estimator_kalman.c

/**
 * Authored by Michael Hamer (http://www.mikehamer.info), June 2016
 * Thank you to Mark Mueller (www.mwm.im) for advice during implementation,
 * and for derivation of the original filter in the below-cited paper.
 *
 * This program 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, in version 3.
 *
 * This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
 *
 * ============================================================================
 *
 * The Kalman filter implemented in this file is based on the papers:
 *
 * "Fusing ultra-wideband range measurements with accelerometers and rate gyroscopes for quadrocopter state estimation"
 * http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7139421
 *
 * and
 *
 * "Covariance Correction Step for Kalman Filtering with an Attitude"
 * http://arc.aiaa.org/doi/abs/10.2514/1.G000848
 *
 * Academic citation would be appreciated.
 *
 * BIBTEX ENTRIES:
      @INPROCEEDINGS{MuellerHamerUWB2015,
      author  = {Mueller, Mark W and Hamer, Michael and D’Andrea, Raffaello},
      title   = {Fusing ultra-wideband range measurements with accelerometers and rate gyroscopes for quadrocopter state estimation},
      booktitle = {2015 IEEE International Conference on Robotics and Automation (ICRA)},
      year    = {2015},
      month   = {May},
      pages   = {1730-1736},
      doi     = {10.1109/ICRA.2015.7139421},
      ISSN    = {1050-4729}}

      @ARTICLE{MuellerCovariance2016,
      author={Mueller, Mark W and Hehn, Markus and D’Andrea, Raffaello},
      title={Covariance Correction Step for Kalman Filtering with an Attitude},
      journal={Journal of Guidance, Control, and Dynamics},
      pages={1--7},
      year={2016},
      publisher={American Institute of Aeronautics and Astronautics}}
 *
 * ============================================================================
 *
 * MAJOR CHANGELOG:
 * 2016.06.28, Mike Hamer: Initial version
 * 2019.04.12, Kristoffer Richardsson: Refactored, separated kalman implementation from OS related functionality
 *
 */

#include "kalman_core.h"
#include "estimator_kalman.h"
#include "kalman_supervisor.h"

#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
#include "semphr.h"
#include "sensors.h"
#include "static_mem.h"

#include "system.h"
#include "log.h"
#include "param.h"
#include "physicalConstants.h"

#include "statsCnt.h"

#define DEBUG_MODULE "ESTKALMAN"
#include "debug.h"


// #define KALMAN_USE_BARO_UPDATE


/**
 * Additionally, the filter supports the incorporation of additional sensors into the state estimate
 *
 * This is done via the external functions:
 * - bool estimatorKalmanEnqueueUWBPacket(uwbPacket_t *uwb)
 * - bool estimatorKalmanEnqueuePosition(positionMeasurement_t *pos)
 * - bool estimatorKalmanEnqueueDistance(distanceMeasurement_t *dist)
 *
 * As well as by the following internal functions and datatypes
 */

// Distance-to-point measurements
static xQueueHandle distDataQueue;
STATIC_MEM_QUEUE_ALLOC(distDataQueue, 10, sizeof(distanceMeasurement_t));

static inline bool stateEstimatorHasDistanceMeasurement(distanceMeasurement_t *dist) {
  return (pdTRUE == xQueueReceive(distDataQueue, dist, 0));
}

// Direct measurements of Crazyflie position
static xQueueHandle posDataQueue;
STATIC_MEM_QUEUE_ALLOC(posDataQueue, 10, sizeof(positionMeasurement_t));

static inline bool stateEstimatorHasPositionMeasurement(positionMeasurement_t *pos) {
  return (pdTRUE == xQueueReceive(posDataQueue, pos, 0));
}

// Direct measurements of Crazyflie pose
static xQueueHandle poseDataQueue;
STATIC_MEM_QUEUE_ALLOC(poseDataQueue, 10, sizeof(poseMeasurement_t));

static inline bool stateEstimatorHasPoseMeasurement(poseMeasurement_t *pose) {
  return (pdTRUE == xQueueReceive(poseDataQueue, pose, 0));
}

// Measurements of a UWB Tx/Rx
static xQueueHandle tdoaDataQueue;
STATIC_MEM_QUEUE_ALLOC(tdoaDataQueue, 10, sizeof(tdoaMeasurement_t));

static inline bool stateEstimatorHasTDOAPacket(tdoaMeasurement_t *uwb) {
  return (pdTRUE == xQueueReceive(tdoaDataQueue, uwb, 0));
}

