mirror of https://github.com/ArduPilot/ardupilot
316 lines
12 KiB
C++
316 lines
12 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
|
|
|
|
#ifndef __AP_INERTIALNAV_H__
|
|
#define __AP_INERTIALNAV_H__
|
|
|
|
#include <AP_AHRS.h>
|
|
#include <AP_InertialSensor.h> // ArduPilot Mega IMU Library
|
|
#include <AP_Baro.h> // ArduPilot Mega Barometer Library
|
|
#include <AP_Buffer.h> // FIFO buffer library
|
|
#include <AP_GPS_Glitch.h> // GPS Glitch detection library
|
|
|
|
#define AP_INTERTIALNAV_TC_XY 2.5f // default time constant for complementary filter's X & Y axis
|
|
#define AP_INTERTIALNAV_TC_Z 5.0f // default time constant for complementary filter's Z axis
|
|
|
|
// #defines to control how often historical accel based positions are saved
|
|
// so they can later be compared to laggy gps readings
|
|
#define AP_INTERTIALNAV_SAVE_POS_AFTER_ITERATIONS 10
|
|
#define AP_INTERTIALNAV_GPS_LAG_IN_10HZ_INCREMENTS 4 // must not be larger than size of _hist_position_estimate_x and _hist_position_estimate_y
|
|
#define AP_INTERTIALNAV_GPS_TIMEOUT_MS 300 // timeout after which position error from GPS will fall to zero
|
|
|
|
/*
|
|
* AP_InertialNav blends accelerometer data with gps and barometer data to improve altitude and position hold.
|
|
*
|
|
* Most of the functions have to be called at 100Hz. (see defines above)
|
|
*
|
|
* The accelerometer values are integrated over time to approximate velocity and position.
|
|
* The inaccurcy of these estimates grows over time due to noisy sensor data.
|
|
* To improve the accuracy, baro and gps readings are used:
|
|
* An error value is calculated as the difference between the sensor's measurement and the last position estimation.
|
|
* This value is weighted with a gain factor and incorporated into the new estimation
|
|
*/
|
|
class AP_InertialNav
|
|
{
|
|
public:
|
|
|
|
// Constructor
|
|
AP_InertialNav(AP_AHRS &ahrs, AP_Baro &baro, GPS_Glitch& gps_glitch ) :
|
|
_ahrs(ahrs),
|
|
_baro(baro),
|
|
_xy_enabled(false),
|
|
_gps_last_update(0),
|
|
_gps_last_time(0),
|
|
_historic_xy_counter(0),
|
|
_baro_last_update(0),
|
|
_glitch_detector(gps_glitch),
|
|
_error_count(0)
|
|
{
|
|
AP_Param::setup_object_defaults(this, var_info);
|
|
}
|
|
|
|
/**
|
|
* initializes the object.
|
|
*/
|
|
virtual void init();
|
|
|
|
/**
|
|
* update - updates velocity and position estimates using latest info from accelerometers
|
|
* augmented with gps and baro readings
|
|
*
|
|
* @param dt : time since last update in seconds
|
|
*/
|
|
virtual void update(float dt);
|
|
|
|
//
|
|
// XY Axis specific methods
|
|
//
|
|
|
|
/**
|
|
* set_time_constant_xy - sets time constant used by complementary filter for horizontal position estimate
|
|
*
|
|
* smaller values means higher influence of gps on position estimation
|
|
* bigger values favor the integrated accelerometer data for position estimation
|
|
*
|
|
* @param time_constant_in_seconds : constant in seconds; 0 < constant < 30 must hold
|
|
*/
|
|
void set_time_constant_xy( float time_constant_in_seconds );
|
|
|
|
/**
|
|
* position_ok - true if inertial based altitude and position can be trusted
|
|
* @return
|
|
*/
|
|
virtual bool position_ok() const;
|
|
|
|
/**
|
|
* get_position - returns the current position relative to the home location in cm.
|
|
*
|
|
* @return
|
|
*/
|
|
virtual const Vector3f& get_position() const { return _position; }
|
|
|
|
/**
|
|
* get_latitude - returns the latitude of the current position estimation in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
|
|
* @return
|
|
*/
|
|
virtual int32_t get_latitude() const;
|
|
|
|
/**
|
|
* get_longitude - returns the longitude of the current position estimation in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
|
|
* @return
|
|
*/
|
|
virtual int32_t get_longitude() const;
|
|
|
|
/**
|
|
* get_latitude_diff - returns the current latitude difference from the home location.
