/****************************************************************************
*
* Copyright (c) 2013 PX4 Development Team. All rights reserved.
* Author: Lorenz Meier <lm@inf.ethz.ch>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file main.c
*
* Example implementation of a fixed wing attitude controller. This file is a complete
* fixed wing controller for manual attitude control or auto waypoint control.
* There is no need to touch any other system components to extend / modify the
* complete control architecture.
*
* @author Lorenz Meier <lm@inf.ethz.ch>
*/
#include <nuttx/config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <math.h>
#include <poll.h>
#include <time.h>
#include <drivers/drv_hrt.h>
#include <uORB/uORB.h>
#include <uORB/topics/vehicle_global_position.h>
#include <uORB/topics/vehicle_global_position_setpoint.h>
#include <uORB/topics/vehicle_attitude.h>
#include <uORB/topics/vehicle_status.h>
#include <uORB/topics/vehicle_attitude_setpoint.h>
#include <uORB/topics/manual_control_setpoint.h>
#include <uORB/topics/actuator_controls.h>
#include <uORB/topics/vehicle_rates_setpoint.h>
#include <uORB/topics/vehicle_global_position.h>
#include <uORB/topics/parameter_update.h>
#include <systemlib/param/param.h>
#include <systemlib/pid/pid.h>
#include <geo/geo.h>
#include <systemlib/perf_counter.h>
#include <systemlib/systemlib.h>
#include <systemlib/err.h>
/* process-specific header files */
#include "params.h"
/* Prototypes */
/**
* Daemon management function.
*
* This function allows to start / stop the background task (daemon).
* The purpose of it is to be able to start the controller on the
* command line, query its status and stop it, without giving up
* the command line to one particular process or the need for bg/fg
* ^Z support by the shell.
*/
__EXPORT int ex_fixedwing_control_main(int argc, char *argv[]);
/**
* Mainloop of daemon.
*/
int fixedwing_control_thread_main(int argc, char *argv[]);
/**
* Print the correct usage.
*/
static void usage(const char *reason);
/**
* Control roll and pitch angle.
*
* This very simple roll and pitch controller takes the current roll angle
* of the system and compares it to a reference. Pitch is controlled to zero and yaw remains
* uncontrolled (tutorial code, not intended for flight).
*
* @param att_sp The current attitude setpoint - the values the system would like to reach.
* @param att The current attitude. The controller should make the attitude match the setpoint
* @param speed_body The velocity of the system. Currently unused.
* @param rates_sp The angular rate setpoint. This is the output of the controller.
*/
void control_attitude(const struct vehicle_attitude_setpoint_s *att_sp, const struct vehicle_attitude_s *att,
float speed_body[], struct vehicle_rates_setpoint_s *rates_sp,
struct actuator_controls_s *actuators);
/**
* Control heading.
*
* This very simple heading to roll angle controller outputs the desired roll angle based on
* the current position of the system, the desired position (the setpoint) and the current
* heading.
*
* @param pos The current position of the system
* @param sp The current position setpoint
* @param att The current attitude
* @param att_sp The attitude setpoint. This is the output of the controller
*/
void control_heading(const struct vehicle_global_position_s *pos, const struct vehicle_global_position_setpoint_s *sp,
const struct vehicle_attitude_s *att, struct vehicle_attitude_setpoint_s *att_sp);
/* Variables */
static bool thread_should_exit = false; /**< Daemon exit flag */
static bool thread_running = false; /**< Daemon status flag */
static int deamon_task; /**< Handle of deamon task / thread */
static struct params p;
static struct param_handles ph;
void control_attitude(const struct vehicle_attitude_setpoint_s *att_sp, const struct vehicle_attitude_s *att,
float speed_body[], struct vehicle_rates_setpoint_s *rates_sp,
struct actuator_controls_s *actuators)
{
/*
* The PX4 architecture provides a mixer outside of the controller.
* The mixer is fed with a default vector of actuator controls, representing
* moments applied to the vehicle frame. This vector
* is structured as:
*
* Control Group 0 (attitude):
*
* 0 - roll (-1..+1)
* 1 - pitch (-1..+1)
* 2 - yaw (-1..+1)
* 3 - thrust ( 0..+1)
* 4 - flaps (-1..+1)
* ...
