Hardware-in-the-Loop Test of a Prosthetic Foot

Abstract

For a targeted development process of foot prostheses, a profound understanding of the dynamic interaction between humans and prostheses is necessary. In engineering, an often employed method to investigate the dynamics of mechanical systems is Hardware-in-the-Loop (HiL). This study conducted a fundamental investigation of whether HiL could be an applicable method to study the dynamics of an amputee wearing a prosthesis. For this purpose, a suitable HiL setup is presented and the first-ever HiL test of a prosthetic foot performed. In this setup, the prosthetic foot was tested on the test bench and coupled in real-time to a cosimulation of the amputee. The amputee was modeled based on the Virtual Pivot Point (VPP) model, and one stride was performed. The Center of Mass (CoM) trajectory, the Ground Reaction Forces (GRFs), and the hip torque were qualitatively analyzed. The results revealed that the basic gait characteristics of the VPP model can be replicated in the HiL test. Still, there were several limitations in the presented HiL setup, such as the limited actuator performance. The results implied that HiL may be a suitable method for testing foot prostheses. Future work will therefore investigate whether changes in the gait pattern can be observed by using different foot prostheses in the HiL test.

Keywords

• hardware-in-the-loop
• prosthetic feet
• prostheses testing
• virtual pivot point model
• real-time hybrid substructuring
• real-time hybrid simulation