Upcoming SlideShare
Loading in …5
×

Lecture 10: Navigation

715 views
534 views

Published on

0 Comments
0 Likes
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
Your message goes here
• Be the first to comment

• Be the first to like this

No Downloads
Views
Total views
715
On SlideShare
0
From Embeds
0
Number of Embeds
51
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Lecture 10: Navigation

1. 1. Introduction to RoboticsNavigation<br />April 5, 2010<br />
2. 2. Review: Localization<br />Localization is probabilistic<br />Error propagation law<br />Markov localization and Kalman Filter<br />Simultaneous Localization and Mapping<br />
3. 3. Last Exercise<br />Beacon-based<br />Line-based<br />Maps are used for LOCALIZATION<br />
4. 4. Today: Navigation<br />How to find a collision-free, shortest path from A to B?<br />Two approaches:<br />Local planning: go towards goal while avoiding obstacles<br />Global planning: calculate shortest path offline<br />
5. 5. Global Planning<br />Workspace<br />Configuration Space<br />
6. 6. Graph-based and Potential-field Planning<br />Grid-decomposition<br />Visibility Graph<br />Potential field<br />
7. 7. Configuration Space<br />Grow obstacles at least by radius of robot<br />
8. 8. Voronoi Decomposition<br />
9. 9. Exact Cell Decomposition<br />
10. 10. Adaptive Cell Decomposition<br />
11. 11. Graph-based planning<br />Dijkstra/<br />Wavefront<br />A*<br />
12. 12. Rapidly Exploring Random Trees<br />Select a random point in the configuration space<br />Grow tree into this direction from the closest point already in the graph<br />Explores space quickly, and eventually completely<br />
13. 13. Potential-field based Planning<br />Potential given by <br />Distance to obstacles<br />Direction to goal<br />Possible to construct more complex behaviors<br />
14. 14. Calculate virtual force pulling at the robot<br />Differential wheel robot<br />Left wheel = Fx – Fy<br />Right wheel = Fx + Fy<br />Potential-Field based Planning<br />x<br />y<br />
15. 15. Reactive Obstacle Avoidance<br />Goal<br />Braitenberg behavior not sufficient (U-obstacle)<br />Classic: bug-algorithms<br />Easy to construct sub-optimal results<br />
16. 16. Vector Field Histogram<br />
17. 17. Practice<br />Localization, actuation and obstacles are uncertain<br />Combination of Local and Global Techniques<br />
18. 18. Debate Outline<br />Constructive speeches<br />10 minutes pro<br />10 minutes contra<br />Rebuttal <br />3 minutes affirmative<br />3 minutes negative<br />Discussion and cross examination<br />5-10 minutes<br />4 Debates total<br />
19. 19. Debates<br />Social:<br />Robots putting humans out of work is a risk that needs to be mitigated.<br />Robots should not have the capability to autonomously discharge weapons.<br />Robotic cars should not be allowed to participate in urban traffic.<br />…<br />Technical:<br />Swarms of simple robots are more attractive than monolithic, more capable robots.<br />Robots do not need to be as cognitive as humans in order to be useful as making the environment intelligent is sufficient.<br />Robots need to be made differently than from links, joints, and gears in order to reach the agility of people.<br />…<br />In both cases: debates should be driven by verifiable, technical arguments!<br />
20. 20. Debates<br />Social:<br />D1: Robots putting humans out of work is a risk that needs to be mitigated.<br />D2: Robots should not have the capability to autonomously discharge weapons / drive around in cities (autonomous cars).<br />Technical:<br />D3: Robots do not need to be as cognitive as humans in order to be useful as making the environment intelligent is sufficient.<br />D4: Robots need to be made differently than from links, joints, and gears in order to reach the agility of people.<br />…<br />In both cases: debates should be driven by verifiable, technical arguments!<br />
21. 21. Random assignments<br />
22. 22. Organization<br />Week 12 + 13: Debates<br />http://courses.csail.mit.edu/6.141/spring2009/pub/debates/Debates.html<br />Week 14: Graduate student presentations<br />Week 15: Final presentations<br />Final exam: Monday, May 3 7:30 p.m. - 10:00 p.m.<br />