Welcome to our final update on the evolution of our mechanical design journey. In this post, we'll explore the refinements made to our device, from addressing challenges with the Peltier to enhancing the battery holder, implementing a protective cover, and improving overall integration.
Peltier
One of the significant challenges we encountered in our exploration was the inefficiency of Peltier devices in converting electrical power into thermal energy. The imbalance between heat generation and cooling capability posed limitations on prolonged usage. To address this, we strategically employed momentary activation of the Peltier to invoke a thermal sensation for the user, allowing us to mitigate overheating issues.
In the pursuit of improved efficiency, efforts were made to enhance the cooling capacity of the Peltier by exposing it to more airflow. Subsequent revisions incorporated design adjustments to facilitate better air circulation, thereby enabling faster cooling and increasing the frequency of Peltier activation.
Taking our efforts further, we invested in a heat sink designed to expedite the cooling process of the Peltier. This investment not only amplified the frequency of Peltier operation but also augmented the thermal capacity of the assembly. Through rigorous testing, we discovered that the heat sink not only bolstered cooling efficiency but also extended the operational period before the Peltier reached its thermal limits, enabling us to achieve a broader temperature range. The figures below show the full assembly and the remaining images showcase the older revisions in descending order.
Batter Holder
Minimal alterations were made to the latest iteration of the battery holder. The primary focus was on enhancing the fit between the battery and the holder, striking a balance between sufficient friction and ease of removal. Additionally, wall thicknesses were reduced where possible to reduce weight and cost while allowing for more deflection for easier battery insertion. Furthermore, widening the surface for mounting the holder ensured compatibility with M3 heat inserts.
Cover
A protective feature was implemented for the electronics to shield them from environmental factors and reduce the risk of accidental damage to the board. To accomplish this, a detailed model of the perfboards was created first, encompassing all electronic components. This step was crucial in ensuring there were no interferences between the cover and the rest of the assembly. The images below are the recreations of both the main perfboard and the side perfboard including all their components at their exact locations on the perfboard.
Several constraints guided the design of this cover. Primarily, it needed to be easily removable to access the reset and reboot buttons on the ESP32, essential for debugging and troubleshooting purposes. Consequently, a sliding feature with a transitional fit between the perfboard and the battery holder was created. This design ensured that the cover remained stable during user interactions with virtual objects but could be intentionally moved when necessary. Additionally, we added a chamfer to one side of the cover for easier insertion and rounded the remaining edges to minimize the risk of sharp edges. The images below show the cover within and without the assembly.
The images below are the 3D printed results of the first iteration. To achive a better fit between the cover, perfboard, and Battery mount modifications were made to the cover and printed agian for the final revision.
Integration
Throughout the design process, inclusivity and accessibility were fundamental guiding principles. Numerous Velcro straps were incorporated, allowing for easy adjustment to accommodate users of varying sizes. Dependencies between different components, such as the glove, Peltier, and battery assemblies, were minimized, enabling users to wear or remove them in any order according to their preference.
After conducting thorough testing, a significant opportunity to enhance accessibility was discovered. It was found feasible to relocate the entire main assembly between the shoulder and elbow without impacting any of the device's functionalities. This simple adjustment only required a longer cable between the glove and the main assembly.
This design choice was rooted in accessibility, aiming to reduce the strain on users' shoulders and alleviate fatigue during prolonged use. By redistributing the device's weight, users can engage in exercises for extended periods with reduced discomfort. The images below depict the second revision of the device in both possible positions compared to the first revision.
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