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LibrePilot/flight/OpenPilot/Modules/Guidance/guidance.c

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/**
******************************************************************************
*
* @file guidance.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
* @brief This module compared @ref PositionActuatl to @ref ActiveWaypoint
* and sets @ref AttitudeDesired. It only does this when the FlightMode field
* of @ref ManualControlCommand is Auto.
*
* @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 object: ActiveWaypoint
* Input object: PositionActual
* Input object: ManualControlCommand
* Output object: AttitudeDesired
*
* This module will periodically update the value of the AttitudeDesired object.
*
* The module executes in its own thread in this example.
*
* 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 "openpilot.h"
#include "guidance.h"
#include "guidancesettings.h"
#include "attitudeactual.h"
#include "attitudedesired.h"
#include "positiondesired.h" // object that will be updated by the module
#include "positionactual.h"
#include "manualcontrolcommand.h"
#include "stabilizationsettings.h"
#include "systemsettings.h"
#include "velocitydesired.h"
#include "velocityactual.h"
// Private constants
#define STACK_SIZE configMINIMAL_STACK_SIZE
#define TASK_PRIORITY (tskIDLE_PRIORITY+1)
// Private types
// Private variables
static xTaskHandle guidanceTaskHandle;
// Private functions
static void guidanceTask(void *parameters);
static float bound(float val, float min, float max);
static void updateVtolDesiredVelocity();
static void updateVtolDesiredAttitude();
/**
* Initialise the module, called on startup
* \returns 0 on success or -1 if initialisation failed
*/
int32_t GuidanceInitialize()
{
// Start main task
xTaskCreate(guidanceTask, (signed char *)"Guidance", STACK_SIZE, NULL, TASK_PRIORITY, &guidanceTaskHandle);
return 0;
}
static float northIntegral = 0;
static float northErrorLast = 0;
static float eastIntegral = 0;
static float eastErrorLast = 0;
static float downIntegral = 0;
static float downErrorLast = 0;
/**
* Module thread, should not return.
*/
static void guidanceTask(void *parameters)
{
SystemSettingsData systemSettings;
GuidanceSettingsData guidanceSettings;
ManualControlCommandData manualControl;
portTickType lastSysTime;
// Main task loop
lastSysTime = xTaskGetTickCount();
while (1) {
ManualControlCommandGet(&manualControl);
SystemSettingsGet(&systemSettings);
GuidanceSettingsGet(&guidanceSettings);
if ((manualControl.FlightMode == MANUALCONTROLCOMMAND_FLIGHTMODE_AUTO) &&
(systemSettings.AirframeType == SYSTEMSETTINGS_AIRFRAMETYPE_VTOL)) {
updateVtolDesiredVelocity();
updateVtolDesiredAttitude();
} else {
// Be cleaner and get rid of global variables
northIntegral = 0;
northErrorLast = 0;
eastIntegral = 0;
eastErrorLast = 0;
downIntegral = 0;
downErrorLast = 0;
}
vTaskDelayUntil(&lastSysTime, guidanceSettings.VelUpdatePeriod / portTICK_RATE_MS);
}
}
void updateVtolDesiredVelocity()
{
GuidanceSettingsData guidanceSettings;
PositionActualData positionActual;
PositionDesiredData positionDesired;
VelocityDesiredData velocityDesired;
GuidanceSettingsGet(&guidanceSettings);
PositionActualGet(&positionActual);
PositionDesiredGet(&positionDesired);
VelocityDesiredGet(&velocityDesired);
// Note all distances in cm
float dNorth = positionDesired.North - positionActual.North;
float dEast = positionDesired.East - positionActual.East;
float distance = sqrt(pow(dNorth, 2) + pow(dEast, 2));
float heading = atan2f(dEast, dNorth);
float groundspeed = bound(guidanceSettings.GroundVelocityP * distance,
0, guidanceSettings.MaxGroundspeed);
velocityDesired.North = groundspeed * cosf(heading);
velocityDesired.East = groundspeed * sinf(heading);
float dDown = positionDesired.Down - positionActual.Down;
velocityDesired.Down = bound(guidanceSettings.VertVelocityP * dDown,
-guidanceSettings.MaxVerticalSpeed,
guidanceSettings.MaxVerticalSpeed);
VelocityDesiredSet(&velocityDesired);
}
/**
* Module thread, should not return.
