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Replace old lowpass with BiQuad for Vbat and Servo

This commit is contained in:
borisbstyle 2016-02-03 14:33:43 +01:00
parent eebacc2542
commit 27772ba56a
7 changed files with 23 additions and 170 deletions
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1
Makefile
View File

@ -291,7 +291,6 @@ COMMON_SRC = build_config.c \
flight/pid.c \
flight/imu.c \
flight/mixer.c \
flight/lowpass.c \
drivers/bus_i2c_soft.c \
drivers/serial.c \
drivers/sound_beeper.c \

2
src/main/config/config.c
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@ -334,7 +334,7 @@ void resetMixerConfig(mixerConfig_t *mixerConfig) {
mixerConfig->yaw_jump_prevention_limit = 200;
#ifdef USE_SERVOS
mixerConfig->tri_unarmed_servo = 1;
mixerConfig->servo_lowpass_freq = 400;
mixerConfig->servo_lowpass_freq = 400.0f;
mixerConfig->servo_lowpass_enable = 0;
#endif
}

118
src/main/flight/lowpass.c
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@ -1,118 +0,0 @@
/*
* This file is part of Cleanflight.
*
* Cleanflight is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Cleanflight is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Cleanflight. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <math.h>
#include "common/maths.h"
#include "flight/lowpass.h"
//#define DEBUG_LOWPASS
void generateLowpassCoeffs2(int16_t freq, lowpass_t *filter)
{
float fixedScaler;
int i;
// generates coefficients for a 2nd-order butterworth low-pass filter
float freqf = (float)freq*0.001f;
float omega = tan_approx((float)M_PI*freqf/2.0f);
float scaling = 1.0f / (omega*omega + 1.4142136f*omega + 1.0f);
#if defined(UNIT_TEST) && defined(DEBUG_LOWPASS)
printf("lowpass cutoff: %f, omega: %f\n", freqf, omega);
#endif
filter->bf[0] = scaling * omega*omega;
filter->bf[1] = 2.0f * filter->bf[0];
filter->bf[2] = filter->bf[0];
filter->af[0] = 1.0f;
filter->af[1] = scaling * (2.0f * omega*omega - 2.0f);
filter->af[2] = scaling * (omega*omega - 1.4142136f * omega + 1.0f);
// Scale for fixed-point
filter->input_bias = 1500; // Typical servo range is 1500 +/- 500
filter->input_shift = 16;
filter->coeff_shift = 24;
fixedScaler = (float)(1ULL << filter->coeff_shift);
for (i = 0; i < LOWPASS_NUM_COEF; i++) {
filter->a[i] = LPF_ROUND(filter->af[i] * fixedScaler);
filter->b[i] = LPF_ROUND(filter->bf[i] * fixedScaler);
#if defined(UNIT_TEST) && defined(DEBUG_LOWPASS)
printf("(%d) bf: %f af: %f b: %ld a: %ld\n", i,
filter->bf[i], filter->af[i], filter->b[i], filter->a[i]);
#endif
}
filter->freq = freq;
}
int32_t lowpassFixed(lowpass_t *filter, int32_t in, int16_t freq)
{
int16_t coefIdx;
int64_t out;
int32_t in_s;
// Check to see if cutoff frequency changed
if (freq != filter->freq) {
filter->init = false;
}
// Initialize if needed
if (!filter->init) {
generateLowpassCoeffs2(freq, filter);
for (coefIdx = 0; coefIdx < LOWPASS_NUM_COEF; coefIdx++) {
filter->x[coefIdx] = (in - filter->input_bias) << filter->input_shift;
filter->y[coefIdx] = (in - filter->input_bias) << filter->input_shift;
}
filter->init = true;
}
// Unbias input and scale
in_s = (in - filter->input_bias) << filter->input_shift;
// Delays
for (coefIdx = LOWPASS_NUM_COEF-1; coefIdx > 0; coefIdx--) {
filter->x[coefIdx] = filter->x[coefIdx-1];
filter->y[coefIdx] = filter->y[coefIdx-1];
}
filter->x[0] = in_s;
// Accumulate result
out = filter->x[0] * filter->b[0];
for (coefIdx = 1; coefIdx < LOWPASS_NUM_COEF; coefIdx++) {
out -= filter->y[coefIdx] * filter->a[coefIdx];
out += filter->x[coefIdx] * filter->b[coefIdx];
}
// Scale output by coefficient shift
out >>= filter->coeff_shift;
filter->y[0] = (int32_t)out;
// Scale output by input shift and round
out = (out + (1 << (filter->input_shift-1))) >> filter->input_shift;
// Reapply bias
out += filter->input_bias;
return (int32_t)out;
}

41
src/main/flight/lowpass.h
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@ -1,41 +0,0 @@
/*
* This file is part of Cleanflight.
*
* Cleanflight is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Cleanflight is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Cleanflight. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#define LOWPASS_NUM_COEF 3
#define LPF_ROUND(x) (x < 0 ? (x - 0.5f) : (x + 0.5f))
typedef struct lowpass_s {
bool init;
int16_t freq; // Normalized freq in 1/1000ths
float bf[LOWPASS_NUM_COEF];
float af[LOWPASS_NUM_COEF];
int64_t b[LOWPASS_NUM_COEF];
int64_t a[LOWPASS_NUM_COEF];
int16_t coeff_shift;
int16_t input_shift;
int32_t input_bias;
float xf[LOWPASS_NUM_COEF];
float yf[LOWPASS_NUM_COEF];
int32_t x[LOWPASS_NUM_COEF];
int32_t y[LOWPASS_NUM_COEF];
} lowpass_t;
void generateLowpassCoeffs2(int16_t freq, lowpass_t *filter);
int32_t lowpassFixed(lowpass_t *filter, int32_t in, int16_t freq);

