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/************************************************************************/
/* Flight Attitude */
/************************************************************************/
 
#include <stdlib.h>
#include <avr/io.h>
 
#include "attitude.h"
#include "dongfangMath.h"
 
// For scope debugging only!
#include "rc.h"
 
// where our main data flow comes from.
#include "analog.h"
 
#include "configuration.h"
#include "output.h"
 
// Some calculations are performed depending on some stick related things.
#include "controlMixer.h"
 
#define CHECK_MIN_MAX(value, min, max) {if(value < min) value = min; else if(value > max) value = max;}
 
/*
* Gyro readings, as read from the analog module. It would have been nice to flow
* them around between the different calculations as a struct or array (doing
* things functionally without side effects) but this is shorter and probably
* faster too.
* The variables are overwritten at each attitude calculation invocation - the values
* are not preserved or reused.
*/
int16_t rate_ATT[2], yawRate;
 
// With different (less) filtering
int16_t rate_PID[2];
int16_t differential[2];
 
/*
* Gyro readings, after performing "axis coupling" - that is, the transfomation
* of rotation rates from the airframe-local coordinate system to a ground-fixed
* coordinate system. If axis copling is disabled, the gyro readings will be
* copied into these directly.
* These are global for the same pragmatic reason as with the gyro readings.
* The variables are overwritten at each attitude calculation invocation - the values
* are not preserved or reused.
*/
int16_t ACRate[2], ACYawRate;
 
/*
* Gyro integrals. These are the rotation angles of the airframe compared to the
* horizontal plane, yaw relative to yaw at start.
*/
int32_t angle[2], yawAngleDiff;
 
int readingHeight = 0;
 
// Yaw angle and compass stuff.
 
// This is updated/written from MM3. Negative angle indicates invalid data.
int16_t compassHeading = -1;
 
// This is NOT updated from MM3. Negative angle indicates invalid data.
int16_t compassCourse = -1;
 
// The difference between the above 2 (heading - course) on a -180..179 degree interval.
// Not necessary. Never read anywhere.
// int16_t compassOffCourse = 0;
 
uint8_t updateCompassCourse = 0;
uint8_t compassCalState = 0;
uint16_t ignoreCompassTimer = 500;
 
int32_t yawGyroHeading; // Yaw Gyro Integral supported by compass
int16_t yawGyroDrift;
 
#define PITCHROLLOVER180 (GYRO_DEG_FACTOR_PITCHROLL * 180L)
#define PITCHROLLOVER360 (GYRO_DEG_FACTOR_PITCHROLL * 360L)
#define YAWOVER360 (GYRO_DEG_FACTOR_YAW * 360L)
 
int16_t correctionSum[2] = { 0, 0 };
 
// For NaviCTRL use.
int16_t averageAcc[2] = { 0, 0 }, averageAccCount = 0;
 
/*
* Experiment: Compensating for dynamic-induced gyro biasing.
*/
int16_t driftComp[2] = { 0, 0 }, driftCompYaw = 0;
// int16_t savedDynamicOffsetPitch = 0, savedDynamicOffsetRoll = 0;
// int32_t dynamicCalPitch, dynamicCalRoll, dynamicCalYaw;
// int16_t dynamicCalCount;
 
uint16_t accVector;
 
/************************************************************************
* Set inclination angles from the acc. sensor data.
* If acc. sensors are not used, set to zero.
* TODO: One could use inverse sine to calculate the angles more
* accurately, but since: 1) the angles are rather small at times when
* it makes sense to set the integrals (standing on ground, or flying at
* constant speed, and 2) at small angles a, sin(a) ~= constant * a,
* it is hardly worth the trouble.
************************************************************************/
 
int32_t getAngleEstimateFromAcc(uint8_t axis) {
int32_t correctionTerm = (dynamicParams.levelCorrection[axis] - 128) * 256L;
return GYRO_ACC_FACTOR * (int32_t) filteredAcc[axis] + correctionTerm;
}
 
void setStaticAttitudeAngles(void) {
#ifdef ATTITUDE_USE_ACC_SENSORS
angle[PITCH] = getAngleEstimateFromAcc(PITCH);
angle[ROLL] = getAngleEstimateFromAcc(ROLL);
#else
angle[PITCH] = angle[ROLL] = 0;
#endif
}
 
/************************************************************************
* Neutral Readings
************************************************************************/
void attitude_setNeutral(void) {
// Servo_Off(); // disable servo output. TODO: Why bother? The servos are going to make a jerk anyway.
dynamicParams.axisCoupling1 = dynamicParams.axisCoupling2 = 0;
 
driftComp[PITCH] = driftComp[ROLL] = yawGyroDrift = driftCompYaw = 0;
correctionSum[PITCH] = correctionSum[ROLL] = 0;
 
