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