root / quad1 / AeroQuad / Compass.h @ 9240aaa3
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1 | 9240aaa3 | Alex | /*
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2 | AeroQuad v2.1 - October 2010
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3 | www.AeroQuad.com
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4 | Copyright (c) 2010 Ted Carancho. All rights reserved.
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5 | An Open Source Arduino based multicopter.
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6 |
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7 | This program is free software: you can redistribute it and/or modify
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8 | it under the terms of the GNU General Public License as published by
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9 | the Free Software Foundation, either version 3 of the License, or
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10 | (at your option) any later version.
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11 | |||
12 | This program is distributed in the hope that it will be useful,
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13 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | GNU General Public License for more details.
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16 | |||
17 | You should have received a copy of the GNU General Public License
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18 | along with this program. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | |||
21 | // Class to define sensors that can determine absolute heading
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22 | |||
23 | // ***********************************************************************
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24 | // ************************** Compass Class ******************************
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25 | // ***********************************************************************
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26 | class Compass { |
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27 | public:
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28 | int compassAddress;
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29 | float heading, absoluteHeading, gyroStartHeading;
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30 | float compass;
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31 | |||
32 | Compass(void) { }
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33 | |||
34 | // **********************************************************************
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35 | // The following function calls must be defined inside any new subclasses
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36 | // **********************************************************************
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37 | virtual void initialize(void); |
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38 | virtual void measure(void); |
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39 | |||
40 | // *********************************************************
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41 | // The following functions are common between all subclasses
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42 | // *********************************************************
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43 | const float getData(void) { |
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44 | return compass;
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45 | } |
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46 | |||
47 | const float getHeading(void) { |
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48 | return heading;
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49 | } |
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50 | |||
51 | const float getAbsoluteHeading(void) { |
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52 | return absoluteHeading;
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53 | } |
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54 | }; |
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55 | |||
56 | // ***********************************************************************
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57 | // ************************ HMC5843 Subclass *****************************
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58 | // ***********************************************************************
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59 | class Compass_AeroQuad_v2 : public Compass { |
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60 | // This sets up the HMC5843 from Sparkfun
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61 | private:
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62 | float cosRoll;
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63 | float sinRoll;
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64 | float cosPitch;
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65 | float sinPitch;
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66 | float magX;
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67 | float magY;
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68 | int measuredMagX;
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69 | int measuredMagY;
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70 | int measuredMagZ;
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71 | float smoothFactor; // time constant for complementary filter |
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72 | float filter1, filter2; // coefficients for complementary filter |
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73 | float adjustedGyroHeading, previousHead;
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74 | int gyroZero;
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75 | |||
76 | public:
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77 | Compass_AeroQuad_v2() : Compass(){ |
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78 | compassAddress = 0x1E;
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79 | // smoothFactor means time in seconds less than smoothFactor, depend on gyro more
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80 | // time greater than smoothFactor depend on magnetometer more (mags are very noisy)
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81 | smoothFactor = 1.0; |
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82 | filter1 = smoothFactor / (smoothFactor + G_Dt); |
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83 | filter2 = 1 - filter1;
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84 | gyroZero = gyro.getZero(YAW); |
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85 | } |
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86 | |||
87 | // ***********************************************************
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88 | // Define all the virtual functions declared in the main class
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89 | // ***********************************************************
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90 | void initialize(void) { |
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91 | // Should do a WhoAmI to know if mag is present
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92 | updateRegisterI2C(compassAddress, 0x01, 0x20); |
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93 | updateRegisterI2C(compassAddress, 0x02, 0x00); // continuous 10Hz mode |
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94 | measure(); |
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95 | gyroStartHeading = getData(); |
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96 | if (gyroStartHeading < 0) gyroStartHeading += 360; |
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97 | gyro.setStartHeading(gyroStartHeading); |
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98 | } |
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99 | |||
100 | void measure(void) { |
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101 | sendByteI2C(compassAddress, 0x03);
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102 | Wire.requestFrom(compassAddress, 6);
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103 | measuredMagX = (Wire.receive() << 8) | Wire.receive();
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104 | measuredMagY = (Wire.receive() << 8) | Wire.receive();
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105 | measuredMagZ = (Wire.receive() << 8) | Wire.receive();
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106 | Wire.endTransmission(); |
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107 | // Heading calculation based on code written by FabQuad
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108 | // http://aeroquad.com/showthread.php?691-Hold-your-heading-with-HMC5843-Magnetometer
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109 | cosRoll = cos(radians(flightAngle.getData(ROLL))); |
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110 | sinRoll = sin(radians(flightAngle.getData(ROLL))); |
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111 | cosPitch = cos(radians(flightAngle.getData(PITCH))); |
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112 | sinPitch = sin(radians(flightAngle.getData(PITCH))); |
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113 | magX = measuredMagX * cosPitch + measuredMagY * sinRoll * sinPitch + measuredMagZ * cosRoll * sinPitch; |
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114 | magY = measuredMagY * cosRoll - measuredMagZ * sinRoll; |
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115 | compass = -degrees(atan2(-magY, magX)); |
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116 | |||
117 | // Check if gyroZero adjusted, if it is, reset gyroHeading to compass value
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118 | if (gyroZero != gyro.getZero(YAW)) {
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119 | gyro.setStartHeading(heading); |
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120 | gyroZero = gyro.getZero(YAW); |
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121 | } |
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122 | |||
123 | adjustedGyroHeading = gyro.getHeading(); |
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124 | // if compass is positive while gyro is negative force gyro positive past 180
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125 | if ((compass > 90) && adjustedGyroHeading < -90) adjustedGyroHeading += 360; |
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126 | // if compass is negative whie gyro is positive force gyro negative past -180
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127 | if ((compass < -90) && adjustedGyroHeading > 90) adjustedGyroHeading -= 360; |
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128 | |||
129 | // Complementry filter from http://chiefdelphi.com/media/papers/2010
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130 | heading = (filter1 * adjustedGyroHeading) + (filter2 * compass); |
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131 | |||
132 | // Change from +/-180 to 0-360
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133 | if (heading < 0) absoluteHeading = 360 + heading; |
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134 | else absoluteHeading = heading;
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135 | } |
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136 | }; |