LibrePilot/flight/Modules/Attitude/attitude.c

/**
 ******************************************************************************
 * @addtogroup OpenPilotModules OpenPilot Modules
 * @{
 * @addtogroup Attitude Copter Control Attitude Estimation
 * @brief Acquires sensor data and computes attitude estimate 
 * Specifically updates the the @ref AttitudeActual "AttitudeActual" and @ref AttitudeRaw "AttitudeRaw" settings objects
 * @{
 *
 * @file       attitude.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      Module to handle all comms to the AHRS on a periodic basis.
 *
 * @see        The GNU Public License (GPL) Version 3
 *
 ******************************************************************************/
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/**
 * Input objects: None, takes sensor data via pios
 * Output objects: @ref AttitudeRaw @ref AttitudeActual
 *
 * This module computes an attitude estimate from the sensor data
 *
 * The module executes in its own thread.
 *
 * UAVObjects are automatically generated by the UAVObjectGenerator from
 * the object definition XML file.
 *
 * Modules have no API, all communication to other modules is done through UAVObjects.
 * However modules may use the API exposed by shared libraries.
 * See the OpenPilot wiki for more details.
 * http://www.openpilot.org/OpenPilot_Application_Architecture
 *
 */

#include "pios.h"
#include "attitude.h"
#include "attituderaw.h"
#include "attitudeactual.h"
#include "attitudedesired.h"
#include "attitudesettings.h"
#include "manualcontrolcommand.h"
#include "CoordinateConversions.h"
#include "pios_flash_w25x.h"

// Private constants
#define STACK_SIZE_BYTES 540
#define TASK_PRIORITY (tskIDLE_PRIORITY+3)

#define UPDATE_RATE  3
#define GYRO_NEUTRAL 1665

#define PI_MOD(x) (fmod(x + M_PI, M_PI * 2) - M_PI)
// Private types

// Private variables
static xTaskHandle taskHandle;

// Private functions
static void AttitudeTask(void *parameters);

static float gyro_correct_int[3] = {0,0,0};
static xQueueHandle gyro_queue;

static void initSensors();
static void updateSensors();
static void updateAttitude();

/**
 * Initialise the module, called on startup
 * \returns 0 on success or -1 if initialisation failed
 */
int32_t AttitudeInitialize(void)
{
	// Initialize quaternion
	AttitudeActualData attitude;
	AttitudeActualGet(&attitude);
	attitude.q1 = 1;
	attitude.q2 = 0;
	attitude.q3 = 0;
	attitude.q4 = 0;
	AttitudeActualSet(&attitude);
	
	// Create queue for passing gyro data, allow 2 back samples in case
	gyro_queue = xQueueCreate(2, sizeof(float) * 4);
	if(gyro_queue == NULL) 
		return -1;
	PIOS_ADC_SetQueue(gyro_queue);
	
	// Start main task
	xTaskCreate(AttitudeTask, (signed char *)"Attitude", STACK_SIZE_BYTES/4, NULL, TASK_PRIORITY, &taskHandle);
	TaskMonitorAdd(TASKINFO_RUNNING_ATTITUDE, taskHandle);
	PIOS_WDG_RegisterFlag(PIOS_WDG_ATTITUDE);
	return 0;
}

/**
 * Module thread, should not return.
 */
static void AttitudeTask(void *parameters)
{

	AlarmsClear(SYSTEMALARMS_ALARM_ATTITUDE);

	PIOS_ADC_Config(PIOS_ADC_RATE / (1000 / UPDATE_RATE));

	// Keep flash CS pin high while talking accel
	PIOS_FLASH_DISABLE;		
	PIOS_ADXL345_Init();
		
	initSensors();
	
	// Main task loop
	while (1) {
		PIOS_WDG_UpdateFlag(PIOS_WDG_ATTITUDE);
		
		updateSensors();		
		updateAttitude();
	}
}

static void initSensors() 
{
	updateSensors();
	
	AttitudeRawData attitudeRaw;
	AttitudeRawGet(&attitudeRaw);	
	
	AttitudeSettingsData settings;
	AttitudeSettingsGet(&settings);

	// Zero initial bias
	gyro_correct_int[0] = - attitudeRaw.gyros[0];
	gyro_correct_int[1] = - attitudeRaw.gyros[1];
	gyro_correct_int[2] = - attitudeRaw.gyros[2];
}

static void updateSensors() 
{
	AttitudeRawData attitudeRaw;
	AttitudeRawGet(&attitudeRaw);		
	
	AttitudeSettingsData settings;
	AttitudeSettingsGet(&settings);
	
	struct pios_adxl345_data accel_data;
	float gyro[4];
	
	// Only wait the time for two nominal updates before setting an alarm
	if(xQueueReceive(gyro_queue, (void * const) gyro, UPDATE_RATE * 2) == errQUEUE_EMPTY) {
		AlarmsSet(SYSTEMALARMS_ALARM_ATTITUDE, SYSTEMALARMS_ALARM_ERROR);
		return;
	}
	
	
	// First sample is temperature
	attitudeRaw.gyros[ATTITUDERAW_GYROS_X] = -(gyro[1] - GYRO_NEUTRAL) * settings.GyroGain;
	attitudeRaw.gyros[ATTITUDERAW_GYROS_Y] = (gyro[2] - GYRO_NEUTRAL) * settings.GyroGain;
	attitudeRaw.gyros[ATTITUDERAW_GYROS_Z] = -(gyro[3] - GYRO_NEUTRAL) * settings.GyroGain;
	
