Revision 913
Odometry works but the precision is awful. Angles are measured fairly accurately, but distance readings are consistently lower then expected.
| trunk/code/projects/mapping/odometry/odometry.c | ||
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| 1 | 1 |
#include "odometry.h" |
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#include "encoders.h"
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#include <encoders.h>
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| 3 | 3 |
#include <math.h> |
| 4 | 4 |
#include <avr/interrupt.h> |
| 5 | 5 |
#include <dragonfly_lib.h> |
| ... | ... | |
| 41 | 41 |
angle = 0.0; |
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} |
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/*Currently assumes robot only goes forward.*/ |
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void odometry_run(void){
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double v_l, v_r; |
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double omega; |
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long encoder_left, encoder_right, dl, dr; |
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double theta; |
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int encoder_left, encoder_right,dl,dr; |
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long distance_um; |
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char buf[100]; |
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//Relative to the inner wheel, the radius of its turn. |
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double turning_radius; |
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encoder_left = encoder_read(LEFT); |
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encoder_right = encoder_read(RIGHT); |
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dl = encoder_left - encoder_ltm1; |
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dr = encoder_right - encoder_rtm1; |
| 54 | 58 |
|
| ... | ... | |
| 56 | 60 |
dl = dl < -512 ? dl + 1024 :dl; |
| 57 | 61 |
dr = dr > 512 ? dr - 1024 :dr; |
| 58 | 62 |
dr = dr < -512 ? dr + 1024 :dr; |
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//idle? |
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if(dl < 2 && dr < 2) return; |
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if(dl == dr){
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diff_x += (long)((double)(dl*CLICK_DISTANCE_UM) * cos(angle)); |
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diff_y += (long)((double)(dr*CLICK_DISTANCE_UM) * sin(angle)); |
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distance_um = dl*CLICK_DISTANCE_UM; |
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//sprintf(buf,"Distance in um: %ld\n\r",distance_um); |
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//usb_puts(buf); |
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diff_x += distance_um*cos(angle)/1000; |
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diff_y += distance_um*sin(angle)/1000; |
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return; |
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} |
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//Relative to the center of the robot, the center of it's turn. |
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double turning_radius; |
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if(dr > dl){ //CCW positive.
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turning_radius = ROBOT_WIDTH_MM * dl / (dr - dl); //mm |
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v_l = (CLICK_DISTANCE_UM * dl) / (ODOMETRY_CLK * 64l); //m/s |
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omega = v_l / (turning_radius/1000); //rad/s |
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turning_radius = ROBOT_WIDTH_UM * dl / (dr - dl); //um |
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theta = ((double)(dr-dl)*CLICK_DISTANCE_UM) / ((double)ROBOT_WIDTH_UM); |
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distance_um = theta*((double)(turning_radius + ROBOT_WIDTH_UM/2)); |
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//sprintf(buf,"Distance in um: %d\n\r",distance_um); |
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//usb_puts(buf); |
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} |
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else{ //CW negative.
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turning_radius = ROBOT_WIDTH_MM * dr / (dl - dr); //mm |
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v_r = (CLICK_DISTANCE_UM * dr) / (ODOMETRY_CLK * 64l); //m/s |
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omega = v_r / (turning_radius/1000); //rad/s |
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turning_radius = ROBOT_WIDTH_UM * dr / (dl - dr); //um |
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theta = -((double)(dl-dr)*CLICK_DISTANCE_UM) / ((double)ROBOT_WIDTH_UM); |
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distance_um = -theta*((double)(turning_radius + ROBOT_WIDTH_UM/2)); |
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//sprintf(buf,"Distance in um: %d\n\r",distance_um); |
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//usb_puts(buf); |
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} |
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diff_x += distance_um * cos(angle)/1000; |
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diff_y += distance_um * sin(angle)/1000; |
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//Omega positive whenever t_r is negative, vica versa. |
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double vmag = omega * ((turning_radius + ROBOT_WIDTH_MM/2)/1000); //m/s |
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angle += theta; |
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angle += omega*ODOMETRY_CLK*64; //rad |
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diff_x += 1000000 * vmag * cos(angle); //um |
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diff_y += 1000000 * vmag * sin(angle); //um |
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encoder_ltm1 = encoder_left; |
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encoder_rtm1 = encoder_right; |
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} |
| 89 | 101 |
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ISR(TIMER2_COMP_vect){
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| trunk/code/projects/mapping/odometry/main.c | ||
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| 5 | 5 |
{
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dragonfly_init(ALL_ON); |
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odometry_init(); |
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int angle;
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char buf[100];
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while(1){
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usb_puts("X: ");
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usb_puti(odometry_dx()); |
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usb_puts(" Y: ");
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usb_puti(odometry_dy()); |
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usb_puts(" Theta: ");
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angle = (int)(odometry_angle()*150.0); |
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usb_puti(angle); |
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usb_puts("\n\r");
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sprintf(buf,"X: %i, Y: %i, Theta: %f\n\r",odometry_dx(),odometry_dy(),odometry_angle()); |
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usb_puts(buf); |
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delay_ms(500); |
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} |
| 20 | 14 |
return 0; |
| trunk/code/projects/mapping/odometry/odometry.h | ||
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| 4 | 4 |
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| 5 | 5 |
//Odometry resolution, *64 microseconds. |
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//= approx. 100 ms |
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#define ODOMETRY_CLK 1600
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#define ODOMETRY_CLK 255u
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//Wheel = 2.613 in. |
| 10 | 10 |
//Circumference = 208.508133 mm |
| 11 | 11 |
//Distance per encoder click (circumference / 1024) = 203.621224 um. |
| 12 | 12 |
//Robot width = 5.3745 in. = 136.5123 mm |
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#define ROBOT_WIDTH_MM 137 //mm
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#define ROBOT_WIDTH_UM 137000 //um
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#define CLICK_DISTANCE_UM 204 //um |
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//Standard measures will be mm and us |
| trunk/code/projects/mapping/odometry/Makefile | ||
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| 155 | 155 |
PRINTF_LIB_FLOAT = -Wl,-u,vfprintf -lprintf_flt |
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# If this is left blank, then it will use the Standard printf version. |
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PRINTF_LIB = |
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#PRINTF_LIB =
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#PRINTF_LIB = $(PRINTF_LIB_MIN) |
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#PRINTF_LIB = $(PRINTF_LIB_FLOAT)
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PRINTF_LIB = $(PRINTF_LIB_FLOAT) |
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# Minimalistic scanf version |
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