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LibrePilot/flight/modules/Stabilization/stabilization.c

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/**
******************************************************************************
* @addtogroup OpenPilotModules OpenPilot Modules
* @{
* @addtogroup StabilizationModule Stabilization Module
* @brief Stabilization PID loops in an airframe type independent manner
* @note This object updates the @ref ActuatorDesired "Actuator Desired" based on the
* PID loops on the @ref AttitudeDesired "Attitude Desired" and @ref AttitudeState "Attitude State"
* @{
*
* @file stabilization.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
* @brief Attitude stabilization module.
*
* @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
*/
#include <openpilot.h>
#include "stabilization.h"
#include "stabilizationsettings.h"
#include "actuatordesired.h"
#include "ratedesired.h"
#include "relaytuning.h"
#include "relaytuningsettings.h"
#include "stabilizationdesired.h"
#include "attitudestate.h"
#include "gyrostate.h"
#include "flightstatus.h"
#include "manualcontrol.h" // Just to get a macro
#include "taskinfo.h"
// Math libraries
#include "CoordinateConversions.h"
#include "pid.h"
#include "sin_lookup.h"
// Includes for various stabilization algorithms
#include "relay_tuning.h"
#include "virtualflybar.h"
// Includes for various stabilization algorithms
#include "relay_tuning.h"
// Private constants
#define MAX_QUEUE_SIZE 1
#if defined(PIOS_STABILIZATION_STACK_SIZE)
#define STACK_SIZE_BYTES PIOS_STABILIZATION_STACK_SIZE
#else
#define STACK_SIZE_BYTES 724
#endif
#define TASK_PRIORITY (tskIDLE_PRIORITY + 4)
#define FAILSAFE_TIMEOUT_MS 30
enum { PID_RATE_ROLL, PID_RATE_PITCH, PID_RATE_YAW, PID_ROLL, PID_PITCH, PID_YAW, PID_MAX };
// Private variables
static xTaskHandle taskHandle;
static StabilizationSettingsData settings;
static xQueueHandle queue;
float gyro_alpha = 0;
float axis_lock_accum[3] = { 0, 0, 0 };
uint8_t max_axis_lock = 0;
uint8_t max_axislock_rate = 0;
float weak_leveling_kp = 0;
uint8_t weak_leveling_max = 0;
bool lowThrottleZeroIntegral;
bool lowThrottleZeroAxis[MAX_AXES];
float vbar_decay = 0.991f;
struct pid pids[PID_MAX];
// Private functions
static void stabilizationTask(void *parameters);
static float bound(float val, float range);
static void ZeroPids(void);
static void SettingsUpdatedCb(UAVObjEvent *ev);
/**
* Module initialization
*/
int32_t StabilizationStart()
{
// Initialize variables
// Create object queue
queue = xQueueCreate(MAX_QUEUE_SIZE, sizeof(UAVObjEvent));
// Listen for updates.