// Measurements of flow (dnx, dny)
static xQueueHandle flowDataQueue;
STATIC_MEM_QUEUE_ALLOC(flowDataQueue, 10, sizeof(flowMeasurement_t));

static inline bool stateEstimatorHasFlowPacket(flowMeasurement_t *flow) {
  return (pdTRUE == xQueueReceive(flowDataQueue, flow, 0));
}

// Measurements of TOF from laser sensor
static xQueueHandle tofDataQueue;
STATIC_MEM_QUEUE_ALLOC(tofDataQueue, 10, sizeof(tofMeasurement_t));

static inline bool stateEstimatorHasTOFPacket(tofMeasurement_t *tof) {
  return (pdTRUE == xQueueReceive(tofDataQueue, tof, 0));
}

// Absolute height measurement along the room Z
static xQueueHandle heightDataQueue;
STATIC_MEM_QUEUE_ALLOC(heightDataQueue, 10, sizeof(heightMeasurement_t));

static inline bool stateEstimatorHasHeightPacket(heightMeasurement_t *height) {
  return (pdTRUE == xQueueReceive(heightDataQueue, height, 0));
}


static xQueueHandle yawErrorDataQueue;
STATIC_MEM_QUEUE_ALLOC(yawErrorDataQueue, 10, sizeof(yawErrorMeasurement_t));

static inline bool stateEstimatorHasYawErrorPacket(yawErrorMeasurement_t *error)
{
  return (pdTRUE == xQueueReceive(yawErrorDataQueue, error, 0));
}

static xQueueHandle sweepAnglesDataQueue;
STATIC_MEM_QUEUE_ALLOC(sweepAnglesDataQueue, 10, sizeof(sweepAngleMeasurement_t));

static inline bool stateEstimatorHasSweepAnglesPacket(sweepAngleMeasurement_t *angles)
{
  return (pdTRUE == xQueueReceive(sweepAnglesDataQueue, angles, 0));
}

// Semaphore to signal that we got data from the stabilzer loop to process
static SemaphoreHandle_t runTaskSemaphore;

// Mutex to protect data that is shared between the task and
// functions called by the stabilizer loop
static SemaphoreHandle_t dataMutex;
static StaticSemaphore_t dataMutexBuffer;


/**
 * Constants used in the estimator
 */

#define CRAZYFLIE_WEIGHT_grams (27.0f)

//thrust is thrust mapped for 65536 <==> 60 GRAMS!
#define CONTROL_TO_ACC (GRAVITY_MAGNITUDE*60.0f/CRAZYFLIE_WEIGHT_grams/65536.0f)


/**
 * Tuning parameters
 */
#define PREDICT_RATE RATE_100_HZ // this is slower than the IMU update rate of 500Hz
#define BARO_RATE RATE_25_HZ

// the point at which the dynamics change from stationary to flying
#define IN_FLIGHT_THRUST_THRESHOLD (GRAVITY_MAGNITUDE*0.1f)
#define IN_FLIGHT_TIME_THRESHOLD (500)

// The bounds on the covariance, these shouldn't be hit, but sometimes are... why?
#define MAX_COVARIANCE (100)
#define MIN_COVARIANCE (1e-6f)



/**
 * Quadrocopter State
 *
 * The internally-estimated state is:
 * - X, Y, Z: the quad's position in the global frame
 * - PX, PY, PZ: the quad's velocity in its body frame
 * - D0, D1, D2: attitude error
 *
 * For more information, refer to the paper
 */

NO_DMA_CCM_SAFE_ZERO_INIT static kalmanCoreData_t coreData;

/**
 * Internal variables. Note that static declaration results in default initialization (to 0)
 */

static bool isInit = false;

static Axis3f accAccumulator;
static float thrustAccumulator;
static Axis3f gyroAccumulator;
static float baroAslAccumulator;
static uint32_t accAccumulatorCount;
static uint32_t thrustAccumulatorCount;
static uint32_t gyroAccumulatorCount;
static uint32_t baroAccumulatorCount;
static bool quadIsFlying = false;
static uint32_t lastFlightCmd;
static uint32_t takeoffTime;

// Data used to enable the task and stabilizer loop to run with minimal locking
static state_t taskEstimatorState; // The estimator state produced by the task, copied to the stabilzer when needed.
static Axis3f gyroSnapshot; // A snpashot of the latest gyro data, used by the task
static Axis3f accSnapshot; // A snpashot of the latest acc data, used by the task

