Download presentation
Presentation is loading. Please wait.
1
P545 – Embedded & Real-Time Systems
Obstacle Avoidance by Yasir Ibrahim
2
Execution per clock tick
One loop on the following: Heading control Path following Laser reading Avoid obstacles Adjust speed Check corridor boundaries
3
Heading PID Continuous control
Cart turns when the error in the feed back is not ZERO. Actually it is not even checking against zero, it continuously feeds back inputs and issues turn commands.
4
waypoint2 waypoint3 waypoint1
5
waypoint2 waypoint3 waypoint1
6
waypoint2 waypoint3 Supposed heading Actual heading (compass) waypoint1
7
waypoint2 waypoint3 Supposed heading Actual heading (compass) error waypoint1
8
waypoint2 waypoint3 Supposed heading Actual heading (compass) Error=supposed heading – actual heading Turn_command_inverse=p*error P=1/(smallest_turn_radius*suitable_angle) P=1/(2.0*90.0) error waypoint1
9
waypoint2 waypoint3 Supposed heading Actual heading (compass) Error=supposed heading – actual heading Turn_command_inverse=p*error P=1/(smallest_turn_radius*suitable_angle) P=1/(2.0*90.0) error waypoint1
10
GPS follower When to pick the next waypoint. Two cases:
1) The distance to the next waypoint is getting shorter. (till it is less than LBO) 2) The distance from the previous waypoint is getting longer. (till it is larger than distance between the two waypoints) The heading is working continuously.
11
waypoint2 waypoint3 waypoint1
12
waypoint2 waypoint3 length waypoint1
13
waypoint2 waypoint3 LBO length waypoint1
14
waypoint2 waypoint3 LBO r length r < LBO Or d >= length d waypoint1
15
waypoint2 waypoint3 LBO r length r < LBO Or d >= length d waypoint1
16
waypoint2 waypoint3 r LBO d length r < LBO Or d >= length waypoint1
17
waypoint2 waypoint3 d length r < LBO Or d >= length waypoint1
18
waypoint2 waypoint3 waypoint1
19
waypoint2 waypoint3 waypoint1
20
Obstacle Avoidance Reading the laser device.
Filtering the list (taking only what is in the cart’s path). Averaging the list of obstacles Adjusting the output obstacle’s LBO. Keeping history of obstacles, specially the previous one.
21
waypoint2 waypoint3 waypoint1
22
waypoint2 waypoint3 waypoint1
23
a Obstacle GPS c a=b*(sin(alpha)) b Outside when a > c/2 + O_lbo alpha GPS
24
Obstacle GPS a c a=b*(sin(alpha)) b Inside when a<=c/2 + O_lbo alpha GPS
25
Obstacle GPS a c a=b*(sin(alpha)) b Inside when a<=c/2 + O_lbo alpha GPS
26
a Obstacle GPS c a=b*(sin(alpha)) b Inside when a<=c/2 + O_lbo alpha GPS
27
a Obstacle3 Obstacle1 c Obstacle2 Obstacle4 b 1 clock tick
28
a Obstacle1 c a=b*(sin(alpha)) b Inside when a<=c/2 + O_lbo alpha GPS
29
Obstacle2 a c a=b*(sin(alpha)) b Inside when a<=c/2 + O_lbo alpha GPS
30
Obstacle3 a c a=b*(sin(alpha)) b Inside when a<=c/2 + O_lbo alpha GPS
31
Obstacle4 a c a=b*(sin(alpha)) b Outside when a>c/2 + O_lbo alpha GPS
32
Obstacle3 Obstacle1 Obstacle2 c 1 clock tick
33
Obstacle3 Obstacle1 Obstacle2 c 1 clock tick
34
1 clock tick AO=0 AO=∑(Oi + AO )/i ALBO=(LBOk-1+d+LBOk)/2
Obstacle3 Obstacle1 Obstacle2 c AO=0 AO=∑(Oi + AO )/i ALBO=(LBOk-1+d+LBOk)/2 d=distance(AO,Oj) 1 clock tick
35
c Obstacle 1 1 clock tick
36
waypoint2 waypoint3 waypoint1
37
waypoint2 waypoint3 Next heading of corridor Current heading of corridor waypoint1
38
waypoint2 waypoint3 Next heading of corridor Current heading of corridor Next turn is left Optimal avoidance from the right of obstacles waypoint1
