19.6 - Conclusions & Future Work

Future Iterations and Lessons Learned

In all, our robot did successfully jump; however, it was not able to jump quite as high as we expected and we were not able to get it to jump entirely under its own weight.  From a simple energy balance, we estimated our mechanism to be able to jump 

where h is the jump height, m is the mass, κ is the spring constant and Δθ is the spring's deflection angle.  From a rough estimate, we found that our mechanism should jump ~30cm, however, we only realized ~5-10cm of jump height.  Some future iterations to improve upon would be to:

• Add more springs.  Adding more springs increases the potential energy storage during loading, increasing the jump height of the mechanism.  Moreover, because of the Δθ² term, the benefit of adding more springs is quadratic, not linear.
• Increase the spring stiffness.  A stiffer spring would increase the jump height of the mechanism.
• Change position of the cam.  With the current position of the cam, it sometimes locks and the motor stalls.  If the cam were placed in a different location, the motor may not stall out.
• Reconsider use of cam directly driven by motor. Many of our actuation problems came from the use of the cam, which was not able to match up with power and was difficult to match with geometry. We could have always introduced a larger gear ratio to increase the torque of the cam. We also could've done away from the cam entirely, instead designing around a more direct transmission of force through a mechanism such as a rack and pinion (adjusting input point motion to be more linear in the process).
• Reducing effective gravity.  Currently, we had to insert a counterweight for our mechanism to jump.  Another way to reduce the effect of gravity on the jumping mechanism would be to angle the entire frame with respect to ground.  Angling the frame at some θ would reduce gravity by an amount proportional to sin(θ)

Some tips for future groups: have a completed prototype at least 2 weeks before the demo day.  The end of the semester is busy for everyone, and iterating on your mechanism takes time.  The sooner you have your first, complete prototype, the better shape your group will be in.

Acknowledgments

We'd like to thank our TAs, Connor and Aayush, for their assistance in designing and troubleshooting and for always being quick to help.  We'd also like to thank the staff at TIW for helping us locate tools and for assisting us while using the laser cutters and 3D printers. We would like to thank Dr. Symmank for giving us the opportunity to complete this project this semester.