root / trunk / code / projects / mapping / odometry / odometry.c @ 929
History | View | Annotate | Download (3.56 KB)
1 |
#include "odometry.h" |
---|---|
2 |
#include <encoders.h> |
3 |
#include <math.h> |
4 |
#include <avr/interrupt.h> |
5 |
#include <dragonfly_lib.h> |
6 |
|
7 |
int encoder_ltm1, encoder_rtm1;
|
8 |
|
9 |
long diff_x,diff_y;
|
10 |
double angle;
|
11 |
|
12 |
|
13 |
long odometry_dx(void){ |
14 |
return diff_x;
|
15 |
} |
16 |
|
17 |
long odometry_dy(void){ |
18 |
return diff_y;
|
19 |
} |
20 |
|
21 |
double odometry_angle(void){ |
22 |
return angle;
|
23 |
} |
24 |
|
25 |
void odometry_init(void){ |
26 |
|
27 |
encoders_init(); |
28 |
|
29 |
delay_ms(100);
|
30 |
|
31 |
odometry_reset(); |
32 |
|
33 |
|
34 |
//CTC Mode. CLK / 1024
|
35 |
TCCR2 = 0; // (Fully disconnected) |
36 |
TCCR2 = _BV(WGM21) | _BV(CS22) | _BV(CS20); //CLK/1024 , CTC Mode.
|
37 |
|
38 |
TIMSK |= _BV(OCIE2); |
39 |
|
40 |
OCR2 = ODOMETRY_CLK; |
41 |
} |
42 |
|
43 |
void odometry_reset(void){ |
44 |
char buf[40]; |
45 |
diff_x = 0;
|
46 |
diff_y = 0;
|
47 |
encoder_ltm1 = encoder_read(LEFT); |
48 |
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 |
angle = 0.0; |
52 |
} |
53 |
|
54 |
/*Currently assumes robot only goes forward.
|
55 |
void odometry_run(void){
|
56 |
double theta;
|
57 |
int encoder_left, encoder_right,dl,dr;
|
58 |
long distance_um;
|
59 |
char buf[100];
|
60 |
//Relative to the inner wheel, the radius of its turn.
|
61 |
double turning_radius;
|
62 |
|
63 |
encoder_left = encoder_read(LEFT);
|
64 |
encoder_right = encoder_read(RIGHT);
|
65 |
|
66 |
dl = encoder_left - encoder_ltm1;
|
67 |
dr = encoder_right - encoder_rtm1;
|
68 |
|
69 |
dl = dl > 512 ? dl - 1024 :dl;
|
70 |
dl = dl < -512 ? dl + 1024 :dl;
|
71 |
dr = dr > 512 ? dr - 1024 :dr;
|
72 |
dr = dr < -512 ? dr + 1024 :dr;
|
73 |
|
74 |
//idle?
|
75 |
if(dl < 2 && dr < 2) return;
|
76 |
|
77 |
if(dl == dr){
|
78 |
distance_um = dl*CLICK_DISTANCE_UM;
|
79 |
//sprintf(buf,"Distance in um: %ld\n\r",distance_um);
|
80 |
//usb_puts(buf);
|
81 |
diff_x += distance_um*cos(angle)/1000;
|
82 |
diff_y += distance_um*sin(angle)/1000;
|
83 |
return;
|
84 |
}
|
85 |
|
86 |
if(dr > dl){ //CCW positive.
|
87 |
turning_radius = ROBOT_WIDTH_UM * dl / (dr - dl); //um
|
88 |
theta = ((double)(dr-dl)*CLICK_DISTANCE_UM) / ((double)ROBOT_WIDTH_UM);
|
89 |
distance_um = theta*((double)(turning_radius + ROBOT_WIDTH_UM/2));
|
90 |
//sprintf(buf,"Distance in um: %d\n\r",distance_um);
|
91 |
//usb_puts(buf);
|
92 |
}
|
93 |
|
94 |
else{ //CW negative.
|
95 |
turning_radius = ROBOT_WIDTH_UM * dr / (dl - dr); //um
|
96 |
theta = -((double)(dl-dr)*CLICK_DISTANCE_UM) / ((double)ROBOT_WIDTH_UM);
|
97 |
distance_um = -theta*((double)(turning_radius + ROBOT_WIDTH_UM/2));
|
98 |
//sprintf(buf,"Distance in um: %d\n\r",distance_um);
|
99 |
//usb_puts(buf);
|
100 |
|
101 |
}
|
102 |
|
103 |
diff_x += distance_um * cos(angle)/1000;
|
104 |
diff_y += distance_um * sin(angle)/1000;
|
105 |
|
106 |
angle += theta;
|
107 |
|
108 |
encoder_ltm1 = encoder_left;
|
109 |
encoder_rtm1 = encoder_right;
|
110 |
}*/
|
111 |
|
112 |
/*Generalized version of odometry.*/
|
113 |
void odometry_run(void){ |
114 |
//Angle swept through in a time step CCW-
|
115 |
double theta, rl, dc;
|
116 |
long dr,dl;
|
117 |
char buf[40]; |
118 |
|
119 |
//Get the change in wheel positions
|
120 |
{ |
121 |
int encoder_right = encoder_read(RIGHT);
|
122 |
int encoder_left = encoder_read(LEFT);
|
123 |
|
124 |
dl = encoder_left - encoder_ltm1; |
125 |
dr = encoder_right - encoder_rtm1; |
126 |
|
127 |
encoder_ltm1 = encoder_left; |
128 |
encoder_rtm1 = encoder_right; |
129 |
|
130 |
// Try to avoid over/underflow.
|
131 |
dl = dl > 512 ? dl - 1024 :dl; |
132 |
dl = dl < -512 ? dl + 1024 :dl; |
133 |
dr = dr > 512 ? dr - 1024 :dr; |
134 |
dr = dr < -512 ? dr + 1024 :dr; |
135 |
|
136 |
//Convert "clicks" to um
|
137 |
dl *= CLICK_DISTANCE_UM; //um
|
138 |
dr *= CLICK_DISTANCE_UM; |
139 |
} |
140 |
|
141 |
if(dl == dr){
|
142 |
diff_x += dl*cos(angle)/1000;
|
143 |
diff_y += dl*sin(angle)/1000;
|
144 |
return;
|
145 |
} |
146 |
|
147 |
//Call the left wheel 0, clockwise positive.
|
148 |
rl = ((double)(ROBOT_WIDTH_UM*dl))/((double)(dl - dr)); //um |
149 |
theta = ((double)(dl - dr))/((double)ROBOT_WIDTH_UM); //rad |
150 |
|
151 |
dc = (rl - ROBOT_WIDTH_UM/2)*theta; //um |
152 |
|
153 |
//Change state variables.
|
154 |
diff_x += ((dc * cos(angle))/1000); //mm |
155 |
diff_y += ((dc * sin(angle))/1000); //mm |
156 |
|
157 |
//angle is necessarily CCW+, so subtract.
|
158 |
angle -= theta; |
159 |
|
160 |
} |
161 |
|
162 |
ISR(TIMER2_COMP_vect){ |
163 |
odometry_run(); |
164 |
} |
165 |
|
166 |
|