Towards Accurate End-Effector Localization for UMI-Style Robotic Manipulation Teaching

Junjie Zhang; Deteng Zhang; Zhisong Xu; Bo Sun; Liuyang Li; Yihong Tian; Jie Yin

cs.ROOct 7, 2026

Towards Accurate End-Effector Localization for UMI-Style Robotic Manipulation Teaching

Authors: Junjie Zhang, Deteng Zhang, Zhisong Xu, Bo Sun, Liuyang Li, Yihong Tian, Jie Yin

Organizations: Chongqing University · Northwestern Polytechnical University · The University of Tokyo · Jiaxing University · Sichuan University · Beijing Institute of Technology · Shanghai Jiao Tong University

Abstract

Robot demonstration learning requires accurate and temporally complete end-effector localization during close-range manipulation and camera occlusion. Existing SLAM benchmarks emphasize navigation motions, whereas manipulation datasets prioritize policy learning over localization evaluation. We introduce MILD, a Manipulation-Interface Localization Dataset with real-world and simulation sequences. The real-world subset provides 86 sensor sequences from Insta360 X5 and Insight9 across 15 repeated tabletop tasks, calibration assets, and a per-execution robot end-effector reference trajectory. The simulation subset, MILD-Sim, extends task coverage in Isaac Sim for controlled manipulation-replay studies. Benchmarking visual-inertial and fiducial-aided systems on instrumented real-world recordings reveals large differences in both TCP-relative trajectory error and temporal coverage, even under the same nominal task. To support marker-augmented teaching workspaces without a pre-surveyed fiducial map, we present AprilVINS, which combines fisheye visual-inertial estimation with sequence-local AprilTag geometry and separates prior admission from guarded export of the jointly optimized state. On Insta360 AprilTag4 recordings, AprilVINS(full) under a unified protocol with sequence-specific profiles reaches millimeter-level SE(3)-aligned TCP-relative APE RMSE with high time completion and lower reported error than the tested routes under their respective protocols, whereas fisheye VIO without tag factors remains at centimeter scale. Ablations separate accuracy from exportability, and a MILD-Sim replay study provides task-specific tolerance references for interpreting those error magnitudes. Together, MILD and AprilVINS provide a diagnostic benchmarking framework for UMI-style demonstration collection. Code, datasets, and evaluation manifests will be released upon acceptance.

Figures & tables

Fig. 1: Representative MILD recordings from Insta360 X5 (fisheye), Insight9 (stereo/RGB-D), and MILD-Sim (simulated fisheye) across pick-and-place, wiping, and rearrangement tasks. The montage shows the multi-sensor, cross-domain coverage of the benchmark.

Fig. 2: MILD acquisition overview. Platform: AGIbot G2 with Insta360 X5 and Insight9 under teleoperation. Scene: plain tabletop, tablecloth, and ArUco/AprilTag marker layouts. Task: 15 tabletop families with executed TCP references; orange curves show trajectories and green/blue/red markers denote start, pick/place, and end events.

Item	Analemma	Circular	Zigzag	Bookshelf	Box	Pick-and- place	Wiping	Throwing	Total
Real-world number	9	9	11	15	7	23	12	0	86
Simulation number	1	1	1	0	0	4	1	1	9
number	10	10	12	15	7	27	13	1	95
Time (min)	5.4	4.9	17.9	31.0	16.0	41.0	28.9	0.2	145.3
Size (GB)	9.6	8.7	27.9	62.6	35.8	100.2	62.7	0.33	307.83

TABLE I: MILD dataset overview by task family.

Fig. 3: MILD-Sim overview. Scene: Isaac Sim workbench and Franka manipulation setup. Task: representative pick-and-place, wiping, and throwing trajectories with executed end-effector paths.

Fig. 4: AprilVINS pipeline. Fisheye images and IMU feed a VINS-Fisheye backbone with point, plane, and line features in a fixed-lag sliding window. A parallel fiducial front end detects AprilTags, estimates sequence-local tag layout via spherical PnP, and supplies admitted tag-pose priors to the window. Guarded continuation then filters the jointly optimized body state before TCP conversion.

