2015-16 Vexmen Downingtown PA 2015-16 The Story of Our Robot
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
2015-16
Vexmen
Downingtown PA
2015-16
The Story of Our Robot
201
5-1
6
1
Table of Contents About Team 81 M ......................................................................................................................................... 2
The Base ........................................................................................................................................................ 3
The Problem .............................................................................................................................................. 4
Relevant Rules and Parameters ................................................................................................................ 4
Brainstorming and Concept Models ......................................................................................................... 7
Changing the Base ..................................................................................................................................... 9
DoubLe reverse 6-bar.................................................................................................................................. 10
The Problem ............................................................................................................................................ 11
Relevant Rules and Parameters .............................................................................................................. 12
Brainstorming ......................................................................................................................................... 14
Designing ................................................................................................................................................. 15
Building the Lift ....................................................................................................................................... 16
Failure and Physics .................................................................................................................................. 17
The PantaGraph .......................................................................................................................................... 18
The Problem ............................................................................................................................................ 19
Rules and Parameters. ............................................................................................................................ 20
Design and Inspiration ............................................................................................................................ 23
Build Montage ......................................................................................................................................... 25
Failures and Struggles ............................................................................................................................. 27
Investigating Material Properties ........................................................................................................... 28
The Skyrise Claw.......................................................................................................................................... 31
The Problem ............................................................................................................................................ 32
Relevant Parameters ............................................................................................................................... 33
Brainstorming.......................................................................................................................................... 34
Building the Skyrise Sweeper .................................................................................................................. 35
The New Scissor Lift .................................................................................................................................... 36
Building the New Scissor ......................................................................................................................... 38
201
5-1
6
2
About Team 81 M Team 81M is a high school Vex Robotics Team. The team is part of the Vexmen Robotics Club
from Downingtown Pennsylvania. This team is dedicated to learning advanced concepts connected to
Science, Technology Engineering and Math by Designing, building and programming a competitive
Robot.
This year we focused on using experimental data and virtual modeling to influence our design
and using Agile Project management to organize our build efforts. We modeled many of our ideas into
fully built, detailed Autodesk Inventor Drawings to fully realize our design before building. Mystique also
used experiments to design our robot. We experimentally tuned our PID control. We also devised an
experiment to test the differences between the material properties of different Vex parts. We
preformed tensile strength tests and analyzed stress strain curves.
We also learned about project management. We learned about Agile project management and
created sprints, burn down charts, epics and stories throughout the season. This helped us keep our
hectic season organized and on track.
Our team attended four competitions this year. We were very successful and won at least one
award at every competition. We attended the Downingtown Classic on January 10, 2015 and won the
build award. On January 24, 2015 we attended the Dockbots competition. There we won our season’s
first design award. The next event we attended was the DC Knights Qualifier on January 31, 2015. There
we won the judges award. Lastly, we attended the Pennsylvania State Championships. There we won
both the design award and the title of Pennsylvania’s Programming Skills Championships
Our team is composed of four members: Rob, Miranda, Sarah and Ian. Rob is a junior at
Downingtown West High school. He has been participating in Vex Robotics for six years. He is an
amazing builder and Designer. He has previously been on teams 81, 80G, and 81G. Miranda is a Junior at
the Downingtown STEM Academy. She has participated in Vex for five years. She is the team’s
programmer and notebooker. She has previously been on teams 80 and 80N. This is her 3rd year on team
81M. Sarah is also a junior at the Downingtown STEM Academy. She is our project manager. She
manages our workload and ensures all our projects are on track. This is her second year in Vex robotics.
Last but not least, 81M’s rookie member is Ian. It is his first year in Vex robotics. He is a Freshman at
Downingtown West High School. Ian is our best coach. Now that you know about the team its time to
learn about the Robot!
201
5-1
6
3
The Base
Team 81M started off the season by designing our base. To
design this subsystem we defined the problem, researched
relevant rules, brainstormed ideas, created concept models,
chose and built a design and then modified that design later
OUR DESIGN PROCESS
201
5-1
6
4
The Problem This year’s 2014- 2015 Vex
Robotics Competition Game is
Skyrise. A picture of the game
field is to the right. The game
field is 12ft by 12ft big.
