1. Path planning for a
mobile robot
in an unknown
environment
using D* lite
Final report
[Special Topics in Robotics]
Jakub Tomášek

2. Outline
1.Introduction
–
Homemate robot
–
Project definition
2.My solution of the problem
–
Obstacle detection and mapping
–
D* lite
–
Moving the robot
3.Conclusion, remarks, questions

3. Homemate v3
●
Intelligent Systems
Research Institute
+
Yujin
●
●
●
Mobile manipulation
robot
Humanoid with one arm
:-)
Helping elderly

4. Homemate v3
●
10 IR range-finders
●
8 motors
●
Robotic hand
●
Stargazer
●
3D camera
●
●
Linux machine controls
HW
Windows notebook is the
brain
–
Ethernet

5. Note: stargazer

6. Project goal
●
Navigation in unknown
environment for
Homemate
●
D* lite
●
C++
●
Obstacle detection using
processed 3D image in
form of octree cells

7. Environment
2 by 3 metres marked area

8. Outline
1.Introduction
–
Homemate robot
–
Project definition
2.My solution of the problem
–
Obstacle detection and mapping
–
D* lite
–
Moving the robot
3.Conclusion, remarks, questions

9. 3D vision and octree cell representation
ISRC develops cognitive
recognition
system
Octree cells are used for object segmentation
and recognition to make decision
Lee et al. 2012

10. Obstacle detection
●
●
●
I simply assume that each
there is an obstacle in
place of the octree cell
Mapping of the octree
cells into 2D map
Grid size: 10cm

11. Octree mapping

12. Octree mapping

13. Outline
1.Introduction
–
Homemate robot
–
Project definition
2.My solution of the problem
–
Obstacle detection and mapping
–
D* lite
–
Moving the robot
3.Conclusion, remarks, questions

14. D* lite
●
●
Koenig, S., and M. Likhachev. “Improved Fast Replanning
for Robot Navigation in Unknown Terrain.” In IEEE
International Conference on Robotics and Automation, 2002.
Proceedings. ICRA ’02, 1:968–975 vol.1, 2002.
doi:10.1109/ROBOT.2002.1013481.
Koenig, S., and M. Likhachev. “Fast Replanning for
Navigation in Unknown Terrain.” IEEE Transactions on
Robotics 21, no. 3 (2005): 354–363.
doi:10.1109/TRO.2004.838026.

15. Interface

16. Outline
1.Introduction
–
Homemate robot
–
Project definition
2.My solution of the problem
–
Obstacle detection and mapping
–
D* lite
–
Moving the robot
3.Conclusion, remarks, questions

17. Moving the robot

18. Moving the robot in reality: troubles
and issues
●
Closed platform : limited control of the robot
–
–
●
●
Move forward/backward X cm
Turn left/right X Degrees
Cannot apply any feedback trajectory tracker →
moving
But feedforward and slipping → very inaccurate →
limiting the grid size

19. Outline
1.Introduction
–
Homemate robot
–
Project definition
2.My solution of the problem
–
Obstacle detection and mapping
–
D* lite
–
Moving the robot
3.Conclusion, remarks, questions

20. Conclusion
Problems
What I achieved
●
●
D* lite and obstacle
mapping seem to work
well
Robot is most of time
able to navigate to the
goal in the simple
environment but it is
troublesome
●
●
Not obstacle forgetting
In more complex
environment the robot
fails

21. What did I taken from the project
●
●
●
●
I wish I use a smaller robot
Robots are fun but life is never as easy as the
simulations
It is useful to know Korean when working on Korean
computer :-)
Confirmed again Murphy's laws
–
"Anything that can go wrong, will go wrong".
→ Opt for more theoretical thesis :-)

22. Special thanks to
Ahmed M. Naguib
Thank you.
Please ask me anything!