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Add scaling, add 1euro filter, force floats for esp8266
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| /* -*- coding: utf-8 -*- | ||
| * | ||
| * OneEuroFilter.cc - | ||
| * | ||
| * Author: Nicolas Roussel ([email protected]) | ||
| * | ||
| * Copyright 2019 Inria | ||
| * | ||
| * BSD License https://opensource.org/licenses/BSD-3-Clause | ||
| * | ||
| * Redistribution and use in source and binary forms, with or without | ||
| * modification, are permitted provided that the following conditions are met: | ||
| * | ||
| * 1. Redistributions of source code must retain the above copyright notice, this list of conditions | ||
| * and the following disclaimer. | ||
| * | ||
| * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions | ||
| * and the following disclaimer in the documentation and/or other materials provided with the distribution. | ||
| * | ||
| * 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or | ||
| * promote products derived from this software without specific prior written permission. | ||
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, | ||
| * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | ||
| * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | ||
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | ||
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | ||
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | ||
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
| * | ||
| */ | ||
|
|
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| #include <iostream> | ||
| #include <cmath> | ||
| #include <ctime> | ||
|
|
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| #define M_PI_FLOAT 3.1415926f | ||
|
|
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| // ----------------------------------------------------------------- | ||
| // Utilities | ||
|
|
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| typedef uint32_t TimeStamp; // in millis | ||
|
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| static const TimeStamp UndefinedTime = 0; | ||
|
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| // ----------------------------------------------------------------- | ||
|
|
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| class LowPassFilter | ||
| { | ||
|
|
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| float y, a, s; | ||
| bool initialized; | ||
|
|
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| void setAlpha(float alpha) | ||
| { | ||
| if (alpha <= 0.0f || alpha > 1.0f) { | ||
| alpha = 0.1f; | ||
| return; | ||
| } | ||
| a = alpha; | ||
| } | ||
|
|
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| public: | ||
| LowPassFilter(float alpha, float initval = 0.0) | ||
| { | ||
| y = s = initval; | ||
| setAlpha(alpha); | ||
| initialized = false; | ||
| } | ||
|
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| float filter(float value) | ||
| { | ||
| float result; | ||
| if (initialized) | ||
| result = a * value + (1.0f - a) * s; | ||
| else | ||
| { | ||
| result = value; | ||
| initialized = true; | ||
| } | ||
| y = value; | ||
| s = result; | ||
| return result; | ||
| } | ||
|
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| float filterWithAlpha(float value, float alpha) | ||
| { | ||
| setAlpha(alpha); | ||
| return filter(value); | ||
| } | ||
|
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| bool hasLastRawValue(void) | ||
| { | ||
| return initialized; | ||
| } | ||
|
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| float lastRawValue(void) | ||
| { | ||
| return y; | ||
| } | ||
| }; | ||
|
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| // ----------------------------------------------------------------- | ||
|
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| class OneEuroFilter | ||
| { | ||
|
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| float freq; | ||
| float mincutoff; | ||
| float beta_; | ||
| float dcutoff; | ||
| LowPassFilter *x; | ||
| LowPassFilter *dx; | ||
| TimeStamp lasttime; | ||
|
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| float alpha(float cutoff) | ||
| { | ||
| float te = 1.0f / freq; | ||
| float tau = 1.0f / (2 * M_PI_FLOAT * cutoff); | ||
| return 1.0f / (1.0f + tau / te); | ||
| } | ||
|
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| void setFrequency(float f) | ||
| { | ||
| if (f <= 0) { | ||
| f = 0.1f; | ||
| return; | ||
| } | ||
| freq = f; | ||
| } | ||
|
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| void setMinCutoff(float mc) | ||
| { | ||
| if (mc <= 0) { | ||
| mc = 0.1f; | ||
| return; | ||
| } | ||
| mincutoff = mc; | ||
| } | ||
|
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| void setBeta(float b) | ||
| { | ||
| beta_ = b; | ||
| } | ||
|
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| void setDerivateCutoff(float dc) | ||
| { | ||
| if (dc <= 0) { | ||
| dc = 0.1f; | ||
| return; | ||
| } | ||
| dcutoff = dc; | ||
| } | ||
|
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||
| public: | ||
| OneEuroFilter(float freq, | ||
| float mincutoff = 1.0f, float beta_ = 0.0, float dcutoff = 1.0f) | ||
| { | ||
| setFrequency(freq); | ||
| setMinCutoff(mincutoff); | ||
| setBeta(beta_); | ||
| setDerivateCutoff(dcutoff); | ||
| x = new LowPassFilter(alpha(mincutoff)); | ||
| dx = new LowPassFilter(alpha(dcutoff)); | ||
| lasttime = UndefinedTime; | ||
| } | ||
|
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| float filter(float value, uint32_t timestamp = UndefinedTime) | ||
| { | ||
| // update the sampling frequency based on timestamps | ||
| if (lasttime != UndefinedTime && timestamp != UndefinedTime) | ||
| freq = 1000000.f / (timestamp - lasttime); | ||
| lasttime = timestamp; | ||
| // estimate the current variation per second | ||
| float dvalue = x->hasLastRawValue() ? (value - x->lastRawValue()) * freq : 0.0; // FIXME: 0.0 or value? | ||
| float edvalue = dx->filterWithAlpha(dvalue, alpha(dcutoff)); | ||
| // use it to update the cutoff frequency | ||
| float cutoff = mincutoff + beta_ * fabs(edvalue); | ||
| // filter the given value | ||
| return x->filterWithAlpha(value, alpha(cutoff)); | ||
| } | ||
|
|
||
| ~OneEuroFilter(void) | ||
| { | ||
| delete x; | ||
| delete dx; | ||
| } | ||
| }; |
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