A unique, robust, robotic transtibial prosthesis with regenerative kinetics was successfully built and a 6-month human subject trial was conducted on one male below-the-knee amputee under linear walking conditions. This paper presents the quasistatic system modeling, DC motor and transmission modeling and analyses, design methodology; and model verification. It also outlines an approach to the design and development of a robotic transtibial prosthesis. The test data will show that the true power and energy requirement predicted in the modeling and analyses is in good agreement with the measured data, verifying that the approach satisfactorily captures the physical system. The modeling and analyses in this paper describes a process to determine an optimal combination of motors, springs, gearboxes, and rotary to linear transmissions to significantly minimize the power and energy consumption. This kinetic minimization, allows the down-sizing of the actuation system and the battery required for daily use to a self-portable level. [DOT: 10.1115/1.4001139]

Purpose The purpose of this paper is to describe a project which seeks to develop a new generation of powered prostheses based on lightweight, uniquely tuned, energy‐storing elastic elements in series with optimal actuator systems that will significantly reduce the peak power requirement of the motor and the total system energy requirement while providing the amputee 100 percent of required “push‐off” power and ankle sagittal plane range‐of‐motion comparable to able‐bodied gait. Design/methodology/approach This paper presents the design, power, and energy‐efficiency analyses, and the results of a five‐month trial with one trans‐tibial amputee subject as part of the first phase of the Spring Ankle with Regenerative Kinetics project. Findings The data show that by leveraging uniquely tuned springs and transmission mechanisms, motor power is easily amplified more than four fold and the electric energy requirement is cut in half compared with traditional approaches. Originality/value This paper describes an energy efficient, powered transtibial prosthesis currently unavailable commercially. Motor power and energy requirements are reduced with use of a unique design that employs regenerative kinetics.

The design process of a powered robotic ankle prosthesis presents many obstacles that must be overcome. To be practically implemented, such a mechanism must not only run on batteries, but sustain a long running time between recharging. Using springs to passively and actively store and supply energy to the robotic ankle, small DC motors can be optimized to perform high peak power tasks without sacrificing efficiency and net energy usage. Additional techniques are explored with the potential of substantially reducing the energy requirements as well as the size and weight of the prosthesis. The benefits of adding a unidirectional parallel spring with a Robotic Tendon are weighed and the possibility of actively varying the lever arm at which the spring force is applied is analyzed. The different actuation methods are compared to determine which methods work best in different gait regimes.

The goal of modern prosthetics is to replicate the function of the replaced limb or organ in the most capable and discreet fashion possible. However, even the most advanced, commercial, transtibial prostheses available today only passively adjust the position of the ankle during the swing phase of gait and return a portion of the userpsilas own gravitational input. To greatly improve the quality of life of a transtibial amputee, new technologies and approaches must be used to create a cutting-edge robotic ankle prosthesis which can perform on par with, if not outperform, the equivalent able-bodied human ankle. Initial attempts by us and others have had great success in providing the natural gait power and motion through all ranges of walking speeds. A new design is presented which governs both the coronal and sagittal angles and moments of the ankle joint to potentially provide unprecedented levels of athleticism and agility among transtibial amputees.