The field has one main pile of
cubes in the middle and cubes
scattered around the outside
edge. The cubes on the floor
may be an obstacle when
trying to maneuver. There is
also the Skyrise bases in the
corners. To reach those bases
we do not need to move far
because they are near the
starting tiles.
Our task is to create a robot
base to navigate around the
field and play the game.
Relevant Rules and Parameters Size Requirement
Specification: The robot base must be no larger than 18in by 18in by 18in large
Testing Method: The sizing tool will be used to test the final base and any concept
models in Autodesk Inventor will be measured before fabrication.
Why? Robot Rule R4 constrains the dimensions. Since the base is the first system we
build, we
have the full
18 in by 18in
by 18 in
dimensions
available.
201
5-1
6
5
Materials Restriction
Specification: The robot base must be made only out of Vex parts.
Testing Method: Comparing the parts list to legal Vex parts
Why? Rules R5 and R 6 limit the materials to only Vex parts. We cannot use any non-vex
parts sold from non-Vex resellers.
There are some parts that do not follow this rule. Any Identical parts can be used as
well. These exceptions are defined in rule R7
Any IDENTICAL Vex part can be used. There is also the option to use polycarbonate to
build. Identical Electrical Non-Vex parts are not allowed.
201
5-1
6
6
Our base must also be light, easy to build and fairly maneuverable. Using these rules and our goals we
brainstormed many different base designs including Tank Drive bases and Holonomic bases. We
narrowed our brainstorms down to Holonomic versus Tank Drive.
201
5-1
6
7
Brainstorming and Concept Models
Holonomic versus
Tank Drive
We brainstormed two
possible designs, made
sketches and rendered
them in Autodesk Inventor.
After a lively debate, we
concluded the tank base
design is far superior to the
holonomic base for a
variety of reasons. Even
though the holonomic base
is more maneuverable,
Holonomic bases are
generally harder to design
and build. The holonomic
base also is less powerful.
This is due to the force
vectors being split over an
angle. The max potential
motor exsertion is the
motor power divided by the
square root of two (see
journal for more info)
The tank base may be less
maneuverable but they
maximize the motor force
and are easy to build.
Because of these factors we
chose to build a tank Drive
base.
201
5-1
6
8
The Base was built almost exactly like the Autodesk
Inventor Model. The only difference between the
virtual and real models is the real model has quad
encoders. The Quad encoders mesure wheel
rotation and will be helpful when programming
later.
201
5-1
6
9
Changing the Base
In late December, we built a
scissor lift (the lift is detailed
later in the book). The lift
required a narrower and
shorter base due to the
internal lift system and a
planned grasping
mechanism.
We first sketched out the
change in base dimensions in
our engineering design
Journal and we then
prototyped the change in
Autodesk Inventor to ensure
it will not conflict with any
existing mechanisms.
The drawing above is the existing base. The
drawing to the right is the improved base. The
base was shortened and it was made narrower.
The New base is 14 in wide and the old base is
17.5. The base now can accommodate the
news lift and the grasping Mechanism.
After this iteration, we also eventually switched
our motors to strength instead of the original
speed.
201
5-1
6
10
DoubLe reverse 6-bar
.
THE CAM SHOOTER
201
5-1
6
11
The Problem
Now that we have a fully
functioning base, we
need a lifting mechanism
to raise the cubes off of
the ground and score
them. The goal heights
are 47”, 40”, and 24”.
The mechanism must be
both tall and stable
because the higher the
robot the greater the risk
of tipping. We need to
keep this in mind when
designing.
Problem Statement:
To play Skyrise we must
create a mechanism to
lift game elements up
into the air and score
them on top of the
various sized posts
scattered around the
field. We must build a
stable mechanism to
perform this task while
also fitting it on the
existing base.
201
5-1
6
12
Relevant Rules and Parameters Size Requirement
Specification: The robot must be no larger than 18in by 18in by 18in large The arm can
be no larger than 14 by 18 by 18 .
Testing Method: The sizing tool will be used to test the final arm design and any
concept models in Autodesk Inventor will be measured before fabrication.
Why? Robot Rule R4 constrains the dimensions. The current base also constrains the
dimensions of the arm. The height of base is four inches tall. To comply with rule R4 we
must
have a
lift no
larger
than 14
inches.
Materials Restriction
Specification: We must construct the arm solely out of Vex parts or Vex legal parts
Testing Method: Comparing the parts list to legal Vex parts
Why? Rules R5 and R 6 limit the materials to only Vex parts. We cannot use any non-vex
parts sold from non-Vex resellers.