39
waypoint2 waypoint3 Does not fit waypoint1
40
waypoint2 waypoint3 Fits waypoint1
41
waypoint2 waypoint3 Fits Synthesized waypoint waypoint1
42
waypoint2 waypoint3 Becomes my next waypoint waypoint1
43
waypoint2 waypoint3 waypoint4 waypoint1
44
waypoint2 waypoint3 waypoint4 waypoint1
45
waypoint2 waypoint3 waypoint4 waypoint1
46
waypoint2 waypoint3 waypoint4 waypoint1
47
waypoint2 waypoint3 waypoint4 waypoint1
48
waypoint2 waypoint3 waypoint4 waypoint1
49
waypoint2 waypoint3 waypoint4 waypoint1
50
waypoint2 waypoint3 waypoint4 waypoint1
51
More obstacles Other configurations
52
waypoint2 waypoint3 waypoint4 waypoint1
53
waypoint2 waypoint3 waypoint4 waypoint1
54
waypoint2 waypoint3 waypoint4 waypoint1
55
waypoint2 waypoint3 waypoint4 waypoint1
56
waypoint2 waypoint3 waypoint4 waypoint1
57
waypoint2 waypoint3 waypoint4 waypoint1
58
waypoint2 waypoint3 waypoint4 waypoint1
59
waypoint2 waypoint3 waypoint1
60
waypoint2 waypoint3 waypoint4 waypoint1
61
waypoint2 waypoint3 waypoint4 waypoint1
62
waypoint2 waypoint3 waypoint4 waypoint1
63
waypoint2 waypoint3 waypoint4 waypoint1
64
waypoint2 waypoint3 waypoint4 waypoint1
65
waypoint2 waypoint3 waypoint4 waypoint1
66
waypoint2 waypoint3 Does not fit waypoint4 waypoint1
67
waypoint2 waypoint3 Fits waypoint4 waypoint1
68
waypoint2 waypoint3 Fits waypoint5 waypoint4 Synthesized waypoint waypoint1
69
waypoint2 waypoint3 Becomes my next waypoint waypoint5 waypoint4 waypoint1
70
waypoint2 waypoint3 Becomes my next waypoint waypoint5 waypoint4 If overlaps with my current waypoint, replace. waypoint1
71
waypoint2 waypoint3 Becomes my next waypoint waypoint5 waypoint4 If overlaps with my current waypoint, replace. waypoint1
72
waypoint2 waypoint3 Becomes my next waypoint waypoint5 waypoint4 If overlaps with my current waypoint, replace. waypoint1
73
waypoint2 waypoint3 Becomes my next waypoint waypoint5 waypoint4 If overlaps with my current waypoint, replace. waypoint1
74
waypoint2 waypoint3 waypoint6 Becomes my next waypoint waypoint5 waypoint1
75
waypoint2 waypoint3 waypoint6 Becomes my next waypoint waypoint5 waypoint1
76
waypoint2 waypoint3 waypoint6 Becomes my next waypoint waypoint5 waypoint1
77
waypoint2 waypoint3 STOP STOP waypoint6 Becomes my next waypoint waypoint5 waypoint1
78
waypoint2 waypoint3 waypoint4 waypoint1
79
waypoint2 waypoint3 waypoint4 waypoint1
80
waypoint2 waypoint3 fits waypoint4 waypoint1
81
waypoint2 waypoint3 waypoint5 Synthesize waypoint waypoint4 waypoint1
82
waypoint2 waypoint3 waypoint5 Synthesize waypoint waypoint4 Average waypoint4 and waypoint5 waypoint1
83
waypoint2 waypoint3 waypoint5 Synthesize waypoint waypoint4 Average waypoint4 and waypoint5 waypoint1
84
waypoint2 waypoint3 waypoint5 Synthesize waypoint waypoint4 Average waypoint4 and waypoint5 waypoint1
85
waypoint2 waypoint3 waypoint5 Synthesize waypoint waypoint4 Average waypoint4 and waypoint5 waypoint1
86
waypoint2 waypoint3 waypoint5 Synthesize waypoint waypoint4 Average waypoint4 and waypoint5 waypoint1
87
waypoint2 waypoint3 waypoint5 Synthesize waypoint waypoint4 Average waypoint4 and waypoint5 waypoint1
88
Staying inside corridor
Synthesized collision bubble. How far it is synthesized depends on cart’s speed. It can be used to control speed (accelerate, decelerate, and stop) and help in heading control (pushing bigger error to the heading control to force on turning if the cart is going out the corridor).
