Subversion Repositories FlightCtrl

/************************************************************************/
/* 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"

// For Servo_On / Off
// #include "timer2.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[3];

/*
 * 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;

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;

/************************************************************************
 * 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.
  driftComp[PITCH] = driftComp[ROLL] = yawGyroDrift = driftCompYaw = 0;
  correctionSum[PITCH] = correctionSum[ROLL] = 0;

  // Calibrate hardware.
  analog_calibrate();

  // 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;

  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];
  }

  differential[YAW] = gyroD[YAW];

  averageAccCount++;
  yawRate = yawGyro + driftCompYaw;

  // We are done reading variables from the analog module.
  // Interrupt-driven sensor reading may restart.
  analogDataReady = 0;
  analog_start();
}

/*
 * 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.GlobalConfig & 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;
  if (acc[Z] >= -dynamicParams.UserParams[7] && acc[Z]
      <= dynamicParams.UserParams[7]) {
    DebugOut.Digital[0] |= DEBUG_ACC0THORDER;

    uint8_t permilleAcc = staticParams.GyroAccFactor; // NOTE!!! The meaning of this value has changed!!
    uint8_t debugFullWeight = 1;
    int32_t accDerived;

    if ((control[YAW] < -64) || (control[YAW] > 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 (debugFullWeight)
      DebugOut.Digital[1] |= DEBUG_ACC0THORDER;
    else
      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]; //(permilleAcc * (accDerived - angle[axis])) / 1000;
      angle[axis] = ((int32_t) (1000L - permilleAcc) * temp
          + (int32_t) permilleAcc * accDerived) / 1000L;
      correctionSum[axis] += angle[axis] - temp;
    }
  } else {
    DebugOut.Digital[0] &= ~DEBUG_ACC0THORDER;
    DebugOut.Digital[1] &= ~DEBUG_ACC0THORDER;
    // DebugOut.Analog[9] = 0;
    // DebugOut.Analog[10] = 0;

    DebugOut.Analog[16] = 0;
    DebugOut.Analog[17] = 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.GyroAccTrim;
      CHECK_MIN_MAX(driftComp[axis], -staticParams.DriftComp, staticParams.DriftComp);
      // DebugOut.Analog[11 + axis] = correctionSum[axis];
      DebugOut.Analog[16 + axis] = correctionSum[axis];
      DebugOut.Analog[28 + axis] = driftComp[axis];

      correctionSum[axis] = 0;
    }
  }
}

/************************************************************************
 * Main procedure.
 ************************************************************************/
void calculateFlightAttitude(void) {
  getAnalogData();
  integrate();

  DebugOut.Analog[3] = rate_PID[PITCH];
  DebugOut.Analog[4] = rate_PID[ROLL];
  DebugOut.Analog[5] = yawRate;

#ifdef ATTITUDE_USE_ACC_SENSORS
  correctIntegralsByAcc0thOrder();
  driftCorrection();
#endif
}