	// Applying integral component here so it can be seen on the gyros and correct bias
	attitudeRaw.gyros[ATTITUDERAW_GYROS_X] += gyro_correct_int[0];
	attitudeRaw.gyros[ATTITUDERAW_GYROS_Y] += gyro_correct_int[1];

	// Because most crafts wont get enough information from gravity to zero yaw gyro
	attitudeRaw.gyros[ATTITUDERAW_GYROS_Z] += gyro_correct_int[2];
	gyro_correct_int[2] += - attitudeRaw.gyros[ATTITUDERAW_GYROS_Z] * 
		settings.AccelKI * UPDATE_RATE / 1000;
	
	
	// Get the accel data
	uint8_t i = 0;
	attitudeRaw.accels[ATTITUDERAW_ACCELS_X] = 0;
	attitudeRaw.accels[ATTITUDERAW_ACCELS_Y] = 0;
	attitudeRaw.accels[ATTITUDERAW_ACCELS_Z] = 0; 
	
	do {
		i++;
		attitudeRaw.gyrotemp[0] = PIOS_ADXL345_Read(&accel_data);
		
		attitudeRaw.accels[ATTITUDERAW_ACCELS_X] += (float) accel_data.x * 0.004f * 9.81;
		attitudeRaw.accels[ATTITUDERAW_ACCELS_Y] += -(float) accel_data.y * 0.004f * 9.81;
		attitudeRaw.accels[ATTITUDERAW_ACCELS_Z] += -(float) accel_data.z * 0.004f * 9.81;
	} while ( (i < 32) && (attitudeRaw.gyrotemp[0] > 0) );
	attitudeRaw.gyrotemp[1] = i;
	
	attitudeRaw.accels[ATTITUDERAW_ACCELS_X] /= i;
	attitudeRaw.accels[ATTITUDERAW_ACCELS_Y] /= i;
	attitudeRaw.accels[ATTITUDERAW_ACCELS_Z] /= i; 
	
	AttitudeRawSet(&attitudeRaw); 	
}

static void updateAttitude()
{
	AttitudeSettingsData settings;
	AttitudeSettingsGet(&settings);
	
	AttitudeActualData attitudeActual;
	AttitudeActualGet(&attitudeActual);
	
	AttitudeRawData attitudeRaw;
	AttitudeRawGet(&attitudeRaw);		
	
	static portTickType lastSysTime = 0;
	static portTickType thisSysTime;
	
	static float dT = 0;
	
	thisSysTime = xTaskGetTickCount();
	if(thisSysTime > lastSysTime) // reuse dt in case of wraparound
		dT = (thisSysTime - lastSysTime) / portTICK_RATE_MS / 1000.0f;
	lastSysTime = thisSysTime;
	
	// Bad practice to assume structure order, but saves memory
	float * q = &attitudeActual.q1;
	float * gyro = attitudeRaw.gyros;
	{
		float * accels = attitudeRaw.accels;
		float grot[3];
		float accel_err[3];
		
		// Rotate gravity to body frame and cross with accels
		grot[0] = -9.81 * (2 * (q[1] * q[3] - q[0] * q[2]));
		grot[1] = -9.81 * (2 * (q[2] * q[3] + q[0] * q[1]));
		grot[2] = -9.81 * (q[0] * q[0] - q[1]*q[1] - q[2]*q[2] + q[3]*q[3]);
		CrossProduct((const float *) accels, (const float *) grot, accel_err);
		
		// Accumulate integral of error.  Scale here so that units are rad/s
		gyro_correct_int[0] += accel_err[0] * settings.AccelKI * dT;
		gyro_correct_int[1] += accel_err[1] * settings.AccelKI * dT;
		//gyro_correct_int[2] += accel_err[2] * settings.AccelKI * dT;
		
		// Correct rates based on error, integral component dealt with in updateSensors
		gyro[0] += accel_err[0] * settings.AccelKp;
		gyro[1] += accel_err[1] * settings.AccelKp;
		gyro[2] += accel_err[2] * settings.AccelKp;
	}
	
	{ // scoping variables to save memory
		// Work out time derivative from INSAlgo writeup
		// Also accounts for the fact that gyros are in deg/s
		float qdot[4];
		qdot[0] = (-q[1] * gyro[0] - q[2] * gyro[1] - q[3] * gyro[2]) * dT * M_PI / 180 / 2;
		qdot[1] = (q[0] * gyro[0] - q[3] * gyro[1] + q[2] * gyro[2]) * dT * M_PI / 180 / 2;
		qdot[2] = (q[3] * gyro[0] + q[0] * gyro[1] - q[1] * gyro[2]) * dT * M_PI / 180 / 2;
		qdot[3] = (-q[2] * gyro[0] + q[1] * gyro[1] + q[0] * gyro[2]) * dT * M_PI / 180 / 2;
		
		// Take a time step
		q[0] = q[0] + qdot[0];
		q[1] = q[1] + qdot[1];
		q[2] = q[2] + qdot[2];
		q[3] = q[3] + qdot[3];
	}
	
	// Renomalize
	float qmag = sqrt(q[0]*q[0] + q[1]*q[1] + q[2]*q[2] + q[3]*q[3]);
	q[0] = q[0] / qmag;
	q[1] = q[1] / qmag;
	q[2] = q[2] / qmag;
	q[3] = q[3] / qmag;
	
	attitudeActual.q1 = q[0];
	attitudeActual.q2 = q[1];
	attitudeActual.q3 = q[2];
	attitudeActual.q4 = q[3];
	
	// Convert into eueler degrees (makes assumptions about RPY order)
	Quaternion2RPY(q,&attitudeActual.Roll);	

	AttitudeActualSet(&attitudeActual);
}
/**
  * @}
  * @}
  */