Organizations: Institute of Automation, Chinese Academy of Sciences · School of Advanced Interdisciplinary Sciences, University of Chinese Academy of Sciences · School of Artificial Intelligence, University of Chinese Academy of Sciences
Existing robot navigation methods primarily focus on isolated tasks, overlooking the need to accumulate knowledge and experience across repeated navigation episodes. Although recent lifelong navigation methods have explored cross-task knowledge accumulation, they mainly focus on scene knowledge while neglecting historical navigation experience and its connection to scene evidence, limiting the ability to reflect on past mistakes and improve future decisions. To address this limitation, this paper presents RetroNav, a training-free self-evolving navigation framework that integrates navigation, memory accumulation, and failure reflection. Specifically, we develop a unified memory system that connects geometric and semantic scene knowledge with historical navigation experience, distinguishing objective observations from task-dependent interpretations. After each navigation attempt, an independent evaluator determines whether a retry is necessary. If so, a Retrospection Agent revisits historical decisions using accumulated scene knowledge and navigation records, generating an evidence-grounded retry brief to guide the next attempt. RetroNav achieves state-of-the-art performance across five navigation benchmarks. Our method will be open-sourced at https://github.com/3dv-casia/RetroNav .
Figures & tables
Figure 1: Overview of the proposed RetroNav framework. The navigator iteratively selects navigation directions and waypoints, while a unified memory system accumulates scene knowledge and historical navigation experience. After each navigation attempt, an independent Evaluator determines whether a retry is necessary. When triggered, a Retrospection Agent revisits historical decisions using accumulated scene knowledge and visual evidence, generating an evidence-grounded Retry Brief to guide the next attempt.
Figure 2: Structure and organization of the unified memory. Left: Cumulative scene knowledge acquired across navigation tasks, including regions, places and trajectories. Top right: Representative scene knowledge at Place 6 of Region 1. Bottom right: Navigation experiences at the same place across distinct tasks, recording different goals, judgments, and actions.
R2R-CE
RxR-CE
Method
SR
SPL
OSR
SR
SPL
OSR
Training-based
NavMorph (HNR) [ 40 ]
64.0
53.0
68.0
58.0
49.0
–
Uni-NaVid [ 44 ]
47.0
42.7
53.3
48.7
40.9
55.5
StreamVLN-Prune-Mem [ 37 ]
57.4
51.1
65.5
53.9
45.1
–
DualVLN [ 36 ]
64.3
58.5
70.7
61.4
51.8
–
Table 1: Evaluation results on R2R-CE and RxR-CE val-unseen. – denotes unreported. † indicates a method retested with an updated model. The best results are shown in bold , and the second best is underlined .
Method
SR
SPL
OSR
Training-based
Uni-NaVid [ 44 ]
39.5
19.8
–
AstraNav-Memory [ 14 ]
62.5
34.9
–
MTU3D [ 47 ]
40.8
12.1
–
Training-free
SpaceVLN (Qwen3.5-Plus/Flash) [ 8 ]
51.6
33.1
–
Table 2: Evaluation results on HM3D-OVON val-unseen. – denotes unreported. The best results are shown in bold , and the second best is underlined .
Method
SR
SPL
t-nDTW
(a) Training-based
CMA [ 19 ]
19.0 ± 1.0
18.0 ± 1.0
38.0 ± 2.0
TourCMA [ 18 ]
18.0 ± 0.0
17.0 ± 1.0
36.0 ± 1.0
PoolCMA [ 18 ]
16.0 ± 1.0
15.0 ± 0.0
36.0 ± 2.0
PoolEndCMA [ 18 ]
18.0 ± 1.0
16.0 ± 1.0
38.0 ± 2.0
OVER-NAV (iterative) [ 45 ]
35.0 ± 1.0
33.0 ± 1.0
50.0 ± 2.0
Table 3: Evaluation results on IR2R-CE val-unseen. † indicates a method retested with an updated model. The best results are shown in bold , and the second best is underlined .
Method
SR
SPL
e-SR
(a) Training-based
SenseAct-NN Skill Chain [ 16 ]
29.5
11.3
–
SenseAct-NN Monolithic [ 16 ]
12.3
6.8
–
AstraNav-Memory [ 14 ]
62.7
56.9
–
MTU3D [ 47 ]
47.2
27.7
–
MemoryExplorer (LMEE) [ 34 ]
46.4
28.0
–
Table 4: Evaluation results on GOAT-Bench val-unseen. – denotes unreported. The best results are shown in bold , and the second best is underlined .
Figure 3: Qualitative trace of memory-guided navigation. Given “ Find and navigate to a rug ”, RetroNav retrieves room context and visual cues from Unified Memory M , steering the agent out of the kitchen (Steps 0–2) to locate and stop at the rug (Steps 3–6).
Component
IR2R-CE
GOAT-Bench
Row
Naive
M
Eval.
Brief
SR
SPL
t-nDTW
SR
SPL
e-SR
(1)
–
–
–
–
65.6
57.0
68.6
67.0
41.8
14.3
(2)
✓
–
–
–
76.7
62.6
71.6
81.0
47.8
28.6
(3)
–
✓
–
–
69.4
59.7
74.2
71.5
49.6
21.4
(4)
–
✓
✓
–
74.5
63.8
75.0
75.5
51.8
26.0
(5)
–
✓
✓
✓
84.1
71.9
75.2
82.3
57.6
35.3
Table 5: Component-wise ablation study on IR2R-CE and GOAT-Bench. We evaluate the contributions of Naive Retry (Naive), Unified Memory ( M ), Evaluator (Eval.), and Retry Brief (Brief).
