void SerialInterface::readData(float deltaTime) {
#ifndef _WIN32
int initialSamples = totalSamples;
if (USING_INVENSENSE_MPU9150) {
// ask the invensense for raw gyro data
short accelData[3];
if (mpu_get_accel_reg(accelData, 0)) {
close(_serialDescriptor);
qDebug("Disconnected SerialUSB.\n");
_active = false;
return; // disconnected
}
const float LSB_TO_METERS_PER_SECOND2 = 1.f / 16384.f * GRAVITY_EARTH;
// From MPU-9150 register map, with setting on
// highest resolution = +/- 2G
_lastAcceleration = glm::vec3(-accelData[2], -accelData[1], -accelData[0]) * LSB_TO_METERS_PER_SECOND2;
short gyroData[3];
mpu_get_gyro_reg(gyroData, 0);
// Convert the integer rates to floats
const float LSB_TO_DEGREES_PER_SECOND = 1.f / 16.4f; // From MPU-9150 register map, 2000 deg/sec.
glm::vec3 rotationRates;
rotationRates[0] = ((float) -gyroData[2]) * LSB_TO_DEGREES_PER_SECOND;
rotationRates[1] = ((float) -gyroData[1]) * LSB_TO_DEGREES_PER_SECOND;
rotationRates[2] = ((float) -gyroData[0]) * LSB_TO_DEGREES_PER_SECOND;
short compassData[3];
mpu_get_compass_reg(compassData, 0);
// Convert integer values to floats, update extents
_lastCompass = glm::vec3(compassData[2], -compassData[0], -compassData[1]);
// update and subtract the long term average
_averageRotationRates = (1.f - 1.f/(float)LONG_TERM_RATE_SAMPLES) * _averageRotationRates +
1.f/(float)LONG_TERM_RATE_SAMPLES * rotationRates;
rotationRates -= _averageRotationRates;
// compute the angular acceleration
glm::vec3 angularAcceleration = (deltaTime < EPSILON) ? glm::vec3() : (rotationRates - _lastRotationRates) / deltaTime;
_lastRotationRates = rotationRates;
// Update raw rotation estimates
glm::quat estimatedRotation = glm::quat(glm::radians(_estimatedRotation)) *
glm::quat(glm::radians(deltaTime * _lastRotationRates));
// Update acceleration estimate: first, subtract gravity as rotated into current frame
_estimatedAcceleration = (totalSamples < GRAVITY_SAMPLES) ? glm::vec3() :
_lastAcceleration - glm::inverse(estimatedRotation) * _gravity;
// update and subtract the long term average
_averageAcceleration = (1.f - 1.f/(float)LONG_TERM_RATE_SAMPLES) * _averageAcceleration +
1.f/(float)LONG_TERM_RATE_SAMPLES * _estimatedAcceleration;
_estimatedAcceleration -= _averageAcceleration;
// Consider updating our angular velocity/acceleration to linear acceleration mapping
if (glm::length(_estimatedAcceleration) > EPSILON &&
(glm::length(_lastRotationRates) > EPSILON || glm::length(angularAcceleration) > EPSILON)) {
// compute predicted linear acceleration, find error between actual and predicted
glm::vec3 predictedAcceleration = _angularVelocityToLinearAccel * _lastRotationRates +
_angularAccelToLinearAccel * angularAcceleration;
glm::vec3 error = _estimatedAcceleration - predictedAcceleration;
// the "error" is actually what we want: the linear acceleration minus rotational influences
_estimatedAcceleration = error;
// adjust according to error in each dimension, in proportion to input magnitudes
for (int i = 0; i < 3; i++) {
if (fabsf(error[i]) < EPSILON) {
continue;
}
const float LEARNING_RATE = 0.001f;
float rateSum = fabsf(_lastRotationRates.x) + fabsf(_lastRotationRates.y) + fabsf(_lastRotationRates.z);
if (rateSum > EPSILON) {
for (int j = 0; j < 3; j++) {
float proportion = LEARNING_RATE * fabsf(_lastRotationRates[j]) / rateSum;
if (proportion > EPSILON) {
_angularVelocityToLinearAccel[j][i] += error[i] * proportion / _lastRotationRates[j];
}
}
}
float accelSum = fabsf(angularAcceleration.x) + fabsf(angularAcceleration.y) + fabsf(angularAcceleration.z);
