A Sensorised Lattice Footplate for a Semi-Active Prosthetic Foot

2026-06-24

AI Summary

This study addresses the challenge of integrating plantar force sensing and structural load-bearing capabilities in low-cost semi-active prosthetic feet. The authors propose a novel approach that embeds magnetic inductive sensors directly into a 3D-printed lattice-based load-bearing footplate, enabling real-time estimation of plantar pressure distribution without requiring external insoles. By combining these embedded sensors with a servo-controlled hydraulic damper and a simplified ankle dynamics model, the system implements an internal-sensing-based feedforward damping modulation strategy. Experimental results demonstrate that the prosthesis accurately tracks external forces, distinguishes forefoot and hindfoot loading, and effectively emulates normative ankle dorsiflexion behavior through tunable damping, thereby validating the feasibility and innovation of embedding perception within a semi-active control framework for prosthetic feet.

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.

Problem

• prosthetic foot
• plantar sensing
• semi-active damping
• load-bearing compliant element
• embedded sensor

Innovation

• embedded sensing
• semi-active prosthetic foot
• 3D-printed lattice
• hydraulic damper
• plantar force estimation