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