// AttitudeStateConnectQueue(queue);
GyroStateConnectQueue(queue);
StabilizationSettingsConnectCallback(SettingsUpdatedCb);
SettingsUpdatedCb(StabilizationSettingsHandle());
// Start main task
xTaskCreate(stabilizationTask, (signed char *)"Stabilization", STACK_SIZE_BYTES / 4, NULL, TASK_PRIORITY, &taskHandle);
PIOS_TASK_MONITOR_RegisterTask(TASKINFO_RUNNING_STABILIZATION, taskHandle);
#ifdef PIOS_INCLUDE_WDG
PIOS_WDG_RegisterFlag(PIOS_WDG_STABILIZATION);
#endif
return 0;
}
/**
* Module initialization
*/
int32_t StabilizationInitialize()
{
// Initialize variables
StabilizationSettingsInitialize();
ActuatorDesiredInitialize();
#ifdef DIAG_RATEDESIRED
RateDesiredInitialize();
#endif
// Code required for relay tuning
sin_lookup_initalize();
RelayTuningSettingsInitialize();
RelayTuningInitialize();
return 0;
}
MODULE_INITCALL(StabilizationInitialize, StabilizationStart);
/**
* Module task
*/
static void stabilizationTask(__attribute__((unused)) void *parameters)
{
UAVObjEvent ev;
uint32_t timeval = PIOS_DELAY_GetRaw();
ActuatorDesiredData actuatorDesired;
StabilizationDesiredData stabDesired;
RateDesiredData rateDesired;
AttitudeStateData attitudeState;
GyroStateData gyroStateData;
FlightStatusData flightStatus;
SettingsUpdatedCb((UAVObjEvent *)NULL);
// Main task loop
ZeroPids();
while (1) {
float dT;
#ifdef PIOS_INCLUDE_WDG
PIOS_WDG_UpdateFlag(PIOS_WDG_STABILIZATION);
#endif
// Wait until the AttitudeRaw object is updated, if a timeout then go to failsafe
if (xQueueReceive(queue, &ev, FAILSAFE_TIMEOUT_MS / portTICK_RATE_MS) != pdTRUE) {
AlarmsSet(SYSTEMALARMS_ALARM_STABILIZATION, SYSTEMALARMS_ALARM_WARNING);
continue;
}
dT = PIOS_DELAY_DiffuS(timeval) * 1.0e-6f;
timeval = PIOS_DELAY_GetRaw();
FlightStatusGet(&flightStatus);
StabilizationDesiredGet(&stabDesired);
AttitudeStateGet(&attitudeState);
GyroStateGet(&gyroStateData);
#ifdef DIAG_RATEDESIRED
RateDesiredGet(&rateDesired);
#endif
#if defined(PIOS_QUATERNION_STABILIZATION)
// Quaternion calculation of error in each axis. Uses more memory.
float rpy_desired[3];
float q_desired[4];
float q_error[4];
float local_error[3];
// Essentially zero errors for anything in rate or none
if (stabDesired.StabilizationMode.fields.Roll == STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE) {
rpy_desired[0] = stabDesired.Roll;
} else {
rpy_desired[0] = attitudeState.Roll;
}
if (stabDesired.StabilizationMode.fields.Pitch == STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE) {
rpy_desired[1] = stabDesired.Pitch;
} else {
rpy_desired[1] = attitudeState.Pitch;
}
if (stabDesired.StabilizationMode.fields.Yaw == STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE) {
rpy_desired[2] = stabDesired.Yaw;
} else {
rpy_desired[2] = attitudeState.Yaw;
}
RPY2Quaternion(rpy_desired, q_desired);
quat_inverse(q_desired);
quat_mult(q_desired, &attitudeState.q1, q_error);
quat_inverse(q_error);
Quaternion2RPY(q_error, local_error);
#else /* if defined(PIOS_QUATERNION_STABILIZATION) */
// Simpler algorithm for CC, less memory
float local_error[3] = { stabDesired.Roll - attitudeState.Roll,
stabDesired.Pitch - attitudeState.Pitch,
stabDesired.Yaw - attitudeState.Yaw };
// find shortest way
float modulo = fmodf(local_error[2] + 180.0f, 360.0f);
if (modulo < 0) {
local_error[2] = modulo + 180.0f;