// Statistics
#define ONE_SECOND 1000
static STATS_CNT_RATE_DEFINE(updateCounter, ONE_SECOND);
static STATS_CNT_RATE_DEFINE(predictionCounter, ONE_SECOND);
static STATS_CNT_RATE_DEFINE(baroUpdateCounter, ONE_SECOND);
static STATS_CNT_RATE_DEFINE(finalizeCounter, ONE_SECOND);
static STATS_CNT_RATE_DEFINE(measurementAppendedCounter, ONE_SECOND);
static STATS_CNT_RATE_DEFINE(measurementNotAppendedCounter, ONE_SECOND);

#ifdef KALMAN_USE_BARO_UPDATE
static const bool useBaroUpdate = true;
#else
static const bool useBaroUpdate = false;
#endif

/**
 * Supporting and utility functions
 */

static inline void mat_trans(const arm_matrix_instance_f32 * pSrc, arm_matrix_instance_f32 * pDst)
  { configASSERT(ARM_MATH_SUCCESS == arm_mat_trans_f32(pSrc, pDst)); }
static inline void mat_inv(const arm_matrix_instance_f32 * pSrc, arm_matrix_instance_f32 * pDst)
  { configASSERT(ARM_MATH_SUCCESS == arm_mat_inverse_f32(pSrc, pDst)); }
static inline void mat_mult(const arm_matrix_instance_f32 * pSrcA, const arm_matrix_instance_f32 * pSrcB, arm_matrix_instance_f32 * pDst)
  { configASSERT(ARM_MATH_SUCCESS == arm_mat_mult_f32(pSrcA, pSrcB, pDst)); }
static inline float arm_sqrt(float32_t in)
  { float pOut = 0; arm_status result = arm_sqrt_f32(in, &pOut); configASSERT(ARM_MATH_SUCCESS == result); return pOut; }

static void kalmanTask(void* parameters);
static bool predictStateForward(uint32_t osTick, float dt);
static bool updateQueuedMeasurments(const Axis3f *gyro, const uint32_t tick);

STATIC_MEM_TASK_ALLOC_STACK_NO_DMA_CCM_SAFE(kalmanTask, 3 * configMINIMAL_STACK_SIZE);

// --------------------------------------------------

// Called one time during system startup
void estimatorKalmanTaskInit() {
  distDataQueue = STATIC_MEM_QUEUE_CREATE(distDataQueue);
  posDataQueue = STATIC_MEM_QUEUE_CREATE(posDataQueue);
  poseDataQueue = STATIC_MEM_QUEUE_CREATE(poseDataQueue);
  tdoaDataQueue = STATIC_MEM_QUEUE_CREATE(tdoaDataQueue);
  flowDataQueue = STATIC_MEM_QUEUE_CREATE(flowDataQueue);
  tofDataQueue = STATIC_MEM_QUEUE_CREATE(tofDataQueue);
  heightDataQueue = STATIC_MEM_QUEUE_CREATE(heightDataQueue);
  yawErrorDataQueue = STATIC_MEM_QUEUE_CREATE(yawErrorDataQueue);
  sweepAnglesDataQueue = STATIC_MEM_QUEUE_CREATE(sweepAnglesDataQueue);

  vSemaphoreCreateBinary(runTaskSemaphore);

  dataMutex = xSemaphoreCreateMutexStatic(&dataMutexBuffer);

  STATIC_MEM_TASK_CREATE(kalmanTask, kalmanTask, KALMAN_TASK_NAME, NULL, KALMAN_TASK_PRI);

  isInit = true;
}

bool estimatorKalmanTaskTest() {
  return isInit;
}

static void kalmanTask(void* parameters) {
  systemWaitStart();

  uint32_t lastPrediction = xTaskGetTickCount();
  uint32_t nextPrediction = xTaskGetTickCount();
  uint32_t lastPNUpdate = xTaskGetTickCount();
  uint32_t nextBaroUpdate = xTaskGetTickCount();

  while (true) {
    xSemaphoreTake(runTaskSemaphore, portMAX_DELAY);

    // If the client triggers an estimator reset via parameter update
    if (coreData.resetEstimation) {
      estimatorKalmanInit();
      coreData.resetEstimation = false;
    }

    // Tracks whether an update to the state has been made, and the state therefore requires finalization
    bool doneUpdate = false;

    uint32_t osTick = xTaskGetTickCount(); // would be nice if this had a precision higher than 1ms...

