1e_filter.h File Reference

Implementation of the 1 euro filter. More...

#include "std.h"
#include <math.h>

Include dependency graph for 1e_filter.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	OneEuroLPFilter
	simple low pass filter. More...
struct	OneEuroFilter
	configuration parameters. More...

Functions
static void	init_1e_filter (struct OneEuroFilter *filter, float rate, float mincutoff, float beta, float dcutoff)
	Initialize a 1 Euro Filter instance. More...
static void	reset_1e_filter (struct OneEuroFilter *filter)
	Reset filter (gains and parameters unchanged) More...
static float	compute_1e_filter_lp (struct OneEuroLPFilter *filter, float x, float alpha)
	Filter a float using the given low-pass filter and the given alpha value. More...
static float	compute_1e_filter_alpha (struct OneEuroFilter *filter, float cutoff)
	Compute Alpha for a given One Euro Filter and a given cutoff frequency. More...
static float	update_1e_filter (struct OneEuroFilter *filter, float x)
	Filter a float using the given One Euro Filter. More...
static float	update_1e_filter_at_time (struct OneEuroFilter *filter, float x, uint32_t timestamp)
	Filter a float using the given One Euro Filter and the given timestamp. More...

Detailed Description

Implementation of the 1 euro filter.

See: http://cristal.univ-lille.fr/~casiez/1euro/

Ref: Casiez, G., Roussel, N. and Vogel, D. (2012). 1€ Filter: A Simple Speed-based Low-pass Filter for Noisy Input in Interactive Systems. Proceedings of the ACM Conference on Human Factors in Computing Systems (CHI '12). Austin, Texas (May 5-12, 2012). New York: ACM Press, pp. 2527-2530.

Definition in file 1e_filter.h.

---

Data Structure Documentation

struct OneEuroLPFilter

simple low pass filter.

TODO use existing implementation ?

Definition at line 42 of file 1e_filter.h.

Data Fields
bool	first_time
float	hatx
float	hatxprev

struct OneEuroFilter

configuration parameters.

Definition at line 51 of file 1e_filter.h.

Collaboration diagram for OneEuroFilter:

Data Fields
float	beta	cutoff slope
float	dcutoff	derivative cutoff freq (in Hz)
struct OneEuroLPFilter	dxfilt	low pass filter for derivative
bool	first_time	first time flag
uint32_t	last_time	last update time in ms
float	mincutoff	min cutoff freq (in Hz)
float	rate	data update rate (in Hz)
struct OneEuroLPFilter	xfilt	low pass filter

Function Documentation

static float compute_1e_filter_alpha ( struct OneEuroFilter *  filter, float  cutoff  )

inlinestatic

Compute Alpha for a given One Euro Filter and a given cutoff frequency.

Definition at line 113 of file 1e_filter.h.

References OneEuroFilter::rate.

Referenced by update_1e_filter().

Here is the caller graph for this function:

static float compute_1e_filter_lp ( struct OneEuroLPFilter *  filter, float  x, float  alpha  )

inlinestatic

Filter a float using the given low-pass filter and the given alpha value.

Definition at line 99 of file 1e_filter.h.

References alpha, OneEuroLPFilter::first_time, OneEuroLPFilter::hatx, and OneEuroLPFilter::hatxprev.

Referenced by update_1e_filter().

Here is the caller graph for this function:

static void init_1e_filter ( struct OneEuroFilter *  filter, float  rate, float  mincutoff, float  beta, float  dcutoff  )

inlinestatic

Initialize a 1 Euro Filter instance.

Definition at line 65 of file 1e_filter.h.

References OneEuroFilter::beta, OneEuroFilter::dcutoff, OneEuroFilter::dxfilt, OneEuroLPFilter::first_time, OneEuroFilter::first_time, OneEuroLPFilter::hatx, OneEuroLPFilter::hatxprev, OneEuroFilter::last_time, OneEuroFilter::mincutoff, OneEuroFilter::rate, and OneEuroFilter::xfilt.

Referenced by filter_1euro_imu_init().

Here is the caller graph for this function:

static void reset_1e_filter ( struct OneEuroFilter *  filter )

inlinestatic

Reset filter (gains and parameters unchanged)

Definition at line 84 of file 1e_filter.h.

References OneEuroFilter::dxfilt, OneEuroLPFilter::first_time, OneEuroFilter::first_time, OneEuroLPFilter::hatx, OneEuroLPFilter::hatxprev, OneEuroFilter::last_time, and OneEuroFilter::xfilt.

Referenced by filter_1euro_imu_reset().

Here is the caller graph for this function:

static float update_1e_filter ( struct OneEuroFilter *  filter, float  x  )

inlinestatic

Filter a float using the given One Euro Filter.

Definition at line 124 of file 1e_filter.h.

References OneEuroFilter::beta, compute_1e_filter_alpha(), compute_1e_filter_lp(), OneEuroFilter::dcutoff, OneEuroFilter::dxfilt, OneEuroFilter::first_time, OneEuroLPFilter::hatxprev, OneEuroFilter::mincutoff, OneEuroFilter::rate, and OneEuroFilter::xfilt.

Referenced by accel_cb(), gyro_cb(), and update_1e_filter_at_time().

Here is the call graph for this function:

Here is the caller graph for this function:

static float update_1e_filter_at_time ( struct OneEuroFilter *  filter, float  x, uint32_t  timestamp  )

inlinestatic

Filter a float using the given One Euro Filter and the given timestamp.

Frequency will be automatically recomputed.

Definition at line 142 of file 1e_filter.h.

References OneEuroFilter::last_time, OneEuroFilter::rate, and update_1e_filter().

Referenced by accel_cb(), and gyro_cb().

Here is the call graph for this function:

Here is the caller graph for this function: