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LibrePilot/flight/modules/Stabilization/relay_tuning.c
2013-04-25 13:13:36 +03:00

152 lines
4.6 KiB
C

/**
******************************************************************************
* @addtogroup OpenPilotModules OpenPilot Modules
* @{
* @addtogroup StabilizationModule Stabilization Module
* @brief Relay tuning controller
* @note This object updates the @ref ActuatorDesired "Actuator Desired" based on the
* PID loops on the @ref AttitudeDesired "Attitude Desired" and @ref AttitudeActual "Attitude Actual"
* @{
*
* @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 "relaytuning.h"
#include "relaytuningsettings.h"
#include "sin_lookup.h"
//! Private variables
static const int SIN_RESOLUTION = 180;
#define MAX_AXES 3
/**
* Apply a step function for the stabilization controller and monitor the
* result
*
* Used to Replace the rate PID with a relay to measure the critical properties of this axis
* i.e. period and gain
*/
int stabilization_relay_rate(float error, float *output, int axis, bool reinit)
{
RelayTuningData relay;
RelayTuningGet(&relay);
static portTickType lastHighTime;
static portTickType lastLowTime;
static float accum_sin, accum_cos;
static uint32_t accumulated = 0;
const uint16_t DEGLITCH_TIME = 20; // ms
const float AMPLITUDE_ALPHA = 0.95;
const float PERIOD_ALPHA = 0.95;
portTickType thisTime = xTaskGetTickCount();
static bool rateRelayRunning[MAX_AXES];
// This indicates the current estimate of the smoothed error. So when it is high
// we are waiting for it to go low.
static bool high = false;
// On first run initialize estimates to something reasonable
if(reinit) {
rateRelayRunning[axis] = false;
relay.Period[axis] = 200;
relay.Gain[axis] = 0;
accum_sin = 0;
accum_cos = 0;
accumulated = 0;
// These should get reinitialized anyway
high = true;
lastHighTime = thisTime;
lastLowTime = thisTime;
RelayTuningSet(&relay);
}
RelayTuningSettingsData relaySettings;
RelayTuningSettingsGet(&relaySettings);
// Compute output, simple threshold on error
*output = high ? relaySettings.Amplitude : -relaySettings.Amplitude;
/**** The code below here is to estimate the properties of the oscillation ****/
// Make sure the period can't go below limit
if (relay.Period[axis] < DEGLITCH_TIME)
relay.Period[axis] = DEGLITCH_TIME;
// Project the error onto a sine and cosine of the same frequency
// to accumulate the average amplitude
int32_t dT = thisTime - lastHighTime;
float phase = ((float)360 * (float)dT) / relay.Period[axis];
if(phase >= 360)
phase = 0;
accum_sin += sin_lookup_deg(phase) * error;
accum_cos += sin_lookup_deg(phase + 90) * error;
accumulated ++;
// Make sure we've had enough time since last transition then check for a change in the output
bool time_hysteresis = (high ? (thisTime - lastHighTime) : (thisTime - lastLowTime)) > DEGLITCH_TIME;
if ( !high && time_hysteresis && error > relaySettings.HysteresisThresh ){
/* POSITIVE CROSSING DETECTED */
float this_amplitude = 2 * sqrtf(accum_sin*accum_sin + accum_cos*accum_cos) / accumulated;
float this_gain = this_amplitude / relaySettings.Amplitude;
accumulated = 0;
accum_sin = 0;
accum_cos = 0;
if(rateRelayRunning[axis] == false) {
rateRelayRunning[axis] = true;
relay.Period[axis] = 200;
relay.Gain[axis] = 0;
} else {
// Low pass filter each amplitude and period
relay.Gain[axis] = relay.Gain[axis] * AMPLITUDE_ALPHA + this_gain * (1 - AMPLITUDE_ALPHA);
relay.Period[axis] = relay.Period[axis] * PERIOD_ALPHA + dT * (1 - PERIOD_ALPHA);
}
lastHighTime = thisTime;
high = true;
RelayTuningSet(&relay);
} else if ( high && time_hysteresis && error < -relaySettings.HysteresisThresh ) {
/* FALLING CROSSING DETECTED */
lastLowTime = thisTime;
high = false;
}
return 0;
}