RatSLAM and Grid Cells
An overview of work by Michael
Milford and colleagues
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People
David Prasser
Janet Wiles
Michael Milford
Gordon Wyeth
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Papers
• Milford, Michael J., Gordon F. Wyeth, and David Prasser. "RatSLAM:
a hippocampal model for simultaneous localization and mapping."
Robotics and Automation, 2004. Proceedings. ICRA'04. 2004 IEEE
International Conference on. Vol. 1. IEEE, 2004.
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• Milford, Michael, and Gordon Wyeth. "Persistent navigation and
mapping using a biologically inspired SLAM system." The
International Journal of Robotics Research 29.9 (2010):
1131-1153.
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• Milford, Michael J., Janet Wiles, and Gordon F. Wyeth. "Solving
navigational uncertainty using grid cells on robots." PLoS
computational biology 6.11 (2010): e1000995.
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RatSLAM
• Biologically inspired and wired for largescale, long-term autonomy
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RatSLAM
• Biologically inspired and wired for largescale, long-term autonomy
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RatSLAM
• Biologically inspired and wired for largescale, long-term autonomy
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RatSLAM
• Biologically inspired and wired for largescale, long-term autonomy
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RatSLAM
• Biologically inspired and wired for largescale, long-term autonomy
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RatSLAM
• Biologically inspired and wired for largescale, long-term autonomy
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Process
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Pose Cells and View Cells
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Network Iteration
Global pose update:
Visual weights:
Visual pose update:
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Re-use of cells
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Relationship to Rodent
Memory
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Place Cells & Head Cells
O'Keefe, John. "Place units in the hippocampus of the freely
moving rat." Experimental neurology 51.1 (1976): 78-109.
Taube, Jeffrey S., Robert U.
Muller, and James B. Ranck.
"Head-direction cells recorded
from the postsubiculum in freely
moving rats. I. Description and
quantitative analysis." The
Journal of Neuroscience 10.2
(1990): 420-435.
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Grid Cells
May-Britt & Edvard Moser
Hafting, Torkel, et al. "Microstructure of a spatial map in the entorhinal cortex."
Nature 436.7052 (2005): 801-806.
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Place Cells vs. Grid Cells
Place Cell
Grid Cell
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Entorhinal Cortex
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Firing Patterns in RatSLAM cells
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“Grids are anchored to external cues”
Moser
Milford
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“Grids persist after cue removal”
Moser
Milford
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Disambiguation Experiments
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Disambiguation Experiments
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The Need for Conjunctive Cells
Place/Head Cells
Grid Cells
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RatSLAM for Long-Term
Autonomy & Goal-Based
Navigation
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Process
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The Experience Map
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Building Experiences
Experience:
Similarity score:
Transition link:
New experience:
Map relaxation:*
* Duckett, Tom, Stephen Marsland, and Jonathan Shapiro. "Fast, on-line learning of globally consistent maps."
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Autonomous Robots 12.3 (2002): 287-300.
Pruning the Experience Map
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Experience Map Results
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Experience Map Results
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Architecture
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Place Recognition
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Global Navigation
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Local Navigation
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Long-Term Stability
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Long-Term Stability
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Long-Term Stability
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Weaknesses
• “The weakness is that the system deals
rather inefficiently with cyclic changes
such as day–night time cycles.”
• “We would not expect the experience
map maintenance and navigation
procedures to handle major changes to
the topology or geometry of the
environment; this capability would
require additional maintenance methods”
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