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inav/src/main/flight/imu.c
Konstantin Sharlaimov (DigitalEntity) c74905cbfd Debug vibration
2018-06-15 22:30:41 +02:00

609 lines
21 KiB
C

/*
* This file is part of Cleanflight.
*
* Cleanflight 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.
*
* Cleanflight 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 Cleanflight. If not, see <http://www.gnu.org/licenses/>.
*/
// Inertial Measurement Unit (IMU)
#include <stdbool.h>
#include <stdint.h>
#include <math.h>
#include "platform.h"
#include "blackbox/blackbox.h"
#include "build/build_config.h"
#include "build/debug.h"
#include "common/axis.h"
#include "common/filter.h"
#include "common/maths.h"
#include "common/vector.h"
#include "common/quaternion.h"
#include "config/feature.h"
#include "config/parameter_group.h"
#include "config/parameter_group_ids.h"
#include "drivers/time.h"
#include "fc/config.h"
#include "fc/runtime_config.h"
#include "flight/hil.h"
#include "flight/imu.h"
#include "flight/mixer.h"
#include "flight/pid.h"
#include "io/gps.h"
#include "sensors/acceleration.h"
#include "sensors/barometer.h"
#include "sensors/compass.h"
#include "sensors/gyro.h"
#include "sensors/sensors.h"
/**
* In Cleanflight accelerometer is aligned in the following way:
* X-axis = Forward
* Y-axis = Left
* Z-axis = Up
* Our INAV uses different convention
* X-axis = North/Forward
* Y-axis = East/Right
* Z-axis = Up
*/
// the limit (in degrees/second) beyond which we stop integrating
// omega_I. At larger spin rates the DCM PI controller can get 'dizzy'
// which results in false gyro drift. See
// http://gentlenav.googlecode.com/files/fastRotations.pdf
#define SPIN_RATE_LIMIT 20
#define MAX_ACC_SQ_NEARNESS 25 // 25% or G^2, accepted acceleration of (0.87 - 1.12G)
#define MAX_GPS_HEADING_ERROR_DEG 60 // Amount of error between GPS CoG and estimated Yaw at witch we stop trusting GPS and fallback to MAG
FASTRAM fpVector3_t imuMeasuredAccelBF;
FASTRAM fpVector3_t imuMeasuredRotationBF;
STATIC_FASTRAM float smallAngleCosZ;
STATIC_FASTRAM bool isAccelUpdatedAtLeastOnce;
STATIC_FASTRAM fpVector3_t vCorrectedMagNorth; // Magnetic North vector in EF (true North rotated by declination)
FASTRAM fpQuaternion_t orientation;
FASTRAM attitudeEulerAngles_t attitude; // absolute angle inclination in multiple of 0.1 degree 180 deg = 1800
FASTRAM float rMat[3][3];
STATIC_FASTRAM imuRuntimeConfig_t imuRuntimeConfig;
STATIC_FASTRAM bool gpsHeadingInitialized;
PG_REGISTER_WITH_RESET_TEMPLATE(imuConfig_t, imuConfig, PG_IMU_CONFIG, 0);
PG_RESET_TEMPLATE(imuConfig_t, imuConfig,
.dcm_kp_acc = 2500, // 0.25 * 10000
.dcm_ki_acc = 50, // 0.005 * 10000
.dcm_kp_mag = 10000, // 1.00 * 10000
.dcm_ki_mag = 0, // 0.00 * 10000
.small_angle = 25
);
