PX4-Autopilot/src/examples/uuv_example_app/uuv_example_app.cpp

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/**
 * @file uuv_example_app.cpp
 *
 * This file let the hippocampus drive in a circle and prints the orientation as well as the acceleration data.
 * The HippoCampus is an autonomous underwater vehicle (AUV) designed by the Technical University Hamburg-Harburg (TUHH).
 * https://www.tuhh.de/mum/forschung/forschungsgebiete-und-projekte/flow-field-estimation-with-a-swarm-of-auvs.html
 *
 * @author Nils Rottann <Nils.Rottmann@tuhh.de>
 */

#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/tasks.h>
#include <px4_platform_common/posix.h>
#include <unistd.h>
#include <stdio.h>
#include <poll.h>
#include <string.h>
#include <math.h>

// system libraries
#include <parameters/param.h>
#include <systemlib/err.h>
#include <perf/perf_counter.h>

// internal libraries
#include <lib/mathlib/mathlib.h>
#include <matrix/math.hpp>
#include <lib/ecl/geo/geo.h>

// Include uORB and the required topics for this app
#include <uORB/uORB.h>
#include <uORB/topics/vehicle_acceleration.h>                // this topics hold the acceleration data
#include <uORB/topics/actuator_controls.h>              // this topic gives the actuators control input
#include <uORB/topics/vehicle_attitude.h>                  // this topic holds the orientation of the hippocampus

extern "C" __EXPORT int uuv_example_app_main(int argc, char *argv[]);

int uuv_example_app_main(int argc, char *argv[])
{
	PX4_INFO("auv_hippocampus_example_app has been started!");

	/* subscribe to vehicle_acceleration topic */
	int sensor_sub_fd = orb_subscribe(ORB_ID(vehicle_acceleration));
	/* limit the update rate to 5 Hz */
	orb_set_interval(sensor_sub_fd, 200);

	/* subscribe to control_state topic */
	int vehicle_attitude_sub_fd = orb_subscribe(ORB_ID(vehicle_attitude));
	/* limit the update rate to 5 Hz */
	orb_set_interval(vehicle_attitude_sub_fd, 200);

	/* advertise to actuator_control topic */
	struct actuator_controls_s act;
	memset(&act, 0, sizeof(act));
	orb_advert_t act_pub = orb_advertise(ORB_ID(actuator_controls_0), &act);

	/* one could wait for multiple topics with this technique, just using one here */
	px4_pollfd_struct_t fds[2] = {};
	fds[0].fd = sensor_sub_fd;
	fds[0].events = POLLIN;
	fds[1].fd = vehicle_attitude_sub_fd;
	fds[1].events = POLLIN;

	int error_counter = 0;

	for (int i = 0; i < 10; i++) {
		/* wait for sensor update of 1 file descriptor for 1000 ms (1 second) */
		int poll_ret = px4_poll(fds, 1, 1000);

		/* handle the poll result */
		if (poll_ret == 0) {
			/* this means none of our providers is giving us data */
			PX4_ERR("Got no data within a second");

		} else if (poll_ret < 0) {
			/* this is seriously bad - should be an emergency */
			if (error_counter < 10 || error_counter % 50 == 0) {
				/* use a counter to prevent flooding (and slowing us down) */
				PX4_ERR("ERROR return value from poll(): %d", poll_ret);
			}

			error_counter++;

		} else {

			if (fds[0].revents & POLLIN) {
				/* obtained data for the first file descriptor */
				vehicle_acceleration_s sensor{};
				/* copy sensors raw data into local buffer */
				orb_copy(ORB_ID(vehicle_acceleration), sensor_sub_fd, &sensor);
				// printing the sensor data into the terminal
				PX4_INFO("Acc:\t%8.4f\t%8.4f\t%8.4f",
					 (double)sensor.xyz[0],
					 (double)sensor.xyz[1],
					 (double)sensor.xyz[2]);

				/* obtained data for the third file descriptor */
				vehicle_attitude_s raw_ctrl_state{};
				/* copy sensors raw data into local buffer */
				orb_copy(ORB_ID(vehicle_attitude), vehicle_attitude_sub_fd, &raw_ctrl_state);

				// get current rotation matrix from control state quaternions, the quaternions are generated by the
				// attitude_estimator_q application using the sensor data
				matrix::Quatf q_att(raw_ctrl_state.q);     // control_state is frequently updated
				matrix::Dcmf R = q_att; // create rotation matrix for the quaternion when post multiplying with a column vector

				// orientation vectors
				matrix::Vector3f x_B(R(0, 0), R(1, 0), R(2, 0));     // orientation body x-axis (in world coordinates)
				matrix::Vector3f y_B(R(0, 1), R(1, 1), R(2, 1));     // orientation body y-axis (in world coordinates)
				matrix::Vector3f z_B(R(0, 2), R(1, 2), R(2, 2));     // orientation body z-axis (in world coordinates)

				PX4_INFO("x_B:\t%8.4f\t%8.4f\t%8.4f",
					 (double)x_B(0),
					 (double)x_B(1),
					 (double)x_B(2));

				PX4_INFO("y_B:\t%8.4f\t%8.4f\t%8.4f",
					 (double)y_B(0),
					 (double)y_B(1),
					 (double)y_B(2));

				PX4_INFO("z_B:\t%8.4f\t%8.4f\t%8.4f \n",
					 (double)z_B(0),
					 (double)z_B(1),
					 (double)z_B(2));
			}
		}

		// Give actuator input to the HippoC, this will result in a circle
		act.control[0] = 0.0f;      // roll
		act.control[1] = 0.0f;      // pitch
		act.control[2] = 1.0f;		// yaw
		act.control[3] = 1.0f;		// thrust
		orb_publish(ORB_ID(actuator_controls_0), act_pub, &act);

	}


	PX4_INFO("Exiting uuv_example_app!");


	return 0;
}