This document proposes sensor deployment strategies for indoor robot navigation. It discusses using a wireless sensor network to provide localization services for robots. The minimum sensor deployment problem is NP-hard. The document presents an initial construction technique that divides the environment graph and estimates errors, then refines placements. It evaluates strategies using testbeds and metrics like deployment set size, configuration error, and refinement ratio.

1. Sensor-Deployment Strategies for
Indoor Robot Navigation
Aaron Chun-Han Lin 林均翰
Research Center for Information Technology Innovation
Academia Sinica
Tel: 886-2-2787-2335 Fax: 886-2-2787-2372
Email: chunhan@citi.sinica.edu.tw

2. Previous Project
 ITRI project
 Demo video
Sensor-Deployment Strategies for
Indoor Robot Navigation
2 2011/8/11

3. Sensor
 Detection
 Display
15-20%
cost
 Embedded system
Market prediction of MEMS sensor on cellular phone
3 2011/8/11

4. Wireless Sensor Network (WSN) Crossbow Mica2
Sense: light, motion, temperature, magnetic fields, gravity, humidity,
vibration, pressure, electrical fields, sound, ...
4 2011/8/11

5. Project Testbed
http://www.csail.mit.edu/
http://fiji.eecs.harvard.edu
/Volcano
Harvard moteLab
COMMON Sense project
http://www2.ece.ohio-state.edu/~ekici/
http://db.csail.mit.edu/
5 2011/8/11

6. Importance of Deployment Technique
 Coverage
 Detection ratio
 Connectivity
 Fault tolerance
 …
 Lifetime
 Energy
 Maintenance
 Deployment cost
6 2011/8/11

7. Design of Deployment Technique
 Various WSN systems
 Different requirements
 Developing 3 techniques
 Indoor robot navigation
 Debris-flow observation
 Environment surveillance
7 2011/8/11

8. Robot
 Routine service
8 2011/8/11

9. Indoor Robot
 Space navigation
 Security
 Housekeeping
 Delivery
 Medical
 …
http://www.worldrobotics.org/
9 2011/8/11

10. Robot Navigation
 Localization
 Positioning sensor
 A set of sensors can
provide localization
service
 Wireless
 Infrastructure
 Coverage
10 2011/8/11

11. Challenge
 Traditional deployment
 Full coverage
 Tradeoff
 Cost  Coverage
Positioning sensor
 How
 Reducing sensor
 Where
 Keeping coverage
 Acceptable error
11 2011/8/11

12. Error Model
 Target model
 x’ = x + d cos(q+r)
y’ = y + d sin(q+r)
q ’=(q+r) mod 2p
 Actual configuration P(f)
 Configuration error
 err(f)=max(P(f) – f)
 |err(f)|
=|max(P(f) – f)|
=(max((P(x) – x)2 +
(P(y) – y)2))1/2 Positioning sensor
12 2011/8/11

13. Minimum Deployment-Set Problem
 MDS (G, Errmax)
 Width of hallway
 Width of track
 …
 The minimum
deployment-set problem is
NP-hard
 Vertex cover problem
13 2011/8/11

14. Deployment Procedure
 Map
 Track
 Deployment strategy
14 2011/8/11

15. Initial Construction
 Divide graph
 Estimate error
 Compute number
 Complexity  Probability
Even
1
 Decide location 1 2 3
 I-EVEN
 I-MAX Max
1
1 2 3
15 2011/8/11

16. Refinement
 Combine sub-graph
 Confinement region
 Circular route
 Tree-based
 Breadth-first
 Utility-based
16 2011/8/11

17. Performance Evaluation
 ITRI
 Cricket
17 2011/8/11

18. Size of Deployment Set
 Refinement ratio
 Improvement ratio
18 2011/8/11

19. Configuration Error
 Average  Variance
19 2011/8/11

20. Conclusion
 Sensor-deployment strategies for indoor robot navigation
 Technique: sensor network
 Problem: indoor robot navigation
 Problem complexity
 Deployment strategy
 Performance
20 2011/8/11