mirror of https://github.com/ArduPilot/ardupilot
473 lines
13 KiB
C++
473 lines
13 KiB
C++
#include "DCM.h"
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// XXX HACKS
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APM_ADC adc;
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// XXX END HACKS
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#define GRAVITY 418 //this equivalent to 1G in the raw data coming from the accelerometer
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#define ADC_CONSTRAINT 900
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#define Kp_ROLLPITCH 0.0014 //0.015 // Pitch&Roll Proportional Gain
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#define Ki_ROLLPITCH 0.0000003 // 0.00001 Pitch&Roll Integrator Gain
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#define Kp_YAW 1.2 // 1.2 Yaw Porportional Gain
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#define Ki_YAW 0.00005 // 0.00005 Yaw Integrator Gain
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// Sensor: GYROX, GYROY, GYROZ, ACCELX, ACCELY, ACCELZ
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const uint8_t AP_DCM::_sensors[6] = {1,2,0,4,5,6}; // For ArduPilot Mega Sensor Shield Hardware
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const int AP_DCM::_sensor_signs[] = {1,-1,-1,-1,1,1,-1,-1,-1}; //{-1,1,-1,1,-1,1,-1,-1,-1} !!!! These are probably not right
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// Temp compensation curve constants
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// These must be produced by measuring data and curve fitting
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// [X/Y/Z gyro][A/B/C or 0 order/1st order/2nd order constants]
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const float AP_DCM::_gyro_temp_curve[3][3] = {
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{1665,0,0},
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{1665,0,0},
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{1665,0,0}
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}; // values may migrate to a Config file
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// Constructors ////////////////////////////////////////////////////////////////
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AP_DCM::AP_DCM(APM_Compass *withCompass) :
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_compass(withCompass),
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_dcm_matrix(1, 0, 0,
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0, 1, 0,
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0, 0, 1),
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_G_Dt(0.02),
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_course_over_ground_x(0),
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_course_over_ground_y(1)
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{
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}
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void
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AP_DCM::update_DCM(void)
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{
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read_adc_raw(); // Get current values for IMU sensors
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matrix_update(); // Integrate the DCM matrix
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normalize(); // Normalize the DCM matrix
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drift_correction(); // Perform drift correction
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euler_angles(); // Calculate pitch, roll, yaw for stabilization and navigation
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}
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// Read the 6 ADC channels needed for the IMU
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// ------------------------------------------
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void
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AP_DCM::read_adc_raw(void)
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{
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int tc_temp = adc.Ch(_gyro_temp_ch);
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for (int i = 0; i < 6; i++) {
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_adc_in[i] = adc.Ch(_sensors[i]);
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if (i < 3) { // XXX magic numbers!
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_adc_in[i] -= _gyro_temp_comp(i, tc_temp); // Subtract temp compensated typical gyro bias
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} else {
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_adc_in[i] -= 2025; // Subtract typical accel bias
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}
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}
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}
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// Returns the temperature compensated raw gyro value
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//---------------------------------------------------
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float
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AP_DCM::_gyro_temp_comp(int i, int temp) const
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{
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// We use a 2nd order curve of the form Gtc = A + B * Graw + C * (Graw)**2
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//------------------------------------------------------------------------
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return _gyro_temp_curve[i][0] + _gyro_temp_curve[i][1] * temp + _gyro_temp_curve[i][2] * temp * temp;
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}
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// Returns an analog value with the offset removed
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// -----------------
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float
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AP_DCM::read_adc(int select)
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{
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float temp;
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if (_sensor_signs[select] < 0)
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temp = (_adc_offset[select] - _adc_in[select]);
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else
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temp = (_adc_in[select] - _adc_offset[select]);
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if (abs(temp) > ADC_CONSTRAINT)
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adc_constraints++; // We keep track of the number of times we constrain the ADC output for performance reporting
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/*
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// For checking the pitch/roll drift correction gain time constants
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switch (select) {
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case 3:
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return 0;
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break;
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case 4:
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return 0;
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break;
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case 5:
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return 400;
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break;
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}
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*/
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//End of drift correction gain test code
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return constrain(temp, -ADC_CONSTRAINT, ADC_CONSTRAINT); // Throw out nonsensical values
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}
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/**************************************************/
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void
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AP_DCM::normalize(void)
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{
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float error = 0;
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DCM_Vector temporary[3];
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uint8_t problem = 0;
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error = -_dcm_matrix(0).dot_product(_dcm_matrix(1)) * 0.5; // eq.19
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temporary[0] = _dcm_matrix(1) * error + _dcm_matrix(0); // eq.19
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temporary[1] = _dcm_matrix(0) * error + _dcm_matrix(1); // eq.19
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temporary[2] = temporary[0] ^ temporary[1]; // c= a x b // eq.20
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_dcm_matrix(0) = _renorm(temporary[0], problem);
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_dcm_matrix(1) = _renorm(temporary[1], problem);
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_dcm_matrix(2) = _renorm(temporary[2], problem);
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if (problem == 1) { // Our solution is blowing up and we will force back to initial condition. Hope we are not upside down!