|
|
*
|
|
* @return difference in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
|
|
*/
|
|
virtual float get_latitude_diff() const;
|
|
|
|
/**
|
|
* get_longitude_diff - returns the current longitude difference from the home location.
|
|
*
|
|
* @return difference in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
|
|
*/
|
|
virtual float get_longitude_diff() const;
|
|
|
|
/**
|
|
* get_velocity - returns the current velocity in cm/s
|
|
*
|
|
* @return velocity vector:
|
|
* .x : latitude velocity in cm/s
|
|
* .y : longitude velocity in cm/s
|
|
* .z : vertical velocity in cm/s
|
|
*/
|
|
virtual const Vector3f& get_velocity() const { return _velocity; }
|
|
|
|
/**
|
|
* get_velocity_xy - returns the current horizontal velocity in cm/s
|
|
*
|
|
* @returns the current horizontal velocity in cm/s
|
|
*/
|
|
virtual float get_velocity_xy() const;
|
|
|
|
/**
|
|
* set_velocity_xy - overwrites the current horizontal velocity in cm/s
|
|
*
|
|
* @param x : latitude velocity in cm/s
|
|
* @param y : longitude velocity in cm/s
|
|
*/
|
|
void set_velocity_xy(float x, float y);
|
|
|
|
/**
|
|
setup_home_position - reset on home position change
|
|
*/
|
|
void setup_home_position(void);
|
|
|
|
//
|
|
// Z Axis methods
|
|
//
|
|
|
|
/**
|
|
* set_time_constant_z - sets timeconstant used by complementary filter for vertical position estimation
|
|
*
|
|
* smaller values means higher influence of barometer in altitude estimation
|
|
* bigger values favor the integrated accelerometer data for altitude estimation
|
|
*
|
|
* @param time_constant_in_seconds : constant in s; 0 < constant < 30 must hold
|
|
*/
|
|
void set_time_constant_z( float time_constant_in_seconds );
|
|
|
|
/**
|
|
* altitude_ok - returns true if inertial based altitude and position can be trusted
|
|
* @return
|
|
*/
|
|
virtual bool altitude_ok() const { return true; }
|
|
|
|
/**
|
|
* get_altitude - get latest altitude estimate in cm above the
|
|
* reference position
|
|
* @return
|
|
*/
|
|
virtual float get_altitude() const { return _position.z; }
|
|
|
|
/**
|
|
* set_altitude - overwrites the current altitude value.
|
|
*
|
|
* @param new_altitude : altitude in cm
|
|
*/
|
|
void set_altitude( float new_altitude);
|
|
|
|
/**
|
|
* get_velocity_z - returns the current climbrate.
|
|
*
|
|
* @see get_velocity().z
|
|
*
|
|
* @return climbrate in cm/s (positive up)
|
|
*/
|
|
virtual float get_velocity_z() const { return _velocity.z; }
|
|
|
|
/**
|
|
* set_velocity_z - overwrites the current climbrate.
|
|
*
|
|
* @param new_velocity : climbrate in cm/s
|
|
*/
|
|
void set_velocity_z( float new_velocity );
|
|
|
|
/**
|
|
* error_count - returns number of missed updates from GPS
|
|
*/
|
|
virtual uint8_t error_count() const { return _error_count; }
|
|
|
|
/**
|
|
* ignore_next_error - the next error (if it occurs immediately) will not be added to the error count
|
|
*/
|
|
void ignore_next_error() { _flags.ignore_error = 7; }
|
|
|
|
// class level parameters
|
|
static const struct AP_Param::GroupInfo var_info[];
|
|
|
|
// public variables
|
|
Vector3f accel_correction_ef; // earth frame accelerometer corrections. here for logging purposes only
|
|
|
|
protected:
|
|
|
|
/**
|
|
* correct_with_gps - calculates horizontal position error using gps
|
|
*
|
|
* @param now : current time since boot in milliseconds
|
|
* @param lon : longitude in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
|
|
* @param lat : latitude in 100 nano degrees (i.e. degree value multiplied by 10,000,000)
|
|
*/
|
|
void correct_with_gps(uint32_t now, int32_t lon, int32_t lat);
|
|
|
|
/**
|
|
* check_gps - checks if new gps readings have arrived and calls correct_with_gps to
|
|
* calculate the horizontal position error
|
|
* @see correct_with_gps(int32_t lon, int32_t lat, float dt);
|
|
*/
|
|
void check_gps();
|
|
|
|
/**
|
|
* check_baro - checks if new baro readings have arrived and calls correct_with_baro to
|
|
* calculate the vertical position error
|
|
*
|
|
* @see correct_with_baro(float baro_alt, float dt);
|
|
*/
|
|
void check_baro();
|
|
|
|
/**
|
|
* correct_with_baro - calculates vertical position error using barometer.