  #ifdef KALMAN_DECOUPLE_XY
    kalmanCoreDecoupleXY(&coreData);
  #endif

    // Run the system dynamics to predict the state forward.
    if (osTick >= nextPrediction) { // update at the PREDICT_RATE
      float dt = T2S(osTick - lastPrediction);
      if (predictStateForward(osTick, dt)) {
        lastPrediction = osTick;
        doneUpdate = true;
        STATS_CNT_RATE_EVENT(&predictionCounter);
      }

      nextPrediction = osTick + S2T(1.0f / PREDICT_RATE);
    }

    /**
     * Add process noise every loop, rather than every prediction
     */
    {
      float dt = T2S(osTick - lastPNUpdate);
      if (dt > 0.0f) {
        kalmanCoreAddProcessNoise(&coreData, dt);
        lastPNUpdate = osTick;
      }
    }

    /**
     * Update the state estimate with the barometer measurements
     */
    // Accumulate the barometer measurements
    if (useBaroUpdate) {
      if (osTick > nextBaroUpdate // update at BARO_RATE
          && baroAccumulatorCount > 0)
      {
        xSemaphoreTake(dataMutex, portMAX_DELAY);
        float baroAslAverage = baroAslAccumulator / baroAccumulatorCount;
        baroAslAccumulator = 0;
        baroAccumulatorCount = 0;
        xSemaphoreGive(dataMutex);

        kalmanCoreUpdateWithBaro(&coreData, baroAslAverage, quadIsFlying);

        nextBaroUpdate = osTick + S2T(1.0f / BARO_RATE);
        doneUpdate = true;

        STATS_CNT_RATE_EVENT(&baroUpdateCounter);
      }
    }

    {
      Axis3f gyro;
      xSemaphoreTake(dataMutex, portMAX_DELAY);
      memcpy(&gyro, &gyroSnapshot, sizeof(gyro));
      xSemaphoreGive(dataMutex);
      doneUpdate = doneUpdate || updateQueuedMeasurments(&gyro, osTick);
    }

    /**
     * If an update has been made, the state is finalized:
     * - the attitude error is moved into the body attitude quaternion,
     * - the body attitude is converted into a rotation matrix for the next prediction, and
     * - correctness of the covariance matrix is ensured
     */

    if (doneUpdate)
    {
      kalmanCoreFinalize(&coreData, osTick);
      STATS_CNT_RATE_EVENT(&finalizeCounter);
      if (! kalmanSupervisorIsStateWithinBounds(&coreData)) {
        coreData.resetEstimation = true;
        DEBUG_PRINT("State out of bounds, resetting\n");
      }
    }

    /**
     * Finally, the internal state is externalized.
     * This is done every round, since the external state includes some sensor data
     */
    xSemaphoreTake(dataMutex, portMAX_DELAY);
    kalmanCoreExternalizeState(&coreData, &taskEstimatorState, &accSnapshot, osTick);
    xSemaphoreGive(dataMutex);

    STATS_CNT_RATE_EVENT(&updateCounter);
  }
}

void estimatorKalman(state_t *state, sensorData_t *sensors, control_t *control, const uint32_t tick)
{
  // This function is called from the stabilizer loop. It is important that this call returns
  // as quickly as possible. The dataMutex must only be locked short periods by the task.
  xSemaphoreTake(dataMutex, portMAX_DELAY);

  // Average the last IMU measurements. We do this because the prediction loop is
  // slower than the IMU loop, but the IMU information is required externally at
  // a higher rate (for body rate control).
  if (sensorsReadAcc(&sensors->acc)) {
    accAccumulator.x += sensors->acc.x;
    accAccumulator.y += sensors->acc.y;
    accAccumulator.z += sensors->acc.z;
    accAccumulatorCount++;
  }

  if (sensorsReadGyro(&sensors->gyro)) {
    gyroAccumulator.x += sensors->gyro.x;
    gyroAccumulator.y += sensors->gyro.y;
    gyroAccumulator.z += sensors->gyro.z;
    gyroAccumulatorCount++;
  }

  // Average the thrust command from the last time steps, generated externally by the controller
  thrustAccumulator += control->thrust;
  thrustAccumulatorCount++;