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_dcm_matrix(0, 0)= 1.0f;
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_dcm_matrix(0, 1)= 0.0f;
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_dcm_matrix(0, 2)= 0.0f;
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_dcm_matrix(1, 0)= 0.0f;
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_dcm_matrix(1, 1)= 1.0f;
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_dcm_matrix(1, 2)= 0.0f;
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_dcm_matrix(2, 0)= 0.0f;
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_dcm_matrix(2, 1)= 0.0f;
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_dcm_matrix(2, 2)= 1.0f;
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}
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}
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DCM_Vector
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AP_DCM::_renorm(DCM_Vector const &a, uint8_t &problem)
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{
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float renorm;
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renorm = a.dot_product(a);
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if (renorm < 1.5625f && renorm > 0.64f) { // Check if we are OK with Taylor expansion
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renorm = 0.5 * (3 - renorm); // eq.21
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} else if (renorm < 100.0f && renorm > 0.01f) {
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renorm = 1.0 / sqrt(renorm);
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renorm_sqrt_count++;
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} else {
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problem = 1;
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renorm_blowup_count++;
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}
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return(a * renorm);
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}
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/**************************************************/
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void
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AP_DCM::drift_correction(void)
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{
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//Compensation the Roll, Pitch and Yaw drift.
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float mag_heading_x;
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float mag_heading_y;
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float error_course = 0;
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static float scaled_omega_P[3];
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static float scaled_omega_I[3];
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float accel_magnitude;
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float accel_weight;
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float integrator_magnitude;
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//*****Roll and Pitch***************
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// Calculate the magnitude of the accelerometer vector
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accel_magnitude = _accel_vector.magnitude() / GRAVITY; // Scale to gravity.
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// Dynamic weighting of accelerometer info (reliability filter)
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// Weight for accelerometer info (<0.5G = 0.0, 1G = 1.0 , >1.5G = 0.0)
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accel_weight = constrain(1 - 2 * abs(1 - accel_magnitude), 0, 1); //
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// We monitor the amount that the accelerometer based drift correction is deweighted for performanc reporting
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imu_health = imu_health + 0.02 * (accel_weight-.5);
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imu_health = constrain(imu_health, 0, 1);
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// adjust the ground of reference
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_error_roll_pitch = _accel_vector ^ _dcm_matrix(2);
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// error_roll_pitch are in Accel ADC units
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// Limit max error_roll_pitch to limit max omega_P and omega_I
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_error_roll_pitch(0) = constrain(_error_roll_pitch(0), -50, 50);
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_error_roll_pitch(1) = constrain(_error_roll_pitch(1), -50, 50);
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_error_roll_pitch(2) = constrain(_error_roll_pitch(2), -50, 50);
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_omega_P = _error_roll_pitch * (Kp_ROLLPITCH * accel_weight);
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_omega_I += _error_roll_pitch * (Ki_ROLLPITCH * accel_weight);
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//*****YAW***************
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if (_compass) {
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// We make the gyro YAW drift correction based on compass magnetic heading
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error_course= (_dcm_matrix(0, 0) * _compass->Heading_Y) - (_dcm_matrix(1, 0) * _compass->Heading_X); // Calculating YAW error
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} else {
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// Use GPS Ground course to correct yaw gyro drift
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if (ground_speed >= SPEEDFILT) {
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// Optimization: We have precalculated course_over_ground_x and course_over_ground_y (Course over Ground X and Y) from GPS info
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error_course = (_dcm_matrix(0, 0) * _course_over_ground_y) - (_dcm_matrix(1, 0) * _course_over_ground_x); // Calculating YAW error
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}
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}
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_error_yaw = _dcm_matrix(2) * error_course; // Applys the yaw correction to the XYZ rotation of the aircraft, depeding the position.
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_omega_P += _error_yaw * Kp_YAW; // Adding Proportional.
