1) The document describes a student's portfolio for a class project to design and build a biologically inspired hopping mechanism. 2) The student went through an iterative design and prototyping process, creating both digital and physical models to test designs. 3) Their final design incorporated bendable joints to allow hopping but they struggled to create a reliable timing mechanism to trigger the hopping. 4) Although the timing mechanism did not work as intended, the device was able to hop on its own, meeting the overall goal of the assignment.

1. Hopper Portfolio
Amara Leazer
IDEA 170 - Intro to Mechanical Design & Engineering | Fall, 2022 | Profesor Ridley

2. The Assignment
The assignment was to create a biologically inspired hopping
mechanism
The design had to include a timing mechanism which when set,
which would initiate its hop after a delay of at least 8
seconds and before 60 seconds “without any intervention after
time zero.”
We also had to develop a personal design goal at the beginning
of the project, which could be changed up to a certain point,
that everyone had to try achieve by the end of the project.

3. Materials
We were restricted in the
materials that we could use
to make out hoppers. Everyone
was given a box with various
items and a list of
everything provided,
detailing exactly what we
could use and how much of
each item we could use.
I was fairly unfamiliar with
many of the materials in our
hopper jits. So, I spent a good
few days just playing around
with the materials to see what
they could do. While we had
access to many helpful thing
like mdf, nuts, and bolts,
there were other materials
that, while helpful, were
difficult to incorporate into a
design, such the rocket
ignitor, resistance bands, etc.

4. List of Allotted Materials

5. HOPPING MECHANISM
Preliminary Sketches
I started with a box of
sorts that has
stabilizing legs and
two additional longer
legs that are fixed to
the hopper with
rotating joints and are
held in place by
resistance bands and
springs roughly an inch
above the table.

6. Prototype Solidworks Model
In my original design, I had too many moving
parts, making coordination difficult. So, I
simplified my design a bit.

7. Hard Models 1 & 2
When making my second hopper, I
decided to switch to ¼ inch mdf for
added durability, as the first one
seemed quite flimsy. I put it together
with wood glue and nails, and it was
fairly durable. *I also changed the
legs but don’t have pictures, sorry!
This was my first
hopper, it was
constructed simply to
visualize the
mechanics of my design
and to explain my idea
to others. While she’s
is broken in this
picture, she certainly
did her job when i
needed her to.

8. Hard Model 3
After realising that
nails were not on the
list of allotted
materials, I tried to
remake my hopper in
accordance with the
materials, but was
having a hard time
glueing it together,
Redesign?
After the first design review, I was going to
make my hopper into a prism, so it could jump
more efficiently and have a better center of
mass. But after trying to change the angles
on SolidWorks and too much frustration, I
abandoned that plan.
I ended up needing to use 2 nails to keep it
together. This hopper was far flimsier than my
last one.

9. Finalized Hopper Body
In my last rebuild, I made my hopper from far fewer parts. I was able to turn many of my
parts into a singular "face," with notches for easy assembly and added durability.
I've also turned the piece that attaches the jumping legs to the body so that I can have
functional joints.
Lastly, I removed one part from each leg, thus removing 4 joints, and reducing my margin of
error (I hope).

10. Finalized Hopper Body
Unfortunately, after completing her first jump, my first finalized hopper promptly broke her
legs so I had to rebuild her as you see here. Unfortunately, the second finalized hopper did
the exact same thing after 3 jumps, but nonetheless, she’s pictured above.

11. TIMING MECHANISM:
Initially, I’d planned to somehow
release both bands (which held the
two jumping legs in place) at the
same time, thus allowing the hopper
to launch itself into the air.
*One thing that I didn't consider is
that this design makes both
mechanisms codependent - one must
work for the other to work. This
proved to be a highly frustrating
conundrum*
My first plan was to find a way to attach
the resistance bands to a balloon that
would sit inside the hopper’s frame. As
the balloon released air the bands would
snap back into place, making the hopper
jump.
However, synchronizing the bend of the
legs, figuring out how to attach the
resistance bands to the balloon, and
figuring out how to release air from the
balloon at a controlled speed that wasn’t
so slow that the hopper wouldn’t hop,
proved to be very difficult.

12. Breakable Timer
After many failed timer ideas and not much time left, I decided to try and
make a part that would simply break away after about ten seconds.
I added a part to my hopper that would allow me to insert the “breakable”
dowel, thus holding it in place until it breaks.

13. I had to test a bunch of different variations of my breakable piece before
determining that one somewhere between ¼ x 20 x 0.42 - 0.48 inches ends up taking
roughly 9-10 seconds to break after my hopper has been set.

14. Design Goal
My design goal was initially to
integrate both bendably joints
and a friction/creep timer &
trigger mechanism.
As I had to change my trigger
mechanism a few times, I ended
up changing it to just be to
include bendable joints in my
hopper.
I ended up accomplishing this
goal, as you can see in this
clip.

15. Energy Calculations Force
(Newtons)
Height
change
(Meters)
0 0
26 0.11
28 0.12
31 0.13
33 0.15
40 0.19
42 0.2

16. Energy Calculations

17. Final Product
To hop, or not to hop?
That is the question-
Thanks to my anxiety (and a
poopy laser cut), I didn’t end
up presenting on celebration
day. But, I was able to present
and have a video of her hopping
(not at all how she was supposed
to).
I wish that my timer mechanism
would’ve worked properly, but
nonetheless, I’m happy she
hopped. And consider this a
mostly successful first
engineering project :)