Searching and Tracking People with Cooperative Mobile Robots
Abstract
Social robots should be able to search and track people in order to help them. In this paper we present two different techniques of coordinated multi-robots for searching and tracking people. A probability map (belief) of a target person location is maintained, and to initialize and update it, two methods were implemented and tested: one based on a reinforcement learning algorithm and the other based on a particle filter. The person is tracked if visible, otherwise an exploration is done by making a balance, for each candidate location, between the belief, the distance, and whether close locations are already being explored by other robots of the team. The validation of the approach was accomplished throughout an extensive set of simulations using up to five agents and a large amount of dynamic obstacles; furthermore, over three hours of real-life experiments with two robots searching and tracking were recorded and analysed.
Experimental Videos
Videos demonstrating the experiments done with the Multi-agent HB-PF Explorer to find and follow people. The robot searches and follows a person recognized using AR Markers.
Video Legend
Each experiment video shows three sections:
- Left: Map and probability maps
- Right-top: Video focusing on robot Tibi
- Right-bottom: Video focusing on robot Dabo
Map Elements
- Dabo: Blue body, white head
- Tibi: Orange body, white head
- Obstacles: Black and dark gray
- Laser detections: Blue/orange line/dots
- Path: Blue/orange lines showing executed path
- Person detection:
- Leg detection: Blue/orange dots
- Last used person location: Red dot
- Last detected person location: White dot
Probability Map Elements
- Robot self: Large blue circle
- Other robot: Small blue circle
- Detected person's location: Large red circle
- Other robot's detection: Small red circle
- Obstacles: Black squares
- Probability: White (low) to red (high probability)
Experiment Statistics
Summary of over 3 hours of real-life experiments with two robots:
| Metric | Exploration | Search & Track | Tracking | Total |
|---|---|---|---|---|
| Distance per robot (km) | 1.2 | 1.2 | 0.7 | 3.2 |
| Total time (h) | 1.1 | 1.2 | 0.9 | 3.2 |
| Avg. visibility (%) | 0 | 16.3 | 36.4 | 15.3 |
| Avg. distance to person (m) | - | 8.4 ± 6.4 | 8.4 ± 5.6 | 8.3 ± 5.9 |
| Avg. time found (s) | - | 106.8 ± 138.7 | 23.5 ± 42.5 | 72.9 ± 117.6 |
More Information
For detailed videos and additional experiment information, please refer to the full page with embedded videos.
Additional materials: Map information