Organizations: University of California, Irvine · University of Pennsylvania · Carnegie Mellon University · Purdue University Northwest · Michigan State University · Independent Researcher · Dartmouth College · University of California, Los Angeles · University of Notre Dame
Vision-language-action models for embodied navigation typically rely on RGB observations, limiting their applicability in lights-out industrial environments where visible illumination may be unavailable. We study illumination-independent navigation using spatial audio for target localization and depth for obstacle-aware geometry. To support this setting, we introduce DarkNav-Bench, a benchmark with 24 industrial scenes and four progressively challenging acoustic conditions. We further propose ADAPT, an audio-depth action-planning framework equipped with spatial-audio perception and optimized for closed-loop navigation through reinforcement learning (RL). Our key RL contribution, transition-aware reward shaping (TARS), defines a pose-aware shortest-action potential over a position-heading graph. Unlike conventional geodesic-progress rewards, TARS accounts for both feasible movements and in-place rotations, providing action-consistent feedback for policy optimization. Experiments show that ADAPT consistently outperforms training-based navigation baselines and zero-shot multimodal models on both seen and unseen scenes. On unseen environments, it achieves 90.6% success under Clean conditions and retains 60.0% success under the most challenging Localized Noise setting. These results demonstrate the potential of spatial audio and depth as complementary modalities for reliable RGB-free navigation in lights-out industrial environments.
Figures & tables
Figure 1: Motivation of ADAPT. Existing RGB-based VLA agents depend on visible illumination and therefore require continuous lighting in lights-out factories. ADAPT instead combines spatial audio for target direction with depth sensing for local obstacle geometry, enabling reliable and energy-efficient navigation without visible light.
Figure 2: Overview of ADAPT . The model is trained in three stages: spatial-audio adaptation, multimodal SFT for audio-depth action prediction, and PPO-based closed-loop optimization with TARS. At inference time, the final policy directly maps spatial audio and depth observations to discrete navigation actions.
Method
Clean
Prop
DN
LN
SR ↑
SPL ↑
SNA ↑
FDG ↓
SR ↑
SPL ↑
SNA ↑
FDG ↓
SR ↑
SPL ↑
SNA ↑
FDG ↓
SR ↑
SPL ↑
SNA ↑
FDG ↓
1. Oracle-assisted methods
1.1 Zero-shot (strict stopping)
Qwen 2.5-Omni Qwen (2025)
19.00
13.60
7.70
15.19
16.00
13.00
6.70
14.96
22.00
17.29
9.35
14.11
19.37
13.91
8.10
15.64
Qwen 3-Omni Xu et al. (2025)
72.00
71.68
59.48
6.00
73.00
72.76
60.87
5.18
70.00
69.83
58.02
5.50
70.20
69.78
59.31
6.53
2. Non-oracle methods
Table 1: Navigation performance in seen scenes.
Method
Clean
Prop
DN
LN
SR ↑
SPL ↑
SNA ↑
FDG ↓
SR ↑
SPL ↑
SNA ↑
FDG ↓
SR ↑
SPL ↑
SNA ↑
FDG ↓
SR ↑
SPL ↑
SNA ↑
FDG ↓
1. Oracle-assisted methods (zero-shot)
1.1 Zero-shot (strict stopping)
Qwen 2.5-Omni Qwen (2025)
14.29
11.40
6.12
16.63
12.71
10.06
5.55
16.79
15.10
12.20
6.41
16.25
17.10
14.34
7.88
16.30
Qwen 3-Omni Xu et al. (2025)
62.14
61.79
52.12
6.36
62.38
61.93
52.87
6.40
63.33
62.92
53.27
6.16
62.62
62.24
52.70
6.31
2. Non-oracle methods
Table 2: Navigation performance in unseen scenes.
Figure 3: Qualitative comparison of navigation trajectories. Each panel reports the number of executed actions, FDG, and traveled path length. More examples are included in the appendix (see Fig. 6 ).
