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LibrePilot/flight/INS/insgps_helper.c
2011-08-22 03:05:02 -05:00

292 lines
8.2 KiB
C

#include "ins.h"
#include "pios.h"
#include "ahrs_spi_comm.h"
#include "insgps.h"
#include "CoordinateConversions.h"
#define DEG_TO_RAD (M_PI / 180.0)
#define RAD_TO_DEG (180.0 / M_PI)
#define INSGPS_GPS_TIMEOUT 2 /* 2 seconds triggers reinit of position */
#define INSGPS_GPS_MINSAT 6 /* 2 seconds triggers reinit of position */
#define INSGPS_GPS_MINPDOP 3.5 /* minimum PDOP for postition updates */
#define timer_rate() 100000
#define timer_count() 1
//! Contains the data from the mag sensor chip
extern struct mag_sensor mag_data;
//! Contains the data from the accelerometer
extern struct accel_sensor accel_data;
//! Contains the data from the gyro
extern struct gyro_sensor gyro_data;
//! Conains the current estimate of the attitude
extern struct attitude_solution attitude_data;
//! Contains data from the altitude sensor
extern struct altitude_sensor altitude_data;
//! Contains data from the GPS (via the SPI link)
extern struct gps_sensor gps_data;
//! Offset correction of barometric alt, to match gps data
static float baro_offset = 0;
extern void send_calibration(void);
extern void send_attitude(void);
extern void send_velocity(void);
extern void send_position(void);
extern volatile int8_t ahrs_algorithm;
extern void get_accel_gyro_data();
extern void get_mag_data();
static uint32_t ins_last_time;
/* INS functions */
/**
* @brief Update the EKF when in outdoor mode. The primary difference is using the GPS values.
*/
void ins_outdoor_update()
{
float gyro[3], accel[3], vel[3];
static uint32_t last_gps_time = 0;
float dT;
uint16_t sensors;
dT = PIOS_DELAY_DiffuS(ins_last_time) / 1e6;
ins_last_time = PIOS_DELAY_GetRaw();
// This should only happen at start up or at mode switches
if(dT > 0.01)
dT = 0.01;
// format data for INS algo
gyro[0] = gyro_data.filtered.x;
gyro[1] = gyro_data.filtered.y;
gyro[2] = gyro_data.filtered.z;
accel[0] = accel_data.filtered.x,
accel[1] = accel_data.filtered.y,
accel[2] = accel_data.filtered.z,
INSStatePrediction(gyro, accel, dT);
attitude_data.quaternion.q1 = Nav.q[0];
attitude_data.quaternion.q2 = Nav.q[1];
attitude_data.quaternion.q3 = Nav.q[2];
attitude_data.quaternion.q4 = Nav.q[3];
send_attitude(); // get message out quickly
send_velocity();
send_position();
INSCovariancePrediction(dT);
sensors = 0;
/*
* Detect if greater than certain time since last gps update and if so
* reset EKF to that position since probably drifted too far for safe
* update
*/
uint32_t this_gps_time = timer_count();
float gps_delay;
if (this_gps_time < last_gps_time)
gps_delay = ((0xFFFF - last_gps_time) - this_gps_time) / timer_rate();
else
gps_delay = (this_gps_time - last_gps_time) / timer_rate();
last_gps_time = this_gps_time;
if (gps_data.updated)
{
vel[0] = gps_data.groundspeed * cos(gps_data.heading * DEG_TO_RAD);
vel[1] = gps_data.groundspeed * sin(gps_data.heading * DEG_TO_RAD);
vel[2] = 0;
if(gps_delay > INSGPS_GPS_TIMEOUT)
INSPosVelReset(gps_data.NED,vel); // position stale, reset
else {
sensors |= HORIZ_SENSORS | POS_SENSORS;
}
/*
* When using gps need to make sure that barometer is brought into NED frame
* we should try and see if the altitude from the home location is good enough
* to use for the offset but for now starting with this conservative filter
*/
if(fabs(gps_data.NED[2] + (altitude_data.altitude - baro_offset)) > 10) {
baro_offset = gps_data.NED[2] + altitude_data.altitude;
} else {
/* IIR filter with 100 second or so tau to keep them crudely in the same frame */
baro_offset = baro_offset * 0.999 + (gps_data.NED[2] + altitude_data.altitude) * 0.001;
}
gps_data.updated = false;
} else if (gps_delay > INSGPS_GPS_TIMEOUT) {
vel[0] = 0;
vel[1] = 0;
vel[2] = 0;
sensors |= VERT_SENSORS | HORIZ_SENSORS;
}
if(mag_data.updated) {
sensors |= MAG_SENSORS;
mag_data.updated = false;
}
if(altitude_data.updated) {
sensors |= BARO_SENSOR;
altitude_data.updated = false;
}
/*
* TODO: Need to add a general sanity check for all the inputs to make sure their kosher