Route

Analemma

Circular

Zigzag

Bookshelf 01

Bookshelf 02

Box 01

Box 02

Pick-and- place 01

Pick-and- place 02

Pick-and- place 03

Pick-and- place 04

Pick-and- place 05

Pick-and- place 06

Wiping 01

Wiping 02

VINS-Fisheye

0.0818/0.98

0.0385/0.98

0.0526/0.99

0.0598/0.99

0.0803/1.00

0.0503/0.99

0.0671/0.87

0.0423/0.99

0.0314/0.99

0.0284/0.99

0.0691/0.99

0.0433/0.92

0.0349/0.99

0.0264/1.00

0.0358/0.99

DM-VIO

0.0504/1.00

\dagger

0.0328/1.00

\dagger

\times

0.2399/0.97

591.5738/0.99

0.1425/1.00

\dagger

\times

0.1479/0.98

0.1064/0.98

0.7871/1.00

\dagger

0.3276/1.00

\dagger

\times

0.2939/1.00

\dagger

\times

\times

ORB-SLAM3

\times

\times

\times

\times

\times

\times

\times

\times

\times

\times

\times

\times

\times

\times

\times

OpenVINS

3.0149/0.78

\times

60.7054/0.88

2.9991/0.91

29.7722/0.92

1.0523/0.92

43.3075/0.96

2.6814/0.89

2.6765/0.88

3.4719/0.89

11.4182/0.94

18.3236/0.96

6.8308/0.94

17.7003/0.94

10.2853/0.95

TagSLAM(single-anchor)

0.0703/1.00

0.0404/1.00

0.3199/1.00

0.0347/1.00

0.0608/1.00

0.1104/1.00

0.0896/1.00

0.0553/1.00

0.0286/1.00

0.0404/1.00

0.2516/1.00

0.4332/1.00

0.0304/1.00

0.0260/1.00

0.0947/1.00

UcoSLAM

4.4863/0.92

\dagger

0.4330/0.96

\dagger

0.3402/0.43

\times

0.6350/0.17

0.9210/0.98

\dagger

0.3342/0.56

\times

0.3035/0.98

0.3684/0.98

0.7185/0.99

\dagger

0.7328/0.64

\times

0.2856/0.99

0.3525/0.72

\dagger

TABLE III: Task-level localization on MILD: APE RMSE (m) / time completion.

Fig. 5: Task-difficulty map from non-AprilVINS baselines. Points show the mean APE RMSE and mean time completion of the three lowest-RMSE evaluable routes per task.

Method	Markers	Analemma	Circular	Zigzag	Bookshelf 01	Bookshelf 02	Wiping 02
UcoSLAM	ArUco2	$\times$	0.027/0.02	0.251/0.37	0.237/0.98	0.574/0.19	$\times$
	ArUco4	$\times$	0.433/0.96	0.340/0.43	$\times$	0.635/0.17	0.352/0.72
OpenVINS(ArUco)	ArUco2	$\times$	$\times$	$\times$	3.050/0.90	4.826/0.93	$\times$
	ArUco4	2.725/0.78	$\times$	$\times$	2.885/0.90	4.603/0.92	$\times$
TagSLAM(actual-count)	AprilTag2	0.063/1.00	$\times$	0.072/1.00	0.035/1.00	$\times$	0.026/1.00
	AprilTag4	$\times$	$\times$	$\times$	$\times$	$\times$	$\times$

TABLE IV: Marker-configuration sensitivity on Insta360 X5: APE RMSE (m) / time completion.

Route	Analemma	Circular	Zigzag	Bookshelf 01	Bookshelf 02	Box 01	Pick-and- place 04	Pick-and- place 05	Pick-and- place 06	Wiping 01	Wiping 02
Body/waist motion	No	No	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes
Insight9 SDK VIO	0.097/1.00	0.015/1.00	0.014/1.00	0.034/1.00	0.063/1.00	0.565/1.00	0.019/1.00	0.025/1.00	0.023/1.00	0.201/1.00	0.029/1.00
PICO Controller	0.043/1.00	0.019/1.00	0.077/1.00	0.140/1.00	0.071/1.00	0.052/1.00	0.043/1.00	0.029/1.00	0.045/1.00	0.025/1.00	0.026/1.00
AprilVINS(full)	0.0049/1.00	0.0053/1.00	0.0059/1.00	0.0031/1.00	0.0076/1.00	0.0051/1.00	0.0044/1.00	0.0036/1.00	0.0028/1.00	0.0021/1.00	0.0033/1.00

TABLE V: Teaching-device trajectories: APE RMSE (m) / time completion.

Fig. 6: AprilVINS ablation visualizations. Left: local trajectory comparisons on four MILD tasks; dashed curves are executed TCP references and solid curves are estimates. Right: output-gate continuity check in the YZ plane; curves split at timestamp gaps larger than 0.15 s.

Fig. 7: 3D practical-route trajectory comparisons for three Table V tasks. Dashed curves are route-specific executed references; solid curves are estimates.

Fig. 8: Replay success versus translational APE–RMSE on six MILD-Sim tasks. Dashed lines mark the zero-noise baseline and the first bin at or below 50% success; error bars show Wilson 95% confidence intervals.

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