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
26namespace android {
27
28typedef mat<float, 3, 4> mat34_t;
29
30class 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
56public:
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
67private:
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