mirror of https://github.com/ArduPilot/ardupilot
253 lines
6.4 KiB
C++
253 lines
6.4 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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//
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//
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// AP_IMU_INS.cpp - IMU Sensor Library for Ardupilot Mega
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// Code by Michael Smith, Doug Weibel, Jordi Muñoz and Jose Julio. DIYDrones.com
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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/// @file AP_IMU_INS.cpp
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/// @brief IMU driver on top of an INS driver. Provides calibration for the
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// inertial sensors (gyro and accel)
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#include <FastSerial.h>
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#include <AP_Common.h>
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#include <avr/eeprom.h>
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#include "AP_IMU_INS.h"
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void
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AP_IMU_INS::init( Start_style style,
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void (*delay_cb)(unsigned long t),
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void (*flash_leds_cb)(bool on),
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AP_PeriodicProcess * scheduler )
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{
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_ins->init(scheduler);
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// if we are warm-starting, load the calibration data from EEPROM and go
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//
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if (WARM_START == style) {
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_sensor_cal.load();
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} else {
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// do cold-start calibration for both accel and gyro
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_init_gyro(delay_cb, flash_leds_cb);
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// save calibration
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_sensor_cal.save();
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}
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}
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/**************************************************/
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void
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AP_IMU_INS::init_gyro(void (*delay_cb)(unsigned long t), void (*flash_leds_cb)(bool on))
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{
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_init_gyro(delay_cb, flash_leds_cb);
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_sensor_cal.save();
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}
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#define FLASH_LEDS(on) do { if (flash_leds_cb != NULL) flash_leds_cb(on); } while (0)
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void
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AP_IMU_INS::_init_gyro(void (*delay_cb)(unsigned long t), void (*flash_leds_cb)(bool on))
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{
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Vector3f last_average, best_avg;
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float ins_gyro[3];
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float best_diff;
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// cold start
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delay_cb(100);
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Serial.printf_P(PSTR("Init Gyro"));
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for(int c = 0; c < 25; c++) {
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// Mostly we are just flashing the LED's here
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// to tell the user to keep the IMU still
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FLASH_LEDS(true);
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delay_cb(20);
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_ins->update();
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_ins->get_gyros(ins_gyro);
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FLASH_LEDS(false);
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delay_cb(20);
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}
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// the strategy is to average 200 points over 1 second, then do it
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// again and see if the 2nd average is within a small margin of
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// the first
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last_average.zero();
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// we try to get a good calibration estimate for up to 10 seconds
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// if the gyros are stable, we should get it in 2 seconds
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for (int j = 0; j <= 10; j++) {
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Vector3f gyro_sum, gyro_avg, gyro_diff;
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float diff_norm;
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uint8_t i;
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Serial.printf_P(PSTR("*"));
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gyro_sum.zero();
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for (i=0; i<200; i++) {
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_ins->update();
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_ins->get_gyros(ins_gyro);
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gyro_sum += Vector3f(ins_gyro[0], ins_gyro[1], ins_gyro[2]);
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if (i % 40 == 20) {
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FLASH_LEDS(true);
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} else if (i % 40 == 0) {
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FLASH_LEDS(false);
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}
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delay_cb(5);
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}
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gyro_avg = gyro_sum / i;
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gyro_diff = last_average - gyro_avg;
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diff_norm = gyro_diff.length();
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if (j == 0) {
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best_diff = diff_norm;
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best_avg = gyro_avg;
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} else if (gyro_diff.length() < ToRad(0.04)) {
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// we want the average to be within 0.1 bit, which is 0.04 degrees/s
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last_average = (gyro_avg * 0.5) + (last_average * 0.5);
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_sensor_cal[0] = last_average.x;
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_sensor_cal[1] = last_average.y;
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_sensor_cal[2] = last_average.z;
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// all done
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return;
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} else if (diff_norm < best_diff) {
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best_diff = diff_norm;
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best_avg = (gyro_avg * 0.5) + (last_average * 0.5);
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}
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last_average = gyro_avg;
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}
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// we've kept the user waiting long enough - use the best pair we
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// found so far
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Serial.printf_P(PSTR("\ngyro did not converge: diff=%f dps\n"), ToDeg(best_diff));
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_sensor_cal[0] = best_avg.x;
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_sensor_cal[1] = best_avg.y;
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_sensor_cal[2] = best_avg.z;
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}
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void
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AP_IMU_INS::save()
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{
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_sensor_cal.save();
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}
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void
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AP_IMU_INS::init_accel(void (*delay_cb)(unsigned long t), void (*flash_leds_cb)(bool on))
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{
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_init_accel(delay_cb, flash_leds_cb);
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_sensor_cal.save();
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}
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void
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AP_IMU_INS::_init_accel(void (*delay_cb)(unsigned long t), void (*flash_leds_cb)(bool on))
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{
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int flashcount = 0;
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float adc_in;
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float prev[6] = {0,0,0};
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float total_change;
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float max_offset;
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float ins_accel[3];
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// cold start
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delay_cb(500);
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Serial.printf_P(PSTR("Init Accel"));
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for (int j=3; j<=5; j++) _sensor_cal[j] = 500; // Just a large value to load prev[j] the first time
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do {
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_ins->update();
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_ins->get_accels(ins_accel);
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for (int j = 3; j <= 5; j++){
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prev[j] = _sensor_cal[j];
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adc_in = ins_accel[j-3];
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_sensor_cal[j] = adc_in;
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}
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for(int i = 0; i < 50; i++){ // We take some readings...
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delay_cb(20);
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_ins->update();
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_ins->get_accels(ins_accel);
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for (int j = 3; j < 6; j++){
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adc_in = ins_accel[j-3];
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_sensor_cal[j] = _sensor_cal[j] * 0.9 + adc_in * 0.1;
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}
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if(flashcount == 5) {
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Serial.printf_P(PSTR("*"));
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FLASH_LEDS(true);
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}
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if(flashcount >= 10) {
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flashcount = 0;
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FLASH_LEDS(false);
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}
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flashcount++;
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}
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// null gravity from the Z accel
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_sensor_cal[5] += 9.805;
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total_change = fabs(prev[3] - _sensor_cal[3]) + fabs(prev[4] - _sensor_cal[4]) +fabs(prev[5] - _sensor_cal[5]);
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max_offset = (_sensor_cal[3] > _sensor_cal[4]) ? _sensor_cal[3] : _sensor_cal[4];
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max_offset = (max_offset > _sensor_cal[5]) ? max_offset : _sensor_cal[5];
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delay_cb(500);
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} while ( total_change > _accel_total_cal_change || max_offset > _accel_max_cal_offset);
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Serial.printf_P(PSTR(" "));
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}
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float
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AP_IMU_INS::_calibrated(uint8_t channel, float ins_value)
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{
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return ins_value - _sensor_cal[channel];
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}
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bool
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AP_IMU_INS::update(void)
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{
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float gyros[3];
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float accels[3];
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_ins->update();
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_ins->get_gyros(gyros);
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_ins->get_accels(accels);
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_sample_time = _ins->sample_time();
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// convert corrected gyro readings to delta acceleration
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//
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_gyro.x = _calibrated(0, gyros[0]);
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_gyro.y = _calibrated(1, gyros[1]);
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_gyro.z = _calibrated(2, gyros[2]);
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// convert corrected accelerometer readings to acceleration
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//
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_accel.x = _calibrated(3, accels[0]);
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_accel.y = _calibrated(4, accels[1]);
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_accel.z = _calibrated(5, accels[2]);
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// always updated
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return true;
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}
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bool AP_IMU_INS::new_data_available(void) {
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return _ins->new_data_available();
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}
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