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_omega_I += _error_yaw * Ki_YAW; // adding integrator to the omega_I
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// Here we will place a limit on the integrator so that the integrator cannot ever exceed half the saturation limit of the gyros
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integrator_magnitude = sqrt(_omega_I.dot_product(_omega_I));
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if (integrator_magnitude > radians(300)) {
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_omega_I *= (0.5f * radians(300) / integrator_magnitude);
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}
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}
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/**************************************************/
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void
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AP_DCM::_accel_adjust(void)
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{
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_accel_vector(1) += accel_scale((ground_speed / 100) * _omega(2)); // Centrifugal force on Acc_y = GPS_speed * GyroZ
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_accel_vector(2) -= accel_scale((ground_speed / 100) * _omega(1)); // Centrifugal force on Acc_z = GPS_speed * GyroY
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}
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/**************************************************/
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void
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AP_DCM::matrix_update(void)
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{
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DCM_Matrix update_matrix;
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_gyro_vector(0) = gyro_scaled_X(read_adc(0)); // gyro x roll
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_gyro_vector(1) = gyro_scaled_Y(read_adc(1)); // gyro y pitch
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_gyro_vector(2) = gyro_scaled_Z(read_adc(2)); // gyro Z yaw
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//Record when you saturate any of the gyros.
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if((abs(_gyro_vector(0)) >= radians(300)) ||
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(abs(_gyro_vector(1)) >= radians(300)) ||
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(abs(_gyro_vector(2)) >= radians(300)))
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gyro_sat_count++;
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/*
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Serial.print (__adc_in[0]);
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Serial.print (" ");
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Serial.print (_adc_offset[0]);
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Serial.print (" ");
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Serial.print (_gyro_vector(0));
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Serial.print (" ");
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Serial.print (__adc_in[1]);
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Serial.print (" ");
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Serial.print (_adc_offset[1]);
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Serial.print (" ");
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Serial.print (_gyro_vector(1));
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Serial.print (" ");
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Serial.print (__adc_in[2]);
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Serial.print (" ");
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Serial.print (_adc_offset[2]);
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Serial.print (" ");
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Serial.println (_gyro_vector(2));
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*/
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// _accel_vector(0) = read_adc(3); // acc x
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// _accel_vector(1) = read_adc(4); // acc y
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// _accel_vector(2) = read_adc(5); // acc z
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// Low pass filter on accelerometer data (to filter vibrations)
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_accel_vector(0) = _accel_vector(0) * 0.6 + (float)read_adc(3) * 0.4; // acc x
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_accel_vector(1) = _accel_vector(1) * 0.6 + (float)read_adc(4) * 0.4; // acc y
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_accel_vector(2) = _accel_vector(2) * 0.6 + (float)read_adc(5) * 0.4; // acc z
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_omega = _gyro_vector + _omega_I; // adding proportional term
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_omega_vector = _omega + _omega_P; // adding Integrator term
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_accel_adjust(); // Remove centrifugal acceleration.
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#if OUTPUTMODE == 1
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update_matrix(0, 0) = 0;
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update_matrix(0, 1) = -_G_Dt * _omega_vector(2); // -z
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update_matrix(0, 2) = _G_Dt * _omega_vector(1); // y
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update_matrix(1, 0) = _G_Dt * _omega_vector(2); // z
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update_matrix(1, 1) = 0;
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update_matrix(1, 2) = -_G_Dt * _omega_vector(0); // -x
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update_matrix(2, 0) = -_G_Dt * _omega_vector(1); // -y
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update_matrix(2, 1) = _G_Dt * _omega_vector(0); // x
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update_matrix(2, 2) = 0;
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#else // Uncorrected data (no drift correction)
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update_matrix(0, 0) = 0;
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update_matrix(0, 1) = -_G_Dt * _gyro_vector(2); // -z
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update_matrix(0, 2) = _G_Dt * _gyro_vector(1); // y
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update_matrix(1, 0) = _G_Dt * _gyro_vector(2); // z
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update_matrix(1, 1) = 0;
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update_matrix(1, 2) = -_G_Dt * _gyro_vector(0);
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update_matrix(2, 0) = -_G_Dt * _gyro_vector(1);
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update_matrix(2, 1) = _G_Dt * _gyro_vector(0);
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update_matrix(2, 2) = 0;
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#endif
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// update
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_dcm_matrix += _dcm_matrix * update_matrix;
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/*
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Serial.print (_G_Dt * 1000);
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Serial.print (" ");
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Serial.print (dcm_matrix(0, 0));
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Serial.print (" ");
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Serial.print (dcm_matrix(0, 1));
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Serial.print (" ");
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Serial.print (dcm_matrix(0, 2));
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Serial.print (" ");
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Serial.print (dcm_matrix(1, 0));
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Serial.print (" ");
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Serial.print (dcm_matrix(1, 1));
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Serial.print (" ");
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Serial.print (dcm_matrix(1, 2));
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Serial.print (" ");
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Serial.print (dcm_matrix(2, 0));
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Serial.print (" ");
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Serial.print (dcm_matrix(2, 1));
