ISBN 978-3-8439-5761-8

978-3-8439-5761-8, Reihe Produktentwicklung

Johanna Baier
Development of a Digital Twin Couple for the Simulation of Individual Muscle Activations

159 Seiten, Dissertation Ruhr-Universität Bochum (2025), Softcover, A5

Zusammenfassung / Abstract

Functional Electrical Stimulation (FES) is an established technology for supporting motor rehabilitation following neurological injuries. Despite extensive research, the stimulation of physiologic hand movements remains challenging due to the anatomical complexity of the forearm, where numerous small muscles are layered intricately. Current technologies have not yet succeeded in providing an everyday-use system that enables selective muscle activation in the forearm with high reliability and minimal additional effort for patients. In biomedical engineering, the concept of digital twin couples consisting of a product digital twin and a human digital twin applies.

The objective of this study is to introduce a novel modeling method to design digital twin couples of a FES setup at the forearm. Unlike existing models, the presented model must allow for analysis and evaluation of individual muscle activations rather than general activation volumes.

The human digital twin consists of an anatomically based 3D volume conductor, a nerve fiber arrangement in muscle-specific Regions of Interest, and a standard nerve model. The product digital twin covers the stimulation setup. Simulated strength-duration diagrams generated with the new setup show good agreement with experimentally measured curves and were used to determine muscle-specific activation thresholds. Applying these thresholds to the simulated activation results enabled the model to accurately predict muscle activation, and the strength-amplitude diagrams also show good agreement with experimental data.

The method was applied to a second test subject. The experimental evaluation shows comparable results, confirming the robustness of the method. The initial model was also applied in a brief case study to design a small electrode array.

The digital twin couple shows strong potential for accurately predicting real muscle activations and appears well suited for creating multiple person-specific couples.