PX4-Autopilot/apps/ardrone_control/attitude_control.c

/****************************************************************************
 *
 *   Copyright (C) 2008-2012 PX4 Development Team. All rights reserved.
 *   Author: Thomas Gubler <thomasgubler@student.ethz.ch>
 *           Julian Oes <joes@student.ethz.ch>
 *           Laurens Mackay <mackayl@student.ethz.ch>
 *           Tobias Naegeli <naegelit@student.ethz.ch>
 *           Martin Rutschmann <rutmarti@student.ethz.ch>
 *           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
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 ****************************************************************************/

/*
 * @file Implementation of attitude controller
 */

#include "attitude_control.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include "ardrone_motor_control.h"
#include <float.h>
#include <math.h>
#include "pid.h"
#include <arch/board/up_hrt.h>

#define CONTROL_PID_ATTITUDE_INTERVAL	5e-3f
#define MAX_MOTOR_COUNT 16

void control_attitude(int ardrone_write, const struct vehicle_attitude_setpoint_s *att_sp, const struct vehicle_attitude_s *att, const struct vehicle_status_s *status)
{
	const unsigned int motor_count = 4;

	static int motor_skip_counter = 0;

	static PID_t yaw_pos_controller;
	static PID_t yaw_speed_controller;
	static PID_t nick_controller;
	static PID_t roll_controller;

	const float min_thrust = 0.02f;			/**< 2% minimum thrust */
	const float max_thrust = 1.0f;			/**< 100% max thrust */
	const float scaling = 512.0f;			/**< 100% thrust equals a value of 512 */

	const float min_gas = min_thrust * scaling;	/**< value range sent to motors, minimum */
	const float max_gas = max_thrust * scaling;	/**< value range sent to motors, maximum */

	/* initialize all fields to zero */
	static uint16_t motor_pwm[MAX_MOTOR_COUNT];
	static float motor_calc[MAX_MOTOR_COUNT];

	static float pid_yawpos_lim;
	static float pid_yawspeed_lim;
	static float pid_att_lim;

	static bool initialized;

	/* initialize the pid controllers when the function is called for the first time */
	if (initialized == false) {

		pid_init(&yaw_pos_controller,
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_P],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_I],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_D],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_AWU],
			 PID_MODE_DERIVATIV_CALC, 154);

		pid_init(&yaw_speed_controller,
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_P],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_I],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_D],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_AWU],
			 PID_MODE_DERIVATIV_CALC, 155);

		pid_init(&nick_controller,
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_P],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_I],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_D],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_AWU],
			 PID_MODE_DERIVATIV_SET, 156);

		pid_init(&roll_controller,
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_P],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_I],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_D],
			 global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_AWU],
			 PID_MODE_DERIVATIV_SET, 157);

		pid_yawpos_lim = 	global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_LIM];
		pid_yawspeed_lim =	(max_gas - min_gas) * global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_LIM];
		pid_att_lim =	(max_gas - min_gas) * global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_LIM];

		initialized = true;
	}

	/* load new parameters with lower rate */
	if (motor_skip_counter % 50 == 0) {
		pid_set_parameters(&yaw_pos_controller,
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_P],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_I],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_D],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_AWU]);

		pid_set_parameters(&yaw_speed_controller,
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_P],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_I],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_D],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_AWU]);

		pid_set_parameters(&nick_controller,
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_P],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_I],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_D],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_AWU]);

		pid_set_parameters(&roll_controller,
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_P],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_I],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_D],
				   global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_AWU]);

		pid_yawpos_lim = global_data_parameter_storage->pm.param_values[PARAM_PID_YAWPOS_LIM];
		pid_yawspeed_lim = (max_gas - min_gas) * global_data_parameter_storage->pm.param_values[PARAM_PID_YAWSPEED_LIM];
		pid_att_lim = (max_gas - min_gas) * global_data_parameter_storage->pm.param_values[PARAM_PID_ATT_LIM];
	}