  // Average barometer data
  if (useBaroUpdate) {
    if (sensorsReadBaro(&sensors->baro)) {
      baroAslAccumulator += sensors->baro.asl;
      baroAccumulatorCount++;
    }
  }

  // Make a copy of sensor data to be used by the task
  memcpy(&gyroSnapshot, &sensors->gyro, sizeof(gyroSnapshot));
  memcpy(&accSnapshot, &sensors->acc, sizeof(accSnapshot));

  // Copy the latest state, calculated by the task
  memcpy(state, &taskEstimatorState, sizeof(state_t));
  xSemaphoreGive(dataMutex);

  xSemaphoreGive(runTaskSemaphore);
}

static bool predictStateForward(uint32_t osTick, float dt) {
  if (gyroAccumulatorCount == 0
      || accAccumulatorCount == 0
      || thrustAccumulatorCount == 0)
  {
    return false;
  }

  xSemaphoreTake(dataMutex, portMAX_DELAY);

  // gyro is in deg/sec but the estimator requires rad/sec
  Axis3f gyroAverage;
  gyroAverage.x = gyroAccumulator.x * DEG_TO_RAD / gyroAccumulatorCount;
  gyroAverage.y = gyroAccumulator.y * DEG_TO_RAD / gyroAccumulatorCount;
  gyroAverage.z = gyroAccumulator.z * DEG_TO_RAD / gyroAccumulatorCount;

  // accelerometer is in Gs but the estimator requires ms^-2
  Axis3f accAverage;
  accAverage.x = accAccumulator.x * GRAVITY_MAGNITUDE / accAccumulatorCount;
  accAverage.y = accAccumulator.y * GRAVITY_MAGNITUDE / accAccumulatorCount;
  accAverage.z = accAccumulator.z * GRAVITY_MAGNITUDE / accAccumulatorCount;

  // thrust is in grams, we need ms^-2
  float thrustAverage = thrustAccumulator * CONTROL_TO_ACC / thrustAccumulatorCount;

  accAccumulator = (Axis3f){.axis={0}};
  accAccumulatorCount = 0;
  gyroAccumulator = (Axis3f){.axis={0}};
  gyroAccumulatorCount = 0;
  thrustAccumulator = 0;
  thrustAccumulatorCount = 0;

  xSemaphoreGive(dataMutex);

  // TODO: Find a better check for whether the quad is flying
  // Assume that the flight begins when the thrust is large enough and for now we never stop "flying".
  if (thrustAverage > IN_FLIGHT_THRUST_THRESHOLD) {
    lastFlightCmd = osTick;
    if (!quadIsFlying) {
      takeoffTime = lastFlightCmd;
    }
  }
  quadIsFlying = (osTick-lastFlightCmd) < IN_FLIGHT_TIME_THRESHOLD;

  kalmanCorePredict(&coreData, thrustAverage, &accAverage, &gyroAverage, dt, quadIsFlying);

  return true;
}


static bool updateQueuedMeasurments(const Axis3f *gyro, const uint32_t tick) {
  bool doneUpdate = false;
  /**
   * Sensor measurements can come in sporadically and faster than the stabilizer loop frequency,
   * we therefore consume all measurements since the last loop, rather than accumulating
   */

  tofMeasurement_t tof;
  while (stateEstimatorHasTOFPacket(&tof))
  {
    kalmanCoreUpdateWithTof(&coreData, &tof);
    doneUpdate = true;
  }

  yawErrorMeasurement_t yawError;
  while (stateEstimatorHasYawErrorPacket(&yawError))
  {
    kalmanCoreUpdateWithYawError(&coreData, &yawError);
    doneUpdate = true;
  }

  heightMeasurement_t height;
  while (stateEstimatorHasHeightPacket(&height))
  {
    kalmanCoreUpdateWithAbsoluteHeight(&coreData, &height);
    doneUpdate = true;
  }

  distanceMeasurement_t dist;
  while (stateEstimatorHasDistanceMeasurement(&dist))
  {
    kalmanCoreUpdateWithDistance(&coreData, &dist);
    doneUpdate = true;
  }

  positionMeasurement_t pos;
  while (stateEstimatorHasPositionMeasurement(&pos))
  {
    kalmanCoreUpdateWithPosition(&coreData, &pos);
    doneUpdate = true;
  }

  poseMeasurement_t pose;
  while (stateEstimatorHasPoseMeasurement(&pose))
  {
    kalmanCoreUpdateWithPose(&coreData, &pose);
    doneUpdate = true;
  }

