16.6: Conclusion and Reflection

Conclusion

The goal of our project was to build a low-cost near 1:1 scale compliant humanoid hand with realistic joint motion and single motor actuation. Our final deliverable was able to meet all of our requirements, though we still have many ideas for future improvements.

Lessons Learned

While the hand could successfully grasp items, the low friction of the plastic fingers led to many items slipping, the simple addition of friction material on the palm and fingertips would tremendously increase the ability of the hand to hold items. Another area of improvement is in the spring stiction, currently, the hand has problems with fully opening and closing. This is due to longitudinal forces that the springs can produce from side-to-side movement in their mounts. This can be fixed with springs better designed for this application and tighter tolerances for the spring mounts. Another solution would be a solution that can be better constrained such as a soft material or pneumatic pistons. Through our tests, we found that 3D-printed plastic parts were not the optimal solution for the fingers given the loose tolerances and being relatively soft. Using metal parts would improve the quality and durability of the hand dramatically. 

Advice for Future Groups

If any group would like to continue our design:

A possible experiment for future groups to experiment with would be the addition of force feedback sensors inside the hand that use mechanical advantage analysis to accurately predict the force applied and the fingertips.

Advice:

• Start the project early on. Procrastinating the design phase of the project could prove detrimental to the overall project progress since it will delay everything from manufacturing to testing.
• Sometimes it's your design. Make sure your design accounts for any unforeseeable variables. If the prototype does not work as well as the design does in CAD, there might need to be changes made to the CAD because simulation does not account for all the factors in the real world.
• Team communication is very important!
• Go the extra mile and structure your design around the goal of ultimately becoming a marketable product that people would want to purchase.
  • Design your mechanism to be compact and integrated. Even for a modular system, create an integrated system of parts. Although it is not easy, it will greatly improve the appearance, usability, mechanical properties, and functionality.
  • Embed tolerances into your CAD.
  • Account for manufacturing accuracies
    • This will save a lot of time from re-manufacturing the parts that do not fit.
• Enjoy creating!

Acknowledgments

We would like to thank our TAs Conner and Aayush for their help throughout the course, and the TIW team for their help and use of their space in the mornings. Finally, we’d like to thank Dr. Symmank for her valuable instruction and mentorship.