|
|
*
|
|
* @param baro_alt : altitude in cm
|
|
* @param dt : time since last baro reading in s
|
|
*/
|
|
void correct_with_baro(float baro_alt, float dt);
|
|
|
|
|
|
/**
|
|
* update gains from time constant.
|
|
*
|
|
* The time constants (in s) can be set with the following methods:
|
|
*
|
|
* @see: AP_InertialNav::set_time_constant_xy(float)
|
|
* @see: AP_InertialNav::set_time_constant_z(float)
|
|
*/
|
|
void update_gains();
|
|
|
|
/**
|
|
* set_position_xy - overwrites the current position relative to the home location in cm
|
|
*
|
|
* the home location was set with AP_InertialNav::set_home_location(int32_t, int32_t)
|
|
*
|
|
* @param x : relative latitude position in cm
|
|
* @param y : relative longitude position in cm
|
|
*/
|
|
void set_position_xy(float x, float y);
|
|
|
|
// structure for holding flags
|
|
struct InertialNav_flags {
|
|
uint8_t gps_glitching : 1; // 1 if glitch detector was previously indicating a gps glitch
|
|
uint8_t ignore_error : 3; // the number of iterations for which we should ignore errors
|
|
} _flags;
|
|
|
|
AP_AHRS &_ahrs; // reference to ahrs object
|
|
AP_Baro &_baro; // reference to barometer
|
|
|
|
// XY Axis specific variables
|
|
bool _xy_enabled; // xy position estimates enabled
|
|
AP_Float _time_constant_xy; // time constant for horizontal corrections in s
|
|
float _k1_xy; // gain for horizontal position correction
|
|
float _k2_xy; // gain for horizontal velocity correction
|
|
float _k3_xy; // gain for horizontal accelerometer offset correction
|
|
uint32_t _gps_last_update; // system time of last gps update in ms
|
|
uint32_t _gps_last_time; // time of last gps update according to the gps itself in ms
|
|
uint8_t _historic_xy_counter; // counter used to slow saving of position estimates for later comparison to gps
|
|
AP_BufferFloat_Size5 _hist_position_estimate_x; // buffer of historic accel based position to account for gpslag
|
|
AP_BufferFloat_Size5 _hist_position_estimate_y; // buffer of historic accel based position to account for gps lag
|
|
float _lon_to_cm_scaling; // conversion of longitude to centimeters
|
|
|
|
// Z Axis specific variables
|
|
AP_Float _time_constant_z; // time constant for vertical corrections in s
|
|
float _k1_z; // gain for vertical position correction
|
|
float _k2_z; // gain for vertical velocity correction
|
|
float _k3_z; // gain for vertical accelerometer offset correction
|
|
uint32_t _baro_last_update; // time of last barometer update in ms
|
|
AP_BufferFloat_Size15 _hist_position_estimate_z; // buffer of historic accel based altitudes to account for barometer lag
|
|
|
|
// general variables
|
|
Vector3f _position_base; // (uncorrected) position estimate in cm - relative to the home location (_base_lat, _base_lon, 0)
|
|
Vector3f _position_correction; // sum of corrections to _position_base from delayed 1st order samples in cm
|
|
Vector3f _velocity; // latest velocity estimate (integrated from accelerometer values) in cm/s
|
|
Vector3f _position_error; // current position error in cm - is set by the check_* methods and used by update method to calculate the correction terms
|
|
Vector3f _position; // sum(_position_base, _position_correction) - corrected position estimate in cm - relative to the home location (_base_lat, _base_lon, 0)
|
|
|
|
// error handling
|
|
GPS_Glitch& _glitch_detector; // GPS Glitch detector
|
|
uint8_t _error_count; // number of missed GPS updates
|
|
|
|
};
|
|
|
|
#if AP_AHRS_NAVEKF_AVAILABLE
|
|
#include "AP_InertialNav_NavEKF.h"
|
|
#endif
|
|
|
|
#endif // __AP_INERTIALNAV_H__
|