Revision 947
Odometry works!!
| trunk/code/projects/mapping/odometry/odometry.c | ||
|---|---|---|
| 6 | 6 |
|
| 7 | 7 |
int encoder_ltm1, encoder_rtm1; |
| 8 | 8 |
|
| 9 |
//Measures mm displacement in x and y from starting position. (+x:theta=0 +y:theta=M_PI/2) |
|
| 9 | 10 |
long diff_x,diff_y; |
| 11 |
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//Measures radian angle displacement from starting position. (initially 0) |
|
| 10 | 13 |
double angle; |
| 11 | 14 |
|
| 12 | 15 |
|
| ... | ... | |
| 41 | 44 |
} |
| 42 | 45 |
|
| 43 | 46 |
void odometry_reset(void){
|
| 44 |
char buf[40]; |
|
| 45 | 47 |
diff_x = 0; |
| 46 | 48 |
diff_y = 0; |
| 47 | 49 |
encoder_ltm1 = encoder_read(LEFT); |
| 48 | 50 |
encoder_rtm1 = encoder_read(RIGHT); |
| 49 |
//sprintf(buf,"(en_right,en_left) in um: (%d,%d)\n\r",encoder_ltm1,encoder_rtm1); |
|
| 50 |
//usb_puts(buf); |
|
| 51 | 51 |
angle = 0.0; |
| 52 | 52 |
} |
| 53 | 53 |
|
| 54 |
/*Currently assumes robot only goes forward. |
|
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/*Currently assumes robot only goes forward (neither wheel goes backward).
|
|
| 55 | 55 |
void odometry_run(void){
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| 56 | 56 |
double theta; |
| 57 | 57 |
int encoder_left, encoder_right,dl,dr; |
| ... | ... | |
| 76 | 76 |
|
| 77 | 77 |
if(dl == dr){
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| 78 | 78 |
distance_um = dl*CLICK_DISTANCE_UM; |
| 79 |
//sprintf(buf,"Distance in um: %ld\n\r",distance_um); |
|
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//usb_puts(buf); |
|
| 81 | 79 |
diff_x += distance_um*cos(angle)/1000; |
| 82 | 80 |
diff_y += distance_um*sin(angle)/1000; |
| 81 |
//sprintf(buf,"Distance in um: %d\n\r",distance_um); |
|
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//usb_puts(buf); |
|
| 83 | 83 |
return; |
| 84 | 84 |
} |
| 85 | 85 |
|
| ... | ... | |
| 87 | 87 |
turning_radius = ROBOT_WIDTH_UM * dl / (dr - dl); //um |
| 88 | 88 |
theta = ((double)(dr-dl)*CLICK_DISTANCE_UM) / ((double)ROBOT_WIDTH_UM); |
| 89 | 89 |
distance_um = theta*((double)(turning_radius + ROBOT_WIDTH_UM/2)); |
| 90 |
//sprintf(buf,"Distance in um: %d\n\r",distance_um); |
|
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//usb_puts(buf); |
|
| 92 | 90 |
} |
| 93 |
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|
| 94 | 91 |
else{ //CW negative.
