/**************************************************************************** * * Copyright (c) 2013 PX4 Development Team. All rights reserved. * Author: Lorenz Meier * * 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 * Implementation of a fixed wing attitude controller. This file is a complete * fixed wing controller flying manual attitude control or auto waypoint control. * There is no need to touch any other system components to extend / modify the * complete control architecture. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* 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 */ /* * PX4 uses 1e7 scaled integers to represent global coordinates for max resolution, * so they need to be scaled by 1e7 and converted to IEEE double precision floating point. */ float bearing = get_bearing_to_next_waypoint(pos->lat/1e7d, pos->lon/1e7d, sp->lat/1e7d, sp->lon/1e7d); /* 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 */ 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); /* 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"); } } /* 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 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 */ if (vstatus.state_machine == SYSTEM_STATE_AUTO || vstatus.state_machine == SYSTEM_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.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; } } } /* 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_create(). */ 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("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); }