	/*Calculate Controllers*/
	//control Nick
	float nick_control = pid_calculate(&nick_controller, att_sp->pitch_body + global_data_parameter_storage->pm.param_values[PARAM_ATT_YOFFSET],
					att->pitch, att->pitchspeed, CONTROL_PID_ATTITUDE_INTERVAL);
	//control Roll
	float roll_control = pid_calculate(&roll_controller, att_sp->roll_body + global_data_parameter_storage->pm.param_values[PARAM_ATT_XOFFSET],
					att->roll, att->rollspeed, CONTROL_PID_ATTITUDE_INTERVAL);
	//control Yaw Speed
	float yaw_rate_control = pid_calculate(&yaw_speed_controller, att_sp->yaw_body, att->yawspeed, 0.0f, CONTROL_PID_ATTITUDE_INTERVAL); 	//attitude_setpoint_bodyframe.z is yaw speed!

	/*
	 * compensate the vertical loss of thrust
	 * when thrust plane has an angle.
	 * start with a factor of 1.0 (no change)
	 */
	float zcompensation = 1.0f;

	if (fabsf(att->roll) > 1.0f) {
		zcompensation *= 1.85081571768f;

	} else {
		zcompensation *= 1.0f / cosf(att->roll);
	}

	if (fabsf(att->pitch) > 1.0f) {
		zcompensation *= 1.85081571768f;

	} else {
		zcompensation *= 1.0f / cosf(att->pitch);
	}

	float motor_thrust;

	// FLYING MODES
	if (status->state_machine == SYSTEM_STATE_MANUAL) {
		motor_thrust = att_sp->thrust;

	} else if (status->state_machine == SYSTEM_STATE_GROUND_READY ||
		status->state_machine == SYSTEM_STATE_STABILIZED ||
		status->state_machine == SYSTEM_STATE_AUTO ||
		status->state_machine == SYSTEM_STATE_MISSION_ABORT) {
		motor_thrust = att_sp->thrust;	//TODO

	} else if (status->state_machine == SYSTEM_STATE_EMCY_LANDING) {
		motor_thrust = att_sp->thrust;	//TODO

	} else if (status->state_machine == SYSTEM_STATE_EMCY_CUTOFF) {
		/* immediately cut off motors */
		motor_thrust = 0.0f;

	} else {
		/* limit motor throttle to zero for an unknown mode */
		motor_thrust = 0.0f;
	}

	/* compensate thrust vector for roll / pitch contributions */
	motor_thrust *= zcompensation;

	/* limit yaw rate output */
	if (yaw_rate_control > pid_yawspeed_lim) {
		yaw_rate_control = pid_yawspeed_lim;
		yaw_speed_controller.saturated = 1;
	}

	if (yaw_rate_control < -pid_yawspeed_lim) {
		yaw_rate_control = -pid_yawspeed_lim;
		yaw_speed_controller.saturated = 1;
	}

	if (nick_control > pid_att_lim) {
		nick_control = pid_att_lim;
		nick_controller.saturated = 1;
	}

	if (nick_control < -pid_att_lim) {
		nick_control = -pid_att_lim;
		nick_controller.saturated = 1;
	}


	if (roll_control > pid_att_lim) {
		roll_control = pid_att_lim;
		roll_controller.saturated = 1;
	}

	if (roll_control < -pid_att_lim) {
		roll_control = -pid_att_lim;
		roll_controller.saturated = 1;
	}

	float output_band = 0.0f;
	float band_factor = 0.75f;
	const float startpoint_full_control = 0.25f;	/**< start full control at 25% thrust */
	float yaw_factor = 1.0f;

	if (motor_thrust <= min_thrust) {
		motor_thrust = min_thrust;
		output_band = 0.0f;

	} else if (motor_thrust < startpoint_full_control && motor_thrust > min_thrust) {
		output_band = band_factor * (motor_thrust - min_thrust);

	} else if (motor_thrust >= startpoint_full_control && motor_thrust < max_thrust - band_factor * startpoint_full_control) {
		output_band = band_factor * startpoint_full_control;

	} else if (motor_thrust >= max_thrust - band_factor * startpoint_full_control) {
		output_band = band_factor * (max_thrust - motor_thrust);
	}

	//add the yaw, nick and roll components to the basic thrust //TODO:this should be done by the mixer