// Calibrate hardware.
analog_setNeutral();
 
// reset gyro integrals to acc guessing
setStaticAttitudeAngles();
yawAngleDiff = 0;
 
// update compass course to current heading
compassCourse = compassHeading;
 
// Inititialize YawGyroIntegral value with current compass heading
yawGyroHeading = (int32_t) compassHeading * GYRO_DEG_FACTOR_YAW;
 
// Servo_On(); //enable servo output
}
 
/************************************************************************
* Get sensor data from the analog module, and release the ADC
* TODO: Ultimately, the analog module could do this (instead of dumping
* the values into variables).
* The rate variable end up in a range of about [-1024, 1023].
*************************************************************************/
void getAnalogData(void) {
uint8_t axis;
 
analog_update();
 
for (axis = PITCH; axis <= ROLL; axis++) {
rate_PID[axis] = gyro_PID[axis] + driftComp[axis];
rate_ATT[axis] = gyro_ATT[axis] + driftComp[axis];
differential[axis] = gyroD[axis];
averageAcc[axis] += acc[axis];
}
 
averageAccCount++;
yawRate = yawGyro + driftCompYaw;
 
// We are done reading variables from the analog module.
// Interrupt-driven sensor reading may restart.
startAnalogConversionCycle();
}
 
/*
* This is the standard flight-style coordinate system transformation
* (from airframe-local axes to a ground-based system). For some reason
* the MK uses a left-hand coordinate system. The tranformation has been
* changed accordingly.
*/
void trigAxisCoupling(void) {
int16_t cospitch = int_cos(angle[PITCH]);
int16_t cosroll = int_cos(angle[ROLL]);
int16_t sinroll = int_sin(angle[ROLL]);
 
ACRate[PITCH] = (((int32_t)rate_ATT[PITCH] * cosroll - (int32_t)yawRate
* sinroll) >> MATH_UNIT_FACTOR_LOG);
 
ACRate[ROLL] = rate_ATT[ROLL] + (((((int32_t)rate_ATT[PITCH] * sinroll
+ (int32_t)yawRate * cosroll) >> MATH_UNIT_FACTOR_LOG) * int_tan(
angle[PITCH])) >> MATH_UNIT_FACTOR_LOG);
 
ACYawRate = ((int32_t)rate_ATT[PITCH] * sinroll + (int32_t)yawRate * cosroll) / cospitch;
 
ACYawRate = ((int32_t)rate_ATT[PITCH] * sinroll + (int32_t)yawRate * cosroll) / cospitch;
}
 
// 480 usec with axis coupling - almost no time without.
void integrate(void) {
// First, perform axis coupling. If disabled xxxRate is just copied to ACxxxRate.
uint8_t axis;
 
if (staticParams.bitConfig & CFG_AXIS_COUPLING_ACTIVE) {
trigAxisCoupling();
} else {
ACRate[PITCH] = rate_ATT[PITCH];
ACRate[ROLL] = rate_ATT[ROLL];
ACYawRate = yawRate;
}
 
/*
* Yaw
* Calculate yaw gyro integral (~ to rotation angle)
* Limit yawGyroHeading proportional to 0 deg to 360 deg
*/
yawGyroHeading += ACYawRate;
yawAngleDiff += yawRate;
 
if (yawGyroHeading >= YAWOVER360) {
yawGyroHeading -= YAWOVER360; // 360 deg. wrap
} else if (yawGyroHeading < 0) {
yawGyroHeading += YAWOVER360;
}
 
/*
* Pitch axis integration and range boundary wrap.
*/
for (axis = PITCH; axis <= ROLL; axis++) {
angle[axis] += ACRate[axis];
if (angle[axis] > PITCHROLLOVER180) {
angle[axis] -= PITCHROLLOVER360;
} else if (angle[axis] <= -PITCHROLLOVER180) {
angle[axis] += PITCHROLLOVER360;
}
}
}
 