STATIC_UNIT_TESTED void imuComputeRotationMatrix(void)
{
float q1q1 = orientation.q1 * orientation.q1;
float q2q2 = orientation.q2 * orientation.q2;
float q3q3 = orientation.q3 * orientation.q3;
float q0q1 = orientation.q0 * orientation.q1;
float q0q2 = orientation.q0 * orientation.q2;
float q0q3 = orientation.q0 * orientation.q3;
float q1q2 = orientation.q1 * orientation.q2;
float q1q3 = orientation.q1 * orientation.q3;
float q2q3 = orientation.q2 * orientation.q3;
rMat[0][0] = 1.0f - 2.0f * q2q2 - 2.0f * q3q3;
rMat[0][1] = 2.0f * (q1q2 + -q0q3);
rMat[0][2] = 2.0f * (q1q3 - -q0q2);
rMat[1][0] = 2.0f * (q1q2 - -q0q3);
rMat[1][1] = 1.0f - 2.0f * q1q1 - 2.0f * q3q3;
rMat[1][2] = 2.0f * (q2q3 + -q0q1);
rMat[2][0] = 2.0f * (q1q3 + -q0q2);
rMat[2][1] = 2.0f * (q2q3 - -q0q1);
rMat[2][2] = 1.0f - 2.0f * q1q1 - 2.0f * q2q2;
}
void imuConfigure(void)
{
imuRuntimeConfig.dcm_kp_acc = imuConfig()->dcm_kp_acc / 10000.0f;
imuRuntimeConfig.dcm_ki_acc = imuConfig()->dcm_ki_acc / 10000.0f;
imuRuntimeConfig.dcm_kp_mag = imuConfig()->dcm_kp_mag / 10000.0f;
imuRuntimeConfig.dcm_ki_mag = imuConfig()->dcm_ki_mag / 10000.0f;
imuRuntimeConfig.small_angle = imuConfig()->small_angle;
}
void imuInit(void)
{
smallAngleCosZ = cos_approx(degreesToRadians(imuRuntimeConfig.small_angle));
for (int axis = 0; axis < XYZ_AXIS_COUNT; axis++) {
imuMeasuredAccelBF.v[axis] = 0;
}
// Explicitly initialize FASTRAM statics
isAccelUpdatedAtLeastOnce = false;
gpsHeadingInitialized = false;
// Create magnetic declination matrix
const int deg = compassConfig()->mag_declination / 100;
const int min = compassConfig()->mag_declination % 100;
imuSetMagneticDeclination(deg + min / 60.0f);
quaternionInitUnit(&orientation);
imuComputeRotationMatrix();
}
void imuSetMagneticDeclination(float declinationDeg)
{
const float declinationRad = -DEGREES_TO_RADIANS(declinationDeg);
vCorrectedMagNorth.x = cos_approx(declinationRad);
vCorrectedMagNorth.y = sin_approx(declinationRad);
vCorrectedMagNorth.z = 0;
}
void imuTransformVectorBodyToEarth(fpVector3_t * v)
{
// From body frame to earth frame
quaternionRotateVectorInv(v, v, &orientation);
// HACK: This is needed to correctly transform from NED (sensor frame) to NEU (navigation)
v->y = -v->y;
}
void imuTransformVectorEarthToBody(fpVector3_t * v)
{
// HACK: This is needed to correctly transform from NED (sensor frame) to NEU (navigation)
v->y = -v->y;
// From earth frame to body frame
quaternionRotateVector(v, v, &orientation);
}
#if defined(USE_GPS) || defined(HIL)
STATIC_UNIT_TESTED void imuComputeQuaternionFromRPY(int16_t initialRoll, int16_t initialPitch, int16_t initialYaw)
{
if (initialRoll > 1800) initialRoll -= 3600;
if (initialPitch > 1800) initialPitch -= 3600;
if (initialYaw > 1800) initialYaw -= 3600;