|
| 95 | 92 |
turning_radius = ROBOT_WIDTH_UM * dr / (dl - dr); //um |
| 96 | 93 |
theta = -((double)(dl-dr)*CLICK_DISTANCE_UM) / ((double)ROBOT_WIDTH_UM); |
| 97 | 94 |
distance_um = -theta*((double)(turning_radius + ROBOT_WIDTH_UM/2)); |
| 98 |
//sprintf(buf,"Distance in um: %d\n\r",distance_um); |
|
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//usb_puts(buf); |
|
| 100 | 95 |
|
| 101 | 96 |
} |
| 97 |
|
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//sprintf(buf,"Distance in um: %d\n\r",distance_um); |
|
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//usb_puts(buf); |
|
| 102 | 100 |
|
| 103 | 101 |
diff_x += distance_um * cos(angle)/1000; |
| 104 | 102 |
diff_y += distance_um * sin(angle)/1000; |
| ... | ... | |
| 109 | 107 |
encoder_rtm1 = encoder_right; |
| 110 | 108 |
}*/ |
| 111 | 109 |
|
| 110 |
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|
| 112 | 111 |
/*Generalized version of odometry.*/ |
| 113 | 112 |
void odometry_run(void){
|
| 114 | 113 |
//Angle swept through in a time step CCW- |
| 115 | 114 |
double theta, rl, dc; |
| 116 | 115 |
long dr,dl; |
| 117 |
char buf[40]; |
|
| 118 | 116 |
|
| 119 | 117 |
//Get the change in wheel positions |
| 120 | 118 |
{
|
| ... | ... | |
| 123 | 121 |
|
| 124 | 122 |
dl = encoder_left - encoder_ltm1; |
| 125 | 123 |
dr = encoder_right - encoder_rtm1; |
| 126 |
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//No motion. |
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if(dl == 0 && dr == 0) return; |
|
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|
|
| 127 | 128 |
encoder_ltm1 = encoder_left; |
| 128 | 129 |
encoder_rtm1 = encoder_right; |
| 129 | 130 |
|
| ... | ... | |
| 137 | 138 |
dl *= CLICK_DISTANCE_UM; //um |
| 138 | 139 |
dr *= CLICK_DISTANCE_UM; |
| 139 | 140 |
} |
| 141 |
|
|
| 140 | 142 |
|
| 141 | 143 |
if(dl == dr){
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diff_x += dl*cos(angle)/1000;
|
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diff_y += dl*sin(angle)/1000;
|
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diff_x += lround(dl*cos(angle)/1000.0); //mm
|
|
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diff_y += lround(dl*sin(angle)/1000.0); //mm
|
|
| 144 | 146 |
return; |
| 145 | 147 |
} |
| 146 | 148 |
|
| 147 | 149 |
//Call the left wheel 0, clockwise positive. |
| 148 | 150 |
rl = ((double)(ROBOT_WIDTH_UM*dl))/((double)(dl - dr)); //um |
| 149 |
theta = ((double)(dl - dr))/((double)ROBOT_WIDTH_UM); //rad |
|
| 150 |
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dc = (rl - ROBOT_WIDTH_UM/2)*theta; //um |
|
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theta = ((double)(dl - dr))/((double)ROBOT_WIDTH_UM); //rad |
|
| 152 | 152 |
|
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//Change state variables. |
|
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diff_x += ((dc * cos(angle))/1000); //mm |
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diff_y += ((dc * sin(angle))/1000); //mm |
|
| 156 |
|
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//Distance the center has traveled. |
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dc = lround( (theta * (rl - ROBOT_WIDTH_UM)) / 2.0 ); //um |
|
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|
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| 157 | 156 |
//angle is necessarily CCW+, so subtract. |
| 158 |
angle -= theta; |
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angle -= ANGLE_SCALE * theta;
|
|
| 159 | 158 |
|
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//Change state variables. |
|
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diff_x += lround((DISTANCE_SCALE * dc * cos(angle))/1000.0); //mm |
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diff_y += lround((DISTANCE_SCALE * dc * sin(angle))/1000.0); //mm |
|
| 160 | 162 |
} |
| 161 | 163 |
|
| 162 | 164 |
ISR(TIMER2_COMP_vect){
|
| 163 | 165 |
odometry_run(); |
| 164 | 166 |
} |
| 165 | 167 |
|
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long lround(double d){
|
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double f = floor(d); |
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return (long)(d - f > 0.5 ? f + 1 : f); |
|
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} |
|
| 166 | 172 |
|
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| trunk/code/projects/mapping/odometry/main.c | ||
|---|---|---|
| 1 | 1 |
#include <dragonfly_lib.h> |
| 2 | 2 |
#include "odometry.h" |
| 3 |
#include <math.h> |
|
| 3 | 4 |
|
| 4 | 5 |
int main(void) |
| 5 | 6 |
{
|
| trunk/code/projects/mapping/odometry/odometry.h | ||
|---|---|---|
| 14 | 14 |
#define ROBOT_WIDTH_UM 137000 //um |
| 15 | 15 |
#define CLICK_DISTANCE_UM 204 //um |
| 16 | 16 |
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#define DISTANCE_SCALE 2.10526316 |
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#define ANGLE_SCALE 1.12823207 |
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|
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| 17 | 20 |
//Standard measures will be mm and us |
| 18 | 21 |
|
| 19 | 22 |
long odometry_dx(void); |
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