Design and Development of a Reconfigurable and Adjustable Compliance System for the Measurement of Orthotic Properties

Custom foot orthoses (CFOs) are effective in the prevention and treatment of lower extremity injuries (LEIs). However, the current design methodologies of CFOs are not efficient due to the limited consideration of soft tissue impedance, orthotic properties and subjective feedback during the measurement. A new design methodology of CFOs is required to determine the desired orthotic properties including geometry and impedance, which satisfy pressure/load distribution, subjective comfort and reduce iterations. A measurement device which provides an Interface with Tunable Ergonomic properties using a Reconfigurable Framework with Adjustable Compliant Elements (INTERFACE) is developed. The INTERFACE system provides locally adjustable geometry and stiffness for the support of Medial Longitudinal Arch (MLA) by applying a mechanism with six degrees of freedom and three Tunable Stiffness Mechanisms (TSMs). Therefore, the Rapid Evaluate and Adjust Device (READ) Methodology can be implemented by adjusting the interface properties based on the pressure/load and subjective evaluation. The prototype of the INTERFACE system was fabricated to conduct the validation test on 10 subjects, in which the interface pressure/load distribution and subjective feedback in different combinations of geometry and stiffness were recorded. The plantar pressure/load increased with stiffness and geometrical height, and the significance has been demonstrated by a correlation analysis. Subjective comfort can be achieved with different combinations of geometry and stiffness. The proposed INTERFACE system can be employed to conduct the plantar measurement to obtain the desired orthotic properties which satisfy objective and subjective requirements.