} else {
local_error[2] = modulo - 180.0f;
}
#endif /* if defined(PIOS_QUATERNION_STABILIZATION) */
float gyro_filtered[3];
gyro_filtered[0] = gyro_filtered[0] * gyro_alpha + gyroStateData.x * (1 - gyro_alpha);
gyro_filtered[1] = gyro_filtered[1] * gyro_alpha + gyroStateData.y * (1 - gyro_alpha);
gyro_filtered[2] = gyro_filtered[2] * gyro_alpha + gyroStateData.z * (1 - gyro_alpha);
float *attitudeDesiredAxis = &stabDesired.Roll;
float *actuatorDesiredAxis = &actuatorDesired.Roll;
float *rateDesiredAxis = &rateDesired.Roll;
ActuatorDesiredGet(&actuatorDesired);
// A flag to track which stabilization mode each axis is in
static uint8_t previous_mode[MAX_AXES] = { 255, 255, 255 };
bool error = false;
// Run the selected stabilization algorithm on each axis:
for (uint8_t i = 0; i < MAX_AXES; i++) {
// Check whether this axis mode needs to be reinitialized
bool reinit = (stabDesired.StabilizationMode.data[i] != previous_mode[i]);
previous_mode[i] = stabDesired.StabilizationMode.data[i];
// Apply the selected control law
switch (stabDesired.StabilizationMode.data[i]) {
case STABILIZATIONDESIRED_STABILIZATIONMODE_RATE:
if (reinit) {
pids[PID_RATE_ROLL + i].iAccumulator = 0;
}
// Store to rate desired variable for storing to UAVO
rateDesiredAxis[i] = bound(attitudeDesiredAxis[i], settings.ManualRate.data[i]);
// Compute the inner loop
actuatorDesiredAxis[i] = pid_apply_setpoint(&pids[PID_RATE_ROLL + i], rateDesiredAxis[i], gyro_filtered[i], dT);
actuatorDesiredAxis[i] = bound(actuatorDesiredAxis[i], 1.0f);
break;
case STABILIZATIONDESIRED_STABILIZATIONMODE_ATTITUDE:
if (reinit) {
pids[PID_ROLL + i].iAccumulator = 0;
pids[PID_RATE_ROLL + i].iAccumulator = 0;
}
// Compute the outer loop
rateDesiredAxis[i] = pid_apply(&pids[PID_ROLL + i], local_error[i], dT);
rateDesiredAxis[i] = bound(rateDesiredAxis[i], settings.MaximumRate.data[i]);
// Compute the inner loop
actuatorDesiredAxis[i] = pid_apply_setpoint(&pids[PID_RATE_ROLL + i], rateDesiredAxis[i], gyro_filtered[i], dT);
actuatorDesiredAxis[i] = bound(actuatorDesiredAxis[i], 1.0f);
break;
case STABILIZATIONDESIRED_STABILIZATIONMODE_VIRTUALBAR:
// Store for debugging output
rateDesiredAxis[i] = attitudeDesiredAxis[i];
// Run a virtual flybar stabilization algorithm on this axis
stabilization_virtual_flybar(gyro_filtered[i], rateDesiredAxis[i], &actuatorDesiredAxis[i], dT, reinit, i, &settings);
break;
case STABILIZATIONDESIRED_STABILIZATIONMODE_WEAKLEVELING:
{
if (reinit) {
pids[PID_RATE_ROLL + i].iAccumulator = 0;
}
float weak_leveling = local_error[i] * weak_leveling_kp;
weak_leveling = bound(weak_leveling, weak_leveling_max);
// Compute desired rate as input biased towards leveling
rateDesiredAxis[i] = attitudeDesiredAxis[i] + weak_leveling;
actuatorDesiredAxis[i] = pid_apply_setpoint(&pids[PID_RATE_ROLL + i], rateDesiredAxis[i], gyro_filtered[i], dT);
actuatorDesiredAxis[i] = bound(actuatorDesiredAxis[i], 1.0f);
break;
}
case STABILIZATIONDESIRED_STABILIZATIONMODE_AXISLOCK:
if (reinit) {
pids[PID_RATE_ROLL + i].iAccumulator = 0;
}
if (fabsf(attitudeDesiredAxis[i]) > max_axislock_rate) {
// While getting strong commands act like rate mode
rateDesiredAxis[i] = attitudeDesiredAxis[i];
axis_lock_accum[i] = 0;
} else {
