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152 lines
4.6 KiB
C
152 lines
4.6 KiB
C
/**
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******************************************************************************
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* @addtogroup OpenPilotModules OpenPilot Modules
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* @{
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* @addtogroup StabilizationModule Stabilization Module
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* @brief Relay tuning controller
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* @note This object updates the @ref ActuatorDesired "Actuator Desired" based on the
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* PID loops on the @ref AttitudeDesired "Attitude Desired" and @ref AttitudeActual "Attitude Actual"
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* @{
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*
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* @file stabilization.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
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* @brief Attitude stabilization module.
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*
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "openpilot.h"
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#include "relaytuning.h"
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#include "relaytuningsettings.h"
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#include "sin_lookup.h"
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//! Private variables
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static const int SIN_RESOLUTION = 180;
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#define MAX_AXES 3
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/**
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* Apply a step function for the stabilization controller and monitor the
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* result
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*
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* Used to Replace the rate PID with a relay to measure the critical properties of this axis
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* i.e. period and gain
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*/
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int stabilization_relay_rate(float error, float *output, int axis, bool reinit)
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{
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RelayTuningData relay;
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RelayTuningGet(&relay);
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static portTickType lastHighTime;
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static portTickType lastLowTime;
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static float accum_sin, accum_cos;
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static uint32_t accumulated = 0;
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const uint16_t DEGLITCH_TIME = 20; // ms
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const float AMPLITUDE_ALPHA = 0.95;
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const float PERIOD_ALPHA = 0.95;
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portTickType thisTime = xTaskGetTickCount();
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static bool rateRelayRunning[MAX_AXES];
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// This indicates the current estimate of the smoothed error. So when it is high
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// we are waiting for it to go low.
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static bool high = false;
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// On first run initialize estimates to something reasonable
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if(reinit) {
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rateRelayRunning[axis] = false;
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relay.Period[axis] = 200;
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relay.Gain[axis] = 0;
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accum_sin = 0;
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accum_cos = 0;
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accumulated = 0;
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// These should get reinitialized anyway
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high = true;
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lastHighTime = thisTime;
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lastLowTime = thisTime;
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RelayTuningSet(&relay);
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}
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RelayTuningSettingsData relaySettings;
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RelayTuningSettingsGet(&relaySettings);
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// Compute output, simple threshold on error
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*output = high ? relaySettings.Amplitude : -relaySettings.Amplitude;
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/**** The code below here is to estimate the properties of the oscillation ****/
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// Make sure the period can't go below limit
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if (relay.Period[axis] < DEGLITCH_TIME)
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relay.Period[axis] = DEGLITCH_TIME;
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// Project the error onto a sine and cosine of the same frequency
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// to accumulate the average amplitude
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int32_t dT = thisTime - lastHighTime;
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float phase = ((float)360 * (float)dT) / relay.Period[axis];
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if(phase >= 360)
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phase = 0;
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accum_sin += sin_lookup_deg(phase) * error;
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accum_cos += sin_lookup_deg(phase + 90) * error;
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accumulated ++;
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// Make sure we've had enough time since last transition then check for a change in the output
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bool time_hysteresis = (high ? (thisTime - lastHighTime) : (thisTime - lastLowTime)) > DEGLITCH_TIME;
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if ( !high && time_hysteresis && error > relaySettings.HysteresisThresh ){
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/* POSITIVE CROSSING DETECTED */
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float this_amplitude = 2 * sqrtf(accum_sin*accum_sin + accum_cos*accum_cos) / accumulated;
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float this_gain = this_amplitude / relaySettings.Amplitude;
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accumulated = 0;
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accum_sin = 0;
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accum_cos = 0;
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if(rateRelayRunning[axis] == false) {
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rateRelayRunning[axis] = true;
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relay.Period[axis] = 200;
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relay.Gain[axis] = 0;
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} else {
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// Low pass filter each amplitude and period
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relay.Gain[axis] = relay.Gain[axis] * AMPLITUDE_ALPHA + this_gain * (1 - AMPLITUDE_ALPHA);
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relay.Period[axis] = relay.Period[axis] * PERIOD_ALPHA + dT * (1 - PERIOD_ALPHA);
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}
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lastHighTime = thisTime;
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high = true;
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RelayTuningSet(&relay);
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} else if ( high && time_hysteresis && error < -relaySettings.HysteresisThresh ) {
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/* FALLING CROSSING DETECTED */
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lastLowTime = thisTime;
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high = false;
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}
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return 0;
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}
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