From b9038e5ed6fcc7bf71e29429ea90e71061be59b9 Mon Sep 17 00:00:00 2001 From: Corvus Corax Date: Fri, 28 Jun 2013 17:22:16 +0200 Subject: [PATCH] new simple complementary filter to calculate current altitude and vertical speed --- .../modules/StateEstimation/filteraltitude.c | 186 ++++++++++++++++++ .../StateEstimation/inc/stateestimation.h | 1 + .../modules/StateEstimation/stateestimation.c | 18 +- 3 files changed, 200 insertions(+), 5 deletions(-) create mode 100644 flight/modules/StateEstimation/filteraltitude.c diff --git a/flight/modules/StateEstimation/filteraltitude.c b/flight/modules/StateEstimation/filteraltitude.c new file mode 100644 index 000000000..01e94a458 --- /dev/null +++ b/flight/modules/StateEstimation/filteraltitude.c @@ -0,0 +1,186 @@ +/** + ****************************************************************************** + * @addtogroup OpenPilotModules OpenPilot Modules + * @{ + * @addtogroup State Estimation + * @brief Acquires sensor data and computes state estimate + * @{ + * + * @file filteraltitude.c + * @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2013. + * @brief Barometric altitude filter, calculates vertical speed and true + * altitude based on Barometric altitude and accelerometers + * + * @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 "inc/stateestimation.h" +#include + +#include + +// Private constants + +#define STACK_REQUIRED 128 + +#define BARO_SENSOR_KP 0.05f +#define ACCEL_DRIFT_KP 0.001f +#define DT_ALPHA 1e-3f + +// Private types +struct data { + float state[3]; // state = altitude,velocity,accel_offset + float pos[3]; // position updates from other filters + float vel[3]; // position updates from other filters + float dTA; + int32_t lastTime; + float baroLast; + int32_t baroLastTime; + bool first_run; +}; + +// Private variables + +// Private functions + +static int32_t init(stateFilter *self); +static int32_t filter(stateFilter *self, stateEstimation *state); + + +int32_t filterAltitudeInitialize(stateFilter *handle) +{ + handle->init = &init; + handle->filter = &filter; + handle->localdata = pvPortMalloc(sizeof(struct data)); + AttitudeStateInitialize(); + return STACK_REQUIRED; +} + +static int32_t init(stateFilter *self) +{ + struct data *this = (struct data *)self->localdata; + + this->state[0] = 0.0f; + this->state[1] = 0.0f; + this->state[2] = 0.0f; + this->pos[0] = 0.0f; + this->pos[1] = 0.0f; + this->pos[2] = 0.0f; + this->vel[0] = 0.0f; + this->vel[1] = 0.0f; + this->vel[2] = 0.0f; + this->dTA = -1; + this->first_run = 1; + return 0; +} + +static int32_t filter(stateFilter *self, stateEstimation *state) +{ + struct data *this = (struct data *)self->localdata; + + if (this->first_run) { + // Initialize to current altitude reading at initial location + if (IS_SET(state->updated, SENSORUPDATES_accel)) { + this->lastTime = PIOS_DELAY_GetRaw(); + } + if (IS_SET(state->updated, SENSORUPDATES_baro)) { + this->first_run = 0; + this->baroLastTime = PIOS_DELAY_GetRaw(); + this->state[0] = state->baro[0]; + this->baroLast = state->baro[0]; + } + } else { + + // save existing position and velocity updates so GPS will still work + if (IS_SET(state->updated, SENSORUPDATES_pos)) { + this->pos[0] = state->pos[0]; + this->pos[1] = state->pos[1]; + this->pos[2] = state->pos[2]; + state->pos[2] = -this->state[0]; + } + if (IS_SET(state->updated, SENSORUPDATES_vel)) { + this->vel[0] = state->vel[0]; + this->vel[1] = state->vel[1]; + this->vel[2] = state->vel[2]; + state->vel[2] = -this->state[1]; + } + if(IS_SET(state->updated, SENSORUPDATES_accel)) { + + // rotate accels into global coordinate frame + AttitudeStateData att; + AttitudeStateGet(&att); + float Rbe[3][3]; + Quaternion2R(&att.q1, Rbe); + float current = -(Rbe[0][2] * state->accel[0] + Rbe[1][2] * state->accel[1] + Rbe[2][2] * state->accel[2] + 9.81f); + + // correct accel offset (low pass zeroing) + this->state[2] = (1.0f - ACCEL_DRIFT_KP) * this->state[2] + ACCEL_DRIFT_KP * current; + + // correct velocity and position state (integration) + // low pass for average dT, compensate timing jitter from scheduler + float dT = PIOS_DELAY_DiffuS(this->lastTime) / 1.0e6f; + if (this->dTA<0) { + this->dTA = dT; + } else { + this->dTA = this->dTA * (1.0f - DT_ALPHA) + dT * DT_ALPHA; + } + this->state[1] += (current - this->state[1]) * this->dTA; + this->state[0] += this->state[1] * this->dTA; + + state->pos[0] = this->pos[0]; + state->pos[1] = this->pos[2]; + state->pos[2] = -this->state[0]; + state->updated |= SENSORUPDATES_pos; + + state->vel[0] = this->vel[0]; + state->vel[1] = this->vel[2]; + state->vel[2] = -this->state[0]; + state->updated |= SENSORUPDATES_vel; + } + if (IS_SET(state->updated, SENSORUPDATES_baro)) { + + // correct the altitude state (simple low pass) + this->state[0] = (1.0f - BARO_SENSOR_KP) * this->state[0] + BARO_SENSOR_KP * state->baro[0]; + + // correct the velocity state (low pass differentiation) + float dT = PIOS_DELAY_DiffuS(this->baroLastTime) / 1.0e6f; + if (dT<0.001f) dT = 0.001f; + this->state[1] = (1.0f - BARO_SENSOR_KP) * this->state[1] + BARO_SENSOR_KP * (state->baro[0] - this->baroLast) / dT; + this->baroLast = state->baro[0]; + + state->pos[0] = this->pos[0]; + state->pos[1] = this->pos[2]; + state->pos[2] = -this->state[0]; + state->updated |= SENSORUPDATES_pos; + + state->vel[0] = this->vel[0]; + state->vel[1] = this->vel[2]; + state->vel[2] = -this->state[0]; + state->updated |= SENSORUPDATES_vel; + } + } + + return 0; +} + + +/** + * @} + * @} + */ diff --git a/flight/modules/StateEstimation/inc/stateestimation.h b/flight/modules/StateEstimation/inc/stateestimation.h index 9b954874a..e80aa3148 100644 --- a/flight/modules/StateEstimation/inc/stateestimation.h +++ b/flight/modules/StateEstimation/inc/stateestimation.h @@ -64,6 +64,7 @@ typedef struct stateFilterStruct { int32_t filterMagInitialize(stateFilter *handle); int32_t filterBaroInitialize(stateFilter *handle); +int32_t filterAltitudeInitialize(stateFilter *handle); int32_t filterAirInitialize(stateFilter *handle); int32_t filterStationaryInitialize(stateFilter *handle); int32_t filterCFInitialize(stateFilter *handle); diff --git a/flight/modules/StateEstimation/stateestimation.c b/flight/modules/StateEstimation/stateestimation.c index 5ed371844..8fa673c2d 100644 --- a/flight/modules/StateEstimation/stateestimation.c +++ b/flight/modules/StateEstimation/stateestimation.c @@ -123,6 +123,7 @@ static filterPipeline *filterChain = NULL; // different filters available to state estimation static stateFilter magFilter; static stateFilter baroFilter; +static stateFilter altitudeFilter; static stateFilter airFilter; static stateFilter stationaryFilter; static stateFilter cfFilter; @@ -138,9 +139,12 @@ static filterPipeline *cfQueue = &(filterPipeline) { .next = &(filterPipeline) { .filter = &baroFilter, .next = &(filterPipeline) { - .filter = &cfFilter, - .next = NULL, - }, + .filter = &altitudeFilter, + .next = &(filterPipeline) { + .filter = &cfFilter, + .next = NULL, + } + } } } }; @@ -151,8 +155,11 @@ static const filterPipeline *cfmQueue = &(filterPipeline) { .next = &(filterPipeline) { .filter = &baroFilter, .next = &(filterPipeline) { - .filter = &cfmFilter, - .next = NULL, + .filter = &altitudeFilter, + .next = &(filterPipeline) { + .filter = &cfmFilter, + .next = NULL, + } } } } @@ -237,6 +244,7 @@ int32_t StateEstimationInitialize(void) // Initialize Filters stack_required = maxint32_t(stack_required, filterMagInitialize(&magFilter)); stack_required = maxint32_t(stack_required, filterBaroInitialize(&baroFilter)); + stack_required = maxint32_t(stack_required, filterAltitudeInitialize(&altitudeFilter)); stack_required = maxint32_t(stack_required, filterAirInitialize(&airFilter)); stack_required = maxint32_t(stack_required, filterStationaryInitialize(&stationaryFilter)); stack_required = maxint32_t(stack_required, filterCFInitialize(&cfFilter));