There are some parts that do not follow this rule. Any Identical parts can be used as
well. These exceptions are defined in rule R7. Any IDENTICAL Vex part can be used.
There is also the option to use polycarbonate to build. Identical Electrical Non-Vex parts
are not allowed. We are allowed to use screws like cap head screws, and identical parts
like Teflon washers.
201
5-1
6
13
Height requirement
Specification: The lift must be able to reach the goals in the game and score cubes on
top of them
Testing Method: A tape measure will be used to measure the final design and all
concept models will be measured.
Why? Since the highest goal is 47 inches tall and the cubes are 8 in tall so the lift must
h
a
v
e
a
r
e
a
c
h
o
f
5
5
i
n
c
h
e
s
201
5-1
6
14
Brainstorming
The Double Reverse
6-Bar
We looked at other robots
in our club for inspiration.
80Y’s double reverse four
bar intrigued us. We
brainstormed a new similar
design.
We analyzed the difference
between a six bar and a
four bar and found that
there was a significant
height difference. This
difference made us wonder
if a double reverse six bar
would have the same
advantage over a double
reverse four bar.
We sketched both double
reverse Six Bars and double
reverse four bars to analyze
the difference.
The height difference was
very evident when two
sketches were drawn side
by side. The double reverse
six bar has a large height
advantage. Because of this
we decided to build a
double reverse 6-bar.
201
5-1
6
15
Designing
Designing the
Double Reverse Six
Bar
When designing the double
reverse Six Bar, we created
a layered drawing. This
drawing broke the design
up into four distinct layers
this helps us build and test
whether the components
will interfere with each
other. The details also help
us streamline the building
process and quickly
assemble the arm.
The layers are all depicted
in the pictures on the right.
The design will use both
high strength motors and
high strength gears to
ensure the lift is durable.
The entire lift is made from
Aluminum to ensure it is
light enough to lift.
We designed one tower
and planned on building
two. The second tower was
a perfect mirror image of
the first one. The two
towers would be connected
with c-channel support bars
and a sync shaft
After we were done
designing, we gathered
materials and prepared to
build.
201
5-1
6
16
Building the Lift
201
5-1
6
17
Failure and Physics After constructing the double reverse 6-bar, we tested it. We ran the motors and the robot began to tip
over before it reached maximum height. It tipped so often that we named it Sir Tipsalot. It became a
serious problem and we decided to investigate into what makes the robot tip and for that we needed to
look at the forces causing the robot to tip over.
To do this, we started by drawing an Free body Diagram of the robot’s center of gravity. That diagram is
below. 𝐹𝑔⃗⃗ ⃗ is the Force of gravity of the robot. 𝐹𝑔⃗⃗ ⃗ = 𝑚𝑔 (m is robot’s mass, g is acceleration due to
gravity). 𝐹𝑥⃗⃗ ⃗ is the force in the x direction. 𝐹𝑥⃗⃗ ⃗ = 𝑚𝑎𝑥⃗⃗⃗⃗ (m is mass, 𝑎𝑥⃗⃗⃗⃗ is acceleration in x direction). S is the
distance between the wheel’s touch point and the center of gravity. Θ is the angle between the Force of
gravity and the line between the center of gravity and the wheel.
The dotted lines
are normal to line
connecting the center of
gravity to the touch
points. For the robot not
to tip, the red
component must be
bigger than the blue
one.
The red line’s magnitude
is defined as:
𝐹𝑔 sin 𝜃 = 𝑟𝑒𝑑𝑙𝑖𝑛e. The
blue part’s magnitude is
defined as 𝐹𝑥 cos 𝜃 =
𝑏𝑙𝑢𝑒𝑙𝑖𝑛𝑒. Since the
redline’s magnitude
must be greater than the blue line’s to avoid tipping, 𝐹𝑔 sin𝜃 > 𝐹𝑥 cos 𝜃. After substituting 𝑚𝑎𝑥⃗⃗⃗⃗ in for
𝐹𝑥⃗⃗ ⃗, substituting 𝑚𝑔 in for 𝐹𝑔⃗⃗ ⃗, and solving for acceleration in the x direction, we found our final equation.
