Date: Feb - Mar 2018
Team Members: Annie Shi, Kaitlyn Gee, Zoe Lee Cheong
A Biomicry Robotic Frog Leg Capable of Jumping a Meter and Velcroing to Surface
While trying to define what the rubber band tension needed to be, and while trying to approximate the weight, we created several prototypes. There were many tests, one of which you can see here. We wanted to not just focus on the math, but also begin understanding the materials we had available to us.
We affixed a motor on top that had a 1000:1 gear ratio that wrapped a string around its shaft. The string attached to a gear on the bottom axle.
The top two linkages were attached with lego gears so that they were forced to move together.
A rubber band held the sides together which stressed as the jumper compressed, causing it to build potential energy. There are barriers on the sides to prevent it from releasing prestored potential energy
The bottom linkages were attached to a bar, loose on one leg and tight on the other, so that as the legs compressed, the gear at the bottom turned.
As the string is pulled taught, and the legs bend, the gear rotates. The string is looped around a gear tooth, and when it reaches a certain point in the twist, the string comes off, allowing the rubber bands to compress and the jumper to jump.
The Jumper in has cross T-beams between each side to help prevent the legs from bending during compression. The total machine weighed 11 grams, jumped up to 110 cm, and was 5.6% efficient.
Here is the final jump, showing the full 30 second wind down and crouch with the jump in slow motion as it attaches to the velcro ceiling above.