Organizations: All authors are with the State Key Laboratory of Robotics and Systems, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China.
In initialized spacecraft tracking, a short-horizon motion prediction remains available as event support changes. Observation-Aligned Event Innovation (OA-EI) uses events to correct selected components of this prediction. A constant-body-twist model propagates the complete pose; the event encoder proposes rotational and normalized image-plane translation corrections, retaining propagated axial depth. Candidate magnitudes come from a bounded Scale Gate and a deterministic activity factor, with empty windows returning the prediction unchanged. Evaluation uses four FRESH physical-event trajectories, twenty rollout starts, and three training seeds. Each rollout starts from two reference poses and then uses self-estimates. At 7.7 seconds, rotation and translation errors fall from 41.63°/57.28 mm for prediction alone to 15.73°/22.41 mm for OA-EI, reductions of 62.2% and 60.9%. Failure rates fall from 20.0% to 1.67%. Matched ablations favor the rotation-bearing interface for overall pose accuracy; combining scaling with activity support gives the lowest errors at every tested event-retention level. On Jetson Orin Nano, the measured in-memory update takes 44.56 milliseconds at the median and 58.77 milliseconds at P95.
Figures & tables
Fig. 1: Self-fed pose-tracking loop. Historical estimates are propagated into the prior Tp=(Rp,tp) , represented by rotation Rp , image-plane coordinates qp , and axial depth zp . Selective correction yields Tf=T^k+1 ; the next history is (T^k,T^k+1) .
Fig. 2: Geometry of selective translation correction. The prior tp projects to qp=[xp/zp,yp/zp]⊤ . The event update changes qf=qp+αqδq^ and retains zf=zp , giving tf=zp[qx,f,qy,f,1]⊤ . Both translations lie on the same axial-depth plane.
Fig. 3: Event candidates, gated weights, and selective pose composition. A causal h=200 -ms window is voxelized into two polarities and B=5 temporal bins. The shared feature fE supplies rotation and image-plane candidates and the Scale Gate. Predicted scale coefficients are multiplied by the deterministic Evidence factor derived from NE and fA to obtain αR,αq∈[0,1] . The right panel applies the weighted corrections, retains zp , and reconstructs tf . Prior-motion and timing scalars condition the gate.
Fig. 4: Recursive tracking behavior. Mean rotation (a) and translation (b) errors over 0.1–7.7 s are paired with endpoint gains relative to the kinematic prior for all four physical trajectories (c,d). Blue squares denote full candidate injection and orange circles denote OA-EI. Separate overall markers show the cohort-level gain with descriptive 95% trajectory-cluster bootstrap intervals.
Tracker
2.0 s
5.0 s
7.7 s
Error area
Failure
eR↓ ( ∘ )
eT↓ (mm)
eR↓ ( ∘ )
eT↓ (mm)
eR↓ ( ∘ )
eT↓ (mm)
AR↓ ( ∘ )
AT↓ (mm)
(%) ↓
Kinematic prior
8.73
13.18
22.64
34.57
41.63
57.28
21.37
30.84
20.00
Full candidate
6.57
11.06
14.83
21.94
24.61
36.42
13.28
20.37
8.33
OA-EI (ours)
5.68
8.31
9.76
15.24
15.73
22.41
8.87
13.62
1.67
TABLE I: Recursive Tracking Performance
State update
eR
eT
exy
ez
Head
Fail.
( ∘ )
(mm)
(mm)
(mm)
(k)
(%)
Kinematic prior
41.63
57.28
55.21
14.23
—
20.00
R+XYZ
24.38
33.71
32.68
7.84
265
6.67
R+q+z
20.76
30.42
29.54
6.71
265
5.00
Unified SE(3)
27.34
37.65
36.31
8.83
133
10.00
OA-EI: R+q
15.73
22.41
21.08
7.26
265
1.67
TABLE II: Matched State-Update Ablation
Scale Gate
Activity factor
100% events
10% events
1% events
×
×
24.61 / 36.42
32.17 / 44.08
45.74 / 62.31
✓
×
20.93 / 30.58
27.64 / 38.21
39.46 / 53.77
×
✓
18.84 / 27.16
23.38 / 32.74
32.71 / 47.35
✓
✓
15.73 / 22.41
19.11 / 28.06
27.28 / 38.64
TABLE III: Scaling and Activity Support Under Event Sparsification: eR/eT at 7.7 s ( ∘ /mm)
Spacecraft pose estimation recovers a spacecraft’s position and orientation from images and other sensor data for navigation, rendezvous, and servicing.
