The project enabled the group to learn various lessons about design theory and practicality. Based on these experiences, the following conclusions are the most prominent:
1) Pay attention to the proper use of fasteners: The group was successful in implementing retaining rings on the Design I and Design II prototype. The pin joints connecting most of the links of the four bar linkage was fixed in place with these rings. However, the fact that these mechanical components were designed to rest in a groove on the pin was ignored. Without a groove, it was very difficult to assemble the joints of our four bar linkage since the ring had to be bent to accommodate a slightly larger diameter. The retaining ring functioned well once in place, but the appropriate groove would need to be added if the product was to be mass produced for ease of assembly.
2) Identify Manufacturing Limitations: The group initially faced problems with quality of 3D-printed parts. Holes were consistently undersized and the group found it necessary to perform a calibration print to determine proper offsets for hole sizes. Other calibrations were necessary to select an appropriate temperature, print-speed, and layer thickness. Once these machine settings were determined the team saved them and consistently used the same printer and the same spool of plastic to print parts. While calibration was a time consuming process, it was a necessary step for producing FDM printed parts with consistent, high quality features and finishes.
3) Understand Customer Needs and Check-In Frequently: An essential aspect of the product design process is frequently touching base with the needs of the target market. This is especially so when the designer does not have first hand experience in the shoes of his customers. Many significant design iterations were the result of feedback from our customer.
- The choice of input signal - Able bodied users have no dearth of methods to activate a device using various motions of their fingers to push buttons, turn dials or move sliders. However, our customer had a very limited set of feasible movements that have sufficient fine motor control. Sharing the version 1 prototype with him allowed us to narrow down the thumb movement as the only feasible choice of input for a mechatronic system. The thumb had very little physical strength, but it was still capable of fine control.
- Methods of attachment - Attaching a strap or brace onto our own hands may seem like a trivial, everyday task, but for our target customer, any operation that requires him to grip or adjust a strap is rather difficult. Interacting with him and observing his methods of handling other objects allowed us to design a device that was actually usable by him. All our velcro bands are designed to have rings at their end for him to put his thumb through and pull. The movements to put the device on and off are also designed to be done with minimal finger control.
Minor feedback like this was what made it possible for him to see and put on the final prototype for the first time during our public demonstration and beat an able student at a tug of war with minimal adjustment to the product. (Yes, and there is a video of it too.)
In Conclusion, the group is happy to have demonstrated a working prototype that was able to perform its function with its intended user, and we hope that, with minor adjustments, it will be possible to use it for solo sailing. A huge shoutout to Mr. Paul Horton for being an inspiration, a great customer and an absolute pleasure to work with! We also thank Dr. Deshpande and Taylor for the support and direction given, and we thank the rest of our class for the fun demonstrations and other cool products that we were able to see.
