Neural Implicit Action Fields: From Discrete Waypoints to Continuous Functions for Vision-Language-Action Models

Fuente: arXiv
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Main Authors: Liu, Haoyun, Zhao, Jianzhuang, Chang, Xinyuan, Shi, Tianle, Meng, Chuanzhang, Tan, Jiayuan, Xiong, Feng, Lin, Tong, Huo, Dongjie, Xu, Mu, Dong, SongLin, Ma, Zhiheng, Gong, Yihong, Zhong, Sheng
Format: Preprint
Published: 2026
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author Liu, Haoyun
Zhao, Jianzhuang
Chang, Xinyuan
Shi, Tianle
Meng, Chuanzhang
Tan, Jiayuan
Xiong, Feng
Lin, Tong
Huo, Dongjie
Xu, Mu
Dong, SongLin
Ma, Zhiheng
Gong, Yihong
Zhong, Sheng
author_facet Liu, Haoyun
Zhao, Jianzhuang
Chang, Xinyuan
Shi, Tianle
Meng, Chuanzhang
Tan, Jiayuan
Xiong, Feng
Lin, Tong
Huo, Dongjie
Xu, Mu
Dong, SongLin
Ma, Zhiheng
Gong, Yihong
Zhong, Sheng
contents Despite the rapid progress of vision-language-action (VLA) models, the prevailing practice of predicting action chunks as discrete waypoints remains structurally misaligned with the intrinsic continuity of physical motion. This discretization arises naturally from fixed-rate robot data collection and the token-by-token prediction paradigm of large language models, but ties actions to rigid sampling rates, does not naturally support analytically consistent higher-order derivatives, and introduces quantization artifacts that hinder precise, compliant interaction. We propose Neural Implicit Action Fields (NIAF), which reformulates chunk-level action representation from discrete waypoints to continuous action functions. Using a vision-language model as a hierarchical spectral modulator over a learnable motion prior, NIAF synthesizes continuous-time action manifolds with arbitrary temporal resolution. This formulation enables analytical differentiation, allowing explicit supervision of velocity and regularization of higher-order derivative signals to promote mathematical consistency, physical plausibility, and control smoothness. Our approach achieves strong results on CALVIN and LIBERO across diverse backbones. Real-world experiments further confirm that NIAF supports stable impedance control, bridging policy-side action generation and execution-side smooth control.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01766
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Neural Implicit Action Fields: From Discrete Waypoints to Continuous Functions for Vision-Language-Action Models
Liu, Haoyun
Zhao, Jianzhuang
Chang, Xinyuan
Shi, Tianle
Meng, Chuanzhang
Tan, Jiayuan
Xiong, Feng
Lin, Tong
Huo, Dongjie
Xu, Mu
Dong, SongLin
Ma, Zhiheng
Gong, Yihong
Zhong, Sheng
Robotics
Despite the rapid progress of vision-language-action (VLA) models, the prevailing practice of predicting action chunks as discrete waypoints remains structurally misaligned with the intrinsic continuity of physical motion. This discretization arises naturally from fixed-rate robot data collection and the token-by-token prediction paradigm of large language models, but ties actions to rigid sampling rates, does not naturally support analytically consistent higher-order derivatives, and introduces quantization artifacts that hinder precise, compliant interaction. We propose Neural Implicit Action Fields (NIAF), which reformulates chunk-level action representation from discrete waypoints to continuous action functions. Using a vision-language model as a hierarchical spectral modulator over a learnable motion prior, NIAF synthesizes continuous-time action manifolds with arbitrary temporal resolution. This formulation enables analytical differentiation, allowing explicit supervision of velocity and regularization of higher-order derivative signals to promote mathematical consistency, physical plausibility, and control smoothness. Our approach achieves strong results on CALVIN and LIBERO across diverse backbones. Real-world experiments further confirm that NIAF supports stable impedance control, bridging policy-side action generation and execution-side smooth control.
title Neural Implicit Action Fields: From Discrete Waypoints to Continuous Functions for Vision-Language-Action Models
topic Robotics
url https://arxiv.org/abs/2603.01766