* although probably should occur within INS itself
*/
INSCorrection(mag_data.scaled.axis, gps_data.NED, vel, altitude_data.altitude - baro_offset, sensors);
}
uint32_t time_val_a;
uint32_t indoor_time;
/**
* @brief Update the EKF when in indoor mode
*/
void ins_indoor_update()
{
time_val_a = PIOS_DELAY_GetRaw();
float gyro[3], accel[3], vel[3];
static uint32_t last_indoor_time = 0;
uint16_t sensors = 0;
float dT;
dT = PIOS_DELAY_DiffuS(ins_last_time) / 1e6;
ins_last_time = PIOS_DELAY_GetRaw();
// This should only happen at start up or at mode switches
if(dT > 0.01)
dT = 0.01;
// format data for INS algo
gyro[0] = gyro_data.filtered.x;
gyro[1] = gyro_data.filtered.y;
gyro[2] = gyro_data.filtered.z;
accel[0] = accel_data.filtered.x,
accel[1] = accel_data.filtered.y,
accel[2] = accel_data.filtered.z,
INSStatePrediction(gyro, accel, dT);
attitude_data.quaternion.q1 = Nav.q[0];
attitude_data.quaternion.q2 = Nav.q[1];
attitude_data.quaternion.q3 = Nav.q[2];
attitude_data.quaternion.q4 = Nav.q[3];
send_attitude(); // get message out quickly
send_velocity();
send_position();
INSCovariancePrediction(dT);
/* Indoors, update with zero position and velocity and high covariance */
vel[0] = 0;
vel[1] = 0;
vel[2] = 0;
uint32_t this_indoor_time = timer_count();
float indoor_delay;
/*
* Detect if greater than certain time since last gps update and if so
* reset EKF to that position since probably drifted too far for safe
* update
*/
if (this_indoor_time < last_indoor_time)
indoor_delay = ((0xFFFF - last_indoor_time) - this_indoor_time) / timer_rate();
else
indoor_delay = (this_indoor_time - last_indoor_time) / timer_rate();
last_indoor_time = this_indoor_time;
if(indoor_delay > INSGPS_GPS_TIMEOUT)
INSPosVelReset(vel,vel);
else
sensors = HORIZ_SENSORS | VERT_SENSORS;
if(mag_data.updated && (ahrs_algorithm == AHRSSETTINGS_ALGORITHM_INSGPS_INDOOR)) {
sensors |= MAG_SENSORS;
mag_data.updated = false;
}
if(altitude_data.updated) {
sensors |= BARO_SENSOR;
altitude_data.updated = false;
}
/*
* TODO: Need to add a general sanity check for all the inputs to make sure their kosher
* although probably should occur within INS itself
*/
INSCorrection(mag_data.scaled.axis, gps_data.NED, vel, altitude_data.altitude, sensors | HORIZ_SENSORS | VERT_SENSORS);
indoor_time = PIOS_DELAY_DiffuS(time_val_a);
}
/**
* @brief Initialize the EKF assuming stationary
*/
void ins_init_algorithm()
{
float Rbe[3][3], q[4], accels[3], rpy[3], mag;
float ge[3]={0,0,-9.81}, zeros[3]={0,0,0}, Pdiag[16]={25,25,25,5,5,5,1e-5,1e-5,1e-5,1e-5,1e-5,1e-5,1e-5,1e-4,1e-4,1e-4};
bool using_mags, using_gps;
INSGPSInit();
HomeLocationData home;
HomeLocationGet(&home);
accels[0]=accel_data.filtered.x;
accels[1]=accel_data.filtered.y;
accels[2]=accel_data.filtered.z;
using_mags = (ahrs_algorithm == AHRSSETTINGS_ALGORITHM_INSGPS_OUTDOOR) || (ahrs_algorithm == AHRSSETTINGS_ALGORITHM_INSGPS_INDOOR);
using_mags &= (home.Be[0] != 0) || (home.Be[1] != 0) || (home.Be[2] != 0); /* only use mags when valid home location */
using_gps = (ahrs_algorithm == AHRSSETTINGS_ALGORITHM_INSGPS_OUTDOOR) && (gps_data.quality != 0);
/* Block till a data update */
get_accel_gyro_data();
/* Ensure we get mag data in a timely manner */
uint16_t fail_count = 50; // 50 at 200 Hz is up to 0.25 sec
while(using_mags && !mag_data.updated && fail_count--) {
get_mag_data();
get_accel_gyro_data();
AhrsPoll();
PIOS_DELAY_WaituS(2000);
}
using_mags &= mag_data.updated;
if (using_mags) {
RotFrom2Vectors(accels, ge, mag_data.scaled.axis, home.Be, Rbe);
R2Quaternion(Rbe,q);
if (using_gps)
INSSetState(gps_data.NED, zeros, q, zeros, zeros);
else
INSSetState(zeros, zeros, q, zeros, zeros);
} else {
// assume yaw = 0
mag = VectorMagnitude(accels);
rpy[1] = asinf(-accels[0]/mag);
rpy[0] = atan2(accels[1]/mag,accels[2]/mag);
rpy[2] = 0;
RPY2Quaternion(rpy,q);
if (using_gps)
INSSetState(gps_data.NED, zeros, q, zeros, zeros);
else
INSSetState(zeros, zeros, q, zeros, zeros);
}
INSResetP(Pdiag);
// TODO: include initial estimate of gyro bias?
}