Chris Styles
An example PID line following program
main.cpp@0:78f9794620a3, 2011-05-12 (annotated)
- Committer:
- chris
- Date:
- Thu May 12 11:48:56 2011 +0000
- Revision:
- 0:78f9794620a3
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| chris | 0:78f9794620a3 | 1 | #include "mbed.h" |
| chris | 0:78f9794620a3 | 2 | #include "m3pi.h" |
| chris | 0:78f9794620a3 | 3 | |
| chris | 0:78f9794620a3 | 4 | m3pi m3pi; |
| chris | 0:78f9794620a3 | 5 | |
| chris | 0:78f9794620a3 | 6 | // Minimum and maximum motor speeds |
| chris | 0:78f9794620a3 | 7 | #define MAX 1.0 |
| chris | 0:78f9794620a3 | 8 | #define MIN 0 |
| chris | 0:78f9794620a3 | 9 | |
| chris | 0:78f9794620a3 | 10 | // PID terms |
| chris | 0:78f9794620a3 | 11 | #define P_TERM 1 |
| chris | 0:78f9794620a3 | 12 | #define I_TERM 0 |
| chris | 0:78f9794620a3 | 13 | #define D_TERM 20 |
| chris | 0:78f9794620a3 | 14 | |
| chris | 0:78f9794620a3 | 15 | int main() { |
| chris | 0:78f9794620a3 | 16 | |
| chris | 0:78f9794620a3 | 17 | m3pi.locate(0,1); |
| chris | 0:78f9794620a3 | 18 | m3pi.printf("Line PID"); |
| chris | 0:78f9794620a3 | 19 | |
| chris | 0:78f9794620a3 | 20 | wait(2.0); |
| chris | 0:78f9794620a3 | 21 | |
| chris | 0:78f9794620a3 | 22 | m3pi.sensor_auto_calibrate(); |
| chris | 0:78f9794620a3 | 23 | |
| chris | 0:78f9794620a3 | 24 | float right; |
| chris | 0:78f9794620a3 | 25 | float left; |
| chris | 0:78f9794620a3 | 26 | float current_pos_of_line = 0.0; |
| chris | 0:78f9794620a3 | 27 | float previous_pos_of_line = 0.0; |
| chris | 0:78f9794620a3 | 28 | float derivative,proportional,integral = 0; |
| chris | 0:78f9794620a3 | 29 | float power; |
| chris | 0:78f9794620a3 | 30 | float speed = MAX; |
| chris | 0:78f9794620a3 | 31 | |
| chris | 0:78f9794620a3 | 32 | while (1) { |
| chris | 0:78f9794620a3 | 33 | |
| chris | 0:78f9794620a3 | 34 | // Get the position of the line. |
| chris | 0:78f9794620a3 | 35 | current_pos_of_line = m3pi.line_position(); |
| chris | 0:78f9794620a3 | 36 | proportional = current_pos_of_line; |
| chris | 0:78f9794620a3 | 37 | |
| chris | 0:78f9794620a3 | 38 | // Compute the derivative |
| chris | 0:78f9794620a3 | 39 | derivative = current_pos_of_line - previous_pos_of_line; |
| chris | 0:78f9794620a3 | 40 | |
| chris | 0:78f9794620a3 | 41 | // Compute the integral |
| chris | 0:78f9794620a3 | 42 | integral += proportional; |
| chris | 0:78f9794620a3 | 43 | |
| chris | 0:78f9794620a3 | 44 | // Remember the last position. |
| chris | 0:78f9794620a3 | 45 | previous_pos_of_line = current_pos_of_line; |
| chris | 0:78f9794620a3 | 46 | |
| chris | 0:78f9794620a3 | 47 | // Compute the power |
| chris | 0:78f9794620a3 | 48 | power = (proportional * (P_TERM) ) + (integral*(I_TERM)) + (derivative*(D_TERM)) ; |
| chris | 0:78f9794620a3 | 49 | |
| chris | 0:78f9794620a3 | 50 | // Compute new speeds |
| chris | 0:78f9794620a3 | 51 | right = speed+power; |
| chris | 0:78f9794620a3 | 52 | left = speed-power; |
| chris | 0:78f9794620a3 | 53 | |
| chris | 0:78f9794620a3 | 54 | // limit checks |
| chris | 0:78f9794620a3 | 55 | if (right < MIN) |
| chris | 0:78f9794620a3 | 56 | right = MIN; |
| chris | 0:78f9794620a3 | 57 | else if (right > MAX) |
| chris | 0:78f9794620a3 | 58 | right = MAX; |
| chris | 0:78f9794620a3 | 59 | |
| chris | 0:78f9794620a3 | 60 | if (left < MIN) |
| chris | 0:78f9794620a3 | 61 | left = MIN; |
| chris | 0:78f9794620a3 | 62 | else if (left > MAX) |
| chris | 0:78f9794620a3 | 63 | left = MAX; |
| chris | 0:78f9794620a3 | 64 | |
| chris | 0:78f9794620a3 | 65 | // set speed |
| chris | 0:78f9794620a3 | 66 | m3pi.left_motor(left); |
| chris | 0:78f9794620a3 | 67 | m3pi.right_motor(right); |
| chris | 0:78f9794620a3 | 68 | |
| chris | 0:78f9794620a3 | 69 | } |
| chris | 0:78f9794620a3 | 70 | } |