	// FRONT (MOTOR 1)
	motor_calc[0] = motor_thrust + (roll_control / 2 + nick_control / 2 - yaw_rate_control);

	// RIGHT (MOTOR 2)
	motor_calc[1] = motor_thrust + (-roll_control / 2 + nick_control / 2 + yaw_rate_control);

	// BACK (MOTOR 3)
	motor_calc[2] = motor_thrust + (-roll_control / 2 - nick_control / 2 - yaw_rate_control);

	// LEFT (MOTOR 4)
	motor_calc[3] = motor_thrust + (roll_control / 2 - nick_control / 2 + yaw_rate_control);

	// if we are not in the output band
	if (!(motor_calc[0] < motor_thrust + output_band && motor_calc[0] > motor_thrust - output_band
	      && motor_calc[1] < motor_thrust + output_band && motor_calc[1] > motor_thrust - output_band
	      && motor_calc[2] < motor_thrust + output_band && motor_calc[2] > motor_thrust - output_band
	      && motor_calc[3] < motor_thrust + output_band && motor_calc[3] > motor_thrust - output_band)) {

		yaw_factor = 0.5f;
		// FRONT (MOTOR 1)
		motor_calc[0] = motor_thrust + (roll_control / 2 + nick_control / 2 - yaw_rate_control * yaw_factor);

		// RIGHT (MOTOR 2)
		motor_calc[1] = motor_thrust + (-roll_control / 2 + nick_control / 2 + yaw_rate_control * yaw_factor);

		// BACK (MOTOR 3)
		motor_calc[2] = motor_thrust + (-roll_control / 2 - nick_control / 2 - yaw_rate_control * yaw_factor);

		// LEFT (MOTOR 4)
		motor_calc[3] = motor_thrust + (roll_control / 2 - nick_control / 2 + yaw_rate_control * yaw_factor);
	}

	for (int i = 0; i < 4; i++) {
		//check for limits
		if (motor_calc[i] < motor_thrust - output_band) {
			motor_calc[i] = motor_thrust - output_band;
		}

		if (motor_calc[i] > motor_thrust + output_band) {
			motor_calc[i] = motor_thrust + output_band;
		}
	}

	/* set the motor values */

	/* scale up from 0..1 to 10..512) */
	motor_pwm[0] = (uint16_t) motor_calc[0] * ((float)max_gas - min_gas) + min_gas;
	motor_pwm[1] = (uint16_t) motor_calc[1] * ((float)max_gas - min_gas) + min_gas;
	motor_pwm[2] = (uint16_t) motor_calc[2] * ((float)max_gas - min_gas) + min_gas;
	motor_pwm[3] = (uint16_t) motor_calc[3] * ((float)max_gas - min_gas) + min_gas;

	/* Keep motors spinning while armed and prevent overflows */

	/* Failsafe logic - should never be necessary */
	motor_pwm[0] = (motor_pwm[0] > 0) ? motor_pwm[0] : 10;
	motor_pwm[1] = (motor_pwm[1] > 0) ? motor_pwm[1] : 10;
	motor_pwm[2] = (motor_pwm[2] > 0) ? motor_pwm[2] : 10;
	motor_pwm[3] = (motor_pwm[3] > 0) ? motor_pwm[3] : 10;

	/* Failsafe logic - should never be necessary */
	motor_pwm[0] = (motor_pwm[0] <= 512) ? motor_pwm[0] : 512;
	motor_pwm[1] = (motor_pwm[1] <= 512) ? motor_pwm[1] : 512;
	motor_pwm[2] = (motor_pwm[2] <= 512) ? motor_pwm[2] : 512;
	motor_pwm[3] = (motor_pwm[3] <= 512) ? motor_pwm[3] : 512;

	/* send motors via UART */
	if (motor_skip_counter % 5 == 0) {
		if (motor_skip_counter % 25) printf("mot: %1.3f-%i\n", motor_thrust, motor_pwm[0]);
		uint8_t buf[5] = {1, 2, 3, 4, 5};
		ar_get_motor_packet(buf, motor_pwm[0], motor_pwm[1], motor_pwm[2], motor_pwm[3]);
		write(ardrone_write, buf, sizeof(buf));
	}

	motor_skip_counter++;

}