*
* Control Group 1 (payloads / special):
*
* ...
*/
/*
* Calculate roll error and apply P gain
*/
float roll_err = att->roll - att_sp->roll_body;
actuators->control[0] = roll_err * p.roll_p;
/*
* Calculate pitch error and apply P gain
*/
float pitch_err = att->pitch - att_sp->pitch_body;
actuators->control[1] = pitch_err * p.pitch_p;
}
void control_heading(const struct vehicle_global_position_s *pos, const struct vehicle_global_position_setpoint_s *sp,
const struct vehicle_attitude_s *att, struct vehicle_attitude_setpoint_s *att_sp)
{
/*
* Calculate heading error of current position to desired position
*/
float bearing = get_bearing_to_next_waypoint(pos->lat, pos->lon, sp->lat, sp->lon);
/* calculate heading error */
float yaw_err = att->yaw - bearing;
/* apply control gain */
float roll_command = yaw_err * p.hdng_p;
/* limit output, this commonly is a tuning parameter, too */
if (att_sp->roll_body < -0.6f) {
att_sp->roll_body = -0.6f;
} else if (att_sp->roll_body > 0.6f) {
att_sp->roll_body = 0.6f;
}
}
/* Main Thread */
int fixedwing_control_thread_main(int argc, char *argv[])
{
/* read arguments */
bool verbose = false;
for (int i = 1; i < argc; i++) {
if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--verbose") == 0) {
verbose = true;
}
}
/* welcome user (warnx prints a line, including an appended\n, with variable arguments */
warnx("[example fixedwing control] started");
/* initialize parameters, first the handles, then the values */
parameters_init(&ph);
parameters_update(&ph, &p);
/*
* PX4 uses a publish/subscribe design pattern to enable
* multi-threaded communication.
*
* The most elegant aspect of this is that controllers and
* other processes can either 'react' to new data, or run
* at their own pace.
*
* PX4 developer guide:
* https://pixhawk.ethz.ch/px4/dev/shared_object_communication
*
* Wikipedia description:
* http://en.wikipedia.org/wiki/Publish–subscribe_pattern
*
*/
/*
* Declare and safely initialize all structs to zero.
*
* These structs contain the system state and things
* like attitude, position, the current waypoint, etc.
*/
struct vehicle_attitude_s att;
memset(&att, 0, sizeof(att));
struct vehicle_attitude_setpoint_s att_sp;
memset(&att_sp, 0, sizeof(att_sp));
struct vehicle_rates_setpoint_s rates_sp;
memset(&rates_sp, 0, sizeof(rates_sp));
struct vehicle_global_position_s global_pos;
memset(&global_pos, 0, sizeof(global_pos));
struct manual_control_setpoint_s manual_sp;
memset(&manual_sp, 0, sizeof(manual_sp));
struct vehicle_status_s vstatus;
memset(&vstatus, 0, sizeof(vstatus));
struct vehicle_global_position_setpoint_s global_sp;
memset(&global_sp, 0, sizeof(global_sp));
/* output structs - this is what is sent to the mixer */
struct actuator_controls_s actuators;
memset(&actuators, 0, sizeof(actuators));
/* publish actuator controls with zero values */
for (unsigned i = 0; i < NUM_ACTUATOR_CONTROLS; i++) {
actuators.control[i] = 0.0f;
}
/*
* Advertise that this controller will publish actuator
* control values and the rate setpoint
*/
orb_advert_t actuator_pub = orb_advertise(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, &actuators);
orb_advert_t rates_pub = orb_advertise(ORB_ID(vehicle_rates_setpoint), &rates_sp);
/* subscribe to topics. */
int att_sub = orb_subscribe(ORB_ID(vehicle_attitude));
int att_sp_sub = orb_subscribe(ORB_ID(vehicle_attitude_setpoint));
int global_pos_sub = orb_subscribe(ORB_ID(vehicle_global_position));
int manual_sp_sub = orb_subscribe(ORB_ID(manual_control_setpoint));
int vstatus_sub = orb_subscribe(ORB_ID(vehicle_status));
int global_sp_sub = orb_subscribe(ORB_ID(vehicle_global_position_setpoint));
int param_sub = orb_subscribe(ORB_ID(parameter_update));
/* Setup of loop */
float speed_body[3] = {0.0f, 0.0f, 0.0f};
/* RC failsafe check */
bool throttle_half_once = false;
struct pollfd fds[2] = {{ .fd = param_sub, .events = POLLIN },
{ .fd = att_sub, .events = POLLIN }};
while (!thread_should_exit) {
/*
* Wait for a sensor or param update, check for exit condition every 500 ms.
