Biorobotics
/
EMG_test
Script to plot both a raw EMG signal and the filtered signal in HIDscope
main.cpp@1:f32f8eac8af1, 2015-10-26 (annotated)
- Committer:
- roosbulthuis
- Date:
- Mon Oct 26 14:45:46 2015 +0000
- Revision:
- 1:f32f8eac8af1
- Parent:
- 0:c85b764527f4
- Child:
- 2:1d29b91bc46a
Plotting raw signal in channel 0 Hidscope works; Plotting raw signal in channel 1 Hidscope doesn't work; Plotting filtered signal in channel 0 or 1 Hidscope doesn't work
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
roosbulthuis | 0:c85b764527f4 | 1 | #include "mbed.h" |
roosbulthuis | 0:c85b764527f4 | 2 | //#include "read_filter_emg.h" |
roosbulthuis | 0:c85b764527f4 | 3 | //included for fabs() function |
roosbulthuis | 0:c85b764527f4 | 4 | #include <math.h> |
roosbulthuis | 0:c85b764527f4 | 5 | #include "HIDScope.h" |
roosbulthuis | 0:c85b764527f4 | 6 | |
roosbulthuis | 0:c85b764527f4 | 7 | Ticker sample_timer; |
roosbulthuis | 0:c85b764527f4 | 8 | HIDScope scope(1); |
roosbulthuis | 0:c85b764527f4 | 9 | |
roosbulthuis | 0:c85b764527f4 | 10 | AnalogIn analog_emg_left(A0); |
roosbulthuis | 0:c85b764527f4 | 11 | AnalogIn analog_emg_right(A1); |
roosbulthuis | 0:c85b764527f4 | 12 | double input_left = 0; |
roosbulthuis | 0:c85b764527f4 | 13 | double input_right = 0; |
roosbulthuis | 0:c85b764527f4 | 14 | |
roosbulthuis | 0:c85b764527f4 | 15 | double v1_left=0; |
roosbulthuis | 0:c85b764527f4 | 16 | double v2_left=0; |
roosbulthuis | 0:c85b764527f4 | 17 | double v1_right=0; |
roosbulthuis | 0:c85b764527f4 | 18 | double v2_right=0; |
roosbulthuis | 0:c85b764527f4 | 19 | |
roosbulthuis | 0:c85b764527f4 | 20 | double filter_left; |
roosbulthuis | 0:c85b764527f4 | 21 | double filter_right; |
roosbulthuis | 0:c85b764527f4 | 22 | |
roosbulthuis | 0:c85b764527f4 | 23 | //general biquad filter that can be called in all the filter functions |
roosbulthuis | 0:c85b764527f4 | 24 | double biquad(double u, double &v1, double &v2, const double a1, |
roosbulthuis | 0:c85b764527f4 | 25 | const double a2, const double b0, const double b1, const double b2) |
roosbulthuis | 0:c85b764527f4 | 26 | { |
roosbulthuis | 1:f32f8eac8af1 | 27 | double v = u - a1*v1 - a2*v2; |
roosbulthuis | 0:c85b764527f4 | 28 | double y = b0*v + b1*v1 + b2*v2; |
roosbulthuis | 0:c85b764527f4 | 29 | //values of v2 and v1 are updated, as they are passed by reference |
roosbulthuis | 0:c85b764527f4 | 30 | //they update globally |
roosbulthuis | 0:c85b764527f4 | 31 | v2 = v1; |
roosbulthuis | 0:c85b764527f4 | 32 | v1 = v; |
roosbulthuis | 0:c85b764527f4 | 33 | return y; |
roosbulthuis | 0:c85b764527f4 | 34 | } |
roosbulthuis | 0:c85b764527f4 | 35 | |
roosbulthuis | 0:c85b764527f4 | 36 | //Specifying filter coefficients highpass |
roosbulthuis | 0:c85b764527f4 | 37 | |
roosbulthuis | 0:c85b764527f4 | 38 | /* high pass filter consists of three cascaded biquads |
roosbulthuis | 0:c85b764527f4 | 39 | blow coefficients for those three biquads */ |
roosbulthuis | 0:c85b764527f4 | 40 | //first high pass biquad |
roosbulthuis | 0:c85b764527f4 | 41 | const double highp1_a1 = -0.67538034389; |
roosbulthuis | 0:c85b764527f4 | 42 | const double highp1_a2 = 0.12769255668; |
roosbulthuis | 0:c85b764527f4 | 43 | const double highp1_b0 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 44 | const double highp1_b1 = -2.00000000000; |
roosbulthuis | 0:c85b764527f4 | 45 | const double highp1_b2 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 46 | |
roosbulthuis | 0:c85b764527f4 | 47 | //second high pass biquad |
roosbulthuis | 0:c85b764527f4 | 48 | const double highp2_a1 = -0.76475499450; |
