ardupilot/libraries/AP_AHRS/AP_AHRS.h
Andrew Tridgell 398a608b83 DCM: drop the 'drop z' method
the 'drop z' method reduced the impact of noise on omegaI, but it also
made us more sensitive to errors in accelerometer calibration and
scaling, as demonstated by the logs from Gabor here:

  http://diydrones.com/xn/detail/705844:Comment:834373

Simulation testing shows that the other noise suppression methods
applied in the DCM code, in particular the slope limiting on omegaI
the removal of the weighting and the upcoming use of a _omega_I_sum
buffer have reduced the impact of noise enough that we can now safely
include z in the acceleration calculation.
2012-04-23 12:13:24 +10:00

115 lines
2.9 KiB
C++

#ifndef AP_AHRS_H
#define AP_AHRS_H
/*
AHRS (Attitude Heading Reference System) interface for ArduPilot
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
*/
#include <AP_Math.h>
#include <inttypes.h>
#include <AP_Compass.h>
#include <AP_GPS.h>
#include <AP_IMU.h>
#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif
class AP_AHRS
{
public:
// Constructor
AP_AHRS(IMU *imu, GPS *&gps):
_imu(imu),
_gps(gps)
{
// base the ki values by the sensors maximum drift
// rate. The APM2 has gyros which are much less drift
// prone than the APM1, so we should have a lower ki,
// which will make us less prone to increasing omegaI
// incorrectly due to sensor noise
_gyro_drift_limit = imu->get_gyro_drift_rate();
}
// Accessors
void set_centripetal(bool b) { _centripetal = b; }
bool get_centripetal(void) { return _centripetal; }
void set_compass(Compass *compass) { _compass = compass; }
// Methods
virtual void update(void) = 0;
// Euler angles (radians)
float roll;
float pitch;
float yaw;
// integer Euler angles (Degrees * 100)
int32_t roll_sensor;
int32_t pitch_sensor;
int32_t yaw_sensor;
// return a smoothed and corrected gyro vector
virtual Vector3f get_gyro(void) = 0;
// return the current estimate of the gyro drift
virtual Vector3f get_gyro_drift(void) = 0;
// reset the current attitude, used on new IMU calibration
virtual void reset(bool recover_eulers=false) = 0;
// how often our attitude representation has gone out of range
uint8_t renorm_range_count;
// how often our attitude representation has blown up completely
uint8_t renorm_blowup_count;
// return the average size of the roll/pitch error estimate
// since last call
virtual float get_error_rp(void) = 0;
// return the average size of the yaw error estimate
// since last call
virtual float get_error_yaw(void) = 0;
// return a DCM rotation matrix representing our current
// attitude
virtual Matrix3f get_dcm_matrix(void) = 0;
static const struct AP_Param::GroupInfo var_info[];
protected:
// pointer to compass object, if enabled
Compass * _compass;
// time in microseconds of last compass update
uint32_t _compass_last_update;
// note: we use ref-to-pointer here so that our caller can change the GPS without our noticing
// IMU under us without our noticing.
IMU *_imu;
GPS *&_gps;
// true if we are doing centripetal acceleration correction
bool _centripetal;
// the limit of the gyro drift claimed by the sensors, in
// radians/s/s
float _gyro_drift_limit;
// acceleration due to gravity in m/s/s
static const float _gravity = 9.80665;
};
#include <AP_AHRS_DCM.h>
#include <AP_AHRS_Quaternion.h>
#include <AP_AHRS_HIL.h>
#endif // AP_AHRS_H