BioModule
Pose-to-Biomechanics: Bridging 3D Human Pose Estimation and Biomechanical Attribute

Abstract
Predicting 17 Biomechanical Criteria from 3D Skeleton
We present BioModule V3, a lightweight transformer that predicts 17 biomechanical criteria per frame — including ground reaction forces, joint coordinates, torques, muscle activations, and neural excitations — directly from a 27-frame sliding window of 3D skeletal pose. The model is pre-trained on ground-truth (GT) pose inputs (GT Frozen) and then fine-tuned on top of seven state-of-the-art 3D pose estimators without updating their weights. Evaluated on Human 3.6M+ Subject 9 (Walking), BioModule V3 achieves low per-joint prediction error across all criteria while generalising across diverse pose estimator backbones. The per-joint architecture exposes spatially-resolved criterion timeseries, enabling downstream biomechanical analysis at the level of individual body segments.
3.8M
Transformer Parameters
17
Biomechanical Criteria
27
Frame Context Window
7
Fine-Tuned Backbones
68
Muscles / DOF Tracked

Method
Two-Stage Frozen Fine-Tuning
3D Pose Estimator
MHFormer / D3DP / etc.
FROZEN
27-Frame Window
17 joints × 3D coords
BioModule V3
Transformer Encoder
FINE-TUNED
17 Criteria / frame
per-joint + body-wide
The pose estimator weights are never updated. Only BioModule V3 learns to map estimated 3D poses to biomechanical outputs.

Sliding Window Encoder

A 4-layer transformer processes 27 consecutive frames of 17-joint 3D poses, capturing temporal dynamics without recurrence.

Per-Joint Head

Separate projection heads produce per-joint criterion timeseries aligned to OpenSim DOF mappings, enabling spatially-resolved analysis.

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Biomechanical Criteria

Ground reaction forces, generalised coordinates, torques (active / passive / ideal), joint power, muscle activation, neural excitation, and contact probabilities.

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Backbone-Agnostic

Fine-tuned independently on 7 frozen pose estimators. BioModule V3 generalises across MHFormer, TCPFormer, PoseMamba, D3DP, and more.


Results
Evaluation on H3.6M+ S9 Walking

MAE per criterion, averaged across all evaluation frames. Lower is better. Best per-column in green.

Model Seat GRF GRF Right GRF Left Coord RMS Speed RMS Accel RMS Act. Torque Pass. Torque Activation Excitation
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