mirror of https://github.com/ArduPilot/ardupilot
157 lines
7.3 KiB
C++
157 lines
7.3 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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#ifndef __AP_INERTIALNAV_H__
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#define __AP_INERTIALNAV_H__
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#include <AP_AHRS.h>
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#include <AP_InertialSensor.h> // ArduPilot Mega IMU Library
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#include <AP_Baro.h> // ArduPilot Mega Barometer Library
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#include <AP_Buffer.h> // FIFO buffer library
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#define AP_INTERTIALNAV_TC_XY 2.5f // default time constant for complementary filter's X & Y axis
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#define AP_INTERTIALNAV_TC_Z 5.0f // default time constant for complementary filter's Z axis
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// #defines to control how often historical accel based positions are saved
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// so they can later be compared to laggy gps readings
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#define AP_INTERTIALNAV_SAVE_POS_AFTER_ITERATIONS 10
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#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
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#define AP_INTERTIALNAV_GPS_TIMEOUT_MS 300 // timeout after which position error from GPS will fall to zero
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/*
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* AP_InertialNav is an attempt to use accelerometers to augment other sensors to improve altitud e position hold
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*/
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class AP_InertialNav
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{
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public:
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// Constructor
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AP_InertialNav( AP_AHRS* ahrs, AP_InertialSensor* ins, AP_Baro* baro, GPS** gps_ptr ) :
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_ahrs(ahrs),
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_ins(ins),
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_baro(baro),
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_gps_ptr(gps_ptr),
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_xy_enabled(false),
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_gps_last_update(0),
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_gps_last_time(0),
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_baro_last_update(0)
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{
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AP_Param::setup_object_defaults(this, var_info);
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}
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// Initialisation
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void init();
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// update - updates velocities and positions using latest info from accelerometers;
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void update(float dt);
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//
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// XY Axis specific methods
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//
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// set time constant - set timeconstant used by complementary filter
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void set_time_constant_xy( float time_constant_in_seconds );
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// altitude_ok, position_ok - true if inertial based altitude and position can be trusted
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bool position_ok() const;
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// check_gps - check if new gps readings have arrived and use them to correct position estimates
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void check_gps();
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// correct_with_gps - modifies accelerometer offsets using gps. dt is time since last gps update
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void correct_with_gps(int32_t lon, int32_t lat, float dt);
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// get_position - returns current position from home in cm
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Vector3f get_position() const { return _position_base + _position_correction; }
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// get latitude & longitude positions
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int32_t get_latitude() const;
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int32_t get_longitude() const;
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// set_current_position - all internal calculations are recorded as the distances from this point
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void set_current_position(int32_t lon, int32_t lat);
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// get latitude & longitude positions from base location (in cm)
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float get_latitude_diff() const;
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float get_longitude_diff() const;
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// get velocity in latitude & longitude directions (in cm/s)
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float get_latitude_velocity() const;
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float get_longitude_velocity() const;
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// get_velocity - returns current velocity in cm/s
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Vector3f get_velocity() const { return _velocity; }
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// set velocity in latitude & longitude directions (in cm/s)
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void set_velocity_xy(float x, float y);
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//
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// Z Axis methods
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//
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// set time constant - set timeconstant used by complementary filter
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void set_time_constant_z( float time_constant_in_seconds );
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// altitude_ok, position_ok - true if inertial based altitude and position can be trusted
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bool altitude_ok() const { return true; }
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// check_baro - check if new baro readings have arrived and use them to correct vertical accelerometer offsets
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void check_baro();
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// correct_with_baro - modifies accelerometer offsets using barometer. dt is time since last baro reading
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void correct_with_baro(float baro_alt, float dt);
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// get_altitude - get latest altitude estimate in cm
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float get_altitude() const { return _position_base.z + _position_correction.z; }
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void set_altitude( float new_altitude);
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// get_velocity_z - get latest climb rate (in cm/s)
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float get_velocity_z() const { return _velocity.z; }
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void set_velocity_z( float new_velocity );
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// class level parameters
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static const struct AP_Param::GroupInfo var_info[];
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// public variables
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Vector3f accel_correction_ef; // earth frame accelerometer corrections. here for logging purposes only
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protected:
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void update_gains(); // update_gains - update gains from time constant (given in seconds)
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AP_AHRS* _ahrs; // pointer to ahrs object
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AP_InertialSensor* _ins; // pointer to inertial sensor
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AP_Baro* _baro; // pointer to barometer
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GPS** _gps_ptr; // pointer to pointer to gps
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// XY Axis specific variables
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bool _xy_enabled; // xy position estimates enabled
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AP_Float _time_constant_xy; // time constant for horizontal corrections
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float _k1_xy; // gain for horizontal position correction
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float _k2_xy; // gain for horizontal velocity correction
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float _k3_xy; // gain for horizontal accelerometer offset correction
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uint32_t _gps_last_update; // system time of last gps update
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uint32_t _gps_last_time; // time of last gps update according to the gps itself
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uint8_t _historic_xy_counter; // counter used to slow saving of position estimates for later comparison to gps
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AP_BufferFloat_Size5 _hist_position_estimate_x; // buffer of historic accel based position to account for lag
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AP_BufferFloat_Size5 _hist_position_estimate_y; // buffer of historic accel based position to account for lag
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int32_t _base_lat; // base latitude
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int32_t _base_lon; // base longitude
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float _lon_to_m_scaling; // conversion of longitude to meters
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// Z Axis specific variables
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AP_Float _time_constant_z; // time constant for vertical corrections
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float _k1_z; // gain for vertical position correction
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float _k2_z; // gain for vertical velocity correction
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float _k3_z; // gain for vertical accelerometer offset correction
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uint32_t _baro_last_update; // time of last barometer update
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AP_BufferFloat_Size15 _hist_position_estimate_z; // buffer of historic accel based altitudes to account for lag
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// general variables
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Vector3f _position_base; // position estimate
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Vector3f _position_correction; // sum of correction to _comp_h from delayed 1st order samples
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Vector3f _velocity; // latest velocity estimate (integrated from accelerometer values)
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Vector3f _position_error;
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};
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#endif // __AP_INERTIALNAV_H__
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