89
waypoint2 waypoint3 waypoint1
90
?
91
It Is a synthesized point.
Same as if it were a synthesized waypoint Or an obstacle. ?
92
It Is a synthesized point.
Same as if it were a synthesized waypoint Or an obstacle. ? Speed
93
It Is a synthesized point.
Same as if it were a synthesized waypoint Or an obstacle. ? Speed (D)istance from GPS to the cart’s font
94
It Is a synthesized point.
Same as if it were a synthesized waypoint Or an obstacle. How far = Speed/2.0+D Speed (D)istance from GPS to the cart’s font
95
It Is a synthesized point.
Same as if it were a synthesized waypoint Or an obstacle. How far = Speed/2.0+D Speed 3.0 m/s (D)istance from GPS to the cart’s font m
96
It Is a synthesized point.
Same as if it were a synthesized waypoint Or an obstacle. How far = Speed/4.0+D How far = 3.0/ = m From the GPS. Or How far= – = 0.75m From the front of the cart. Speed 3.0 m/s (D)istance from GPS to the cart’s font m
97
waypoint2 waypoint3 0.5 2 waypoint1
98
waypoint2 waypoint3 0.75 3 waypoint1
99
waypoint2 waypoint3 1.0 4 The cart is going out waypoint1
100
waypoint2 waypoint3 1.0 4 The cart is going out Signal to slow down waypoint1
101
waypoint2 waypoint3 0.75 3 Slowed down waypoint1
102
2 50 waypoint2 waypoint3 Slowed down waypoint1
103
3 0.75 waypoint2 waypoint3 Slowed down waypoint1
104
Also, Collision bubble can be used to know if the cart is going out from the side of corridor.
105
waypoint2 waypoint3 2 0.5 waypoint1
106
waypoint2 waypoint3 3 0.75 waypoint1
107
Bubble LBO a a=b*(sin(alpha)) b Outside when a + Bubble LBO > LBO alpha LBO
108
Bubble LBO a a=b*(sin(alpha)) b Outside when a + Bubble LBO > LBO alpha LBO
109
Bubble LBO a b a=b*(sin(alpha)) Inside when a + Bubble LBO<= LBO alpha LBO
110
Path planning At each cycle, an algorithm iterates through all the waypoints and obstacles together. The algorithm adds two more waypoints at each existing waypoint. One before and one after the waypoint. The algorithm synthesizes the best waypoint around obstacles.
111
Previous Labs
113
Safety
114
try : adjust_speed() if (signal_stop == False): read_laser() follow_path() if(panic==True): self.which_side_of_obstacle() self.synthesize_waypoint() self.put_synthesized_waypoint() self.panic=False catch:
115
Default value for speed. Always storing the previous value.
If one of the following sensors are providing unacceptable values (same value for along time or empty values), exception is thrown: GPS, Compass, or Laser.
116
TheEND
Similar presentations
