First order low-pass filter with delay. More...

#include "paparazzi.h"

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Data Structures
struct	delayed_first_order_lowpass_filter_t

Macros
#define	DELAYED_FIRST_ORDER_LOWPASS_FILTER_BUFFER_SIZE 20

#define	DELAYED_FIRST_ORDER_LOWPASS_FILTER_FILTER_ALPHA_SHIFT 14

Functions
static int32_t	delayed_first_order_lowpass_propagate (struct delayed_first_order_lowpass_filter_t *f, int32_t input)
	delayed_first_order_lowpass_propagate More...

static void	delayed_first_order_lowpass_set_omega (struct delayed_first_order_lowpass_filter_t *f, uint32_t omega)
	delayed_first_order_lowpass_set_omega More...

static void	delayed_first_order_lowpass_set_delay (struct delayed_first_order_lowpass_filter_t *f, uint8_t delay)
	delayed_first_order_lowpass_set_delay More...

static void	delayed_first_order_lowpass_initialize (struct delayed_first_order_lowpass_filter_t *f, uint32_t omega, uint8_t delay, uint16_t max_inc, uint16_t sample_frequency)
	delayed_first_order_lowpass_initialize More...

Detailed Description

First order low-pass filter with delay.

Definition in file delayed_first_order_lowpass_filter.h.

Data Structure Documentation

struct delayed_first_order_lowpass_filter_t

Definition at line 35 of file delayed_first_order_lowpass_filter.h.

Data Fields
int32_t	alpha
int32_t	buffer[DELAYED_FIRST_ORDER_LOWPASS_FILTER_BUFFER_SIZE]
uint8_t	delay
uint8_t	idx
uint16_t	max_inc
uint32_t	omega
uint16_t	sample_frequency

Macro Definition Documentation

#define DELAYED_FIRST_ORDER_LOWPASS_FILTER_BUFFER_SIZE 20

Definition at line 32 of file delayed_first_order_lowpass_filter.h.

Referenced by delayed_first_order_lowpass_initialize(), delayed_first_order_lowpass_propagate(), and delayed_first_order_lowpass_set_delay().

#define DELAYED_FIRST_ORDER_LOWPASS_FILTER_FILTER_ALPHA_SHIFT 14

Definition at line 33 of file delayed_first_order_lowpass_filter.h.

Referenced by delayed_first_order_lowpass_propagate(), delayed_first_order_lowpass_set_omega(), indi_apply_compensator_filters(), and stabilization_attitude_init().

Function Documentation

static void delayed_first_order_lowpass_initialize	(	struct delayed_first_order_lowpass_filter_t *	f,
		uint32_t	omega,
		uint8_t	delay,
		uint16_t	max_inc,
		uint16_t	sample_frequency
	)

inlinestatic

delayed_first_order_lowpass_initialize

Parameters

f	Reference to the filter.
omega	Filter bandwidth in [rad/s], only positive integer values.
delay	Number of timesteps delay in the signal. Maximum defined by buffer size.
sample_frequency	Frequency at which the filter is going to be updated.

Initializes the filter, should be done before using it.

Definition at line 120 of file delayed_first_order_lowpass_filter.h.

References delayed_first_order_lowpass_filter_t::buffer, DELAYED_FIRST_ORDER_LOWPASS_FILTER_BUFFER_SIZE, delayed_first_order_lowpass_set_delay(), delayed_first_order_lowpass_set_omega(), delayed_first_order_lowpass_filter_t::idx, delayed_first_order_lowpass_filter_t::max_inc, and delayed_first_order_lowpass_filter_t::sample_frequency.

Referenced by stabilization_attitude_init().

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static int32_t delayed_first_order_lowpass_propagate	(	struct delayed_first_order_lowpass_filter_t *	f,
		int32_t	input
	)

inlinestatic

delayed_first_order_lowpass_propagate

Parameters

f	Reference to the filter.
input	Value that needs to be filtered.

Returns: alpha*previous + (1 - alpha)*input

The actual low-pass filter with delay. Delay is accomplished by internal buffer.

Definition at line 54 of file delayed_first_order_lowpass_filter.h.

References delayed_first_order_lowpass_filter_t::alpha, delayed_first_order_lowpass_filter_t::buffer, delayed_first_order_lowpass_filter_t::delay, DELAYED_FIRST_ORDER_LOWPASS_FILTER_BUFFER_SIZE, DELAYED_FIRST_ORDER_LOWPASS_FILTER_FILTER_ALPHA_SHIFT, delayed_first_order_lowpass_filter_t::idx, and delayed_first_order_lowpass_filter_t::max_inc.

Referenced by indi_apply_actuator_models().

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static void delayed_first_order_lowpass_set_delay	(	struct delayed_first_order_lowpass_filter_t *	f,
		uint8_t	delay
	)

inlinestatic

delayed_first_order_lowpass_set_delay

Parameters

f	Reference to the filter.
delay	Number of timesteps delay in the signal. Maximum defined by buffer size.

Function to change the number of timesteps delay. This can be done during run-time. It basically changes the offset to the buffer value which is returned on a propagation.

Definition at line 101 of file delayed_first_order_lowpass_filter.h.

References delayed_first_order_lowpass_filter_t::delay, and DELAYED_FIRST_ORDER_LOWPASS_FILTER_BUFFER_SIZE.

Referenced by delayed_first_order_lowpass_initialize().

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