RAGent: Physics-Aware Agentic Reasoning for Training-Free mmWave Human Activity Recognition

Fuente: arXiv
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Auteurs principaux: Han, Mingda, Yang, Huanqi, Sun, Zehua, Li, Wenhao, Yang, Yanni, Zhang, Guoming, Cao, Yetong, Xu, Weitao, Hu, Pengfei
Format: Preprint
Publié: 2026
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author Han, Mingda
Yang, Huanqi
Sun, Zehua
Li, Wenhao
Yang, Yanni
Zhang, Guoming
Cao, Yetong
Xu, Weitao
Hu, Pengfei
author_facet Han, Mingda
Yang, Huanqi
Sun, Zehua
Li, Wenhao
Yang, Yanni
Zhang, Guoming
Cao, Yetong
Xu, Weitao
Hu, Pengfei
contents Millimeter-wave (mmWave) radar enables privacy-preserving human activity recognition (HAR), yet real-world deployment remains hindered by costly annotation and poor transferability under domain shift. Although prior efforts partially alleviate these challenges, most still require retraining or adaptation for each new deployment setting. This keeps mmWave HAR in a repeated collect-tune-redeploy cycle, making scalable real-world deployment difficult. In this paper, we present RAGent, a deployment-time training-free framework for mmWave HAR that reformulates recognition as evidence-grounded inference over reusable radar knowledge rather than deployment-specific model optimization. Offline, RAGent constructs a reusable radar knowledge base through constrained cross-modal supervision, where a Vision-Language Model (VLM) transfers activity semantics from synchronized videos to paired radar segments without manual radar annotation. At deployment time, RAGent recognizes activities from radar alone by retrieving physically comparable precedents in an explicit kinematic space and resolving the final label through structured multi-role reasoning. The reasoning protocol is further refined offline through zero-gradient self-evolution. Extensive experiments on a self-collected dataset show that RAGent achieves 93.39% accuracy without per-domain retraining or target-domain adaptation, while generalizing robustly across domains.
format Preprint
id arxiv_https___arxiv_org_abs_2603_27571
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle RAGent: Physics-Aware Agentic Reasoning for Training-Free mmWave Human Activity Recognition
Han, Mingda
Yang, Huanqi
Sun, Zehua
Li, Wenhao
Yang, Yanni
Zhang, Guoming
Cao, Yetong
Xu, Weitao
Hu, Pengfei
Human-Computer Interaction
Millimeter-wave (mmWave) radar enables privacy-preserving human activity recognition (HAR), yet real-world deployment remains hindered by costly annotation and poor transferability under domain shift. Although prior efforts partially alleviate these challenges, most still require retraining or adaptation for each new deployment setting. This keeps mmWave HAR in a repeated collect-tune-redeploy cycle, making scalable real-world deployment difficult. In this paper, we present RAGent, a deployment-time training-free framework for mmWave HAR that reformulates recognition as evidence-grounded inference over reusable radar knowledge rather than deployment-specific model optimization. Offline, RAGent constructs a reusable radar knowledge base through constrained cross-modal supervision, where a Vision-Language Model (VLM) transfers activity semantics from synchronized videos to paired radar segments without manual radar annotation. At deployment time, RAGent recognizes activities from radar alone by retrieving physically comparable precedents in an explicit kinematic space and resolving the final label through structured multi-role reasoning. The reasoning protocol is further refined offline through zero-gradient self-evolution. Extensive experiments on a self-collected dataset show that RAGent achieves 93.39% accuracy without per-domain retraining or target-domain adaptation, while generalizing robustly across domains.
title RAGent: Physics-Aware Agentic Reasoning for Training-Free mmWave Human Activity Recognition
topic Human-Computer Interaction
url https://arxiv.org/abs/2603.27571