* This means that the execution will block here without consuming any resources,
* but will continue to execute the very moment a new attitude measurement or
* a param update is published. So no latency in contrast to the polling
* design pattern (do not confuse the poll() system call with polling).
*
* This design pattern makes the controller also agnostic of the attitude
* update speed - it runs as fast as the attitude updates with minimal latency.
*/
int ret = poll(fds, 2, 500);
if (ret < 0) {
/*
* Poll error, this will not really happen in practice,
* but its good design practice to make output an error message.
*/
warnx("poll error");
} else if (ret == 0) {
/* no return value = nothing changed for 500 ms, ignore */
} else {
/* only update parameters if they changed */
if (fds[0].revents & POLLIN) {
/* read from param to clear updated flag (uORB API requirement) */
struct parameter_update_s update;
orb_copy(ORB_ID(parameter_update), param_sub, &update);
/* if a param update occured, re-read our parameters */
parameters_update(&ph, &p);
}
/* only run controller if attitude changed */
if (fds[1].revents & POLLIN) {
/* Check if there is a new position measurement or position setpoint */
bool pos_updated;
orb_check(global_pos_sub, &pos_updated);
bool global_sp_updated;
orb_check(global_sp_sub, &global_sp_updated);
bool manual_sp_updated;
orb_check(manual_sp_sub, &manual_sp_updated);
/* get a local copy of attitude */
orb_copy(ORB_ID(vehicle_attitude), att_sub, &att);
if (global_sp_updated)
orb_copy(ORB_ID(vehicle_global_position_setpoint), global_sp_sub, &global_sp);
/* currently speed in body frame is not used, but here for reference */
if (pos_updated) {
orb_copy(ORB_ID(vehicle_global_position), global_pos_sub, &global_pos);
if (att.R_valid) {
speed_body[0] = att.R[0][0] * global_pos.vx + att.R[0][1] * global_pos.vy + att.R[0][2] * global_pos.vz;
speed_body[1] = att.R[1][0] * global_pos.vx + att.R[1][1] * global_pos.vy + att.R[1][2] * global_pos.vz;
speed_body[2] = att.R[2][0] * global_pos.vx + att.R[2][1] * global_pos.vy + att.R[2][2] * global_pos.vz;
} else {
speed_body[0] = 0;
speed_body[1] = 0;
speed_body[2] = 0;
warnx("Did not get a valid R\n");
}
}
if (manual_sp_updated)
/* get the RC (or otherwise user based) input */
orb_copy(ORB_ID(manual_control_setpoint), manual_sp_sub, &manual_sp);
/* check if the throttle was ever more than 50% - go later only to failsafe if yes */
if (isfinite(manual_sp.throttle) &&
(manual_sp.throttle >= 0.6f) &&
(manual_sp.throttle <= 1.0f)) {
throttle_half_once = true;
}
/* get the system status and the flight mode we're in */
orb_copy(ORB_ID(vehicle_status), vstatus_sub, &vstatus);
/* control */
#warning fix this
#if 0
if (vstatus.navigation_state == NAVIGATION_STATE_AUTO_ ||
vstatus.navigation_state == NAVIGATION_STATE_STABILIZED) {
/* simple heading control */
control_heading(&global_pos, &global_sp, &att, &att_sp);
/* nail pitch and yaw (rudder) to zero. This example only controls roll (index 0) */
actuators.control[1] = 0.0f;
actuators.control[2] = 0.0f;
/* simple attitude control */
control_attitude(&att_sp, &att, speed_body, &rates_sp, &actuators);
/* pass through throttle */
actuators.control[3] = att_sp.thrust;
/* set flaps to zero */
actuators.control[4] = 0.0f;
} else if (vstatus.navigation_state == NAVIGATION_STATE_MANUAL) {
/* if in manual mode, decide between attitude stabilization (SAS) and full manual pass-through */
