Inspired by work of Montagnani et al. (2015), who found that for prosthetic hands a complex wrist mechanism worked functionally equal to a multi-DOF hand mechanism, new work has been set in motion to extrapolate and test this hypothesis. The goal of this work consisted of building a multi-DOF wrist mechanism, while it was crucial to keep the mechanism small, light, and efficient. A study preliminary to this work has found a single, synergetic relational "path" between all degree of freedom of the human wrist, thereby proving a three dimensional, functional output of orientation by a theoretical mechanism, driven by a single input. This work seeks to design such mechanism, capable of following the proven synergy while remaining small, able, and effective.
Starting from scratch, several theoretical mechanism are tested on their ability to create general, non-linear translations. Some of these theories are worked-out into concepts after which a selection is made of the most promising. Further developing these concepts into adequate designs, a set of prototypes, digital and physical, have been used to prove their competence in re-producing the path as found by the preliminary study. Finally, after a fusion of two designs, a final design is developed to a state-of-production. Though the production of a prototype was scheduled, it was not accomplished within the period of this work.
This reports finishes with a final design proven theoretically to be successful in re-creating the theoretical synergetic path through a set of compound mechanics. The mechanism thereby proves the mechanical feasibility of the theoretical synergetic path. Though at a greater cost of size and weight, the mechanism is fully able to function as a prosthetic wrist mechanism as required by two individual partner projects. Due the lack of a physical prototype of this final design, testing and result-checks have been limited to a theoretical and digital environment.
In the discussion, several options of improvements are given, as well as speculations on a parallel, alternative design course for future work. After outlining a set of important decisions made in this design, an alternative set of decisions is mentioned which are hypothesized to work without some of the sacrifices needed in this design, predominately the volume. Whether this alternative design proves successful, if at all feasible, remains to be attempted. Whether the wrist mechanism has benefited from the synergetic approach remains unanswered as well. Due the lack of physical testing several questions around functionality cannot yet be concluded. After the acknowledgement of this design's drawbacks, and the hypothesis of an improved alternative, no statements on the mechanical benefits of the synergetic approach have been made either. After the mechanism succeeds in proving that the theoretical synergetic relation is physically achievable, it is stated that such (alternative) mechanism without the mentioned drawbacks would, in a mechanical sense, be outstanding.