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| Rev | Author | Line No. | Line |
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| 1910 | - | 1 | /*********************************************************************************/ |
| 2 | /* Attitude sense system (processing of gyro, accelerometer and altimeter data) */ |
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| 3 | /*********************************************************************************/ |
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| 4 | |||
| 5 | #ifndef _ATTITUDE_H |
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| 6 | #define _ATTITUDE_H |
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| 7 | |||
| 8 | #include <inttypes.h> |
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| 9 | |||
| 10 | #include "analog.h" |
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| 11 | |||
| 12 | // For debugging only. |
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| 13 | #include "uart0.h" |
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| 14 | |||
| 15 | /* |
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| 16 | * If you have no acc. sensor or do not want to use it, remove this define. This will cause the |
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| 17 | * acc. sensor to be ignored at attitude calibration. |
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| 18 | */ |
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| 2099 | - | 19 | //#define ATTITUDE_USE_ACC_SENSORS yes |
| 1910 | - | 20 | |
| 21 | /* |
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| 22 | * The frequency at which numerical integration takes place. 488 in original code. |
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| 23 | */ |
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| 24 | #define INTEGRATION_FREQUENCY 488 |
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| 25 | |||
| 26 | /* |
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| 27 | * Constant for deriving an attitude angle from acceleration measurement. |
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| 28 | * |
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| 29 | * The value is derived from the datasheet of the ACC sensor where 5g are scaled to VRef. |
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| 30 | * 1g is (3V * 1024) / (5 * 3V) = 205 counts. The ADC ISR sums 2 acc. samples to each |
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| 31 | * [pitch/roll]AxisAcc and thus reads about acc = 410 counts / g. |
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| 32 | * We approximate a small pitch/roll angle v by assuming that the copter does not accelerate: |
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| 33 | * In this explanation it is assumed that the ADC values are 0 based, and gravity is included. |
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| 34 | * The sine of v is the far side / the hypothenusis: |
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| 35 | * sin v = acc / sqrt(acc^2 + acc_z^2) |
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| 36 | * Using that v is a small angle, and the near side is about equal to the the hypothenusis: |
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| 37 | * sin v ~= acc / acc_z |
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| 38 | * Assuming that the helicopter is hovering at small pitch and roll angles, acc_z is about 410, |
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| 39 | * and sin v ~= v (small angles, in radians): |
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| 40 | * sin v ~= acc / 410 |
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| 41 | * v / 57.3 ~= acc / 410 |
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| 42 | * v ~= acc * 57.3 / 410 |
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| 43 | * acc / v ~= 410 / 57.3 ~= 7, that is: There are about 7 counts per degree. |
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| 44 | * |
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| 45 | * Summary: DEG_ACC_FACTOR = (2 * 1024 * [sensitivity of acc. meter in V/g]) / (3V * 57.3) |
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| 46 | */ |
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| 47 | #define DEG_ACC_FACTOR 7 |
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| 48 | |||
| 49 | /* |
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| 50 | * Growth of the integral per degree: |
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| 51 | * The hiResXXXX value per deg / s * INTEGRATION_FREQUENCY samples / sec * correction / a number divided by |
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| 52 | * HIRES_GYRO_INTEGRATION_FACTOR (why???) before integration. |
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| 53 | * The value of this expression should be about 1250 (by setting HIRES_GYRO_INTEGRATION_FACTOR to something suitable). |
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| 54 | */ |
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| 2099 | - | 55 | #define GYRO_DEG_FACTOR (GYRO_RATE_FACTOR * INTEGRATION_FREQUENCY * GYRO_CORRECTION) |
| 1910 | - | 56 | |
| 57 | /* |
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| 58 | * This is ([gyro integral value] / degree) / (degree / acc. sensor value) = gyro integral value / acc.sensor value |
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| 59 | * = the factor an acc. sensor should be multiplied by to get the gyro integral |
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| 60 | * value for the same (small) angle. |
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| 61 | * The value is about 200. |
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| 62 | */ |
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| 2099 | - | 63 | //#define GYRO_ACC_FACTOR ((GYRO_DEG_FACTOR_PITCHROLL) / (DEG_ACC_FACTOR)) |
| 1910 | - | 64 | |
| 2099 | - | 65 | #define OVER180 ((int32_t)GYRO_DEG_FACTOR * 180) |
| 66 | #define OVER360 ((int32_t)GYRO_DEG_FACTOR * 360) |
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| 1910 | - | 67 | |
| 68 | /* |
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| 69 | * Rotation rates |
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| 70 | */ |
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| 2099 | - | 71 | extern int16_t rate_PID[3], rate_ATT[3]; |
| 1910 | - | 72 | extern int16_t differential[3]; |
| 73 | |||
| 74 | /* |
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| 75 | * Attitudes calculated by numerical integration of gyro rates |
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| 76 | */ |
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| 2099 | - | 77 | extern int32_t attitude[3]; |
| 1910 | - | 78 | |
| 2099 | - | 79 | // extern volatile int32_t ReadingIntegralTop; // calculated in analog.c |
| 80 | |||
| 1910 | - | 81 | /* |
| 2099 | - | 82 | * Compass navigation |
| 83 | */ |
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| 84 | // extern int16_t compassHeading; |
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| 85 | // extern int16_t compassCourse; |
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| 86 | // extern int16_t compassOffCourse; |
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| 87 | // extern uint8_t compassCalState; |
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| 88 | // extern int32_t yawGyroHeading; |
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| 89 | // extern int16_t yawGyroHeadingInDeg; |
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| 90 | // extern uint8_t updateCompassCourse; |
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| 91 | // extern uint16_t ignoreCompassTimer; |
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| 92 | |||
| 93 | /* |
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| 1910 | - | 94 | * Dynamic gyro offsets. These are signed values that are subtracted from the gyro measurements, |
| 95 | * to help canceling out drift and vibration noise effects. The dynamic offsets themselves |
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| 96 | * can be updated in flight by different ways, for example: |
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| 97 | * - Just taking them from parameters, so the pilot can trim manually in a PC or mobile tool |
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| 98 | * - Summing up how much acc. meter correction was done to the gyro integrals over the last n |
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| 99 | * integration, and then adding the sum / n to the dynamic offset |
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| 100 | * - Detect which way the pilot pulls the stick to keep the copter steady, and correct by that |
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| 101 | * - Invent your own... |
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| 102 | */ |
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| 2099 | - | 103 | // extern int16_t dynamicOffset[2], dynamicOffsetYaw; |
| 1910 | - | 104 | |
| 105 | /* |
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| 106 | * For NaviCtrl use. |
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| 107 | */ |
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| 2099 | - | 108 | // extern int16_t averageAcc[2], averageAccCount; |
| 1910 | - | 109 | |
| 110 | /* |
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| 111 | * Re-init flight attitude, setting all angles to 0 (or to whatever can be derived from acc. sensor). |
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| 112 | * To be called when the pilot commands gyro calibration (eg. by moving the left stick up-left or up-right). |
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| 113 | */ |
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| 114 | void attitude_setNeutral(void); |
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| 115 | |||
| 116 | /* |
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| 117 | * Experiment. |
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| 118 | */ |
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| 119 | // void attitude_startDynamicCalibration(void); |
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| 120 | // void attitude_continueDynamicCalibration(void); |
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| 121 | |||
| 122 | int32_t getAngleEstimateFromAcc(uint8_t axis); |
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| 123 | |||
| 124 | /* |
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| 125 | * Main routine, called from the flight loop. |
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| 126 | */ |
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| 127 | void calculateFlightAttitude(void); |
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| 128 | #endif //_ATTITUDE_H |