if (accelSum > EPSILON) {
for (int j = 0; j < 3; j++) {
float proportion = LEARNING_RATE * fabsf(angularAcceleration[j]) / accelSum;
if (proportion > EPSILON) {
_angularAccelToLinearAccel[j][i] += error[i] * proportion / angularAcceleration[j];
}
}
}
}
}
// rotate estimated acceleration into global rotation frame
_estimatedAcceleration = estimatedRotation * _estimatedAcceleration;
// Update estimated position and velocity
float const DECAY_VELOCITY = 0.975f;
float const DECAY_POSITION = 0.975f;
_estimatedVelocity += deltaTime * _estimatedAcceleration;
_estimatedPosition += deltaTime * _estimatedVelocity;
_estimatedVelocity *= DECAY_VELOCITY;
// Attempt to fuse gyro position with webcam position
Webcam* webcam = Application::getInstance()->getWebcam();
if (webcam->isActive()) {
const float WEBCAM_POSITION_FUSION = 0.5f;
_estimatedPosition = glm::mix(_estimatedPosition, webcam->getEstimatedPosition(), WEBCAM_POSITION_FUSION);
} else {
_estimatedPosition *= DECAY_POSITION;
}
// Accumulate a set of initial baseline readings for setting gravity
if (totalSamples == 0) {
_gravity = _lastAcceleration;
}
else {
if (totalSamples < GRAVITY_SAMPLES) {
_gravity = glm::mix(_gravity, _lastAcceleration, 1.0f / GRAVITY_SAMPLES);
// North samples start later, because the initial compass readings are screwy
int northSample = totalSamples - (GRAVITY_SAMPLES - NORTH_SAMPLES);
if (northSample == 0) {
_north = _lastCompass;
} else if (northSample > 0) {
_north = glm::mix(_north, _lastCompass, 1.0f / NORTH_SAMPLES);
}
} else {
// Use gravity reading to do sensor fusion on the pitch and roll estimation
estimatedRotation = safeMix(estimatedRotation,
rotationBetween(estimatedRotation * _lastAcceleration, _gravity) * estimatedRotation,
1.0f / ACCELERATION_SENSOR_FUSION_SAMPLES);
// Update the compass extents
_compassMinima = glm::min(_compassMinima, _lastCompass);
_compassMaxima = glm::max(_compassMaxima, _lastCompass);
// Same deal with the compass heading
estimatedRotation = safeMix(estimatedRotation,
rotationBetween(estimatedRotation * recenterCompass(_lastCompass),
recenterCompass(_north)) * estimatedRotation,
1.0f / COMPASS_SENSOR_FUSION_SAMPLES);
}
}
_estimatedRotation = safeEulerAngles(estimatedRotation);
totalSamples++;
}
if (initialSamples == totalSamples) {
timeval now;
gettimeofday(&now, NULL);
if (diffclock(&lastGoodRead, &now) > NO_READ_MAXIMUM_MSECS) {
qDebug("No data - Shutting down SerialInterface.\n");
resetSerial();
}
} else {
gettimeofday(&lastGoodRead, NULL);
}
#endif
}
void SerialInterface::readData(float deltaTime) {
#ifdef __APPLE__
int initialSamples = totalSamples;
if (USING_INVENSENSE_MPU9150) {
unsigned char sensorBuffer[36];
// ask the invensense for raw gyro data
write(_serialDescriptor, "RD683B0E\n", 9);
read(_serialDescriptor, sensorBuffer, 36);
int accelXRate, accelYRate, accelZRate;
convertHexToInt(sensorBuffer + 6, accelZRate);
convertHexToInt(sensorBuffer + 10, accelYRate);
convertHexToInt(sensorBuffer + 14, accelXRate);
const float LSB_TO_METERS_PER_SECOND2 = 1.f / 16384.f * GRAVITY_EARTH;
// From MPU-9150 register map, with setting on
// highest resolution = +/- 2G
_lastAcceleration = glm::vec3(-accelXRate, -accelYRate, -accelZRate) * LSB_TO_METERS_PER_SECOND2;
int rollRate, yawRate, pitchRate;
convertHexToInt(sensorBuffer + 22, rollRate);
convertHexToInt(sensorBuffer + 26, yawRate);
convertHexToInt(sensorBuffer + 30, pitchRate);
// Convert the integer rates to floats
const float LSB_TO_DEGREES_PER_SECOND = 1.f / 16.4f; // From MPU-9150 register map, 2000 deg/sec.
