Promotheus: design and development of a fully 3d printed shoe insole for measurements of 3d ground reaction forces during jumping trials
Luca Grignaffini (ET-BRT), Dr. Jasper Reenalda (BSS), Judith olde Heuvel (OCON Orthopedische kliniek), Dr. Ali Sadeghi (ET-BRT).
Abstract
Anterior cruciate ligament (ACL) rupture is a prevalent sports injury with a long and demanding postoperative recovery process, which can last for more than a year in severe cases. In recent decades, human movement analysis is being integrated more frequently as part of the rehabilitation program, aiding to assess, for instance, whether a patient has successfully recovered from the injury.
A pivotal step of the latter discipline resides in the evaluation of Ground Reaction Forces (GRFs), which is usually done with expensive force sensors that are usually fixed to the ground in a laboratory environment.
In this project, we designed and developed a novel low-cost, soft fully 3D printed sensorized shoe insole, which it is completely made with low-cost materials, with the aim to directly predict 3D GRFs in subjects performing standardized jumping trials that are commonly performed by patients recovering from ACL rupture.
After testing the insole on ten different healthy subjects performing the Hop Test Cluster by Gustavsson over fixed force plates, we performed its calibration using system identification. Through this method we were able to create three different generalized dynamic models (one of each force component) that are able to directly predict 3D GRFs with relatively low errors (average RMS errors ranging from 7-10% across all subjects).
We believe that the proposed prototype offers a valid low-cost alternative for the direct measurement of GRFs not only for patients performing jumping tests, but also for other activities such as walking and running in a wider variety of environments.