𝑔 tan 𝜃 > 𝑎𝑥
The acceleration due to gravity multiplied by the tangent of the angle from the touch point to
the center of gravity must be greater than the acceleration in the X direction for the robot not to tip
over. Due to the double reverse 6-bar’s weight distribution, the center of gravity constantly moved. The
center gravity often hung over the back of the wheels so any acceleration in the x direction would be
greater than the tangent of the angle times the acceleration due to gravity. Basically, both the design’s
geometry and weight distribution caused the tipping. The physics revealed that major changes would be
needed to prevent tipping
After a long debate, we decided to redesign a new mechanism because we thought the
problems were too severe to fix without scrapping the whole thing.
𝐹𝑥⃗⃗ ⃗
𝐹𝑔⃗⃗ ⃗
θ
θ
90 - θ
Center of Gravity
Wheel
S
201
5-1
6
18
The PantaGraph THE PANTAGRAPH
201
5-1
6
19
The Problem Since our double reverse six bar was a complete
failure, we needed to redesign a lift system. We
reanalyzed the game and redefined our problem.
Rob and Miranda noticed that this year’s game
Skyrise closely resembled an older game, Gateway. There
was a similar scoring method, de-scoring rules, post
owning bonus points and goal heights. The fields also had
a large pile of game elements in a pyramid shape with
other elements scattered around the field. There are a
few differences between the two games but the methods
of scoring points are fundamentally the same.
Since the two games are so
similar, examining previous
successful gateway robots could
help us with our design for
Skyrise. Our team had not been
to a Skyrise competition at this
point in the season but Rob and
Miranda were very experienced
when it came to Gateway.
Keeping the game similarity in
mind, we redefined the
problem.
Updated Problem Statement: We
must create a lifting mechanism
inspired by Gateway to lift game
elements onto the various sized posts
without tipping over.
201
5-1
6
20
Rules and Parameters.
Size Requirement
Specification: The robot must be no larger than 18in by 18in by 18in large The arm can
be no larger than 14 by 18 by 18 .
Testing Method: The sizing tool will be used to test the final arm design and any
concept models in Autodesk Inventor will be measured before fabrication.
Why? Robot Rule R4 constrains the dimensions. The current base also constrains the
dimensions of the arm. The height of base is four inches tall. To comply with rule R4 we
must have a lift no larger than 14 inches.
Height requirement
Specification: The lift must be able to reach all posts and must be high enough to
successfully score on all the goals WITHOUT tipping over.
Testing Method: A tape measure will be used to measure the final design and all
concept models will be measured. The final design will be placed on a field and will
attempt to score goals.
Why? Since the highest goal is 47 inches tall and the cubes are 8 in tall so the lift must
have a reach of 55 inches because to lift the cube on top of the goal, the bottom of the
cube must be higher than the top of the highest post.
201
5-1
6
21
201
5-1
6
22
Design Constraint
Specification: The robot must be inspired by a mechanism used in the game Gateway.
Testing Method: We will examine pictures of gateway robots and improve upon the
designs from those robots.
Why? Our old mechanism was inspired by a toss up robot and toss up was a very
different game with much lower goals. The highest gateway goal was 30in tall. Robots
for gateway were designed to reach lofty heights. Any extremely successful design from
that game should also potentially be successful in Skyrise. We will not copy the
mechanism but we will take inspiration only from gateway designs.
Stability requirement
Specification: The lift must be stable and have a stable center of gravity. A lift where the
center of gravity only moves up and down and does not shift left or right would be ideal.
Any particularly back heavy designs like the double reverse 6-bar are not acceptable.
Testing Method: To test this we will run the robot and see if it tips over and we will
guestimate the center of gravity in any of our designs.
Why? We want our lift to refrain from tipping over during game play and we do not
want it to fail like Sir Tipsalot failed. We want to incorporate the stability into the overall
design because it is a crucial aspect.
201
5-1
6
23
Design and Inspiration
Our inspiration
Three years ago Miranda
designed and built a special
scissor lift for Gateway. The
final height of her design
was an astonishing 5ft tall.
Her original inspiration for
the design was an episode
of the show “How its
Made”. On the show,
collapsible room dividers
were created using a
special scissor lift called a
pantograph. Miranda was
inspired by this design and
created the gigantic robot
seen in the picture on the
bottom right. Her robot
was taller than she was.