glm::vec3 rotationRates;
rotationRates[0] = ((float) -pitchRate) * LSB_TO_DEGREES_PER_SECOND;
rotationRates[1] = ((float) -yawRate) * LSB_TO_DEGREES_PER_SECOND;
rotationRates[2] = ((float) -rollRate) * LSB_TO_DEGREES_PER_SECOND;
// update and subtract the long term average
_averageRotationRates = (1.f - 1.f/(float)LONG_TERM_RATE_SAMPLES) * _averageRotationRates +
1.f/(float)LONG_TERM_RATE_SAMPLES * rotationRates;
rotationRates -= _averageRotationRates;
// compute the angular acceleration
glm::vec3 angularAcceleration = (deltaTime < EPSILON) ? glm::vec3() : (rotationRates - _lastRotationRates) / deltaTime;
_lastRotationRates = rotationRates;
// Update raw rotation estimates
glm::quat estimatedRotation = glm::quat(glm::radians(_estimatedRotation)) *
glm::quat(glm::radians(deltaTime * _lastRotationRates));
// Update acceleration estimate: first, subtract gravity as rotated into current frame
_estimatedAcceleration = (totalSamples < GRAVITY_SAMPLES) ? glm::vec3() :
_lastAcceleration - glm::inverse(estimatedRotation) * _gravity;
// update and subtract the long term average
_averageAcceleration = (1.f - 1.f/(float)LONG_TERM_RATE_SAMPLES) * _averageAcceleration +
1.f/(float)LONG_TERM_RATE_SAMPLES * _estimatedAcceleration;
_estimatedAcceleration -= _averageAcceleration;
// Consider updating our angular velocity/acceleration to linear acceleration mapping
if (glm::length(_estimatedAcceleration) > EPSILON &&
(glm::length(_lastRotationRates) > EPSILON || glm::length(angularAcceleration) > EPSILON)) {
// compute predicted linear acceleration, find error between actual and predicted
glm::vec3 predictedAcceleration = _angularVelocityToLinearAccel * _lastRotationRates +
_angularAccelToLinearAccel * angularAcceleration;
glm::vec3 error = _estimatedAcceleration - predictedAcceleration;
// the "error" is actually what we want: the linear acceleration minus rotational influences
_estimatedAcceleration = error;
// adjust according to error in each dimension, in proportion to input magnitudes
for (int i = 0; i < 3; i++) {
if (fabsf(error[i]) < EPSILON) {
continue;
}
const float LEARNING_RATE = 0.001f;
float rateSum = fabsf(_lastRotationRates.x) + fabsf(_lastRotationRates.y) + fabsf(_lastRotationRates.z);
if (rateSum > EPSILON) {
for (int j = 0; j < 3; j++) {
float proportion = LEARNING_RATE * fabsf(_lastRotationRates[j]) / rateSum;
if (proportion > EPSILON) {
_angularVelocityToLinearAccel[j][i] += error[i] * proportion / _lastRotationRates[j];
}
}
}
float accelSum = fabsf(angularAcceleration.x) + fabsf(angularAcceleration.y) + fabsf(angularAcceleration.z);
if (accelSum > EPSILON) {
for (int j = 0; j < 3; j++) {
float proportion = LEARNING_RATE * fabsf(angularAcceleration[j]) / accelSum;
if (proportion > EPSILON) {
_angularAccelToLinearAccel[j][i] += error[i] * proportion / angularAcceleration[j];
}
}
}
}
}
// rotate estimated acceleration into global rotation frame
_estimatedAcceleration = estimatedRotation * _estimatedAcceleration;
// Update estimated position and velocity
float const DECAY_VELOCITY = 0.975f;
float const DECAY_POSITION = 0.975f;
_estimatedVelocity += deltaTime * _estimatedAcceleration;
_estimatedPosition += deltaTime * _estimatedVelocity;
_estimatedVelocity *= DECAY_VELOCITY;
// Attempt to fuse gyro position with webcam position
Webcam* webcam = Application::getInstance()->getWebcam();
if (webcam->isActive()) {
const float WEBCAM_POSITION_FUSION = 0.5f;
_estimatedPosition = glm::mix(_estimatedPosition, webcam->getEstimatedPosition(), WEBCAM_POSITION_FUSION);
} else {
_estimatedPosition *= DECAY_POSITION;
}
// Accumulate a set of initial baseline readings for setting gravity
if (totalSamples == 0) {
_gravity = _lastAcceleration;
}
else {
if (totalSamples < GRAVITY_SAMPLES) {
_gravity = (1.f - 1.f/(float)GRAVITY_SAMPLES) * _gravity +
1.f/(float)GRAVITY_SAMPLES * _lastAcceleration;
} else {
// Use gravity reading to do sensor fusion on the pitch and roll estimation
estimatedRotation = safeMix(estimatedRotation,
rotationBetween(estimatedRotation * _lastAcceleration, _gravity) * estimatedRotation,
1.0f / SENSOR_FUSION_SAMPLES);
// Without a compass heading, always decay estimated Yaw slightly
const float YAW_DECAY = 0.999f;
glm::vec3 forward = estimatedRotation * glm::vec3(0.0f, 0.0f, -1.0f);
estimatedRotation = safeMix(glm::angleAxis(glm::degrees(atan2f(forward.x, -forward.z)),
glm::vec3(0.0f, 1.0f, 0.0f)) * estimatedRotation, estimatedRotation, YAW_DECAY);
}
}
_estimatedRotation = safeEulerAngles(estimatedRotation);
totalSamples++;
}
if (initialSamples == totalSamples) {
timeval now;
gettimeofday(&now, NULL);
if (diffclock(&lastGoodRead, &now) > NO_READ_MAXIMUM_MSECS) {
printLog("No data - Shutting down SerialInterface.\n");
resetSerial();
}
} else {
gettimeofday(&lastGoodRead, NULL);
}
#endif
}