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IROS · 2024 · First author

CLP: Continually Learning Prototypes

A prototype-based online learner for robots that meet new objects after deployment: it learns from few labels, detects novel objects and keeps learning them without supervision, with no replay buffer.

  • 85%less catastrophic forgetting
  • 99%base-class accuracy in the open world
  • 65 / 76%novel-class accuracy (5 / 10-shot), learned without labels
Top: IID samples versus a continuous, correlated stream of robot camera frames. Bottom: a pretrained feature extractor feeds CLP, which holds consolidated, plastic, unlabeled and unallocated prototypes in feature space, handling concept drift and novel classes.
CLP learns from a continuous stream (top) with plastic and consolidated prototypes on top of a pretrained backbone (bottom). Figure from the paper.

Problem

A deployed robot sees objects as a correlated stream, few of them labeled, with new classes and concept drift. Most existing continual-learning methods need buffering and balanced replay of training data, which does not suit this setting.

Approach

A rehearsal-free, prototype-based online learner on pretrained CNN / ViT representations: few-shot and semi-supervised updates, novelty detection, and new prototypes for novel inputs. A metaplasticity mechanism adapts the learning rate per prototype to limit forgetting. I optimized the algorithm with evolutionary search over discrete learning-rule components.

Evaluation

OpenLORIS, in class-incremental, few-shot online and open-world settings.

Result

85% reduction in catastrophic forgetting in dynamic environments and state-of-the-art results in the low-instance few-shot online setting. In the open world, CLP detects novelties with higher precision and recall than the baselines and learns the new classes without supervision: 99% base-class and 65% / 76% (5-shot / 10-shot) novel-class accuracy.

Paper

Continual Learning for Autonomous Robots: A Prototype-based Approach

Elvin Hajizada, Balachandran Swaminathan, Yulia Sandamirskaya

IROS 2024