Table 3: Ablation study under the LN setting. (a) SFT-only ablation. (b) RL ablation.
Metric
Clean
Prop
DN @ 20 dB
DN @ 10 dB
DN @ 0 dB
DN @ −10 dB
MAE ↓
35.45∘
25.03∘
28.45∘
32.02∘
34.06∘
34.17∘
Median error ↓
13.23∘
10.93∘
10.74∘
11.47∘
14.93∘
17.89∘
Table 4: DoA estimation under different difficulties.
SNR (dB)
SR ↑
SPL ↑
SNA ↑
FDG ↓
10
67.10
59.30
39.00
7.89
0
61.90
51.00
32.60
9.18
-5
52.60
41.50
27.40
12.42
-10
31.20
23.70
14.40
18.39
Table 5: Navigation performance under different SNR under the DN setting.
Appendix figures & tables6 assets
Supplementary material from the paper’s appendix.
Appendix
Material
Abs.-L
Abs.-M
Abs.-H
Scat.
Trans.-L
Trans.-M
Trans.-H
Concrete
0.05
0.07
0.08
0.05
0.015
0.002
0.001
Metal
0.20
0.07
0.06
0.05
0.200
0.025
0.010
Wood
0.11
0.07
0.06
0.05
0.070
0.014
0.005
Plastic
0.03
0.04
0.05
0.05
0.080
0.030
0.015
Rubber
0.05
0.10
0.15
0.10
0.020
0.010
0.005
Appendix
Table 6: Acoustic material parameters used for geometry-dependent sound propagation. Abs.-L/M/H denote low-, mid-, and high-frequency absorption coefficients; Scat. denotes the scattering coefficient; and Trans.-L/M/H denote low-, mid-, and high-frequency transmission coefficients.
Source
SPL snd @1 m unweighted
SPL snd @1 m A-weighted
10–90% Energy Band
Energy in 500–900 Hz
Temporal Structure
Target
95.1
93.6
560–840 Hz
96.0%
50 ms sweep, 20 Hz
Conveyor
72.0
65.6
178–477 Hz
5.8%
steady hum
Forklift
68.0
58.4
110–265 Hz
0.15%
steady hum
Reach truck
66.0
60.6
183–443 Hz
5.6%
steady hum
AGV
62.0
60.7
551–1480 Hz
74.7%
steady hum
Appendix
Table 7: Acoustic characteristics of the target and localized equipment-noise sources. SPL snd values are nominal levels at 1 m under our waveform calibration. The 10–90% energy band denotes the frequency range containing the central 80% of spectral energy, and the overlap column reports the fraction of total energy within the target chirp band (500–900 Hz).
Figure 4: Comparison of geodesic progress and TARS. (a). In-place rotations leave geodesic distance unchanged, providing no feedback on heading changes. (b). TARS uses a position–heading action graph to measure the minimum remaining action count ( N(s) ). (c). With γΦ=1 , TARS rewards turns that reduce N(s) and penalizes those that increase it, distinguishing helpful from counterproductive rotations at the same position.
Input / Information
Zero-shot w/o Oracle Info.
Zero-shot w/ Oracle Info.
Current FOA audio
✓
✓
Current depth image
✓
✓
Recent action history
✓
–
Previous sensory observations
–
–
Ground-truth source bearing
–
✓
Ground-truth source distance
–
✓
Appendix
Table 8: Input information provided to the zero-shot multimodal baselines. Oracle bearing and distance are used only in the oracle-assisted diagnostic and are never available to ADAPT at inference time.
Figure 5: DoA estimation accuracy across difficulty levels. Accuracy is the percentage of predictions with angular error within 10∘ , 20∘ , or 45∘ of target direction.
Figure 6: More qualitative comparison of navigation trajectories.
Joint Research Laboratory for Embodied Intelligence, Xinjiang University · Joint International Research Laboratory of Silk Road Multilingual Cognitive Computing, Xinjiang University · School of Computer Science and Technology, Xinjiang University, Urumqi 830017, China