Instrumented Ankle–Foot Orthosis: Toward a Clinical Assessment Tool for Patient-Specific Optimization of Orthotic Ankle Stiffness

In this paper, we detail the design and operation of the instrumented ankle–foot orthosis ( i AFO), a clinical assessment tool that can be used to quantify the functional consequences of selectively modifying orthotic ankle joint stiffness, particularly for individuals with locomotor deficits such as foot drop. We discuss the sensing capabilities of the system, which include ankle joint kinematics and kinetics, electromyography, and orthosis interface pressures. We further describe the mechanical design of the device, which allows for user-defined manipulation of orthotic stiffness through an interchangeable extension spring mechanism. Finally, we demonstrate a validation of the i AFO's capabilities by presenting results both of benchtop testing and of a preliminary human-subject study. Future work will include in-depth signal analyses of gait parameters and algorithmic development for patient-specific orthosis optimization.