  tdoaMeasurement_t tdoa;
  while (stateEstimatorHasTDOAPacket(&tdoa))
  {
    kalmanCoreUpdateWithTDOA(&coreData, &tdoa);
    doneUpdate = true;
  }

  flowMeasurement_t flow;
  while (stateEstimatorHasFlowPacket(&flow))
  {
    kalmanCoreUpdateWithFlow(&coreData, &flow, gyro);
    doneUpdate = true;
  }

  sweepAngleMeasurement_t angles;
  while (stateEstimatorHasSweepAnglesPacket(&angles))
  {
    kalmanCoreUpdateWithSweepAngles(&coreData, &angles, tick);
    doneUpdate = true;
  }

  return doneUpdate;
}

// Called when this estimator is activated
void estimatorKalmanInit(void) {
  xQueueReset(distDataQueue);
  xQueueReset(posDataQueue);
  xQueueReset(poseDataQueue);
  xQueueReset(tdoaDataQueue);
  xQueueReset(flowDataQueue);
  xQueueReset(tofDataQueue);

  xSemaphoreTake(dataMutex, portMAX_DELAY);
  accAccumulator = (Axis3f){.axis={0}};
  gyroAccumulator = (Axis3f){.axis={0}};
  thrustAccumulator = 0;
  baroAslAccumulator = 0;

  accAccumulatorCount = 0;
  gyroAccumulatorCount = 0;
  thrustAccumulatorCount = 0;
  baroAccumulatorCount = 0;
  xSemaphoreGive(dataMutex);

  kalmanCoreInit(&coreData);
}

static bool appendMeasurement(xQueueHandle queue, void *measurement)
{
  portBASE_TYPE result;
  bool isInInterrupt = (SCB->ICSR & SCB_ICSR_VECTACTIVE_Msk) != 0;

  if (isInInterrupt) {
    portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
    result = xQueueSendFromISR(queue, measurement, &xHigherPriorityTaskWoken);
    if(xHigherPriorityTaskWoken == pdTRUE)
    {
      portYIELD();
    }
  } else {
    result = xQueueSend(queue, measurement, 0);
  }

  if (result == pdTRUE) {
    STATS_CNT_RATE_EVENT(&measurementAppendedCounter);
    return true;
  } else {
    STATS_CNT_RATE_EVENT(&measurementNotAppendedCounter);
    return true;
  }
}

bool estimatorKalmanEnqueueTDOA(const tdoaMeasurement_t *uwb)
{
  ASSERT(isInit);
  return appendMeasurement(tdoaDataQueue, (void *)uwb);
}

bool estimatorKalmanEnqueuePosition(const positionMeasurement_t *pos)
{
  ASSERT(isInit);
  return appendMeasurement(posDataQueue, (void *)pos);
}

bool estimatorKalmanEnqueuePose(const poseMeasurement_t *pose)
{
  ASSERT(isInit);
  return appendMeasurement(poseDataQueue, (void *)pose);
}

bool estimatorKalmanEnqueueDistance(const distanceMeasurement_t *dist)
{
  ASSERT(isInit);
  return appendMeasurement(distDataQueue, (void *)dist);
}

bool estimatorKalmanEnqueueFlow(const flowMeasurement_t *flow)
{
  // A flow measurement (dnx,  dny) [accumulated pixels]
  ASSERT(isInit);
  return appendMeasurement(flowDataQueue, (void *)flow);
}

bool estimatorKalmanEnqueueTOF(const tofMeasurement_t *tof)
{
  // A distance (distance) [m] to the ground along the z_B axis.
  ASSERT(isInit);
  return appendMeasurement(tofDataQueue, (void *)tof);
}

bool estimatorKalmanEnqueueAbsoluteHeight(const heightMeasurement_t *height)
{
  // A distance (height) [m] to the ground along the z axis.
  ASSERT(isInit);
  return appendMeasurement(heightDataQueue, (void *)height);
}

bool estimatorKalmanEnqueueYawError(const yawErrorMeasurement_t* error)
{
  ASSERT(isInit);
  return appendMeasurement(yawErrorDataQueue, (void *)error);
}

bool estimatorKalmanEnqueueSweepAngles(const sweepAngleMeasurement_t *angles)
{
  ASSERT(isInit);
  return appendMeasurement(sweepAnglesDataQueue, (void *)angles);
}

bool estimatorKalmanTest(void)
{
  return isInit;
}

void estimatorKalmanGetEstimatedPos(point_t* pos) {
  pos->x = coreData.S[KC_STATE_X];
  pos->y = coreData.S[KC_STATE_Y];
  pos->z = coreData.S[KC_STATE_Z];
}

void estimatorKalmanGetEstimatedRot(float * rotationMatrix) {
  memcpy(rotationMatrix, coreData.R, 9*sizeof(float));
}

