Cross-validation of a portable, six-degree-of-freedom load cell for use in lower-limb prosthetics research

Sara R. Koehler*, Yasin Y. Dhaher, Andrew H. Hansen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


The iPecsTM load cell is a lightweight, six-degree-of-freedom force transducer designed to fit easily into an endoskeletal prosthesis via a universal mounting interface. Unlike earlier tethered systems, it is capable of wireless data transmission and on-board memory storage, which facilitate its use in both clinical and real-world settings. To date, however, the validity of the iPecsTM load cell has not been rigorously established, particularly for loading conditions that represent typical prosthesis use. The aim of this study was to assess the accuracy of an iPecsTM load cell during in situ human subject testing by cross-validating its force and moment measurements with those of a typical gait analysis laboratory. Specifically, the gait mechanics of a single person with transtibial amputation were simultaneously measured using an iPecsTM load cell, multiple floor-mounted force platforms, and a three-dimensional motion capture system. Overall, the forces and moments measured by the iPecsTM were highly correlated with those measured by the gait analysis laboratory (r>0.86) and RMSEs were less than 3.4% and 5.2% full scale output across all force and moment channels, respectively. Despite this favorable comparison, however, the results of a sensitivity analysis suggest that care should be taken to accurately identify the axes and instrumentation center of the load cell in situations where iPecsTM data will be interpreted in a coordinate system other than its own (e.g., inverse dynamics analysis).

Original languageEnglish (US)
Pages (from-to)1542-1547
Number of pages6
JournalJournal of Biomechanics
Issue number6
StatePublished - Apr 11 2014


  • Amputation
  • Force transducer
  • Gait analysis
  • Load cell
  • Prosthesis

ASJC Scopus subject areas

  • Biophysics
  • Rehabilitation
  • Biomedical Engineering
  • Orthopedics and Sports Medicine


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