Digital Prototyping of a Microprocessor Controlled Active Knee Prosthesis

The human knee plays a crucial role in gait. Because of that, the biomechanics of transfemoral amputees is severely affected due to lower-limb loss. In the past few years, many researchers sought to develop transfemoral prostheses capable of reproducing the performance of a healthy knee to rehabilitate those amputees. That implicates the design of powered or active prostheses instead of passive or semiactive ones. This paper approaches the design, digital prototyping, and dynamic modeling of an active knee prosthesis that is affordable, lightweight, easier to control, and capable of replicating the knee movement during walking. Digital prototyping is an efficient way to build and develop new products before manufacturing. The prosthesis' powertrain is composed of a 200 W EC motor in series with a harmonic drive that is driven by an embedded microcontroller. The digital prototype was created to facilitate the design, visualization, and detailing of the technical drawings. The dynamic modeling of mechanical and electrical systems consider the prototype parameters such as inertia, mass, damping, and electrical characteristics of the motor. Results showed great performance of the system in reproducing the movement of the knee during a gait cycle.