Fusion.h revision 984826cc158193e61e3a00359ef4f6699c7d748a 
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 "vec.h"
23#include "mat.h"
24
25namespace android {
26
27class Fusion {
28    /*
29     * the state vector is made of two sub-vector containing respectively:
30     * - modified Rodrigues parameters
31     * - the estimated gyro bias
32     */
33    vec<vec3_t, 2> x;
34
35    /*
36     * the predicated covariance matrix is made of 4 3x3 sub-matrices and it
37     * semi-definite positive.
38     *
39     * P = | P00  P10 | = | P00  P10 |
40     *     | P01  P11 |   | P10t  Q1 |
41     *
42     * Since P01 = transpose(P10), the code below never calculates or
43     * stores P01. P11 is always equal to Q1, so we don't store it either.
44     */
45    mat<mat33_t, 2, 2> P;
46
47    /*
48     * the process noise covariance matrix is made of 2 3x3 sub-matrices
49     * Q0 encodes the attitude's noise
50     * Q1 encodes the bias' noise
51     */
52    vec<mat33_t, 2> Q;
53
54    static const float gyroSTDEV = 1.0e-5;  // rad/s (measured 1.2e-5)
55    static const float accSTDEV  = 0.05f;   // m/s^2 (measured 0.08 / CDD 0.05)
56    static const float magSTDEV  = 0.5f;    // uT    (measured 0.7  / CDD 0.5)
57    static const float biasSTDEV = 2e-9;    // rad/s^2 (guessed)
58
59public:
60    Fusion();
61    void init();
62    void handleGyro(const vec3_t& w, float dT);
63    status_t handleAcc(const vec3_t& a);
64    status_t handleMag(const vec3_t& m);
65    vec3_t getAttitude() const;
66    vec3_t getBias() const;
67    mat33_t getRotationMatrix() const;
68    bool hasEstimate() const;
69
70private:
71    vec3_t Ba, Bm;
72    uint32_t mInitState;
73    vec<vec3_t, 3> mData;
74    size_t mCount[3];
75    enum { ACC=0x1, MAG=0x2, GYRO=0x4 };
76    bool checkInitComplete(int, const vec3_t&);
77    bool checkState(const vec3_t& v);
78    void predict(const vec3_t& w);
79    void update(const vec3_t& z, const vec3_t& Bi, float sigma);
80    static mat33_t getF(const vec3_t& p);
81    static mat33_t getdFdp(const vec3_t& p, const vec3_t& we);
82};
83
84}; // namespace android
85
86#endif // ANDROID_FUSION_H
87