4.6 - Conclusions and Future Work

1. Conclusions

This project designed and built a single-finger exoskeleton prototype. The design used four-bar linkages to help the finger bend at the MCP, PIP, and DIP joints. The MCP and PIP joints were powered, while the DIP joint moved with the fingertip.

The analysis showed how the motors moved the linkages and helped the finger curl. It also showed that the design could reach the needed range of motion.

The prototype was made with 3D-printed parts. It showed that the linkage system could create a curved bending motion that was more natural than a simple hinge.

Testing the final prototype showed that the biggest problem was the actuation system. The motors were not strong enough to pull the bicycle wires and move the mechanism consistently. Because of this, some parts had to be moved by hand by turning the gears. Even with this problem, the final design showed that the linkage idea worked.

Overall, the project showed that a linkage-based finger exoskeleton can help guide finger bending. The prototype was a good starting point and showed what needs to be improved in future designs.

2. Lessons Learned

One lesson learned was that the actuation system is very important. The linkage made the finger-curling motion, but testing showed that the motors and cable tension affected how well it worked. This helped the team understand that future versions need stronger motors and better cable tension control to ensure a more reliable way to transfer motion from the motors to the linkage.

The team also learned that moving the motion from the motors to the linkage is important. The bicycle wires worked, but they were hard to control because the tension had to be precise. Loose wires did not move the linkage enough, while tight wires made the motors work harder and added stress to the parts.

The wires also caused reliability issues. They could stretch, slip, or shift during testing, making the motion less consistent. Friction from guides and bends also made the system harder to control.

One improvement is to place the motors closer to the linkage. This would shorten the wires and make motion transfer more direct, but it could add weight and take up space near the fingers.

Another option is a direct gear system. This would make motion transfer more reliable because the motor would drive the linkage directly. However, it would need accurate gear alignment and could make the design more complex.

Testing the real prototype was important. The CAD model and initial prototype showed that the design might work, but the real test showed problems with the motors and cables.

3. Future Work

Future work could focus on making the mechanism move smoother and more reliably. This could be done by using stronger motors, such as metal gear motors, higher-ratio gear motors, or servo motors. The motion system could also be improved by replacing the bicycle wires with a simpler setup, like placing the motors closer to the linkage or connecting them directly to the mechanism. This would make the motion easier to control. Future versions could also include sensors to improve safety and accuracy. Comfort could be improved by using softer pads and adjustable mounting points.

4. Tips for Future Groups

Choose motors early and make sure they are strong enough to move the whole mechanism.

Test the motors and wires before building the full prototype.

Be careful with bicycle wires. They need the right tension. Too much slack limits movement, but too much tension makes the system hard to move.

Build and test early because CAD does not show every real-world issue.

Leave enough space around joints and moving parts so they do not rub or get stuck.

Keep the first prototype simple, but make sure the actuation system works well in later prototypes.

5. Acknowledgements

We would like to thank Dr. Symmank for her guidance and support throughout this project. She helped us improve the mechanism concept, refine the final prototype, and explore other design ideas. We would also like to thank the teaching staff for their feedback during the design, analysis, and testing process, and for helping us get some of the parts needed for the final build.