9.7 - Conclusions & Future Work
Ultimately, when it comes to our project, we did achieve what we set out to do. We created a mechanism that generates pseudo-random motion using a complex linkage mechanism and a single input actuator. In the end, if our mechanism is run at its intended speed of one revolution per 10 seconds of the input gear, the cycle time of the output manipulator would be around 4.8 hours. We estimate that this is more than enough time for the user to either return to their workstation or for the AI detection algorithm to write off the repetition as insignificant. This does not, however, mean that our design is perfect. There are many steps we would pursue to take our design to the next level. These include sizing down our mechanism, as right now its profile is around a square foot, as shown in Figure 1. For any average consumer, that would be far too much desk real estate to dedicate to our product. We do believe that the design could be scaled down relatively easily; however, for the purposes of this project, we wanted the components to be large enough to be both easy to manufacture and observe while in motion.
Another aspect that has definite room for improvement is the manner in which the device mounts to a desk. Right now, the 3D printed feet shown in Figure 2 act as the point of contact between the mechanism and the surface it sits on. They provide more than enough stability when the device is static; however, when it is turned on, it provides very little resistance to the inertia of the mouse/linkages. This leads to the product sliding around on the desk. For our demonstration, we prevented this by adding a small amount of double-sided tape to the bottoms of each of the feet, but in a completed product, we could add some kind of suction mechanism or a more reliable adhesive.
The final point of improvement has to do with the spacers. In the current model, the 3D printed axle spacers are adhered to the threaded rods with two-part epoxy and then slot into the acrylic gears/linkages with hexagonal geometry, as shown in Figure 3. So the basic chain of power transmission is as follows: the axle is turned by the motor, the spacers, which are adhered to the axles, rotate with them, and then the links/gears rotate because they are locked in place with the spacers. The problem we ran into with this plan is that the adhesive was very unreliable. It had very long cure times, sheared off very easily, and was very hard to maintain a solid connection. This led to linkages slipping and not rotating as intended. Arguably, this isn’t a huge issue, as it simply makes the motion of the end manipulator more unpredictable, which is of course our goal. However, for the sake of consistency, we would like to have a design that has solid connections throughout that work as intended. Despite this issue having led to the majority of our complications, it also has the easiest fix. If we swapped out the spacers for flanged collars and used those to fasten the various components to the axles, we would have very little issues when it comes to stability. The reason we didn’t do this in the first place is simply that we were trying to minimize costs and were having trouble sourcing some of our materials. This is, however, one of the first changes we would make if we were to recreate this project.
Overall, we are very satisfied with how our project came together. We would like to specifically acknowledge Dr. Symmank, both for her excellent teaching of the curriculum and organization of the project. Additionally, we would like to acknowledge both Connor Hennig and Mila Wetz, the two teaching assistants for this course, who were instrumental in helping us hone in on a final design. Finally, we would like to acknowledge Texas Invention Works and its staff for allowing us to use both their tools and facilities to work on this project.