// For weaker commands or no command simply attitude lock (almost) on no gyro change
axis_lock_accum[i] += (attitudeDesiredAxis[i] - gyro_filtered[i]) * dT;
axis_lock_accum[i] = bound(axis_lock_accum[i], max_axis_lock);
rateDesiredAxis[i] = pid_apply(&pids[PID_ROLL + i], axis_lock_accum[i], dT);
}
rateDesiredAxis[i] = bound(rateDesiredAxis[i], settings.ManualRate.data[i]);
actuatorDesiredAxis[i] = pid_apply_setpoint(&pids[PID_RATE_ROLL + i], rateDesiredAxis[i], gyro_filtered[i], dT);
actuatorDesiredAxis[i] = bound(actuatorDesiredAxis[i], 1.0f);
break;
case STABILIZATIONDESIRED_STABILIZATIONMODE_RELAYRATE:
// Store to rate desired variable for storing to UAVO
rateDesiredAxis[i] = bound(attitudeDesiredAxis[i], settings.ManualRate.data[i]);
// Run the relay controller which also estimates the oscillation parameters
stabilization_relay_rate(rateDesiredAxis[i] - gyro_filtered[i], &actuatorDesiredAxis[i], i, reinit);
actuatorDesiredAxis[i] = bound(actuatorDesiredAxis[i], 1.0f);
break;
case STABILIZATIONDESIRED_STABILIZATIONMODE_RELAYATTITUDE:
if (reinit) {
pids[PID_ROLL + i].iAccumulator = 0;
}
// Compute the outer loop like attitude mode
rateDesiredAxis[i] = pid_apply(&pids[PID_ROLL + i], local_error[i], dT);
rateDesiredAxis[i] = bound(rateDesiredAxis[i], settings.MaximumRate.data[i]);
// Run the relay controller which also estimates the oscillation parameters
stabilization_relay_rate(rateDesiredAxis[i] - gyro_filtered[i], &actuatorDesiredAxis[i], i, reinit);
actuatorDesiredAxis[i] = bound(actuatorDesiredAxis[i], 1.0f);
break;
case STABILIZATIONDESIRED_STABILIZATIONMODE_NONE:
actuatorDesiredAxis[i] = bound(attitudeDesiredAxis[i], 1.0f);
break;
default:
error = true;
break;
}
}
if (settings.VbarPiroComp == STABILIZATIONSETTINGS_VBARPIROCOMP_TRUE) {
stabilization_virtual_flybar_pirocomp(gyro_filtered[2], dT);
}
#ifdef DIAG_RATEDESIRED
RateDesiredSet(&rateDesired);
#endif
// Save dT
actuatorDesired.UpdateTime = dT * 1000;
actuatorDesired.Throttle = stabDesired.Throttle;
// Suppress desired output while disarmed or throttle low, for configured axis
if (flightStatus.Armed != FLIGHTSTATUS_ARMED_ARMED || stabDesired.Throttle < 0) {
if (lowThrottleZeroAxis[ROLL]) {
actuatorDesired.Roll = 0.0f;
}
if (lowThrottleZeroAxis[PITCH]) {
actuatorDesired.Pitch = 0.0f;
}
if (lowThrottleZeroAxis[YAW]) {
actuatorDesired.Yaw = 0.0f;
}
}
if (PARSE_FLIGHT_MODE(flightStatus.FlightMode) != FLIGHTMODE_MANUAL) {
ActuatorDesiredSet(&actuatorDesired);
} else {
// Force all axes to reinitialize when engaged
for (uint8_t i = 0; i < MAX_AXES; i++) {
previous_mode[i] = 255;
}
}
if (flightStatus.Armed != FLIGHTSTATUS_ARMED_ARMED ||
(lowThrottleZeroIntegral && stabDesired.Throttle < 0)) {
// Force all axes to reinitialize when engaged
for (uint8_t i = 0; i < MAX_AXES; i++) {
previous_mode[i] = 255;
}
}
// Clear or set alarms. Done like this to prevent toggline each cycle
// and hammering system alarms
if (error) {
AlarmsSet(SYSTEMALARMS_ALARM_STABILIZATION, SYSTEMALARMS_ALARM_ERROR);
} else {
AlarmsClear(SYSTEMALARMS_ALARM_STABILIZATION);
}
}
}
/**
* Clear the accumulators and derivatives for all the axes
*/
static void ZeroPids(void)
{
for (uint32_t i = 0; i < PID_MAX; i++) {
pid_zero(&pids[i]);
}
for (uint8_t i = 0; i < 3; i++) {
axis_lock_accum[i] = 0.0f;
}
}
/**
