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63 lines
2.3 KiB
63 lines
2.3 KiB
/**************************************************************************** |
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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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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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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) { _x = (1.f - alpha) * _x + alpha * input; } |
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// Typical 0.9/0.1 lowpass filter |
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void update(const T &input) { update(input, 0.1f); } |
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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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