WebSVN - FlightCtrl - Diff - Rev 1978 and 1980 - /branches/dongfang_FC


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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) {
  return GYRO_ACC_FACTOR * (int32_t) filteredAcc[axis];
}
 
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;
  debugOut.digital[0] &= ~DEBUG_ACC0THORDER;
  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 (controlActivity > 10000) { // reduce effect during stick control activity
      permilleAcc /= 4;
      debugOut.digital[1] |= DEBUG_ACC0THORDER;
      if (controlActivity > 20000) { // reduce effect during stick control activity
        permilleAcc /= 4;
        debugOut.digital[1] |= DEBUG_ACC0THORDER;
      }
    }
 
    /*
     * 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;
  }
}
 
/************************************************************************
 * 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[19] = accVector;
}
 
/************************************************************************
 * 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;
 }
 */
 
Subversion Repositories FlightCtrl

(root)/branches/dongfang_FC_rewrite/attitude.c @ 2035 - Rev 1978 → 1980
