Kim Bruil / Mbed 2 deprecated EMG_Input

EMG input library biorobortics 31-10-2016

Dependencies:   HIDScope mbed

Fork of EMG by Tom Tom

EMG_input.cpp@27:869ec80f2bf7, 2016-10-17 (annotated)

Committer:
kbruil
Date:
Mon Oct 17 16:02:07 2016 +0000
Revision:
27:869ec80f2bf7
Child:
28:ceed9f02b815
Convert to class

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kbruil 27:869ec80f2bf7 1 #include "mbed.h"
kbruil 27:869ec80f2bf7 2 #include "HIDScope.h"
kbruil 27:869ec80f2bf7 3 #include "BiQuad.h"
kbruil 27:869ec80f2bf7 4 #include "math.h"
kbruil 27:869ec80f2bf7 5 #define EMG_DEBUG
kbruil 27:869ec80f2bf7 6 #ifndef M_PI
kbruil 27:869ec80f2bf7 7 #define M_PI 3.14159265358979323846
kbruil 27:869ec80f2bf7 8 #endif
kbruil 27:869ec80f2bf7 9
kbruil 27:869ec80f2bf7 10 #define EMG_THRESHOLD 0.2
kbruil 27:869ec80f2bf7 11
kbruil 27:869ec80f2bf7 12 class EMG_input {
kbruil 27:869ec80f2bf7 13 private:
kbruil 27:869ec80f2bf7 14 AnalogIn emg0; // Declare port
kbruil 27:869ec80f2bf7 15 BiQuad bq1, bq2, bq3, bq4, bq5, bq6, bq7, bq8; // Declare biquads
kbruil 27:869ec80f2bf7 16 BiQuadChain bqc1, bqc2; // Declare biquad chains
kbruil 27:869ec80f2bf7 17 double maxsig;
kbruil 27:869ec80f2bf7 18 public:
kbruil 27:869ec80f2bf7 19 double e0, e0f, e0flow, discrete;
kbruil 27:869ec80f2bf7 20 EMG_input(PinName pin);
kbruil 27:869ec80f2bf7 21 void tick(void);
kbruil 27:869ec80f2bf7 22 bool read(void);
kbruil 27:869ec80f2bf7 23 ~EMG_input();
kbruil 27:869ec80f2bf7 24
kbruil 27:869ec80f2bf7 25 };
kbruil 27:869ec80f2bf7 26
kbruil 27:869ec80f2bf7 27 EMG_input::EMG_input(PinName pin) : emg0(pin),
kbruil 27:869ec80f2bf7 28 bq1(9.755715E-01, -1.951143E+00, 9.755715E-01, 1.000000E+00, -1.949216E+00, 9.530699E-01), // High pass 10 Hz (4th order)
kbruil 27:869ec80f2bf7 29 bq2(9.442373E-01, -1.888475E+00, 9.442373E-01, 1.000000E+00, -1.886610E+00, 8.903397E-01),
kbruil 27:869ec80f2bf7 30 bq3(9.955670E-01, -1.893718E+00, 9.955670E-01, 1.000000E+00, -1.890851E+00, 9.910331E-01), // Notch (stop band) 49 - 51 Hz (4th order)
kbruil 27:869ec80f2bf7 31 bq4(9.955670E-01, -1.893718E+00, 9.955670E-01, 1.000000E+00, -1.896548E+00, 9.912741E-01),
kbruil 27:869ec80f2bf7 32 bq5(4.798613E-01, 9.597225E-01, 4.798613E-01, 1.000000E+00, 4.531195E-01, 4.663256E-01), // Low pass 300 Hz (4th order)
kbruil 27:869ec80f2bf7 33 bq6(3.483908E-01, 6.967817E-01, 3.483908E-01, 1.000000E+00, 3.289757E-01, 6.458765E-02),
kbruil 27:869ec80f2bf7 34 bq7(8.818771E-05, 1.763754E-04, 8.818771E-05, 1.000000E+00, -1.985325E+00, 9.856773E-01), // Low pass 3Hz on rectified signal (4th order)
kbruil 27:869ec80f2bf7 35 bq8(8.730353E-05, 1.746071E-04, 8.730353E-05, 1.000000E+00, -1.965420E+00, 9.657687E-01),
kbruil 27:869ec80f2bf7 36 maxsig(0) {
kbruil 27:869ec80f2bf7 37 bqc1.add(&bq1).add(&bq2).add(&bq3).add(&bq4).add(&bq5).add(&bq6); // Add filters to filter chain
kbruil 27:869ec80f2bf7 38 bqc2.add(&bq7).add(&bq8); // Add filters to filter chain
kbruil 27:869ec80f2bf7 39 }
kbruil 27:869ec80f2bf7 40
kbruil 27:869ec80f2bf7 41
kbruil 27:869ec80f2bf7 42 void EMG_input::tick(void){
kbruil 27:869ec80f2bf7 43 double e0 = emg0.read(); // Read emg signal
kbruil 27:869ec80f2bf7 44 double e0f = fabs(bqc1.step(e0)); // Filter signal, rectify
kbruil 27:869ec80f2bf7 45 double e0flow = bqc2.step(e0f); // Low pass filter rectified emg signal
kbruil 27:869ec80f2bf7 46 if (e0flow>maxsig){ maxsig = e0flow;} // Remember maximum peak (used for calibrating signal)
kbruil 27:869ec80f2bf7 47 double discrete = floor(sqrt(e0flow/maxsig)*10.0)/10.0; // Discretise signal non linearly (low muscle activity means higher gain on the input signal, sqrt used as envelope)
kbruil 27:869ec80f2bf7 48 }
kbruil 27:869ec80f2bf7 49
kbruil 27:869ec80f2bf7 50 bool EMG_input::read(void){
kbruil 27:869ec80f2bf7 51 return (discrete>=EMG_THRESHOLD)?true:false;
kbruil 27:869ec80f2bf7 52 }
kbruil 27:869ec80f2bf7 53
kbruil 27:869ec80f2bf7 54 EMG_input::~EMG_input(){
kbruil 27:869ec80f2bf7 55 }