roosbulthuis | 0:c85b764527f4 | 49 | const double highp2_a2 = 0.27692273367; |
roosbulthuis | 0:c85b764527f4 | 50 | const double highp2_b0 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 51 | const double highp2_b1 = -2.00000000000; |
roosbulthuis | 0:c85b764527f4 | 52 | const double highp2_b2 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 53 | |
roosbulthuis | 0:c85b764527f4 | 54 | //third high pass biquad |
roosbulthuis | 0:c85b764527f4 | 55 | const double highp3_a1 = -0.99216561242; |
roosbulthuis | 0:c85b764527f4 | 56 | const double highp3_a2 = 0.65663360837; |
roosbulthuis | 0:c85b764527f4 | 57 | const double highp3_b0 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 58 | const double highp3_b1 = -2.00000000000; |
roosbulthuis | 0:c85b764527f4 | 59 | const double highp3_b2 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 60 | |
roosbulthuis | 0:c85b764527f4 | 61 | //Specifying filter coefficients lowpass |
roosbulthuis | 0:c85b764527f4 | 62 | |
roosbulthuis | 0:c85b764527f4 | 63 | /* lowpass filter consists of three cascaded biquads |
roosbulthuis | 0:c85b764527f4 | 64 | below the coefficients for those three biquads */ |
roosbulthuis | 0:c85b764527f4 | 65 | //first high pass biquad |
roosbulthuis | 0:c85b764527f4 | 66 | const double lowp1_a1 = -1.05207469728; |
roosbulthuis | 0:c85b764527f4 | 67 | const double lowp1_a2 = 0.28586907478; |
roosbulthuis | 0:c85b764527f4 | 68 | const double lowp1_b0 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 69 | const double lowp1_b1 = 2.00000000000; |
roosbulthuis | 0:c85b764527f4 | 70 | const double lowp1_b2 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 71 | |
roosbulthuis | 0:c85b764527f4 | 72 | //second high pass biquad |
roosbulthuis | 0:c85b764527f4 | 73 | const double lowp2_a1 = -1.16338171052; |
roosbulthuis | 0:c85b764527f4 | 74 | const double lowp2_a2 = 0.42191097989; |
roosbulthuis | 0:c85b764527f4 | 75 | const double lowp2_b0 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 76 | const double lowp2_b1 = 2.00000000000; |
roosbulthuis | 0:c85b764527f4 | 77 | const double lowp2_b2 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 78 | |
roosbulthuis | 0:c85b764527f4 | 79 | //third high pass biquad |
roosbulthuis | 0:c85b764527f4 | 80 | const double lowp3_a1 = -1.42439823874; |
roosbulthuis | 0:c85b764527f4 | 81 | const double lowp3_a2 = 0.74093118112; |
roosbulthuis | 0:c85b764527f4 | 82 | const double lowp3_b0 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 83 | const double lowp3_b1 = 2.00000000000; |
roosbulthuis | 0:c85b764527f4 | 84 | const double lowp3_b2 = 1.00000000000; |
roosbulthuis | 0:c85b764527f4 | 85 | |
roosbulthuis | 0:c85b764527f4 | 86 | //input to each filter is output of the filter before(excl. first which uses input_sample) |
roosbulthuis | 0:c85b764527f4 | 87 | /* NOT SURE IF PASSING V1 AND V2 IS CORRECT, |
roosbulthuis | 0:c85b764527f4 | 88 | WILL IT UPDATE IN THE MEMORY POSITION SO THAT |
roosbulthuis | 0:c85b764527f4 | 89 | V1 IS CHANGED GLOBALLY */ |
roosbulthuis | 0:c85b764527f4 | 90 | |
roosbulthuis | 0:c85b764527f4 | 91 | //highpass |
roosbulthuis | 0:c85b764527f4 | 92 | |
roosbulthuis | 0:c85b764527f4 | 93 | double highpass_filter(double input, double &v1, double &v2) |
roosbulthuis | 0:c85b764527f4 | 94 | { |
roosbulthuis | 0:c85b764527f4 | 95 | double y1 = biquad(input, v1, v2, highp1_a1, highp1_a2, highp1_b0, highp1_b1, highp1_b2); |
roosbulthuis | 0:c85b764527f4 | 96 | double y2 = biquad(y1, v1, v2, highp2_a1, highp2_a2, highp2_b0, highp2_b1, highp2_b2); |