const float cosRoll = cos_approx(DECIDEGREES_TO_RADIANS(initialRoll) * 0.5f);
const float sinRoll = sin_approx(DECIDEGREES_TO_RADIANS(initialRoll) * 0.5f);
const float cosPitch = cos_approx(DECIDEGREES_TO_RADIANS(initialPitch) * 0.5f);
const float sinPitch = sin_approx(DECIDEGREES_TO_RADIANS(initialPitch) * 0.5f);
const float cosYaw = cos_approx(DECIDEGREES_TO_RADIANS(-initialYaw) * 0.5f);
const float sinYaw = sin_approx(DECIDEGREES_TO_RADIANS(-initialYaw) * 0.5f);
orientation.q0 = cosRoll * cosPitch * cosYaw + sinRoll * sinPitch * sinYaw;
orientation.q1 = sinRoll * cosPitch * cosYaw - cosRoll * sinPitch * sinYaw;
orientation.q2 = cosRoll * sinPitch * cosYaw + sinRoll * cosPitch * sinYaw;
orientation.q3 = cosRoll * cosPitch * sinYaw - sinRoll * sinPitch * cosYaw;
imuComputeRotationMatrix();
}
#endif
static bool imuUseFastGains(void)
{
return !ARMING_FLAG(ARMED) && millis() < 20000;
}
static float imuGetPGainScaleFactor(void)
{
if (imuUseFastGains()) {
return 10.0f;
}
else {
return 1.0f;
}
}
static void imuResetOrientationQuaternion(const fpVector3_t * accBF)
{
const float accNorm = sqrtf(vectorNormSquared(accBF));
orientation.q0 = accBF->z + accNorm;
orientation.q1 = accBF->y;
orientation.q2 = -accBF->x;
orientation.q3 = 0.0f;
quaternionNormalize(&orientation, &orientation);
}
static void imuCheckAndResetOrientationQuaternion(const fpVector3_t * accBF)
{
// Check if some calculation in IMU update yield NAN or zero quaternion
// Reset quaternion from accelerometer - this might be incorrect, but it's better than no attitude at all
const float check = fabs(orientation.q0) + fabs(orientation.q1) + fabs(orientation.q2) + fabs(orientation.q3);
if (!isnan(check) && !isinf(check)) {
return;
}
const float normSq = quaternionNormSqared(&orientation);
if (normSq > (1.0f - 1e-6f) && normSq < (1.0f + 1e-6f)) {
return;
}
imuResetOrientationQuaternion(accBF);
DEBUG_TRACE("AHRS orientation quaternion error");
#ifdef USE_BLACKBOX
if (feature(FEATURE_BLACKBOX)) {
blackboxLogEvent(FLIGHT_LOG_EVENT_IMU_FAILURE, NULL);
}
#endif
}
static void imuMahonyAHRSupdate(float dt, const fpVector3_t * gyroBF, const fpVector3_t * accBF, const fpVector3_t * magBF, bool useCOG, float courseOverGround)
{
STATIC_FASTRAM fpVector3_t vGyroDriftEstimate = { 0 };
fpVector3_t vRotation = *gyroBF;
/* Calculate general spin rate (rad/s) */
const float spin_rate_sq = vectorNormSquared(&vRotation);
/* Step 1: Yaw correction */
// Use measured magnetic field vector
if (magBF || useCOG) {
static const fpVector3_t vForward = { .v = { 1.0f, 0.0f, 0.0f } };
fpVector3_t vErr = { .v = { 0.0f, 0.0f, 0.0f } };
if (magBF && vectorNormSquared(magBF) > 0.01f) {
fpVector3_t vMag;
// For magnetometer correction we make an assumption that magnetic field is perpendicular to gravity (ignore Z-component in EF).