Figure 4: Failure retrospection and retry on R2R-CE. After the initial attempt branches into a dead end at Step 12 and stops prematurely (top), the Retry Brief isolates the branch confusion (middle), guiding the retry to bypass the error and reach the bedroom door (bottom).
Figure 5: Real-world navigation with RetroNav on a CASBOT 02 humanoid robot. Given the instruction “Find the vending machine,” the robot navigates through a lobby and reaches the target autonomously. (a) Bird’s-eye view of the recorded trajectory. (b,c) Third-person and onboard views at four numbered stages. Orange boxes highlight the target vending machine.
Row
Route
Review
Images
Rec.
(1)
–
–
–
12.1
(2)
✓
✓
–
21.2
(3)
✓
–
✓
18.2
(4)
✓
✓
✓
25.8
Table 6: Ablation of the Retry Brief on 33 fixed first-attempt failures from R2R-CE, without scene memory. Each variant receives one retry from the same first-attempt traces. Rec. denotes retry recovery rate (%). Checkmarks indicate enabled components.
Method
Succ. Recall
Fail. Recall
Accuracy
Self-Stopping
100.0
0.0
55.6
Evaluator (Ours)
76.0
65.0
71.1
Oracle
100.0
100.0
100.0
Table 7: Failure-detection quality on R2R-CE. We compare navigator self-stopping, our Evaluator, and the Oracle upper bound.
Benchmark
Evaluation size
Cross-task memory
Max. steps per attempt
R2R-CE
100 episodes
Disabled
30
RxR-CE
100 episodes
Disabled
50
HM3D-OVON
150 episodes
Disabled
40
IR2R-CE
299 episodes
Enabled
30
GOAT-Bench
307 subtasks
Enabled
40
Table 8: Evaluation subsets, cross-task memory, and navigation step budgets across the five benchmarks.
Track / Record
Stored fields and evidence references
Observation Anchor (Immutable Evidence)
Observation
Scene-global ID, source attempt ID, local step, 6-DoF pose, camera intrinsics/extrinsics, and filesystem image references.
Scene Knowledge ( S )
Place
Unique ID, parent region ID, member observation IDs, visual description, representative viewpoint image references.
Region
Unique ID, semantic room category label, natural-language architectural summary, and member place IDs.
Object
Instance ID, semantic category, 3D metric bounding box, fused point cloud, and multi-view RGB/mask evidence.
Table 9: Unified memory schemas and stored record fields.
Figure 6: Progressive scene-memory accumulation. Gray lines show navigation trajectories, red dots mark places, and colored polygons indicate regions.
Figure 7: Navigation performance over repeated tours in IR2R-CE. Solid lines show the mean across three independent runs; dashed lines show individual runs.
Benchmark
Model
First
Final
Cumulative
SR
SPL
Steps
PL (m)
SR
SPL
Steps
PL (m)
SPL
Steps
PL (m)
R2R-CE
GPT-6-Astra
77.3
71.5
12.1
9.7
84.0
75.4
16.2
13.5
66.3
17.6
14.3
GPT-5.6-Sol
66.3
52.2
14.3
11.4
76.3
66.4
18.3
15.0
52.0
21.2
17.1
Qwen3.8-27B
50.7
39.6
14.5
11.7
58.0
49.5
18.7
15.5
38.3
21.6
17.6
RxR-CE
GPT-6-Astra
75.3
69.8
15.9
13.6
84.0
70.9
16.3
14.2
66.9
21.2
18.2
GPT-5.6-Sol
62.0
55.5
18.0
15.2
76.7
61.0
17.8
15.1
54.2
26.1
22.0
Table 10: Retry performance and navigation cost per episode (subtask for GOAT-Bench). First and Final report the corresponding attempt; Cumulative includes all attempts. SR and SPL are percentages. PL denotes path length in meters.
Benchmark
Model
Calls
Tokens (K)
Cumulative model-call time (s)
Input
Output
Navigation
Retry brief
Evaluator
Object annot.
Memory builder
Total
R2R-CE
GPT-5.6-Sol
65.3
663.0
12.2
302.0
47.7
49.9
/
/
399.6
GPT-6-Astra
44.8
445.0
5.8
218.0
19.5
41.1
/
/
278.6
RxR-CE
GPT-5.6-Sol
53.0
629.5
9.2
366.5
25.0
60.9
/
/
452.4
GPT-6-Astra
39.3
382.4
3.6
247.8
5.8
57.2
/
/
310.8
HM3D-OVON
GPT-5.6-Sol
29.2
199.1
5.3
162.0
23.1
27.6
/
/
212.7
Table 11: Total inference cost per episode (subtask for GOAT-Bench) across all attempts. / means the component was not used.
Scheme
SR ↑
SPL ↑
OSR ↑
Steps ↓
Tokens (K) ↓
Time (s) ↓
Two-stage
56.0
48.77
72.0
17.65
265.41
156.77
Joint
47.0
39.65
61.0
18.29
390.92
125.93
Table 12: Two-stage versus joint view and waypoint selection with Qwen on R2R-CE. Costs are averaged per episode. Tokens include input and output; time is cumulative model-call time. – denotes an unreported value.