roosbulthuis | 0:c85b764527f4 | 97 | double y3 = biquad(y2, v1, v2, highp3_a1, highp3_a2, highp3_b0, highp3_b1, highp3_b2); |
roosbulthuis | 0:c85b764527f4 | 98 | |
roosbulthuis | 0:c85b764527f4 | 99 | return y3; |
roosbulthuis | 0:c85b764527f4 | 100 | } |
roosbulthuis | 0:c85b764527f4 | 101 | |
roosbulthuis | 0:c85b764527f4 | 102 | |
roosbulthuis | 0:c85b764527f4 | 103 | //rectifier |
roosbulthuis | 0:c85b764527f4 | 104 | double rectify(double y3) |
roosbulthuis | 0:c85b764527f4 | 105 | { |
roosbulthuis | 0:c85b764527f4 | 106 | y3 = fabs(y3); |
roosbulthuis | 0:c85b764527f4 | 107 | return y3; |
roosbulthuis | 0:c85b764527f4 | 108 | } |
roosbulthuis | 0:c85b764527f4 | 109 | |
roosbulthuis | 0:c85b764527f4 | 110 | //lowpass |
roosbulthuis | 0:c85b764527f4 | 111 | |
roosbulthuis | 0:c85b764527f4 | 112 | double lowpass_filter(double y3, double &v1, double &v2) |
roosbulthuis | 0:c85b764527f4 | 113 | { |
roosbulthuis | 0:c85b764527f4 | 114 | double y4 = biquad(y3, v1, v2, lowp1_a1, lowp1_a2, lowp1_b0, lowp1_b1, lowp1_b2); |
roosbulthuis | 0:c85b764527f4 | 115 | double y5 = biquad(y4, v1, v2, lowp2_a1, lowp2_a2, lowp2_b0, lowp2_b1, lowp2_b2); |
roosbulthuis | 0:c85b764527f4 | 116 | double filtered_signal = biquad(y5, v1, v2, lowp3_a1, lowp3_a2, lowp3_b0, lowp3_b1, lowp3_b2); |
roosbulthuis | 0:c85b764527f4 | 117 | |
roosbulthuis | 0:c85b764527f4 | 118 | return filtered_signal; |
roosbulthuis | 0:c85b764527f4 | 119 | } |
roosbulthuis | 0:c85b764527f4 | 120 | |
roosbulthuis | 0:c85b764527f4 | 121 | double filter(double input, double &v1, double &v2) |
roosbulthuis | 0:c85b764527f4 | 122 | { |
roosbulthuis | 0:c85b764527f4 | 123 | /* function passes the input through the three filters |
roosbulthuis | 0:c85b764527f4 | 124 | returns the final output value as filtered sample |
roosbulthuis | 0:c85b764527f4 | 125 | this is used in check_state() function to determine state of system |
roosbulthuis | 0:c85b764527f4 | 126 | */ |
roosbulthuis | 0:c85b764527f4 | 127 | double y1 = highpass_filter(input, v1, v2); |
roosbulthuis | 0:c85b764527f4 | 128 | double y2 = rectify(y1); |
roosbulthuis | 0:c85b764527f4 | 129 | double filtered_signal = lowpass_filter(y2, v1, v2); |
roosbulthuis | 0:c85b764527f4 | 130 | |
roosbulthuis | 0:c85b764527f4 | 131 | return filtered_signal; |
roosbulthuis | 0:c85b764527f4 | 132 | } |
roosbulthuis | 0:c85b764527f4 | 133 | |
roosbulthuis | 0:c85b764527f4 | 134 | double test=1; |
roosbulthuis | 0:c85b764527f4 | 135 | |
roosbulthuis | 0:c85b764527f4 | 136 | void sample() |
roosbulthuis | 0:c85b764527f4 | 137 | { |
roosbulthuis | 0:c85b764527f4 | 138 | input_left = analog_emg_left.read(); |
roosbulthuis | 0:c85b764527f4 | 139 | input_right = analog_emg_right.read(); |
roosbulthuis | 0:c85b764527f4 | 140 | filter_left = filter(input_left, v1_left, v2_left); |
roosbulthuis | 0:c85b764527f4 | 141 | filter_right = filter(input_right, v1_right, v2_right); |
roosbulthuis | 0:c85b764527f4 | 142 | |
roosbulthuis | 1:f32f8eac8af1 | 143 | scope.set(1, input_left); |
roosbulthuis | 1:f32f8eac8af1 | 144 | scope.set(0, filter_left); |
roosbulthuis | 0:c85b764527f4 | 145 | scope.send(); |
roosbulthuis | 0:c85b764527f4 | 146 | } |
roosbulthuis | 0:c85b764527f4 | 147 | |
roosbulthuis | 0:c85b764527f4 | 148 | |
roosbulthuis | 0:c85b764527f4 | 149 | int main() |
roosbulthuis | 0:c85b764527f4 | 150 | { |
roosbulthuis | 0:c85b764527f4 | 151 | sample_timer.attach(&sample, 0.002); |
roosbulthuis | 0:c85b764527f4 | 152 | while(1){} |
roosbulthuis | 0:c85b764527f4 | 153 | } |