// Temporary development groups
LOG_GROUP_START(kalman_states)
  LOG_ADD(LOG_FLOAT, ox, &coreData.S[KC_STATE_X])
  LOG_ADD(LOG_FLOAT, oy, &coreData.S[KC_STATE_Y])
  LOG_ADD(LOG_FLOAT, vx, &coreData.S[KC_STATE_PX])
  LOG_ADD(LOG_FLOAT, vy, &coreData.S[KC_STATE_PY])
LOG_GROUP_STOP(kalman_states)


// Stock log groups
LOG_GROUP_START(kalman)
  LOG_ADD(LOG_UINT8, inFlight, &quadIsFlying)
  LOG_ADD(LOG_FLOAT, stateX, &coreData.S[KC_STATE_X])
  LOG_ADD(LOG_FLOAT, stateY, &coreData.S[KC_STATE_Y])
  LOG_ADD(LOG_FLOAT, stateZ, &coreData.S[KC_STATE_Z])
  LOG_ADD(LOG_FLOAT, statePX, &coreData.S[KC_STATE_PX])
  LOG_ADD(LOG_FLOAT, statePY, &coreData.S[KC_STATE_PY])
  LOG_ADD(LOG_FLOAT, statePZ, &coreData.S[KC_STATE_PZ])
  LOG_ADD(LOG_FLOAT, stateD0, &coreData.S[KC_STATE_D0])
  LOG_ADD(LOG_FLOAT, stateD1, &coreData.S[KC_STATE_D1])
  LOG_ADD(LOG_FLOAT, stateD2, &coreData.S[KC_STATE_D2])
  LOG_ADD(LOG_FLOAT, varX, &coreData.P[KC_STATE_X][KC_STATE_X])
  LOG_ADD(LOG_FLOAT, varY, &coreData.P[KC_STATE_Y][KC_STATE_Y])
  LOG_ADD(LOG_FLOAT, varZ, &coreData.P[KC_STATE_Z][KC_STATE_Z])
  LOG_ADD(LOG_FLOAT, varPX, &coreData.P[KC_STATE_PX][KC_STATE_PX])
  LOG_ADD(LOG_FLOAT, varPY, &coreData.P[KC_STATE_PY][KC_STATE_PY])
  LOG_ADD(LOG_FLOAT, varPZ, &coreData.P[KC_STATE_PZ][KC_STATE_PZ])
  LOG_ADD(LOG_FLOAT, varD0, &coreData.P[KC_STATE_D0][KC_STATE_D0])
  LOG_ADD(LOG_FLOAT, varD1, &coreData.P[KC_STATE_D1][KC_STATE_D1])
  LOG_ADD(LOG_FLOAT, varD2, &coreData.P[KC_STATE_D2][KC_STATE_D2])
  LOG_ADD(LOG_FLOAT, q0, &coreData.q[0])
  LOG_ADD(LOG_FLOAT, q1, &coreData.q[1])
  LOG_ADD(LOG_FLOAT, q2, &coreData.q[2])
  LOG_ADD(LOG_FLOAT, q3, &coreData.q[3])

  STATS_CNT_RATE_LOG_ADD(rtUpdate, &updateCounter)
  STATS_CNT_RATE_LOG_ADD(rtPred, &predictionCounter)
  STATS_CNT_RATE_LOG_ADD(rtBaro, &baroUpdateCounter)
  STATS_CNT_RATE_LOG_ADD(rtFinal, &finalizeCounter)
  STATS_CNT_RATE_LOG_ADD(rtApnd, &measurementAppendedCounter)
  STATS_CNT_RATE_LOG_ADD(rtRej, &measurementNotAppendedCounter)
LOG_GROUP_STOP(kalman)

PARAM_GROUP_START(kalman)
  PARAM_ADD(PARAM_UINT8, resetEstimation, &coreData.resetEstimation)
  PARAM_ADD(PARAM_UINT8, quadIsFlying, &quadIsFlying)
PARAM_GROUP_STOP(kalman)