*/
static void updateVtolDesiredAttitude()
{
static portTickType lastSysTime;
portTickType thisSysTime = xTaskGetTickCount();;
float dT;
VelocityDesiredData velocityDesired;
VelocityActualData velocityActual;
AttitudeDesiredData attitudeDesired;
AttitudeActualData attitudeActual;
GuidanceSettingsData guidanceSettings;
StabilizationSettingsData stabSettings;
SystemSettingsData systemSettings;
float northError;
float northDerivative;
float northCommand;
float eastError;
float eastDerivative;
float eastCommand;
float downError;
float downDerivative;
// Check how long since last update
if(thisSysTime > lastSysTime) // reuse dt in case of wraparound
dT = (thisSysTime - lastSysTime) / portTICK_RATE_MS / 1000.0f;
lastSysTime = thisSysTime;
SystemSettingsGet(&systemSettings);
GuidanceSettingsGet(&guidanceSettings);
VelocityActualGet(&velocityActual);
VelocityDesiredGet(&velocityDesired);
AttitudeDesiredGet(&attitudeDesired);
VelocityDesiredGet(&velocityDesired);
AttitudeActualGet(&attitudeActual);
StabilizationSettingsGet(&stabSettings);
attitudeDesired.Yaw = 0; // try and face north
// Yaw and pitch output from ground speed PID loop
northError = velocityDesired.North - velocityActual.North;
northDerivative = (northError - northErrorLast) / dT;
northIntegral =
bound(northIntegral + northError * dT, -guidanceSettings.MaxVelIntegral,
guidanceSettings.MaxVelIntegral);
northErrorLast = northError;
northCommand =
northError * guidanceSettings.VelP + northDerivative * guidanceSettings.VelD + northIntegral * guidanceSettings.VelI;
eastError = velocityDesired.East - velocityActual.East;
eastDerivative = (eastError - eastErrorLast) / dT;
eastIntegral = bound(eastIntegral + eastError * dT,
-guidanceSettings.MaxVelIntegral,
guidanceSettings.MaxVelIntegral);
eastErrorLast = eastError;
eastCommand = eastError * guidanceSettings.VelP + eastDerivative * guidanceSettings.VelD + eastIntegral * guidanceSettings.VelI;
// Project the north and east command signals into the pitch and roll based on yaw. For this to behave well the
// craft should move similarly for 5 deg roll versus 5 deg pitch
attitudeDesired.Pitch = bound(-northCommand * cosf(attitudeActual.Yaw * M_PI / 180) +
eastCommand * sinf(attitudeActual.Yaw * M_PI / 180),
-stabSettings.PitchMax, stabSettings.PitchMax);
attitudeDesired.Roll = bound(-northCommand * sinf(attitudeActual.Yaw * M_PI / 180) +
eastCommand * cosf(attitudeActual.Yaw * M_PI / 180),
-stabSettings.RollMax, stabSettings.RollMax);
downError = velocityDesired.Down - velocityActual.Down;
downDerivative = (downError - downErrorLast) / guidanceSettings.VelPIDUpdatePeriod;
downIntegral = bound(downIntegral + downError * guidanceSettings.VelPIDUpdatePeriod,
-guidanceSettings.MaxThrottleIntegral,
guidanceSettings.MaxThrottleIntegral);
downErrorLast = downError;
attitudeDesired.Throttle = bound(downError * guidanceSettings.DownP + downDerivative * guidanceSettings.DownD +
downIntegral * guidanceSettings.DownI, 0, 1);
// For now override throttle with manual control. Disable at your risk, quad goes to China.
ManualControlCommandData manualControl;
ManualControlCommandGet(&manualControl);
attitudeDesired.Throttle = manualControl.Throttle;
AttitudeDesiredSet(&attitudeDesired);
}
/**
* Bound input value between limits
*/
static float bound(float val, float min, float max)
{
if (val < min) {
val = min;
} else if (val > max) {
val = max;
}
return val;
}