From 8093f1f21fbd50efb30c9ab2a13effbd84030d92 Mon Sep 17 00:00:00 2001
From: Federico Lolli <federico.lolli@skywarder.eu>
Date: Mon, 16 Oct 2023 17:46:57 +0200
Subject: [PATCH] [LowPass] added first draft of LowPass filter
---
cmake/boardcore.cmake | 1 +
src/shared/algorithms/Filters/LowPass.cpp | 40 ++++++++++++++++
src/shared/algorithms/Filters/LowPass.h | 56 +++++++++++++++++++++++
3 files changed, 97 insertions(+)
create mode 100644 src/shared/algorithms/Filters/LowPass.cpp
create mode 100644 src/shared/algorithms/Filters/LowPass.h
diff --git a/cmake/boardcore.cmake b/cmake/boardcore.cmake
index 8d572af01..78cef4792 100644
--- a/cmake/boardcore.cmake
+++ b/cmake/boardcore.cmake
@@ -43,6 +43,7 @@ foreach(OPT_BOARD ${BOARDS})
${SBS_BASE}/src/shared/algorithms/NAS/StateInitializer.cpp
${SBS_BASE}/src/shared/algorithms/SFD/SFDAscent.cpp
${SBS_BASE}/src/shared/algorithms/SFD/SFDDescent.cpp
+ ${SBS_BASE}/src/shared/algorithms/Filters/LowPass.cpp
# Debug
${SBS_BASE}/src/shared/utils/Debug.cpp
diff --git a/src/shared/algorithms/Filters/LowPass.cpp b/src/shared/algorithms/Filters/LowPass.cpp
new file mode 100644
index 000000000..72e609911
--- /dev/null
+++ b/src/shared/algorithms/Filters/LowPass.cpp
@@ -0,0 +1,40 @@
+/* Copyright (c) 2023 Skyward Experimental Rocketry
+ * Author: Federico Lolli
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "LowPass.h"
+
+namespace Boardcore
+{
+
+// TODO: WARNING! initialized at 0
+LowPass::LowPass(float gain, float cutoff_freq, float lambda)
+ : gain(gain), cutoff_freq(cutoff_freq), lambda(lambda), output(0)
+{
+}
+
+float LowPass::filter(float input)
+{
+ output = lambda * output + (gain / cutoff_freq) * (1 - lambda) * input;
+ return output;
+}
+
+} // namespace Boardcore
diff --git a/src/shared/algorithms/Filters/LowPass.h b/src/shared/algorithms/Filters/LowPass.h
new file mode 100644
index 000000000..d562d8015
--- /dev/null
+++ b/src/shared/algorithms/Filters/LowPass.h
@@ -0,0 +1,56 @@
+/* Copyright (c) 2023 Skyward Experimental Rocketry
+ * Author: Federico Lolli
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#pragma once
+
+namespace Boardcore
+{
+
+class LowPass
+{
+public:
+ /**
+ * @brief Construct a new Low Pass object
+ *
+ * @param gain The gain of the filter
+ * @param cutoff_freq The cutoff frequency of the filter
+ * @param lambda The lambda parameter of the filter
+ *
+ * @note WARNING: Initialize output at 0 at first
+ */
+ LowPass(float gain, float cutoff_freq, float lambda);
+
+ /**
+ * @brief Filter the input
+ *
+ * @param input The input to filter
+ */
+ float filter(float input);
+
+private:
+ float cutoff_freq;
+ float lambda;
+ float gain;
+ float output;
+};
+
+} // namespace Boardcore
--
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