offboard_control_srv.cpp

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/**
 * @brief Offboard control example
 * @file offboard_control.cpp
 * @addtogroup examples * 
 * @author Beniamino Pozzan <beniamino.pozzan@gmail.com>
 * @author Mickey Cowden <info@cowden.tech>
 * @author Nuno Marques <nuno.marques@dronesolutions.io>
 */

#include <px4_msgs/msg/offboard_control_mode.hpp>
#include <px4_msgs/msg/trajectory_setpoint.hpp>
#include <px4_msgs/msg/vehicle_control_mode.hpp>
#include <px4_msgs/srv/vehicle_command.hpp>
#include <rclcpp/rclcpp.hpp>
#include <stdint.h>

#include <chrono>
#include <iostream>
#include <string>

using namespace std::chrono;
using namespace std::chrono_literals;
using namespace px4_msgs::msg;

class OffboardControl : public rclcpp::Node
{
public:
	OffboardControl(std::string px4_namespace) :
		Node("offboard_control_srv"),
		state_{State::init},
		service_result_{0},
		service_done_{false},
		offboard_control_mode_publisher_{this->create_publisher<OffboardControlMode>(px4_namespace+"in/offboard_control_mode", 10)},
		trajectory_setpoint_publisher_{this->create_publisher<TrajectorySetpoint>(px4_namespace+"in/trajectory_setpoint", 10)},
		vehicle_command_client_{this->create_client<px4_msgs::srv::VehicleCommand>(px4_namespace+"vehicle_command")}
	{
		RCLCPP_INFO(this->get_logger(), "Starting Offboard Control example with PX4 services");
		RCLCPP_INFO_STREAM(this->get_logger(), "Waiting for " << px4_namespace << "vehicle_command service");
		while (!vehicle_command_client_->wait_for_service(1s)) {
			if (!rclcpp::ok()) {
				RCLCPP_ERROR(this->get_logger(), "Interrupted while waiting for the service. Exiting.");
				return;
			}
			RCLCPP_INFO(this->get_logger(), "service not available, waiting again...");
		}

		timer_ = this->create_wall_timer(100ms, std::bind(&OffboardControl::timer_callback, this));
	}

	void switch_to_offboard_mode();
	void arm();
	void disarm();

private:
	enum class State{
		init,
		offboard_requested,
		wait_for_stable_offboard_mode,
		arm_requested,
		armed
	} state_;
	uint8_t service_result_;
	bool service_done_;
	rclcpp::TimerBase::SharedPtr timer_;

	rclcpp::Publisher<OffboardControlMode>::SharedPtr offboard_control_mode_publisher_;
	rclcpp::Publisher<TrajectorySetpoint>::SharedPtr trajectory_setpoint_publisher_;
	rclcpp::Client<px4_msgs::srv::VehicleCommand>::SharedPtr vehicle_command_client_;


	void publish_offboard_control_mode();
	void publish_trajectory_setpoint();
	void request_vehicle_command(uint16_t command, float param1 = 0.0, float param2 = 0.0);
	void response_callback(rclcpp::Client<px4_msgs::srv::VehicleCommand>::SharedFuture future);
	void timer_callback(void);
};

/**
 * @brief Send a command to switch to offboard mode
 */
void OffboardControl::switch_to_offboard_mode(){
	RCLCPP_INFO(this->get_logger(), "requesting switch to Offboard mode");
	request_vehicle_command(VehicleCommand::VEHICLE_CMD_DO_SET_MODE, 1, 6);
}

/**
 * @brief Send a command to Arm the vehicle
 */
void OffboardControl::arm()
{
	RCLCPP_INFO(this->get_logger(), "requesting arm");
	request_vehicle_command(VehicleCommand::VEHICLE_CMD_COMPONENT_ARM_DISARM, 1.0);
}

/**
 * @brief Send a command to Disarm the vehicle
 */
void OffboardControl::disarm()
{
	RCLCPP_INFO(this->get_logger(), "requesting disarm");
	request_vehicle_command(VehicleCommand::VEHICLE_CMD_COMPONENT_ARM_DISARM, 0.0);
}

/**
 * @brief Publish the offboard control mode.
 *        For this example, only position and altitude controls are active.
 */
void OffboardControl::publish_offboard_control_mode()
{
	OffboardControlMode msg{};
	msg.position = true;
	msg.velocity = false;
	msg.acceleration = false;
	msg.attitude = false;
	msg.body_rate = false;
	msg.timestamp = this->get_clock()->now().nanoseconds() / 1000;
	offboard_control_mode_publisher_->publish(msg);
}

