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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ANDROID_FUSION_H
     18 #define ANDROID_FUSION_H
     19 
     20 #include <utils/Errors.h>
     21 
     22 #include "quat.h"
     23 #include "mat.h"
     24 #include "vec.h"
     25 
     26 namespace android {
     27 
     28 typedef mat<float, 3, 4> mat34_t;
     29 
     30 enum FUSION_MODE{
     31     FUSION_9AXIS, // use accel gyro mag
     32     FUSION_NOMAG, // use accel gyro (game rotation, gravity)
     33     FUSION_NOGYRO, // use accel mag (geomag rotation)
     34     NUM_FUSION_MODE
     35 };
     36 
     37 class Fusion {
     38     /*
     39      * the state vector is made of two sub-vector containing respectively:
     40      * - modified Rodrigues parameters
     41      * - the estimated gyro bias
     42      */
     43     quat_t  x0;
     44     vec3_t  x1;
     45 
     46     /*
     47      * the predicated covariance matrix is made of 4 3x3 sub-matrices and it is
     48      * semi-definite positive.
     49      *
     50      * P = | P00  P10 | = | P00  P10 |
     51      *     | P01  P11 |   | P10t P11 |
     52      *
     53      * Since P01 = transpose(P10), the code below never calculates or
     54      * stores P01.
     55      */
     56     mat<mat33_t, 2, 2> P;
     57 
     58     /*
     59      * the process noise covariance matrix
     60      */
     61     mat<mat33_t, 2, 2> GQGt;
     62 
     63 public:
     64     Fusion();
     65     void init(int mode = FUSION_9AXIS);
     66     void handleGyro(const vec3_t& w, float dT);
     67     status_t handleAcc(const vec3_t& a, float dT);
     68     status_t handleMag(const vec3_t& m);
     69     vec4_t getAttitude() const;
     70     vec3_t getBias() const;
     71     mat33_t getRotationMatrix() const;
     72     bool hasEstimate() const;
     73 
     74 private:
     75     struct Parameter {
     76         float gyroVar;
     77         float gyroBiasVar;
     78         float accStdev;
     79         float magStdev;
     80     } mParam;
     81 
     82     mat<mat33_t, 2, 2> Phi;
     83     vec3_t Ba, Bm;
     84     uint32_t mInitState;
     85     float mGyroRate;
     86     vec<vec3_t, 3> mData;
     87     size_t mCount[3];
     88     int mMode;
     89 
     90     enum { ACC=0x1, MAG=0x2, GYRO=0x4 };
     91     bool checkInitComplete(int, const vec3_t& w, float d = 0);
     92     void initFusion(const vec4_t& q0, float dT);
     93     void checkState();
     94     void predict(const vec3_t& w, float dT);
     95     void update(const vec3_t& z, const vec3_t& Bi, float sigma);
     96     static mat34_t getF(const vec4_t& p);
     97     static vec3_t getOrthogonal(const vec3_t &v);
     98 };
     99 
    100 }; // namespace android
    101 
    102 #endif // ANDROID_FUSION_H
    103