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Serial.print (" ");
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Serial.println (dcm_matrix(2, 2));
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*/
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}
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/**************************************************/
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void
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AP_DCM::euler_angles(void)
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{
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#if (OUTPUTMODE == 2) // Only accelerometer info (debugging purposes)
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roll = atan2(_accel_vector(1), _accel_vector(2)); // atan2(acc_y, acc_z)
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roll_sensor = degrees(roll) * 100;
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pitch = -asin((_accel_vector(0)) / (double)GRAVITY); // asin(acc_x)
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pitch_sensor = degrees(pitch) * 100;
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yaw = 0;
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#else
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pitch = -asin(_dcm_matrix(2, 0));
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pitch_sensor = degrees(pitch) * 100;
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roll = atan2(_dcm_matrix(2, 1), _dcm_matrix(2, 2));
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roll_sensor = degrees(roll) * 100;
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yaw = atan2(_dcm_matrix(1, 0), _dcm_matrix(0, 0));
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yaw_sensor = degrees(yaw) * 100;
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#endif
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/*
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Serial.print ("Roll ");
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Serial.print (roll_sensor / 100);
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Serial.print (", Pitch ");
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Serial.print (pitch_sensor / 100);
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Serial.print (", Yaw ");
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Serial.println (yaw_sensor / 100);
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*/
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}
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/**************************************************/
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//Computes the dot product of two vectors
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float
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DCM_Vector::dot_product(DCM_Vector const &vector2) const
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{
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float op = 0;
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for(int c = 0; c < 3; c++)
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op += _v[c] * vector2(c);
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return op;
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}
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// cross-product
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DCM_Vector
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DCM_Vector::operator^(DCM_Vector const &a) const
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{
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DCM_Vector result;
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result(0) = (_v[1] * a(2)) - (_v[2] * a(1));
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result(1) = (_v[2] * a(0)) - (_v[0] * a(2));
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result(2) = (_v[0] * a(1)) - (_v[1] * a(0));
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return(result);
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}
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// scale
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DCM_Vector
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DCM_Vector::operator*(float scale) const
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{
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DCM_Vector result;
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result(0) = _v[0] * scale;
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result(1) = _v[1] * scale;
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result(2) = _v[2] * scale;
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return(result);
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}
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// scale
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void
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DCM_Vector::operator*=(float scale)
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{
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_v[0] *= scale;
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_v[1] *= scale;
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_v[2] *= scale;
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}
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// add
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DCM_Vector
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DCM_Vector::operator+(DCM_Vector const &a) const
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{
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DCM_Vector result;
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result(0) = _v[0] + a(0);
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result(1) = _v[1] + a(1);
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result(2) = _v[2] + a(2);
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return(result);
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}
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// add
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void
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DCM_Vector::operator+=(DCM_Vector const &a)
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{
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_v[0] += a(0);
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_v[1] += a(1);
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_v[2] += a(2);
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}
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// magnitude
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float
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DCM_Vector::magnitude(void) const
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{
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return(sqrt((_v[0] * _v[0]) +
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(_v[1] * _v[1]) +
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(_v[2] * _v[2])));
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}
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// 3x3 matrix multiply
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DCM_Matrix
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DCM_Matrix::operator*(DCM_Matrix const &a) const
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{
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DCM_Matrix result;
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for (int x = 0; x < 3; x++) {
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for (int y = 0; y < 3; y++) {
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result(x, y) =
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_m[x](0) * a(0, y) +
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_m[x](1) * a(1, y) +
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_m[x](2) * a(2, y);
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}
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}
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return(result);
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}
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// 3x3 matrix add
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void
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DCM_Matrix::operator+=(DCM_Matrix const &a)
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{
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for (int x = 0; x < 3; x++)
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for (int y = 0; y < 3; y++)
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_m[x](y) += a(x,y);
|
|
}
|
|
|