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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "SensorDevice.h"
#include "SensorFusion.h"
#include "SensorService.h"
namespace android {
// ---------------------------------------------------------------------------
ANDROID_SINGLETON_STATIC_INSTANCE(SensorFusion)
SensorFusion::SensorFusion()
: mSensorDevice(SensorDevice::getInstance()),
mEnabled(false), mHasGyro(false), mGyroTime(0), mRotationMatrix(1),
mLowPass(M_SQRT1_2, 1.0f), mAccData(mLowPass),
mFilteredMag(0.0f), mFilteredAcc(0.0f)
{
sensor_t const* list;
size_t count = mSensorDevice.getSensorList(&list);
for (size_t i=0 ; i<count ; i++) {
if (list[i].type == SENSOR_TYPE_ACCELEROMETER) {
mAcc = Sensor(list + i);
}
if (list[i].type == SENSOR_TYPE_MAGNETIC_FIELD) {
mMag = Sensor(list + i);
}
if (list[i].type == SENSOR_TYPE_GYROSCOPE) {
mGyro = Sensor(list + i);
// 200 Hz for gyro events is a good compromise between precision
// and power/cpu usage.
mTargetDelayNs = 1000000000LL/200;
mGyroRate = 1000000000.0f / mTargetDelayNs;
mHasGyro = true;
}
}
mFusion.init();
mAccData.init(vec3_t(0.0f));
}
void SensorFusion::process(const sensors_event_t& event) {
if (event.type == SENSOR_TYPE_GYROSCOPE && mHasGyro) {
if (mGyroTime != 0) {
const float dT = (event.timestamp - mGyroTime) / 1000000000.0f;
const float freq = 1 / dT;
const float alpha = 2 / (2 + dT); // 2s time-constant
mGyroRate = mGyroRate*alpha + freq*(1 - alpha);
}
mGyroTime = event.timestamp;
mFusion.handleGyro(vec3_t(event.data), 1.0f/mGyroRate);
} else if (event.type == SENSOR_TYPE_MAGNETIC_FIELD) {
const vec3_t mag(event.data);
if (mHasGyro) {
mFusion.handleMag(mag);
} else {
const float l(length(mag));
if (l>5 && l<100) {
mFilteredMag = mag * (1/l);
}
}
} else if (event.type == SENSOR_TYPE_ACCELEROMETER) {
const vec3_t acc(event.data);
if (mHasGyro) {
mFusion.handleAcc(acc);
mRotationMatrix = mFusion.getRotationMatrix();
} else {
const float l(length(acc));
if (l > 0.981f) {
// remove the linear-acceleration components
mFilteredAcc = mAccData(acc * (1/l));
}
if (length(mFilteredAcc)>0 && length(mFilteredMag)>0) {
vec3_t up(mFilteredAcc);
vec3_t east(cross_product(mFilteredMag, up));
east *= 1/length(east);
vec3_t north(cross_product(up, east));
mRotationMatrix << east << north << up;
}
}
}
}
template <typename T> inline T min(T a, T b) { return a<b ? a : b; }
template <typename T> inline T max(T a, T b) { return a>b ? a : b; }
status_t SensorFusion::activate(void* ident, bool enabled) {
LOGD_IF(DEBUG_CONNECTIONS,
"SensorFusion::activate(ident=%p, enabled=%d)",
ident, enabled);
const ssize_t idx = mClients.indexOf(ident);
if (enabled) {
if (idx < 0) {
mClients.add(ident);
}
} else {
if (idx >= 0) {
mClients.removeItemsAt(idx);
}
}
mSensorDevice.activate(ident, mAcc.getHandle(), enabled);
mSensorDevice.activate(ident, mMag.getHandle(), enabled);
if (mHasGyro) {
mSensorDevice.activate(ident, mGyro.getHandle(), enabled);
}
const bool newState = mClients.size() != 0;
if (newState != mEnabled) {
mEnabled = newState;
if (newState) {
mFusion.init();
}
}
return NO_ERROR;
}
status_t SensorFusion::setDelay(void* ident, int64_t ns) {
if (mHasGyro) {
mSensorDevice.setDelay(ident, mAcc.getHandle(), ns);
mSensorDevice.setDelay(ident, mMag.getHandle(), ms2ns(20));
mSensorDevice.setDelay(ident, mGyro.getHandle(), mTargetDelayNs);
} else {
const static double NS2S = 1.0 / 1000000000.0;
mSensorDevice.setDelay(ident, mAcc.getHandle(), ns);
mSensorDevice.setDelay(ident, mMag.getHandle(), max(ns, mMag.getMinDelayNs()));
mLowPass.setSamplingPeriod(ns*NS2S);
}
return NO_ERROR;
}
float SensorFusion::getPowerUsage() const {
float power = mAcc.getPowerUsage() + mMag.getPowerUsage();
if (mHasGyro) {
power += mGyro.getPowerUsage();
}
return power;
}
int32_t SensorFusion::getMinDelay() const {
return mAcc.getMinDelay();
}
void SensorFusion::dump(String8& result, char* buffer, size_t SIZE) {
const Fusion& fusion(mFusion);
snprintf(buffer, SIZE, "Fusion (%s) %s (%d clients), gyro-rate=%7.2fHz, "
"MRPS=< %g, %g, %g > (%g), "
"BIAS=< %g, %g, %g >\n",
mHasGyro ? "9-axis" : "6-axis",
mEnabled ? "enabled" : "disabled",
mClients.size(),
mGyroRate,
fusion.getAttitude().x,
fusion.getAttitude().y,
fusion.getAttitude().z,
dot_product(fusion.getAttitude(), fusion.getAttitude()),
fusion.getBias().x,
fusion.getBias().y,
fusion.getBias().z);
result.append(buffer);
}
// ---------------------------------------------------------------------------
}; // namespace android
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