Nick van den Berg / Mbed 2 deprecated EMGfilter24

Filter for EMG signals The signal will be filtered using a notch, highpass and lowpass filter. The filtered signal will be compared to a preset threshold and according to the strength of the signal the program will perform an action. In this case it will assign a colour to a led.

Dependencies:   HIDScope MODSERIAL mbed

Fork of EMGfilter24 by Steven Spoolder

main.cpp@2:6402a7071ba3, 2016-10-25 (annotated)

Committer:
s1601822
Date:
Tue Oct 25 12:53:45 2016 +0000
Revision:
2:6402a7071ba3
Parent:
1:6081dc1ecd1f
Child:
3:faed8b7f6542
Shows the raw and filtered EMG signal in HIDscope

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Iknowright 0:41226c0fd285 1 #include "mbed.h"
Iknowright 0:41226c0fd285 2 #include "BiQuad.h"
Iknowright 0:41226c0fd285 3 #include "HIDScope.h"
Iknowright 0:41226c0fd285 4 #include "MODSERIAL.h"
Nickname 1:6081dc1ecd1f 5 #include <cmath>
Iknowright 0:41226c0fd285 6
Nickname 1:6081dc1ecd1f 7 MODSERIAL pc(USBTX, USBRX);
Nickname 1:6081dc1ecd1f 8 Ticker emgSampleTicker;
Nickname 1:6081dc1ecd1f 9 AnalogIn emg0(A0);
Nickname 1:6081dc1ecd1f 10 AnalogIn emg1(A1);
Nickname 1:6081dc1ecd1f 11 DigitalOut ledje(LED_GREEN);
Nickname 1:6081dc1ecd1f 12 HIDScope scope(2);
Nickname 1:6081dc1ecd1f 13
Nickname 1:6081dc1ecd1f 14 double hf_b0 = 0.9355;
Nickname 1:6081dc1ecd1f 15 double hf_b1 = -1.8711;
Nickname 1:6081dc1ecd1f 16 double hf_b2 = 0.9355;
Nickname 1:6081dc1ecd1f 17 double hf_a1 = -1.8669;
Nickname 1:6081dc1ecd1f 18 double hf_a2 = 0.8752;
Iknowright 0:41226c0fd285 19
Nickname 1:6081dc1ecd1f 20 double lf_b0 = 8.7656e-5;
Nickname 1:6081dc1ecd1f 21 double lf_b1 = 1.17531e-4;
Nickname 1:6081dc1ecd1f 22 double lf_b2 = 8.7656e-5;
Nickname 1:6081dc1ecd1f 23 double lf_a1 = -1.9733;
Nickname 1:6081dc1ecd1f 24 double lf_a2 = 0.9737;
Nickname 1:6081dc1ecd1f 25
Nickname 1:6081dc1ecd1f 26 double v1 = 0, v2 = 0, u = 0;
Iknowright 0:41226c0fd285 27
Nickname 1:6081dc1ecd1f 28 /** Sample function
Nickname 1:6081dc1ecd1f 29 * this function samples the emg and sends it to HIDScope
Nickname 1:6081dc1ecd1f 30 **/
Nickname 1:6081dc1ecd1f 31 void sample()
Nickname 1:6081dc1ecd1f 32 {
Nickname 1:6081dc1ecd1f 33 // Set the sampled emg values in channel 0 (the first channel) and 1 (the second channel) in the 'HIDScope' instance named 'scope'
Nickname 1:6081dc1ecd1f 34 scope.set(0, emg0.read() );
s1601822 2:6402a7071ba3 35 /* Repeat the step above if required for more channels of required (channel 0 up to 5 = 6 channels)
Nickname 1:6081dc1ecd1f 36 * Ensure that enough channels are available (HIDScope scope( 2 ))
Nickname 1:6081dc1ecd1f 37 * Finally, send all channels to the PC at once */
Nickname 1:6081dc1ecd1f 38 scope.send();
Nickname 1:6081dc1ecd1f 39 // To indicate that the function is working, the LED is toggled
s1601822 2:6402a7071ba3 40 ledje = ledje;
Nickname 1:6081dc1ecd1f 41 }
Iknowright 0:41226c0fd285 42
Iknowright 0:41226c0fd285 43
Iknowright 0:41226c0fd285 44 int main(){
Nickname 1:6081dc1ecd1f 45
Nickname 1:6081dc1ecd1f 46 /**Attach the 'sample' function to the timer 'sample_timer'.
Nickname 1:6081dc1ecd1f 47 * this ensures that 'sample' is executed every... 0.002 seconds = 500 Hz
Nickname 1:6081dc1ecd1f 48 */
Nickname 1:6081dc1ecd1f 49 emgSampleTicker.attach(&sample, 0.002);
Nickname 1:6081dc1ecd1f 50 // empty loop, sample() is executed periodically
Nickname 1:6081dc1ecd1f 51 while(1) {
Iknowright 0:41226c0fd285 52
Nickname 1:6081dc1ecd1f 53 double emgFilter();
Nickname 1:6081dc1ecd1f 54 {
Iknowright 0:41226c0fd285 55
Nickname 1:6081dc1ecd1f 56 //High Pass Filter (biquad)
Nickname 1:6081dc1ecd1f 57 double hf_v = u - hf_a1*v1 - hf_a2*v2;
Nickname 1:6081dc1ecd1f 58 double hf_y = hf_b0*hf_v + hf_b1*v1 + hf_b2*v2;
Iknowright 0:41226c0fd285 59 v2 = v1;
Nickname 1:6081dc1ecd1f 60 v1 = hf_v;
Iknowright 0:41226c0fd285 61
Nickname 1:6081dc1ecd1f 62 //Rectification
Nickname 1:6081dc1ecd1f 63 double rect_y = fabs(hf_y);
Nickname 1:6081dc1ecd1f 64
Nickname 1:6081dc1ecd1f 65 //Low Pass Filter (biquad)
Nickname 1:6081dc1ecd1f 66 double lf_v = rect_y - lf_a1*v1 - lf_a2*v2;
Nickname 1:6081dc1ecd1f 67 double lf_y = lf_b0*hf_v + lf_b1*v1 + lf_b2*v2;
Iknowright 0:41226c0fd285 68 v2 = v1;
Nickname 1:6081dc1ecd1f 69 v1 = lf_v;
Nickname 1:6081dc1ecd1f 70
Nickname 1:6081dc1ecd1f 71 while(1){
Nickname 1:6081dc1ecd1f 72
s1601822 2:6402a7071ba3 73 scope.set(1, lf_y);
s1601822 2:6402a7071ba3 74 scope.send();
Nickname 1:6081dc1ecd1f 75
Nickname 1:6081dc1ecd1f 76 }
Nickname 1:6081dc1ecd1f 77
Nickname 1:6081dc1ecd1f 78 }
Nickname 1:6081dc1ecd1f 79
Iknowright 0:41226c0fd285 80 }
Nickname 1:6081dc1ecd1f 81 }