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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 class Fusion {
     31     /*
     32      * the state vector is made of two sub-vector containing respectively:
     33      * - modified Rodrigues parameters
     34      * - the estimated gyro bias
     35      */
     36     quat_t  x0;
     37     vec3_t  x1;
     38 
     39     /*
     40      * the predicated covariance matrix is made of 4 3x3 sub-matrices and it is
     41      * semi-definite positive.
     42      *
     43      * P = | P00  P10 | = | P00  P10 |
     44      *     | P01  P11 |   | P10t P11 |
     45      *
     46      * Since P01 = transpose(P10), the code below never calculates or
     47      * stores P01.
     48      */
     49     mat<mat33_t, 2, 2> P;
     50 
     51     /*
     52      * the process noise covariance matrix
     53      */
     54     mat<mat33_t, 2, 2> GQGt;
     55 
     56 public:
     57     Fusion();
     58     void init();
     59     void handleGyro(const vec3_t& w, float dT);
     60     status_t handleAcc(const vec3_t& a);
     61     status_t handleMag(const vec3_t& m);
     62     vec4_t getAttitude() const;
     63     vec3_t getBias() const;
     64     mat33_t getRotationMatrix() const;
     65     bool hasEstimate() const;
     66 
     67 private:
     68     mat<mat33_t, 2, 2> Phi;
     69     vec3_t Ba, Bm;
     70     uint32_t mInitState;
     71     float mGyroRate;
     72     vec<vec3_t, 3> mData;
     73     size_t mCount[3];
     74     enum { ACC=0x1, MAG=0x2, GYRO=0x4 };
     75     bool checkInitComplete(int, const vec3_t& w, float d = 0);
     76     void initFusion(const vec4_t& q0, float dT);
     77     void checkState();
     78     void predict(const vec3_t& w, float dT);
     79     void update(const vec3_t& z, const vec3_t& Bi, float sigma);
     80     static mat34_t getF(const vec4_t& p);
     81 };
     82 
     83 }; // namespace android
     84 
     85 #endif // ANDROID_FUSION_H
     86