/************************************************************************
* A kind of 0'th order integral correction, that corrects the integrals
* directly. This is the "gyroAccFactor" stuff in the original code.
* There is (there) also a drift compensation
* - it corrects the differential of the integral = the gyro offsets.
* That should only be necessary with drifty gyros like ENC-03.
************************************************************************/
void correctIntegralsByAcc0thOrder(void) {
// TODO: Consider changing this to: Only correct when integrals are less than ...., or only correct when angular velocities
// are less than ....., or reintroduce Kalman.
// Well actually the Z axis acc. check is not so silly.
uint8_t axis;
int32_t temp;
 
uint8_t ca = controlActivity >> 8;
uint8_t highControlActivity = (ca > staticParams.maxControlActivity);
 
if (highControlActivity) {
debugOut.digital[1] |= DEBUG_ACC0THORDER;
} else {
debugOut.digital[1] &= ~DEBUG_ACC0THORDER;
}
 
if (accVector <= dynamicParams.maxAccVector) {
debugOut.digital[0] |= DEBUG_ACC0THORDER;
uint8_t permilleAcc = staticParams.zerothOrderCorrection;
int32_t accDerived;
 
/*
if ((controlYaw < -64) || (controlYaw > 64)) { // reduce further if yaw stick is active
permilleAcc /= 2;
debugFullWeight = 0;
}
 
if ((maxControl[PITCH] > 64) || (maxControl[ROLL] > 64)) { // reduce effect during stick commands. Replace by controlActivity.
permilleAcc /= 2;
debugFullWeight = 0;
*/
 
if (highControlActivity) { // reduce effect during stick control activity
permilleAcc /= 4;
if (controlActivity > staticParams.maxControlActivity*2) { // reduce effect during stick control activity
permilleAcc /= 4;
}
}
 
/*
* Add to each sum: The amount by which the angle is changed just below.
*/
for (axis = PITCH; axis <= ROLL; axis++) {
accDerived = getAngleEstimateFromAcc(axis);
debugOut.analog[9 + axis] = (10 * accDerived) / GYRO_DEG_FACTOR_PITCHROLL;
 
// 1000 * the correction amount that will be added to the gyro angle in next line.
temp = angle[axis];
angle[axis] = ((int32_t) (1000L - permilleAcc) * temp
+ (int32_t) permilleAcc * accDerived) / 1000L;
correctionSum[axis] += angle[axis] - temp;
}
} else {
debugOut.analog[9] = 0;
debugOut.analog[10] = 0;
// experiment: Kill drift compensation updates when not flying smooth.
// correctionSum[PITCH] = correctionSum[ROLL] = 0;
debugOut.digital[0] &= ~DEBUG_ACC0THORDER;
}
}
 
/************************************************************************
* This is an attempt to correct not the error in the angle integrals
* (that happens in correctIntegralsByAcc0thOrder above) but rather the
* cause of it: Gyro drift, vibration and rounding errors.
* All the corrections made in correctIntegralsByAcc0thOrder over
* DRIFTCORRECTION_TIME cycles are summed up. This number is
* then divided by DRIFTCORRECTION_TIME to get the approx.
* correction that should have been applied to each iteration to fix
* the error. This is then added to the dynamic offsets.
************************************************************************/
// 2 times / sec. = 488/2
#define DRIFTCORRECTION_TIME 256L
void driftCorrection(void) {
static int16_t timer = DRIFTCORRECTION_TIME;
int16_t deltaCorrection;
int16_t round;
uint8_t axis;
 
if (!--timer) {
timer = DRIFTCORRECTION_TIME;
for (axis = PITCH; axis <= ROLL; axis++) {
// Take the sum of corrections applied, add it to delta
if (correctionSum[axis] >=0)
round = DRIFTCORRECTION_TIME / 2;
else
round = -DRIFTCORRECTION_TIME / 2;
deltaCorrection = (correctionSum[axis] + round) / DRIFTCORRECTION_TIME;
// Add the delta to the compensation. So positive delta means, gyro should have higher value.
driftComp[axis] += deltaCorrection / staticParams.driftCompDivider;
CHECK_MIN_MAX(driftComp[axis], -staticParams.driftCompLimit, staticParams.driftCompLimit);
// DebugOut.Analog[11 + axis] = correctionSum[axis];
// DebugOut.Analog[16 + axis] = correctionSum[axis];
debugOut.analog[28 + axis] = driftComp[axis];
 
correctionSum[axis] = 0;
}
}
}
 
void calculateAccVector(void) {
uint16_t temp;
temp = filteredAcc[0]/4;
accVector = temp * temp;
temp = filteredAcc[1]/4;
accVector += temp * temp;
temp = filteredAcc[2]/4;
accVector += temp * temp;
debugOut.analog[18] = accVector;
debugOut.analog[19] = dynamicParams.maxAccVector;
}
 
/************************************************************************
* Main procedure.
************************************************************************/
void calculateFlightAttitude(void) {
getAnalogData();
calculateAccVector();
integrate();
 
