forked from Archive/PX4-Autopilot
72 lines
2.3 KiB
C++
72 lines
2.3 KiB
C++
/****************************************************************************
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*
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* Copyright (c) 2019 PX4 Development Team. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* First order "alpha" IIR digital filter
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* @author Mathieu Bresciani <brescianimathieu@gmail.com>
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*/
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#pragma once
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template<typename T>
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class AlphaFilter final
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{
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public:
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AlphaFilter() = default;
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~AlphaFilter() = default;
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void reset(const T &val) { _x = val; }
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void update(const T &input, float tau, float dt)
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{
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const float alpha = dt / tau;
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update(input, alpha);
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}
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void update(const T &input, float alpha)
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{
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_x = (1.f - alpha) * _x + alpha * input;
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}
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// Typical 0.9/0.1 lowpass filter
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void update(const T &input)
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{
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update(input, 0.1f);
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}
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const T& getState() const { return _x; }
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private:
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T _x{}; ///< current state of the filter
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};
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