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arxiv: 2606.25966 · v1 · pith:T6V7ZOUGnew · submitted 2026-06-24 · 💻 cs.RO

A Sensorised Lattice Footplate for a Semi-Active Prosthetic Foot

Jinze Ge , Jingcheng Sun , Chengxu Zhou This is my paper

Pith reviewed 2026-06-25 20:25 UTC · model grok-4.3

classification 💻 cs.RO
keywords prosthetic footlattice structuremagnetic sensingsemi-active dampingplantar force3D printinghydraulic damper
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The pith

Magnetic plantar sensing can be embedded inside the load-bearing lattice of a semi-active prosthetic foot to estimate forces and control damping.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper tests whether magnetic sensors can be placed directly within the compliant footplate of a prosthetic rather than added as a separate layer. The authors built a prototype using a 3D-printed lattice structure with embedded magnets, paired with an adjustable hydraulic damper. Experiments confirm the lattice stiffness can be tuned, the sensors track applied forces accurately, and different stance postures produce distinct loading patterns. A simple control schedule using the sensor data approximates natural ankle motion during early stance. The work shows that integrated sensing inside the structure itself is feasible for driving semi-active adjustments.

Core claim

The paper demonstrates that a sensorised lattice footplate allows magnetic plantar sensing to be integrated into the load-bearing element of a low-cost semi-active prosthetic foot. Combined with a servo-controlled hydraulic damper and a reduced-order ankle model, the system supports force estimation and damping adjustment. Tests show the embedded sensors match reference forces during cyclic loading and distinguish forefoot versus rearfoot loading in static postures. A feedforward schedule based on the sensing approximates dorsiflexion in early-to-mid stance, highlighting the limit of dissipative-only mechanisms for push-off.

What carries the argument

The sensorised 3D-printed lattice footplate embedding magnetic sensing for plantar force estimation within the compliant structure.

If this is right

  • The lattice stiffness is tunable through its design parameters.
  • Embedded sensors can estimate plantar force without an external insole.
  • Forefoot and rearfoot loading can be separated based on sensor readings in different stances.
  • Damping adjustment can follow a schedule to match reference ankle dorsiflexion trends in early stance.
  • Purely dissipative damping cannot produce active push-off.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • This integration might simplify prosthetic manufacturing by eliminating separate sensor components.
  • Future designs could use the same lattice for both compliance and sensing in other wearable devices.
  • Dynamic gait testing would be needed to confirm performance beyond static and cyclic lab conditions.

Load-bearing premise

The controlled compression, cyclic loading, and static-posture trials under body-weight loading provide a sufficient preliminary check that the embedded sensing pipeline will function during dynamic gait in actual use.

What would settle it

Observing whether the embedded sensors maintain accurate force tracking and allow effective damping control during actual walking trials on a treadmill or overground, compared to reference measurements from force plates.

Figures

Figures reproduced from arXiv: 2606.25966 by Chengxu Zhou, Jingcheng Sun, Jinze Ge.

Figure 1
Figure 1. Figure 1: Overview of the proposed semi-active prosthetic foot. [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Embedded plantar sensing module. (a) Assembly of [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Reduced-order dynamic model of the articulated [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Prototype sensing and control platform. (a) Experi [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 6
Figure 6. Figure 6: Results for Experiment 2: prototype evaluation under [PITH_FULL_IMAGE:figures/full_fig_p005_6.png] view at source ↗
read the original abstract

This paper investigates whether magnetic plantar sensing can be embedded directly inside the load-bearing compliant element of a low-cost semi-active prosthetic foot. We present a prototype integrating a sensorised 3D-printed lattice footplate, a servo-adjustable hydraulic damper, and a reduced-order ankle model. The damper is experimentally characterised to relate adjustment angle to damping coefficient. Controlled compression tests show tunable lattice stiffness, while cyclic normal loading shows that the embedded sensor tracks the testing-machine reference force, supporting plantar-force estimation without an external insole layer. Static-posture trials under approximately body-weight loading show that forefoot and rearfoot loading distributions are separable across four prescribed stance configurations, providing a preliminary check of the sensing pipeline. A feedforward damping schedule approximates the dorsiflexion trend of a reference ankle trajectory through early-to-mid stance, while exposing the expected limitation that a purely dissipative mechanism cannot generate active push-off. Together, these results demonstrate that sensing can be embedded inside the load-bearing compliant element of a prosthetic foot and used to drive semi-active damping.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 1 minor

