Updating to integral filter.

Author: finnkuusisto

Devlpr.cpp

@@ -34,25 +34,32 @@ int Devlpr::lastValue()
     return buf[bufInd];
 }
 
-float filt[155] = {0.001513386020877483, 0.0065815188379678286, 0.002386245075165573, 0.007566874896062961, 0.0019103137662135668, 0.006992501751352943, -4.495537256296272e-05, 0.0051834687785310895, -0.002648935758060934, 0.0033582848135394524, -0.004403527605449877, 0.0030360303136534005, -0.003970335570216464, 0.005088770411351987, -0.0010939546033377785, 0.009000196239377003, 0.0029797542078670355, 0.012873573885430926, 0.0059781068429677255, 0.014341550635307414, 0.005839078055311389, 0.011962177185195152, 0.0020540826800157686, 0.00628910346542397, -0.0037297389859886764, -0.00012797925377133632, -0.008360410071453508, -0.0039928957513214345, -0.008878628957170818, -0.0031739484856050243, -0.004358329258205972, 0.0018195934592311605, 0.0032359982373611025, 0.007774757946784205, 0.009842353743397264, 0.010355335400477728, 0.01147309137873063, 0.006565601478880059, 0.006608133637858301, -0.0032987826122814258, -0.002619853769121824, -0.01545390682749638, -0.011297979146828542, -0.024490682105516394, -0.01435098160629302, -0.026385833993863368, -0.009505783044341567, -0.02096941545317657, 0.0011335663648171434, -0.01233293740414986, 0.01195399467829908, -0.006767237737413448, 0.016825048377839883, -0.009258440470070626, 0.012608322724518551, -0.020500324958948334, 0.0011602156609500842, -0.03620786400461252, -0.011438446353649424, -0.04927237222277001, -0.018137619347845493, -0.053662062433447046, -0.014898493047407273, -0.047894076917303914, -0.0031289843896549954, -0.0360514341092553, 0.010898270201266994, -0.025659125374167382, 0.019426167695941163, -0.023527141221818995, 0.017546298160676748, -0.031878568213663964, 0.006034030764155489, -0.04698185315200764, -0.008967266965349297, -0.06112055411706036, -0.01929407495907671, 0.9363988033051267, -0.019294074959076694, -0.06112055411706037, -0.008967266965349314, -0.04698185315200765, 0.006034030764155483, -0.03187856821366395, 0.01754629816067676, -0.023527141221819026, 0.019426167695941157, -0.025659125374167382, 0.010898270201266975, -0.03605143410925534, -0.003128984389654987, -0.04789407691730391, -0.014898493047407264, -0.053662062433447046, -0.018137619347845493, -0.04927237222277002, -0.011438446353649422, -0.036207864004612525, 0.0011602156609500855, -0.020500324958948334, 0.012608322724518554, -0.00925844047007063, 0.01682504837783989, -0.006767237737413443, 0.011953994678299076, -0.012332937404149856, 0.0011335663648171465, -0.020969415453176564, -0.009505783044341567, -0.026385833993863354, -0.014350981606293018, -0.02449068210551641, -0.011297979146828535, -0.01545390682749638, -0.002619853769121825, -0.0032987826122814244, 0.006608133637858307, 0.006565601478880057, 0.011473091378730633, 0.010355335400477728, 0.009842353743397265, 0.007774757946784199, 0.0032359982373610994, 0.0018195934592311596, -0.004358329258205973, -0.003173948485605027, -0.008878628957170814, -0.003992895751321437, -0.008360410071453508, -0.0001279792537713359, -0.0037297389859886764, 0.00628910346542397, 0.00205408268001577, 0.011962177185195154, 0.005839078055311389, 0.014341550635307412, 0.0059781068429677255, 0.012873573885430931, 0.0029797542078670333, 0.009000196239377003, -0.0010939546033377785, 0.005088770411351986, -0.003970335570216465, 0.003036030313653403, -0.004403527605449876, 0.0033582848135394537, -0.002648935758060934, 0.005183468778531092, -4.4955372562961925e-05, 0.0069925017513529425, 0.0019103137662135673, 0.007566874896062961, 0.002386245075165573, 0.00658151883796783, 0.0015133860208774836};
+int filt[93] = {24, 23, 100, 109, 130, 128, 81, 68, -39, -41, -181, -140, -280, -170, -294, -109, -225, 14, -124, 134, -61, 184, -87, 136, -205, 14, -365, -115, -491, -176, -523, -132, -450, -4, -320, 140, -215, 218, -204, 181, -306, 43, -479, -128, -637, -244, 9329, -244, -637, -128, -479, 43, -306, 181, -204, 218, -215, 140, -320, -4, -450, -132, -523, -176, -491, -115, -365, 14, -205, 136, -87, 184, -61, 134, -124, 14, -225, -109, -294, -170, -280, -140, -181, -41, -39, 68, 81, 128, 130, 109, 100, 23, 24};
+float filtFactor = 10000.0; // the multiplier on the integral filter
 float Devlpr::lastValueFiltered()
 {
+    // should help to roughly recenter data (use quick integral math)
+    long sampAvg = emgRunningSum / BUFSIZE;
     // the buffer is the same size as the filter so filtered data
     // will be roughly len/2 ticks in the past
-    float ret = 0.0;
+    long ret = 0;
     int currInd = bufInd + 1; // start at the tail
     // the filter is also symmetric, so convolve=linear combination
     for (int i = 0; i < BUFSIZE; i++) {
         // check the current circular buffer index
         if (currInd >= BUFSIZE) { // faster than modulo
             currInd = 0;
         }
+        // we will need to coerce the ints to longs to avoid overflow
+        long filtVal = (long)filt[i];
+        long sampVal = (long)buf[currInd] - sampAvg;
         // do the multiply/add
-        ret = ret + (filt[i] * buf[currInd]);
+        ret = ret + (filtVal * sampVal);
         // and update the current buffer index for next
         currInd++;
     }
-    return ret;
+    // our integral filter is multiplied by some factor, so correct
+    return ret / filtFactor;
 }
 
 float Devlpr::windowAvg()

Devlpr.h

@@ -13,7 +13,7 @@ class Devlpr
         float windowAvg();
     private:
         // general buffer bookkeeping
-        static const byte BUFSIZE = 155; // size of filter
+        static const byte BUFSIZE = 93; // size of filter
         byte bufInd;
         int buf[BUFSIZE];
         unsigned long lastTickMicros = 0;