Diff: PSDdetection.cpp

Revision:

0:6863633bf8a4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PSDdetection.cpp	Fri Mar 24 11:22:30 2017 +0000
@@ -0,0 +1,59 @@
+
+#include "PSDdetection.h"
+
+Arm::Arm(){
+	for (int i = 0; i<4; i++)
+		prevEMG[i] = 0;
+
+	EMGreference = 140;
+}
+
+// Sets a new reference level
+void Arm::setReference(int reflevel){
+	this->EMGreference = reflevel;
+}
+
+// Updates the array with a new sample and checks wheter a muscle is active
+bool Arm::checksample(int emgsample){
+
+	bool MuscleIsActive = false;
+
+	// Shift all the previous values in time
+	for (int i = 3; i>0; i--){
+		prevEMG[i] = prevEMG[i - 1];
+	}
+
+	// Put in the latest sample
+	prevEMG[0] = emgsample;
+
+	// Weighted average filter to smoothen out the response
+	int average = (prevEMG[0] * 1 + prevEMG[1] * 0.63 + prevEMG[2] * 0.45 + prevEMG[3] * 0.22) / (1 + 0.63 + 0.45 + 0.22);
+
+	// Check with reference level to determine if it is 
+	if (average > (EMGreference + EMGtriggerlevel)){
+		MuscleIsActive = true;
+	}
+
+	return MuscleIsActive;
+}
+
+int biquad10(int emgsample){
+	//initialize filter values 
+	float filteredValue,a0,a1,a2,b1,b2;
+	float intermediateValue1[2]intermediateValue2[2];
+	//filter for 10hz -6bd biquad
+	a0=0.0009446857782217186;
+	a1=0.0018893715564434373;
+	a2=0.0009446857782217186;
+	b1=-1.9111847961312216;
+	b2=0.9149635392441086;
+	//calculations for transposed direct form 2
+	intermediateValue1[0] = a2*emgsample-b2*filteredValue;
+	intermediateValue2[0] = a2*emgsample-b1*filteredValue+intermediateValue1[1];
+	filteredValue = a0*filteredValue+intermediateValue2[1];
+	intermediateValue1[1] = intermediateValue1[0];
+	intermediateValue2[1] = intermediateValue2[0];
+	
+	
+	return ((int)filteredValue);
+	}
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