Summary. The manuscript describes the design and preliminary experimental evaluation of a semi-active prosthetic foot featuring an embedded magnetic sensor in a 3D-printed lattice footplate, paired with a servo-controlled hydraulic damper. Key experiments include damper characterization relating angle to damping coefficient, lattice compression tests showing tunable stiffness, cyclic normal loading where the sensor tracks reference force, static-posture trials under body-weight loading demonstrating separable forefoot/rearfoot distributions across four configurations, and a feedforward damping schedule approximating early-stance dorsiflexion. The central claim is that these results demonstrate sensing can be embedded inside the load-bearing compliant element and used to drive semi-active damping.

Significance. If validated, the integration of sensing directly into the load-bearing lattice structure could advance low-cost semi-active prosthetics by removing the need for external sensor layers while enabling force-based control. The component-level characterizations provide a useful starting point for tunable compliance and plantar-force estimation, though the decoupled nature of the sensing and actuation results limits immediate applicability to dynamic gait.

major comments (1)
  1. [Abstract] Abstract: The assertion that the results demonstrate sensing 'used to drive semi-active damping' is not supported by the experiments. Cyclic loading and static-posture trials establish sensor performance independently of the damper, while the damping schedule is applied via a separate feedforward schedule not derived from sensor data. No closed-loop experiment is described in which real-time plantar-force estimates from the embedded sensor modulate damper angle under load.
minor comments (1)
  1. [Abstract/Results] The manuscript would benefit from inclusion of quantitative metrics (e.g., RMSE or correlation coefficients for force tracking), error analysis, and fuller methods details to strengthen the evidence presented for the sensing pipeline.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their constructive feedback. We address the single major comment below and agree that the abstract requires clarification to avoid overstatement.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The assertion that the results demonstrate sensing 'used to drive semi-active damping' is not supported by the experiments. Cyclic loading and static-posture trials establish sensor performance independently of the damper, while the damping schedule is applied via a separate feedforward schedule not derived from sensor data. No closed-loop experiment is described in which real-time plantar-force estimates from the embedded sensor modulate damper angle under load.

    Authors: We agree that the presented experiments characterize the embedded sensor and the adjustable damper as independent subsystems. The cyclic loading and static-posture trials evaluate sensor performance without active damper modulation, and the feedforward damping schedule is applied open-loop rather than derived from real-time sensor estimates. No closed-loop test is reported. The manuscript's central claim is therefore better described as demonstrating the feasibility of embedding sensing within the load-bearing lattice and the separate controllability of damping, which together enable future sensor-driven semi-active control. We will revise the abstract (and the corresponding sentence in the conclusion) to state this distinction explicitly and remove the phrasing that implies direct use of sensor data to drive the damper in the reported experiments. revision: yes

Circularity Check

0 steps flagged

No circularity; claims rest on independent experimental measurements

full rationale

The paper describes a prototype and reports results from separate experimental characterizations (damper angle vs. damping coefficient, lattice compression stiffness, cyclic force tracking against reference load cell, and static posture force distribution separability). No mathematical derivation chain, fitted-parameter predictions, or self-citation load-bearing steps are present. The feedforward damping schedule is explicitly described as an approximation schedule, not derived from sensor data, and the sensing and actuation results remain decoupled as stated. All load-bearing claims are grounded in direct bench-test data rather than any reduction to prior fitted values or self-referential definitions.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review provides no explicit free parameters, axioms, or invented entities; work is experimental hardware demonstration without mathematical derivations or postulated entities.

pith-pipeline@v0.9.1-grok · 5711 in / 1166 out tokens · 31873 ms · 2026-06-25T20:25:32.403124+00:00 · methodology

discussion (0)

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Reference graph

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