That robot competed in
Gateway and attended the
Vex Robotics World
Championship in 2012. It
was a surprisingly stable
design. It was very
effective at playing
Gateway and won multiple
tournaments in the
Pennsylvania region.
We decided an improved
pantograph would be the
best lift solution due to its
stability and success in
Gateway.
201
5-1
6
24
Improving the Old
Design
We kept the main
structural elements from
the old lift design but we
improved the lifting
mechanism by making it
lighter and more compact.
The top pictures shows the
old robot lifting
mechanism. It was spaced
out and primarily made
from steel. The sync shaft
required many 12 tooth
gears and was fairly
inefficient.
The new lift design is
narrower and lighter.
Unlike the old deign, the
new one uses the new style
of linear slides to propel
the tracks up and down.
The new style is lighter
because only one of the
two components is steel.
The new lift is also more
compact because instead
of a sync shaft, it uses two
60- tooth gears to
synchronize the motors.
The final rack design also
was longer and allowed a
greater range of scissor lift
motion.
201
5-1
6
25
Build Montage
201
5-1
6
26
201
5-1
6
27
Failures and Struggles
Failure
The design was tall, refused
to tip over and was fairly
light but it ultimately failed.
The top levels of the scissor
did not extend upwards at
the same rate. This led to
one side raising higher than
the other. The top was
tilted and unstable.
Instead of a tipping
problem we had a tilting
problem. On top of the tilt,
some of the bars in the
lower sections began to
bend. We tried multiple
solutions to stop the
bending and tilting. All
failed.
Eventually we removed
over half of the scissor
levels severely shortening
the reach. We eliminated
the bending but we limited
our reach to the short goals
Our lift was almost identical
to the one Miranda built in
Gateway. We wondered
why our lift failed because
the previous design worked
perfectly.
201
5-1
6
28
Investigating Material Properties
After the failure of our lift, we decided to examine the
pictures of Miranda’s old Scissor to see if there were
any differences between the two. We observed that
the metal Miranda’s scissor was constructed from was
slightly different than our current Aluminum. We
closely examined the aluminum in our box and
realized there were two distinct types of aluminum:
old aluminum and new aluminum. Our scissor was
made from the new aluminum but the Gateway
scissor was made from the old Aluminum. We
investigated the material properties of the New and
old Aluminum by preforming tensile strength tests on
a special material properties testing machine found in
Miranda and Sarah’s high school. They tested the
tensile strength of old and new Aluminum. The stress
strain curve is displayed below:
201
5-1
6
29
201
5-1
6
30
A Stress Strain curve shows the elongation when a part is subjected to a force. It
We analyzed the stress strain curve for the yield strengths, the ultimate strengths, the strains at break
and the strain at the yield. We compared those points on both the old and New Aluminum Alloys. These
results are displayed in the table below.
New Aluminum Old Aluminum % difference
Yield Strength (ksi) 20.9 22.6 -7.5%
Ultimate Strength (ksi) 27.1 30.5 -11.1%
Strain at Break (in/in) 0.91 0.6 51.7%
Strain at Yield (in/in) 0.24 0.29 -17.2%
It is plain to see that the only advantage New Aluminum has over old Aluminum is that it
stretches 51% longer before it breaks. Otherwise, the old Aluminum preformed much better than the
new. Could this be the source of our failure?
We decided to investigate and discover the old aluminum’s exact alloy. Based on the published
alloy for the new Aluminum (5052 H32) we determined that the old aluminum is 5086 H32. A table
displaying the differences between the two is below.
Aluminum Alloy
Price Amount Yield Stress (psi)
% diff Ultimate Stress (psi)
5052 H32 Aluminum Sheet $ 5.72 1x1 sheet 28000 33000
5086 H32 Aluminum sheet $ 6.16 1x1 sheet 30000 7.14% 42000
So there is a distinct difference between the old and new Aluminum. We found the old aluminum is
superior to the new. Knowing this we found bars of old aluminum and replaced the top half of our
scissor with the Old bars.
Combining the new bars with The old bars allowed us to build more levels and achieve greater heights.
Now our robot is five skyrises tall. It still was not tall enough to achieve all our goals, but it was a start.
201
5-1
6
31
The Skyrise Claw THE SKYRISE CLAW
201
5-1
6
32
The Problem
After we built a lift, we needed a mechanism to
score. We decided to focus on building Skyrises
because Skyrises seemed the best possible way
to efficiently score the most points.