// This way magnetic field will only affect heading and wont mess roll/pitch angles
// (hx; hy; 0) - measured mag field vector in EF (assuming Z-component is zero)
// This should yield direction to magnetic North (1; 0; 0)
quaternionRotateVectorInv(&vMag, magBF, &orientation); // BF -> EF
// Ignore magnetic inclination
vMag.z = 0.0f;
// Normalize to unit vector
vectorNormalize(&vMag, &vMag);
// Reference mag field vector heading is Magnetic North in EF. We compute that by rotating True North vector by declination and assuming Z-component is zero
// magnetometer error is cross product between estimated magnetic north and measured magnetic north (calculated in EF)
vectorCrossProduct(&vErr, &vMag, &vCorrectedMagNorth);
// Rotate error back into body frame
quaternionRotateVector(&vErr, &vErr, &orientation);
}
else if (useCOG) {
fpVector3_t vHeadingEF;
// Use raw heading error (from GPS or whatever else)
while (courseOverGround > M_PIf) courseOverGround -= (2.0f * M_PIf);
while (courseOverGround < -M_PIf) courseOverGround += (2.0f * M_PIf);
// William Premerlani and Paul Bizard, Direction Cosine Matrix IMU - Eqn. 22-23
// (Rxx; Ryx) - measured (estimated) heading vector (EF)
// (-cos(COG), sin(COG)) - reference heading vector (EF)
// Compute heading vector in EF from scalar CoG
fpVector3_t vCoG = { .v = { -cos_approx(courseOverGround), sin_approx(courseOverGround), 0.0f } };
// Rotate Forward vector from BF to EF - will yield Heading vector in Earth frame
quaternionRotateVectorInv(&vHeadingEF, &vForward, &orientation);
vHeadingEF.z = 0.0f;
// Normalize to unit vector
vectorNormalize(&vHeadingEF, &vHeadingEF);
// error is cross product between reference heading and estimated heading (calculated in EF)
vectorCrossProduct(&vErr, &vCoG, &vHeadingEF);
// Rotate error back into body frame
quaternionRotateVector(&vErr, &vErr, &orientation);
}
// Compute and apply integral feedback if enabled
if (imuRuntimeConfig.dcm_ki_mag > 0.0f) {
// Stop integrating if spinning beyond the certain limit
if (spin_rate_sq < sq(DEGREES_TO_RADIANS(SPIN_RATE_LIMIT))) {
fpVector3_t vTmp;
// integral error scaled by Ki
vectorScale(&vTmp, &vErr, imuRuntimeConfig.dcm_ki_mag * dt);
vectorAdd(&vGyroDriftEstimate, &vGyroDriftEstimate, &vTmp);
}
}
// Calculate kP gain and apply proportional feedback
vectorScale(&vErr, &vErr, imuRuntimeConfig.dcm_kp_mag * imuGetPGainScaleFactor());
vectorAdd(&vRotation, &vRotation, &vErr);
}
/* Step 2: Roll and pitch correction - use measured acceleration vector */
if (accBF) {
static const fpVector3_t vGravity = { .v = { 0.0f, 0.0f, 1.0f } };
fpVector3_t vEstGravity, vAcc, vErr;
// Calculate estimated gravity vector in body frame
quaternionRotateVector(&vEstGravity, &vGravity, &orientation); // EF -> BF
// Error is sum of cross product between estimated direction and measured direction of gravity
vectorNormalize(&vAcc, accBF);
vectorCrossProduct(&vErr, &vAcc, &vEstGravity);
// Compute and apply integral feedback if enabled
if (imuRuntimeConfig.dcm_ki_acc > 0.0f) {
// Stop integrating if spinning beyond the certain limit
if (spin_rate_sq < sq(DEGREES_TO_RADIANS(SPIN_RATE_LIMIT))) {
fpVector3_t vTmp;
// integral error scaled by Ki
vectorScale(&vTmp, &vErr, imuRuntimeConfig.dcm_ki_acc * dt);
vectorAdd(&vGyroDriftEstimate, &vGyroDriftEstimate, &vTmp);
}
}
// Calculate kP gain and apply proportional feedback
vectorScale(&vErr, &vErr, imuRuntimeConfig.dcm_kp_acc * imuGetPGainScaleFactor());
vectorAdd(&vRotation, &vRotation, &vErr);
}
// Apply gyro drift correction
vectorAdd(&vRotation, &vRotation, &vGyroDriftEstimate);
// Integrate rate of change of quaternion
fpVector3_t vTheta;
fpQuaternion_t deltaQ;
vectorScale(&vTheta, &vRotation, 0.5f * dt);
quaternionInitFromVector(&deltaQ, &vTheta);
const float thetaMagnitudeSq = vectorNormSquared(&vTheta);
// If calculated rotation is zero - don't update quaternion
if (thetaMagnitudeSq >= 1e-20) {
// Calculate quaternion delta:
// Theta is a axis/angle rotation. Direction of a vector is axis, magnitude is angle/2.
// Proper quaternion from axis/angle involves computing sin/cos, but the formula becomes numerically unstable as Theta approaches zero.