* Bound input value between limits
*/
static float bound(float val, float range)
{
if (val < -range) {
val = -range;
} else if (val > range) {
val = range;
}
return val;
}
static void SettingsUpdatedCb(__attribute__((unused)) UAVObjEvent *ev)
{
StabilizationSettingsGet(&settings);
// Set the roll rate PID constants
pid_configure(&pids[PID_RATE_ROLL], settings.RollRatePID.fields.Kp,
settings.RollRatePID.fields.Ki,
pids[PID_RATE_ROLL].d = settings.RollRatePID.fields.Kd,
pids[PID_RATE_ROLL].iLim = settings.RollRatePID.fields.ILimit);
// Set the pitch rate PID constants
pid_configure(&pids[PID_RATE_PITCH], settings.PitchRatePID.fields.Kp,
pids[PID_RATE_PITCH].i = settings.PitchRatePID.fields.Ki,
pids[PID_RATE_PITCH].d = settings.PitchRatePID.fields.Kd,
pids[PID_RATE_PITCH].iLim = settings.PitchRatePID.fields.ILimit);
// Set the yaw rate PID constants
pid_configure(&pids[PID_RATE_YAW], settings.YawRatePID.fields.Kp,
pids[PID_RATE_YAW].i = settings.YawRatePID.fields.Ki,
pids[PID_RATE_YAW].d = settings.YawRatePID.fields.Kd,
pids[PID_RATE_YAW].iLim = settings.YawRatePID.fields.ILimit);
// Set the roll attitude PI constants
pid_configure(&pids[PID_ROLL], settings.RollPI.fields.Kp,
settings.RollPI.fields.Ki, 0,
pids[PID_ROLL].iLim = settings.RollPI.fields.ILimit);
// Set the pitch attitude PI constants
pid_configure(&pids[PID_PITCH], settings.PitchPI.fields.Kp,
pids[PID_PITCH].i = settings.PitchPI.fields.Ki, 0,
settings.PitchPI.fields.ILimit);
// Set the yaw attitude PI constants
pid_configure(&pids[PID_YAW], settings.YawPI.fields.Kp,
settings.YawPI.fields.Ki, 0,
settings.YawPI.fields.ILimit);
// Set up the derivative term
pid_configure_derivative(settings.DerivativeCutoff, settings.DerivativeGamma);
// Maximum deviation to accumulate for axis lock
max_axis_lock = settings.MaxAxisLock;
max_axislock_rate = settings.MaxAxisLockRate;
// Settings for weak leveling
weak_leveling_kp = settings.WeakLevelingKp;
weak_leveling_max = settings.MaxWeakLevelingRate;
// Whether to zero the PID integrals while throttle is low
lowThrottleZeroIntegral = settings.LowThrottleZeroIntegral == STABILIZATIONSETTINGS_LOWTHROTTLEZEROINTEGRAL_TRUE;
// Whether to suppress (zero) the StabilizationDesired output for each axis while disarmed or throttle is low
lowThrottleZeroAxis[ROLL] = settings.LowThrottleZeroAxis.fields.Roll== STABILIZATIONSETTINGS_LOWTHROTTLEZEROAXIS_TRUE;
lowThrottleZeroAxis[PITCH] = settings.LowThrottleZeroAxis.fields.Pitch == STABILIZATIONSETTINGS_LOWTHROTTLEZEROAXIS_TRUE;
lowThrottleZeroAxis[YAW] = settings.LowThrottleZeroAxis.fields.Yaw == STABILIZATIONSETTINGS_LOWTHROTTLEZEROAXIS_TRUE;
// The dT has some jitter iteration to iteration that we don't want to
// make thie result unpredictable. Still, it's nicer to specify the constant
// based on a time (in ms) rather than a fixed multiplier. The error between
// update rates on OP (~300 Hz) and CC (~475 Hz) is negligible for this
// calculation
const float fakeDt = 0.0025f;
if (settings.GyroTau < 0.0001f) {
gyro_alpha = 0; // not trusting this to resolve to 0
} else {
gyro_alpha = expf(-fakeDt / settings.GyroTau);
}
// Compute time constant for vbar decay term based on a tau
vbar_decay = expf(-fakeDt / settings.VbarTau);
}
/**
* @}
* @}
*/
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