Each Skyrise section is worth 4 points and
each cube on the Skyrise is worth 4 points. Since
the Skyrise is close to the starting tile, building
Skyrises is an easy way to score points in the
autonomous period. This is important to us
because there is a 10 point autonomous point
bonus and that bonus can sway the match
significantly.
Our current lift configuration is perfect
for Skyrise building. The linear motion of the
scissor lift is perfect for nesting the Skyrises and
for removing them from the Skyrise holders. This
is because the front of the scissor lift travels up
and down within the same plane. This keeps any
front mechanism from traveling forwards and
backwards. In other lift designs like 8-bar
linkages, the manipulator travels forwards when
raised. The arm travels in an arc instead of a
straight line. The scissor travels in a line making it
perfect for delivering Skyrise sections to the base
no matter what the height.
The current base design does not move
in any direction. This is a problem for Skyrise
building because it would need to turn to move a
Skyrise from the holder to the base. This problem
can be avoided if our grasping mechanism can
swing and reach both the Skyrise and the holder
without moving the base
PROBLEM STATEMENT: After analyzing the
scoring opportunities we decided our grasper
must score Skyrises while the base remains
stationary.
201
5-1
6
33
Relevant Parameters
Size requirement.
Specification: The robot must be no larger than 18in by 18in by 18in large The
manipulator can be no larger than 18 long by 5 wide by 12 tall
Testing Method: The sizing tool will be used to test the final arm design and any
concept models will be measured before fabrication.
Why? Robot Rule R4 constrains the dimensions. The current base and arm also
constrain the dimensions of the manipulator The width of base is 14 in wide. To comply
with the rule the manipulator must stick out no farther than 4 inches past the edge of
the base
Reach requirement
Specification: The lift must be able to reach all posts and must be high enough to
successfully score on all the goals WITHOUT tipping over.
Testing Method: A tape measure will be used to measure the final design and all
concept models will be measured. The final design will be placed on a field and will
attempt to score goals.
Why? Since the highest goal is 47 inches tall and the cubes are 8 in tall so the lift must
have a reach of 55 inches because to lift the cube on top of the goal, the bottom of the
cube must be higher than the top of the highest post.
Grasping requirement
Specification: The claw must be at least 3.5 inches wide and long.
Testing Method: A tape measure will be used to measure the dimensions. All to scale
drawings and models must meet this specification.
Why? The largest Skyrise piece section has a diameter of 3.13 in. We need our claw to
be a bit larger than that to accommodate for any misalignment. 3.25 in gives us a bit of
wiggle room when grasping the sections
201
5-1
6
34
Brainstorming
Brainstorming the
Claw
We brainstormed a
swinging skyrise arm design
with a linear slide grasper
and claw made from forty
fie degree angle brackets.
The whole claw will be
mounted on the scissor. A
motor with a 12 tooth gear
will turn the 36 tooth gear
connected to the end of the
manipulator. This will
sweep the sweep back and
forth and allow us to pick
up skyrises with ease.
The liner slide grasping
mechanism ensures the
skyrise is grabbed and will
not tilt in transit. It also
allow one side of the
grasper to remain open.
This will make clamping
onto the skyrises easier.
The drawings to the right
show each claw layer in
detail.
201
5-1
6
35
Building the Skyrise Sweeper
201
5-1
6
36
The New Scissor Lift
THE NEW SCISSOR
201
5-1
6
37
The New Scissor
After successfully winning
the design Award at the
Pennslyvania State
championships, we decided
to redesign the scissor lift.
We used the same criteria
and problem statement as
before only this time we
tried to think outside the
box.
We decided to design a c-
channel 1x25 hybrid scissor
lift because we believed a
hybrid lift would be more
stable than any other
design. We also used bering
blocks and lock nuts at each
connection point to
stabilize the lift.
We designed an
screwheadless bearing
block system to minimize
interference while lifting. It
involves wedging two
Bering blocks, piece of
plastic nut bar and a spacer
between the inside walls of
a c-channel. A standoff
coupler is screwed through
the entire bar. This creates
a solid Bering block
connection with no screw
heads on the outside.
We created this lift and
built an entirely new (yet
almost identical) robot
around it.
201
5-1
6
38
Building the New Scissor
201
5-1
6
39
Related Documents