// For near-zero cases we use the first 3 terms of the Taylor series expansion for sin/cos. We check if fourth term is less than machine precision -
// then we can safely use the "low angle" approximated version without loss of accuracy.
if (thetaMagnitudeSq < sqrtf(24.0f * 1e-6f)) {
quaternionScale(&deltaQ, &deltaQ, 1.0f - thetaMagnitudeSq / 6.0f);
deltaQ.q0 = 1.0f - thetaMagnitudeSq / 2.0f;
}
else {
const float thetaMagnitude = sqrtf(thetaMagnitudeSq);
quaternionScale(&deltaQ, &deltaQ, sin_approx(thetaMagnitude) / thetaMagnitude);
deltaQ.q0 = cos_approx(thetaMagnitude);
}
// Calculate final orientation and renormalize
quaternionMultiply(&orientation, &orientation, &deltaQ);
quaternionNormalize(&orientation, &orientation);
}
// Check for invalid quaternion
imuCheckAndResetOrientationQuaternion(accBF);
// Pre-compute rotation matrix from quaternion
imuComputeRotationMatrix();
}
STATIC_UNIT_TESTED void imuUpdateEulerAngles(void)
{
/* Compute pitch/roll angles */
attitude.values.roll = RADIANS_TO_DECIDEGREES(atan2_approx(rMat[2][1], rMat[2][2]));
attitude.values.pitch = RADIANS_TO_DECIDEGREES((0.5f * M_PIf) - acos_approx(-rMat[2][0]));
attitude.values.yaw = RADIANS_TO_DECIDEGREES(-atan2_approx(rMat[1][0], rMat[0][0]));
if (attitude.values.yaw < 0)
attitude.values.yaw += 3600;
/* Update small angle state */
if (calculateCosTiltAngle() > smallAngleCosZ) {
ENABLE_STATE(SMALL_ANGLE);
} else {
DISABLE_STATE(SMALL_ANGLE);
}
}
static bool imuCanUseAccelerometerForCorrection(void)
{
float accMagnitudeSq = 0;
for (int axis = 0; axis < 3; axis++) {
accMagnitudeSq += acc.accADCf[axis] * acc.accADCf[axis];
}
// Magnitude^2 in percent of G^2
const float nearness = ABS(100 - (accMagnitudeSq * 100));
return (nearness > MAX_ACC_SQ_NEARNESS) ? false : true;
}
static void imuCalculateEstimatedAttitude(float dT)
{
#if defined(USE_MAG)
const bool canUseMAG = sensors(SENSOR_MAG) && compassIsHealthy();
#else
const bool canUseMAG = false;
#endif
const bool useAcc = imuCanUseAccelerometerForCorrection();
float courseOverGround = 0;
bool useMag = false;
bool useCOG = false;
#if defined(USE_GPS)
if (STATE(FIXED_WING)) {
bool canUseCOG = isGPSHeadingValid();
if (canUseCOG) {
if (gpsHeadingInitialized) {
// Use GPS heading if error is acceptable or if it's the only source of heading
if (ABS(gpsSol.groundCourse - attitude.values.yaw) < DEGREES_TO_DECIDEGREES(MAX_GPS_HEADING_ERROR_DEG) || !canUseMAG) {
courseOverGround = DECIDEGREES_TO_RADIANS(gpsSol.groundCourse);
useCOG = true;
}
}
else {
// Re-initialize quaternion from known Roll, Pitch and GPS heading
imuComputeQuaternionFromRPY(attitude.values.roll, attitude.values.pitch, gpsSol.groundCourse);
gpsHeadingInitialized = true;
// Force reset of heading hold target
resetHeadingHoldTarget(DECIDEGREES_TO_DEGREES(attitude.values.yaw));
}
// If we can't use COG and there's MAG available - fallback
if (!useCOG && canUseMAG) {
useMag = true;
}
}
else if (canUseMAG) {
useMag = true;
gpsHeadingInitialized = true; // GPS heading initialised from MAG, continue on GPS if possible
}
}
else {
// Multicopters don't use GPS heading
if (canUseMAG) {
useMag = true;
}
}
#else
// In absence of GPS MAG is the only option
if (canUseMAG) {
useMag = true;
}
#endif
fpVector3_t measuredMagBF = { .v = { mag.magADC[X], mag.magADC[Y], mag.magADC[Z] } };
imuMahonyAHRSupdate(dT, &imuMeasuredRotationBF,
useAcc ? &imuMeasuredAccelBF : NULL,
useMag ? &measuredMagBF : NULL,
useCOG, courseOverGround);
imuUpdateEulerAngles();
}
#ifdef HIL
void imuHILUpdate(void)
{
/* Set attitude */
attitude.values.roll = hilToFC.rollAngle;
attitude.values.pitch = hilToFC.pitchAngle;
attitude.values.yaw = hilToFC.yawAngle;
/* Compute rotation quaternion for future use */
imuComputeQuaternionFromRPY(attitude.values.roll, attitude.values.pitch, attitude.values.yaw);
/* Fake accADC readings */
accADCf[X] = hilToFC.bodyAccel[X] / GRAVITY_CMSS;
accADCf[Y] = hilToFC.bodyAccel[Y] / GRAVITY_CMSS;
accADCf[Z] = hilToFC.bodyAccel[Z] / GRAVITY_CMSS;
}
#endif
void imuUpdateAccelerometer(void)
{
#ifdef HIL
if (sensors(SENSOR_ACC) && !hilActive) {
accUpdate();
isAccelUpdatedAtLeastOnce = true;
}
#else
if (sensors(SENSOR_ACC)) {
accUpdate();
isAccelUpdatedAtLeastOnce = true;
}
#endif
}
void imuCheckVibrationLevels(void)
{
fpVector3_t accVibeLevels;
accGetVibrationLevels(&accVibeLevels);
const uint32_t accClipCount = accGetClipCount();
DEBUG_SET(DEBUG_VIBE, 0, accVibeLevels.x * 100);
DEBUG_SET(DEBUG_VIBE, 1, accVibeLevels.y * 100);
DEBUG_SET(DEBUG_VIBE, 2, accVibeLevels.z * 100);
DEBUG_SET(DEBUG_VIBE, 3, accClipCount);
}
void imuUpdateAttitude(timeUs_t currentTimeUs)
{
/* Calculate dT */
static timeUs_t previousIMUUpdateTimeUs;
const float dT = (currentTimeUs - previousIMUUpdateTimeUs) * 1e-6;
previousIMUUpdateTimeUs = currentTimeUs;
if (sensors(SENSOR_ACC) && isAccelUpdatedAtLeastOnce) {
#ifdef HIL
if (!hilActive) {
gyroGetMeasuredRotationRate(&imuMeasuredRotationBF); // Calculate gyro rate in body frame in rad/s
accGetMeasuredAcceleration(&imuMeasuredAccelBF); // Calculate accel in body frame in cm/s/s
imuCheckVibrationLevels();
imuCalculateEstimatedAttitude(dT); // Update attitude estimate
}
else {
imuHILUpdate();
imuUpdateMeasuredAcceleration();
}
#else
gyroGetMeasuredRotationRate(&imuMeasuredRotationBF); // Calculate gyro rate in body frame in rad/s
accGetMeasuredAcceleration(&imuMeasuredAccelBF); // Calculate accel in body frame in cm/s/s
imuCheckVibrationLevels();
imuCalculateEstimatedAttitude(dT); // Update attitude estimate
#endif
} else {
acc.accADCf[X] = 0.0f;
acc.accADCf[Y] = 0.0f;
acc.accADCf[Z] = 0.0f;
}
}
bool isImuReady(void)
{
return sensors(SENSOR_ACC) && gyroIsCalibrationComplete();
}
bool isImuHeadingValid(void)
{
return (sensors(SENSOR_MAG) && STATE(COMPASS_CALIBRATED)) || (STATE(FIXED_WING) && gpsHeadingInitialized);
}
float calculateCosTiltAngle(void)
{
return 1.0f - 2.0f * sq(orientation.q1) - 2.0f * sq(orientation.q2);
}