Reliable relative pose estimation is a key enabler for autonomous rendezvous and proximity operations, yet space imagery is notoriously challenging due to extreme illumination, high contrast, and fast target motion. Event cameras provide asynchronous, change-driven measurements that can remain informative when frame-based imagery saturates or blurs, while neuromorphic processors can exploit sparse activations for low-latency, energy-efficient inferences. This paper presents a spacecraft 6-DoF pose-estimation pipeline that couples event-based vision with the BrainChip Akida neuromorphic processor. Using the SPADES dataset, we train compact MobileNet-style keypoint regression networks on lightweight event-frame representations, apply quantization-aware training (8/4-bit), and convert the models to Akida-compatible spiking neural networks. We benchmark three event representations and demonstrate real-time, low-power inference on Akida V1 hardware. We additionally design a heatmap-based model targeting Akida V2 and evaluate it on Akida Cloud, yielding improved pose accuracy. To our knowledge, this is the first end-to-end demonstration of spacecraft pose estimation running on Akida hardware, highlighting a practical route to low-latency, low-power perception for future autonomous space missions.
Sparse event responses produce uneven keypoint errors whose effects on spacecraft pose depend on correspondence geometry and the reliability of successive observations. We present a reliability-aware framework connecting polarity--time localization, geometric recovery, event--CAD refinement, and trajectory optimization. A three-branch representation combines positive events, negative events, and recent-event timing through cross-branch attention and gating, followed by spatiotemporal aggregation. An ordered semantic-point head estimates relative correspondence precision for geometrically constrained pose recovery. Event-edge and CAD-projection agreement then guide local pose refinement under keypoint-geometry safeguards. At the sequence level, a ten-dimensional descriptor combines heatmap shape, reprojection consistency, and geometric conditioning to set time-aligned observation scales. On the official SPADES challenge test set, the complete system achieves a combined pose score of 0.0474, approximately 5.4% below PASAN+IRIS. Validation ablations reduce the score from 0.0772 for base localization with uniform PnP to 0.0514 for the complete cascade; on identical single-frame observations, quality weighting reduces the score from 0.0549 with constant-weight optimization to 0.0514.
Long-horizon spacecraft trajectory forecasting suffers from error accumulation due to the absence of corrective observations in the forecast regime, making reliable uncertainty estimation crucial for safety-critical decision-making such as space domain awareness and conjunction assessment. While high-fidelity physics-based orbit propagators provide accurate deterministic forecasts, they typically lack calibrated uncertainty estimates over long horizons. We introduce a Predictor--Corrector framework in which a physics-based continuous-time deterministic forecaster is augmented with a learned continuous-time probabilistic Corrector that models forecast errors. The proposed Corrector can be wrapped around an existing deterministic propagator to improve forecast accuracy while producing sharp and calibrated full-covariance uncertainty estimates. The Corrector is based on Latent Neural Controlled Differential Equations (Latent NCDEs) and models the probabilistic temporal evolution of forecast errors in continuous time, naturally supporting irregular sampling and missing features. We further introduce a loss function that promotes calibration and sharpness in long-horizon uncertainty propagation. We evaluate the proposed framework on long-horizon spacecraft trajectory forecasting using real-world data from NASA's Crustal Dynamics Data Information System (CDDIS), wrapping the Corrector around NASA's General Mission Analysis Tool (GMAT). Across forecast horizons of 2--4 days without observations and six rolling test windows, the proposed approach consistently improves accuracy and uncertainty calibration compared to deterministic baselines and Latent ODE-based correctors, demonstrating the effectiveness of the continuous-time probabilistic Corrector for trajectory forecasting.
Muhammad Bilal Shahid, Zhanhong Jiang, Soumik Sarkar +1