Development of a functional and low-complexity robotic hand

Abstract

The loss of an upper limb significantly impacts an individual's life, directly affecting their ability to perform activities of daily living. Prosthetic devices play a crucial role in aiding amputees' rehabilitation in society, primarily driven by advancements in externally powered prostheses. Although prosthetic devices on the market offer excellent functionality, they come with a high price tag and use complex control algorithms.
Over recent years, a noticeable shift towards simplifying prosthetic devices has emerged, often facilitated by soft robotic principles. For example, the adaptive synergy approach has led to devices that are highly adaptable to their environment with a reduced degree of actuation (DoA), thereby improving functionality at low complexity. This thesis explores a novel research direction by combining the concept of adaptive synergy actuation with additional, parallel actuation of individual fingers. The main goal of this research is to assess the viability of using such a parallel adaptive synergy actuation structure for prosthetic hands. We designed a prototype incorporating this actuation structure, with the main design goals of high functionality, low complexity, robustness, and anthropomorphic sizing. The hand, which features a tendon-driven design, has 15 joints, including 14 dislocatable joints and one revolute hinge joint. The entire hand is powered by a single primary actuator, with two smaller additional motors operating in parallel on the index and thumb. We empirically validated the prototype's performance through qualitative experiments, and its performance was compared to that of other prosthetic devices available on the market through quantitative analysis. Evaluation of the prototype revealed promising results, such as its ability to adaptively grasp various functional objects and execute complex tasks. Force measurements revealed performance comparable to devices on the market. The results indicate that this novel actuation principle, with future refinement, is an interesting new approach to increasing functionality with minimal increase in complexity and can offer an excellent alternative to costly prosthetic devices currently on the market, thereby enhancing the accessibility of functional prosthetic devices for individuals with upper limb loss and improving their quality of life.