Diff: EncoderCounter/LowpassFilter.h

Revision:

18:3ee1b02ed3aa

diff -r caf5ae550f2e -r 3ee1b02ed3aa EncoderCounter/LowpassFilter.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/EncoderCounter/LowpassFilter.h	Tue May 09 15:25:54 2017 +0000
@@ -0,0 +1,39 @@
+/*
+ * LowpassFilter.h
+ * Copyright (c) 2016, ZHAW
+ * All rights reserved.
+ */
+
+#ifndef LOWPASS_FILTER_H_
+#define LOWPASS_FILTER_H_
+
+#include <cstdlib>
+#include <cmath>
+
+/**
+ * This class implements a time-discrete 2nd order low-pass filter for a series of data values.
+ * This filter can typically be used within a periodic task that takes measurements that need
+ * to be filtered, like speed or position values.
+ */
+class LowpassFilter {
+    
+    public:
+    
+                LowpassFilter();
+        virtual ~LowpassFilter();
+        void    reset();
+        void    reset(float value);
+        void    setPeriod(float period);
+        void    setFrequency(float frequency);
+        float   getFrequency();
+        float   filter(float value);
+        
+    private:
+        
+        float   period;
+        float   frequency;
+        float   a11, a12, a21, a22, b1, b2;
+        float   x1, x2;
+};
+
+#endif /* LOWPASS_FILTER_H_ */