accwin.h File Reference

Windowed accelerometer mean, compensated for rotation. More...

#include <stdint.h>

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Data Structures
struct	accwin_t

Functions
void	accwin_reset (accwin_t *w)
void	accwin_add (accwin_t *w, const float acc[3])
	sample in the current body
void	accwin_rotate (accwin_t *w, const float E[9])
	after every propagation
int	accwin_mean (const accwin_t *w, float out[3])
	in the current body, 0 = OK

Detailed Description

Windowed accelerometer mean, compensated for rotation.

A plain mean of N samples taken while the body rotates is "smeared" over different orientations and lags by half a window (at 360 deg/s with a 4 ms window that is ~0.7 deg). Here every sample is brought into the body frame at the START of the window with the propagated rotation D, averaged, and the result is brought back into the CURRENT body frame:

a_mean = D_N' * (1/N) * sum_i D_i * a_i ,   D = E_1 E_2 ... E_k

The E are the rotation increments of the IEKF propagation (iekf.E_last), so the cost is a few 3x3 multiplications per sample.

Definition in file accwin.h.

Function Documentation

accwin_reset()

void accwin_reset

(

accwin_t *

w

)

Definition at line 8 of file accwin.c.

References accwin_t::D.

Referenced by est_init(), on_acc_window(), and on_mag().

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accwin_add()

void accwin_add	(	accwin_t *	w,
		const float	acc[3]
	)

sample in the current body

Definition at line 14 of file accwin.c.

References accwin_t::D, mat3_vec(), accwin_t::n, and accwin_t::sum.

Referenced by est_process().

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accwin_rotate()

void accwin_rotate	(	accwin_t *	w,
		const float	E[9]
	)

after every propagation

Definition at line 22 of file accwin.c.

References accwin_t::D, and mat3_mul().

Referenced by on_step().

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accwin_mean()

int accwin_mean	(	const accwin_t *	w,
		float	out[3]
	)

in the current body, 0 = OK

Definition at line 29 of file accwin.c.

References accwin_t::D, mat3t_vec(), accwin_t::n, and accwin_t::sum.

Referenced by on_acc_window().

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