/log/2017-11-21/0 (mavlink_system.cpp:286)
[10:24:43|Debug] Discovered 4294967298 (mavlink_system.cpp:483)
Discovered system with UUID: 4294967298
Arming...
Taking off...
[10:24:44|Debug] MAVLink: info: ARMED by arm/disarm component command (mavlink_system.cpp:286)
[10:24:44|Debug] MAVLink: info: Using minimum takeoff altitude: 10.00 m (mavlink_system.cpp:286)
[10:24:44|Debug] MAVLink: info: Takeoff detected (mavlink_system.cpp:286)
[10:24:44|Debug] MAVLink: critical: Using minimum takeoff altitude: 10.00 m (mavlink_system.cpp:286)
Altitude: 0.079 m
Altitude: 0.507 m
...
Altitude: 10.254 m
Transition to fixedwing...
Altitude: 10.263 m
...
Altitude: 20.72 m
Altitude: 24.616 m
Altitude: 22.262 m
Transition back to multicopter...
Altitude: 17.083 m
...
Return to launch...
Altitude: 11.884 m
[10:25:09|Debug] MAVLink: info: RTL: climb to 518 m (29 m above home) (mavlink_system.cpp:286)
Altitude: 13.61 m
...
Altitude: 27.489 m
Altitude: 28.892 m
[10:25:18|Debug] MAVLink: info: RTL: return at 517 m (29 m above home) (mavlink_system.cpp:286)
Altitude: 29.326 m
Altitude: 29.33 m
...
Altitude: 29.323 m
Altitude: 29.357 m
Landing...
[10:25:29|Debug] MAVLink: info: Landing at current position (mavlink_system.cpp:286)
Altitude: 29.199 m
Altitude: 28.722 m
Altitude: 28.189 m
Altitude: 27.62 m
Finished...
How it works
The operation of the transition code is discussed in the guide: Takeoff and Landing (and other actions).
Source code
The full source code for the example can be found on Github here.
cmake_minimum_required(VERSION 2.8.12)
project(transition_vtol_fixed_wing)
if(NOT MSVC)
add_definitions("-std=c++11 -Wall -Wextra -Werror")
else()
add_definitions("-std=c++11 -WX -W2")
endif()
find_package(MAVSDK REQUIRED)
add_executable(transition_vtol_fixed_wing
transition_vtol_fixed_wing.cpp
)
target_link_libraries(transition_vtol_fixed_wing
MAVSDK::mavsdk_action
MAVSDK::mavsdk_telemetry
MAVSDK::mavsdk
)
transition_vtol_fixed_wing.cpp
#include <chrono>
#include <cstdint>
#include <iostream>
#include <thread>
#include <cmath>
#include <mavsdk/mavsdk.h>
#include <mavsdk/plugins/action/action.h>
#include <mavsdk/plugins/telemetry/telemetry.h>
using std::this_thread::sleep_for;
using std::chrono::seconds;
using std::chrono::milliseconds;
using namespace mavsdk;
static constexpr auto ERROR_CONSOLE_TEXT = "\033[31m";
static constexpr auto TELEMETRY_CONSOLE_TEXT = "\033[34m";
static constexpr auto NORMAL_CONSOLE_TEXT = "\033[0m";
void usage(const std::string &bin_name);
int main(int argc, char **argv)
{
if (argc != 2) {
usage(argv[0]);
return 1;
}
const std::string connection_url = argv[1];
Mavsdk dc;
// Add connection specified by CLI argument.
const ConnectionResult connection_result = dc.add_any_connection(connection_url);
if (connection_result != ConnectionResult::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT
<< "Connection failed: " << connection_result_str(connection_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// We need an autopilot connected to start.
while (!dc.system().has_autopilot()) {
sleep_for(seconds(1));
std::cout << "Waiting for system to connect." << std::endl;
}
// Get system and plugins.
System &system = dc.system();
auto telemetry = std::make_shared<Telemetry>(system);
auto action = std::make_shared<Action>(system);
// We want to listen to the altitude of the drone at 1 Hz.
const Telemetry::Result set_rate_result = telemetry->set_rate_position(1.0);
if (set_rate_result != Telemetry::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT
<< "Setting rate failed: " << Telemetry::result_str(set_rate_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// Set up callback to monitor altitude.
telemetry->position_async([](Telemetry::Position position) {
std::cout << TELEMETRY_CONSOLE_TEXT << "Altitude: " << position.relative_altitude_m << " m"
<< NORMAL_CONSOLE_TEXT << std::endl;
});
// Wait until we are ready to arm.
while (!telemetry->health_all_ok()) {
std::cout << "Waiting for vehicle to be ready to arm..." << std::endl;
sleep_for(seconds(1));
}
// Arm vehicle
std::cout << "Arming." << std::endl;
const Action::Result arm_result = action->arm();
if (arm_result != Action::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT << "Arming failed: " << Action::result_str(arm_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// Take off
std::cout << "Taking off." << std::endl;
const Action::Result takeoff_result = action->takeoff();
if (takeoff_result != Action::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT << "Takeoff failed:n" << Action::result_str(takeoff_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// Wait while it takes off.
sleep_for(seconds(10));
std::cout << "Transition to fixedwing." << std::endl;
const Action::Result fw_result = action->transition_to_fixedwing();
if (fw_result != Action::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT
<< "Transition to fixed wing failed: " << Action::result_str(fw_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// Let it transition and start loitering.
sleep_for(seconds(30));
// Send it South.
std::cout << "Sending it to location." << std::endl;
// We pass latitude and longitude but leave altitude and yaw unset by passing NAN.
const Action::Result goto_result = action->goto_location(47.3633001, 8.5428515, NAN, NAN);
if (goto_result != Action::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT
<< "Goto command failed: " << Action::result_str(goto_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// Let it fly South for a bit.
sleep_for(seconds(20));
// Let's stop before reaching the goto point and go back to hover.
std::cout << "Transition back to multicopter..." << std::endl;
const Action::Result mc_result = action->transition_to_multicopter();
if (mc_result != Action::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT
<< "Transition to multi copter failed: " << Action::result_str(mc_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// Wait for the transition to be carried out.
sleep_for(seconds(5));
// Now just land here.
std::cout << "Landing..." << std::endl;
const Action::Result land_result = action->land();
if (land_result != Action::Result::SUCCESS) {
std::cout << ERROR_CONSOLE_TEXT << "Land failed: " << Action::result_str(land_result)
<< NORMAL_CONSOLE_TEXT << std::endl;
return 1;
}
// Wait until disarmed.
while (telemetry->armed()) {
std::cout << "Waiting for vehicle to land and disarm." << std::endl;
sleep_for(seconds(1));
}
std::cout << "Disarmed, exiting." << std::endl;
return 0;
}
void usage(const std::string &bin_name)
{
std::cout << NORMAL_CONSOLE_TEXT << "Usage : " << bin_name << " <connection_url>" << std::endl
<< "Connection URL format should be :" << std::endl
<< " For TCP : tcp://[server_host][:server_port]" << std::endl
<< " For UDP : udp://[bind_host][:bind_port]" << std::endl
<< " For Serial : serial:///path/to/serial/dev[:baudrate]" << std::endl
<< std::endl
<< "For example, to connect to the simulator use URL: udp://:14540" << std::endl;
}