/**
 * @brief Publish a trajectory setpoint
 *        For this example, it sends a trajectory setpoint to make the
 *        vehicle hover at 5 meters with a yaw angle of 180 degrees.
 */
void OffboardControl::publish_trajectory_setpoint()
{
	TrajectorySetpoint msg{};
	msg.position = {0.0, 0.0, -5.0};
	msg.yaw = -3.14; // [-PI:PI]
	msg.timestamp = this->get_clock()->now().nanoseconds() / 1000;
	trajectory_setpoint_publisher_->publish(msg);
}

/**
 * @brief Publish vehicle commands
 * @param command   Command code (matches VehicleCommand and MAVLink MAV_CMD codes)
 * @param param1    Command parameter 1
 * @param param2    Command parameter 2
 */
void OffboardControl::request_vehicle_command(uint16_t command, float param1, float param2)
{
	auto request = std::make_shared<px4_msgs::srv::VehicleCommand::Request>();

	VehicleCommand msg{};
	msg.param1 = param1;
	msg.param2 = param2;
	msg.command = command;
	msg.target_system = 1;
	msg.target_component = 1;
	msg.source_system = 1;
	msg.source_component = 1;
	msg.from_external = true;
	msg.timestamp = this->get_clock()->now().nanoseconds() / 1000;
	request->request = msg;

	service_done_ = false;
	auto result = vehicle_command_client_->async_send_request(request, std::bind(&OffboardControl::response_callback, this,
                           std::placeholders::_1));
	RCLCPP_INFO(this->get_logger(), "Command send");
}

void OffboardControl::timer_callback(void){
	static uint8_t num_of_steps = 0;

	// offboard_control_mode needs to be paired with trajectory_setpoint
	publish_offboard_control_mode();
	publish_trajectory_setpoint();

	switch (state_)
	{
	case State::init :
		switch_to_offboard_mode();
		state_ = State::offboard_requested;
		break;
	case State::offboard_requested :
		if(service_done_){
			if (service_result_==0){
				RCLCPP_INFO(this->get_logger(), "Entered offboard mode");
				state_ = State::wait_for_stable_offboard_mode;				
			}
			else{
				RCLCPP_ERROR(this->get_logger(), "Failed to enter offboard mode, exiting");
				rclcpp::shutdown();
			}
		}
		break;
	case State::wait_for_stable_offboard_mode :
		if (++num_of_steps>10){
			arm();
			state_ = State::arm_requested;
		}
		break;
	case State::arm_requested :
		if(service_done_){
			if (service_result_==0){
				RCLCPP_INFO(this->get_logger(), "vehicle is armed");
				state_ = State::armed;
			}
			else{
				RCLCPP_ERROR(this->get_logger(), "Failed to arm, exiting");
				rclcpp::shutdown();
			}
		}
		break;
	default:
		break;
	}
}

void OffboardControl::response_callback(
      rclcpp::Client<px4_msgs::srv::VehicleCommand>::SharedFuture future) {
    auto status = future.wait_for(1s);
    if (status == std::future_status::ready) {
	  auto reply = future.get()->reply;
	  service_result_ = reply.result;
      switch (service_result_)
		{
		case reply.VEHICLE_CMD_RESULT_ACCEPTED:
			RCLCPP_INFO(this->get_logger(), "command accepted");
			break;
		case reply.VEHICLE_CMD_RESULT_TEMPORARILY_REJECTED:
			RCLCPP_WARN(this->get_logger(), "command temporarily rejected");
			break;
		case reply.VEHICLE_CMD_RESULT_DENIED:
			RCLCPP_WARN(this->get_logger(), "command denied");
			break;
		case reply.VEHICLE_CMD_RESULT_UNSUPPORTED:
			RCLCPP_WARN(this->get_logger(), "command unsupported");
			break;
		case reply.VEHICLE_CMD_RESULT_FAILED:
			RCLCPP_WARN(this->get_logger(), "command failed");
			break;
		case reply.VEHICLE_CMD_RESULT_IN_PROGRESS:
			RCLCPP_WARN(this->get_logger(), "command in progress");
			break;
		case reply.VEHICLE_CMD_RESULT_CANCELLED:
			RCLCPP_WARN(this->get_logger(), "command cancelled");
			break;
		default:
			RCLCPP_WARN(this->get_logger(), "command reply unknown");
			break;
		}
      service_done_ = true;
    } else {
      RCLCPP_INFO(this->get_logger(), "Service In-Progress...");
    }
  }

int main(int argc, char *argv[])
{
	setvbuf(stdout, NULL, _IONBF, BUFSIZ);
	rclcpp::init(argc, argv);
	rclcpp::spin(std::make_shared<OffboardControl>("/fmu/"));

	rclcpp::shutdown();
	return 0;
}