@ Maxon today video
Maxon.net

Role: Art Direction, Design, Animation, Modelling, Compositing, Sound Design
Co-worker : Jaehong Park(Yonsei Univ)
Date: 2010.11.01~12.14
Format: 1280*720 HD
Sound: Basique Little People
Tools: Cinema4d r12, aftereffects, premiere
Render time : 3 Days
atenis@nate.com
blog.naver.com/~atenis
atenis.cafe24.com

This time, my friend and I had a chance to do a project about
mechanism design. In this video, we will show you especially about
four-bar linkage and gear trains. For instance, riding a bicycle has
two mechanisms, one for four bar linkage, and the other for gear
trains. And the watch, for example, is consist of numerous gears.

Almost everyone takes the watch in daily life, but just a few knows
about the principle how it works. Synthesis of mechanism is not
shown in this video, only analysis is presented.

When we analyze the mechanisms, we used "Graphical analysis method" and "Analytical
analysis method". Calculating with vector loop equation, and
reviewing with graphical method.

Showing how the gears in the watch rotates was really difficult for
us. We knew the theoretical angular velocity, but C4D was not
accurate to realize them. Finally, we tried FPS division method and it
worked,

On analyzing four-bar linkage with bicycle, we used tracking
function with AE.
We hope all of you can be more familiar with mechanism design
through this movie. Merry christmas and Happy new year.

Intro Preview
vimeo.com/17593568

S1 Preview
vimeo.com/17593507

Xpresso Preview
vimeo.com/17593083

Case : the bicycle
We first thought that analyzing the mechanism of riding a bicycle would be
really easy because the length of every linkage was determined so we could
parameterize every four angle, angular velocity and angular acceleration
with one specific angle. But it was totally a mistake. Finally we divided 2Π
rad in to 10 sections, which means every 36°, and found values related to the
angle and interpolated them to make continuous numbers.
When climbing up the ascent, we assumed the length between the saddle and the
crank axis varies. We set up the equation (which is used in this movie) of the
length as "85+5sin(angular velocity of the crank*Π*t)cm" so that the length varies
from 80cm to 90cm. It was quite reasonable to set up the equation as above
except for a few errors. For instance, following that equation, the length becomes
the smallest when the pedal is on the lowest position and largest when on the top,
but that assumption makes the motion of the bones seem forced or unnatural.
This equation is to be complemented soon enough. We calculated 7 sorts of
variables; angular velocity, angular acceleration, velocity, tangential acceleration,
normal acceleration, relative velocity, relative acceleration; but inserting all of
those values made the pictures disoriented thus we got rid of every value except
for angular velocity.

Case : the watch
In designing the gears, we did not consider the pitch radius or pressure angle so
it does not fit to the engineering models. But the angular velocity ratio of each
gear related to the number of teeth ratio was designed precisely. In engineering
concept, the gear must have at leat 12 teeth so the second gear, called
Escapement gear, has 12 teeth in the video which has actually only 6 teeth. And
we want you to watch very carefully how the minute hand gear affects the hour
hand gear with converting gear 2, because even concepts of those concentric hand
gears movement was not easily understood, we costed about 3 days to realize it. In
this film, we do not present the torque of the gears in the bike or watch. With a
piece of paper and a pen, most of you can caluculate it with no longer than 10
minutes.