13
src/main/flight/mixer.c
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@ -19,6 +19,7 @@
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "platform.h"
#include "debug.h"
@ -27,6 +28,7 @@
#include "common/axis.h"
#include "common/maths.h"
#include "common/filter.h"
#include "drivers/system.h"
#include "drivers/pwm_output.h"
@ -34,6 +36,7 @@
#include "drivers/sensor.h"
#include "drivers/accgyro.h"
#include "drivers/system.h"
#include "drivers/gyro_sync.h"
#include "rx/rx.h"
@ -48,7 +51,6 @@
#include "flight/failsafe.h"
#include "flight/pid.h"
#include "flight/imu.h"
#include "flight/lowpass.h"
#include "config/runtime_config.h"
#include "config/config.h"
@ -77,7 +79,6 @@ int16_t servo[MAX_SUPPORTED_SERVOS];
static int useServo;
STATIC_UNIT_TESTED uint8_t servoCount;
static servoParam_t *servoConf;
static lowpass_t lowpassFilters[MAX_SUPPORTED_SERVOS];
#endif
static const motorMixer_t mixerQuadX[] = {
@ -924,6 +925,8 @@ void filterServos(void)
{
#ifdef USE_SERVOS
int16_t servoIdx;
static bool servoFilterIsSet;
biquad_t servoFitlerState[MAX_SUPPORTED_SERVOS];
#if defined(MIXER_DEBUG)
uint32_t startTime = micros();
@ -931,7 +934,11 @@ void filterServos(void)
if (mixerConfig->servo_lowpass_enable) {
for (servoIdx = 0; servoIdx < MAX_SUPPORTED_SERVOS; servoIdx++) {
servo[servoIdx] = (int16_t)lowpassFixed(&lowpassFilters[servoIdx], servo[servoIdx], mixerConfig->servo_lowpass_freq);
if (!servoFilterIsSet) {
BiQuadNewLpf(mixerConfig->servo_lowpass_freq, &servoFitlerState[servoIdx], targetLooptime);
servoFilterIsSet = true;
}
servo[servoIdx] = lrintf(applyBiQuadFilter((float) servo[servoIdx], &servoFitlerState[servoIdx]));
// Sanity check
servo[servoIdx] = constrain(servo[servoIdx], servoConf[servoIdx].min, servoConf[servoIdx].max);

2
src/main/io/serial_cli.c
View File

@ -620,7 +620,7 @@ const clivalue_t valueTable[] = {
{ "yaw_jump_prevention_limit", VAR_UINT16 | MASTER_VALUE, &masterConfig.mixerConfig.yaw_jump_prevention_limit, .config.minmax = { YAW_JUMP_PREVENTION_LIMIT_LOW, YAW_JUMP_PREVENTION_LIMIT_HIGH } },
#ifdef USE_SERVOS
{ "tri_unarmed_servo", VAR_INT8 | MASTER_VALUE | MODE_LOOKUP, &masterConfig.mixerConfig.tri_unarmed_servo, .config.lookup = { TABLE_OFF_ON } },
{ "servo_lowpass_freq", VAR_INT16 | MASTER_VALUE, &masterConfig.mixerConfig.servo_lowpass_freq, .config.minmax = { 10, 400} },
{ "servo_lowpass_freq", VAR_FLOAT | MASTER_VALUE, &masterConfig.mixerConfig.servo_lowpass_freq, .config.minmax = { 10, 400} },
{ "servo_lowpass_enable", VAR_INT8 | MASTER_VALUE | MODE_LOOKUP, &masterConfig.mixerConfig.servo_lowpass_enable, .config.lookup = { TABLE_OFF_ON } },
#endif

16
src/main/sensors/battery.c
View File

@ -17,10 +17,12 @@
#include "stdbool.h"
#include "stdint.h"
#include <math.h>
#include "platform.h"
#include "common/maths.h"
#include "common/filter.h"
#include "drivers/adc.h"
#include "drivers/system.h"
@ -33,7 +35,6 @@
#include "rx/rx.h"
#include "io/rc_controls.h"
#include "flight/lowpass.h"
#include "io/beeper.h"
#define VBATT_PRESENT_THRESHOLD_MV 10
@ -54,7 +55,6 @@ int32_t mAhDrawn = 0; // milliampere hours drawn from the battery
batteryConfig_t *batteryConfig;
static batteryState_e batteryState;
static lowpass_t lowpassFilter;
uint16_t batteryAdcToVoltage(uint16_t src)
{
@ -66,12 +66,18 @@ uint16_t batteryAdcToVoltage(uint16_t src)
static void updateBatteryVoltage(void)
{
uint16_t vbatSample;
uint16_t vbatFiltered;
biquad_t vbatFilterState;
static bool vbatFilterIsSet;
if (!vbatFilterIsSet) {
BiQuadNewLpf(0.5f, &vbatFilterState, 20000);
vbatFilterIsSet = true;
}
// store the battery voltage with some other recent battery voltage readings
vbatSample = vbatLatestADC = adcGetChannel(ADC_BATTERY);
vbatFiltered = (uint16_t)lowpassFixed(&lowpassFilter, vbatSample, VBATT_LPF_FREQ);
vbat = batteryAdcToVoltage(vbatFiltered);
vbatSample = lrintf(applyBiQuadFilter((float) vbatSample, &vbatFilterState));
vbat = batteryAdcToVoltage(vbatSample);
}
#define VBATTERY_STABLE_DELAY 40