#ifdef ATTITUDE_USE_ACC_SENSORS
correctIntegralsByAcc0thOrder();
driftCorrection();
#endif
}
 
void updateCompass(void) {
int16_t w, v, r, correction, error;
 
if (compassCalState && !(MKFlags & MKFLAG_MOTOR_RUN)) {
if (controlMixer_testCompassCalState()) {
compassCalState++;
if (compassCalState < 5)
beepNumber(compassCalState);
else
beep(1000);
}
} else {
// get maximum attitude angle
w = abs(angle[PITCH] / 512);
v = abs(angle[ROLL] / 512);
if (v > w)
w = v;
correction = w / 8 + 1;
// calculate the deviation of the yaw gyro heading and the compass heading
if (compassHeading < 0)
error = 0; // disable yaw drift compensation if compass heading is undefined
else if (abs(yawRate) > 128) { // spinning fast
error = 0;
} else {
// compassHeading - yawGyroHeading, on a -180..179 deg interval.
error = ((540 + compassHeading - (yawGyroHeading / GYRO_DEG_FACTOR_YAW))
% 360) - 180;
}
if (!ignoreCompassTimer && w < 25) {
yawGyroDrift += error;
// Basically this gets set if we are in "fix" mode, and when starting.
if (updateCompassCourse) {
beep(200);
yawGyroHeading = (int32_t) compassHeading * GYRO_DEG_FACTOR_YAW;
compassCourse = compassHeading; //(int16_t)(yawGyroHeading / GYRO_DEG_FACTOR_YAW);
updateCompassCourse = 0;
}
}
yawGyroHeading += (error * 8) / correction;
 
/*
w = (w * dynamicParams.CompassYawEffect) / 32;
w = dynamicParams.CompassYawEffect - w;
*/
w = dynamicParams.compassYawEffect - (w * dynamicParams.compassYawEffect)
/ 32;
 
// As readable formula:
// w = dynamicParams.CompassYawEffect * (1-w/32);
 
if (w >= 0) { // maxAttitudeAngle < 32
if (!ignoreCompassTimer) {
/*v = 64 + (maxControl[PITCH] + maxControl[ROLL]) / 8;*/
v = 64 + controlActivity / 100;
// yawGyroHeading - compassCourse on a -180..179 degree interval.
r
= ((540 + yawGyroHeading / GYRO_DEG_FACTOR_YAW - compassCourse)
% 360) - 180;
v = (r * w) / v; // align to compass course
// limit yaw rate
w = 3 * dynamicParams.compassYawEffect;
if (v > w)
v = w;
else if (v < -w)
v = -w;
yawAngleDiff += v;
} else { // wait a while
ignoreCompassTimer--;
}
} else { // ignore compass at extreme attitudes for a while
ignoreCompassTimer = 500;
}
}
}
 
/*
* This is part of an experiment to measure average sensor offsets caused by motor vibration,
* and to compensate them away. It brings about some improvement, but no miracles.
* As long as the left stick is kept in the start-motors position, the dynamic compensation
* will measure the effect of vibration, to use for later compensation. So, one should keep
* the stick in the start-motors position for a few seconds, till all motors run (at the wrong
* speed unfortunately... must find a better way)
*/
/*
void attitude_startDynamicCalibration(void) {
dynamicCalPitch = dynamicCalRoll = dynamicCalYaw = dynamicCalCount = 0;
savedDynamicOffsetPitch = savedDynamicOffsetRoll = 1000;
}
 
void attitude_continueDynamicCalibration(void) {
// measure dynamic offset now...
dynamicCalPitch += hiResPitchGyro;
dynamicCalRoll += hiResRollGyro;
dynamicCalYaw += rawYawGyroSum;
dynamicCalCount++;
 
// Param6: Manual mode. The offsets are taken from Param7 and Param8.
if (dynamicParams.UserParam6 || 1) { // currently always enabled.
// manual mode
driftCompPitch = dynamicParams.UserParam7 - 128;
driftCompRoll = dynamicParams.UserParam8 - 128;
} else {
// use the sampled value (does not seem to work so well....)
driftCompPitch = savedDynamicOffsetPitch = -dynamicCalPitch / dynamicCalCount;
driftCompRoll = savedDynamicOffsetRoll = -dynamicCalRoll / dynamicCalCount;
driftCompYaw = -dynamicCalYaw / dynamicCalCount;
}
 
// keep resetting these meanwhile, to avoid accumulating errors.
setStaticAttitudeIntegrals();
yawAngle = 0;
}
*/