} else if (vstatus.state_machine == SYSTEM_STATE_MANUAL) {
if (vstatus.manual_control_mode == VEHICLE_MANUAL_CONTROL_MODE_SAS) {
/* if the RC signal is lost, try to stay level and go slowly back down to ground */
if (vstatus.rc_signal_lost && throttle_half_once) {
/* put plane into loiter */
att_sp.roll_body = 0.3f;
att_sp.pitch_body = 0.0f;
/* limit throttle to 60 % of last value if sane */
if (isfinite(manual_sp.throttle) &&
(manual_sp.throttle >= 0.0f) &&
(manual_sp.throttle <= 1.0f)) {
att_sp.thrust = 0.6f * manual_sp.throttle;
} else {
att_sp.thrust = 0.0f;
}
att_sp.yaw_body = 0;
// XXX disable yaw control, loiter
} else {
att_sp.roll_body = manual_sp.roll;
att_sp.pitch_body = manual_sp.pitch;
att_sp.yaw_body = 0;
att_sp.thrust = manual_sp.throttle;
}
att_sp.timestamp = hrt_absolute_time();
/* attitude control */
control_attitude(&att_sp, &att, speed_body, &rates_sp, &actuators);
/* pass through throttle */
actuators.control[3] = att_sp.thrust;
/* pass through flaps */
if (isfinite(manual_sp.flaps)) {
actuators.control[4] = manual_sp.flaps;
} else {
actuators.control[4] = 0.0f;
}
} else if (vstatus.manual_control_mode == VEHICLE_MANUAL_CONTROL_MODE_DIRECT) {
/* directly pass through values */
actuators.control[0] = manual_sp.roll;
/* positive pitch means negative actuator -> pull up */
actuators.control[1] = manual_sp.pitch;
actuators.control[2] = manual_sp.yaw;
actuators.control[3] = manual_sp.throttle;
if (isfinite(manual_sp.flaps)) {
actuators.control[4] = manual_sp.flaps;
} else {
actuators.control[4] = 0.0f;
}
}
}
#endif
/* publish rates */
orb_publish(ORB_ID(vehicle_rates_setpoint), rates_pub, &rates_sp);
/* sanity check and publish actuator outputs */
if (isfinite(actuators.control[0]) &&
isfinite(actuators.control[1]) &&
isfinite(actuators.control[2]) &&
isfinite(actuators.control[3])) {
orb_publish(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, actuator_pub, &actuators);
}
}
}
}
printf("[ex_fixedwing_control] exiting, stopping all motors.\n");
thread_running = false;
/* kill all outputs */
for (unsigned i = 0; i < NUM_ACTUATOR_CONTROLS; i++)
actuators.control[i] = 0.0f;
orb_publish(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, actuator_pub, &actuators);
fflush(stdout);
return 0;
}
/* Startup Functions */
static void
usage(const char *reason)
{
if (reason)
fprintf(stderr, "%s\n", reason);
fprintf(stderr, "usage: ex_fixedwing_control {start|stop|status}\n\n");
exit(1);
}
/**
* The daemon app only briefly exists to start
* the background job. The stack size assigned in the
* Makefile does only apply to this management task.
*
* The actual stack size should be set in the call
* to task_spawn_cmd().
*/
int ex_fixedwing_control_main(int argc, char *argv[])
{
if (argc < 1)
usage("missing command");
if (!strcmp(argv[1], "start")) {
if (thread_running) {
printf("ex_fixedwing_control already running\n");
/* this is not an error */
exit(0);
}
thread_should_exit = false;
deamon_task = task_spawn_cmd("ex_fixedwing_control",
SCHED_DEFAULT,
SCHED_PRIORITY_MAX - 20,
2048,
fixedwing_control_thread_main,
(argv) ? (const char **)&argv[2] : (const char **)NULL);
thread_running = true;
exit(0);
}
if (!strcmp(argv[1], "stop")) {
thread_should_exit = true;
exit(0);
}
if (!strcmp(argv[1], "status")) {
if (thread_running) {
printf("\tex_fixedwing_control is running\n");
} else {
printf("\tex_fixedwing_control not started\n");
}
exit(0);
}
usage("unrecognized command");
exit(1);
}
