This is our first regional. After having scares on the way
from El Paso to Carlsbad involving gas and not being any gas stations for about
150 miles or so, we were ready to play with robots, and see other
designs/approaches to problems. Also, it was time to make the several
fixes (and rebuild half of the robot) needed, as the tweaks are a large part of
the detailed design phase.
Shooter
Shooter requirements for the robot:
- Winch back consistently and effectively
-Shoot consistently
-Have a continuous hit range (make the peak of the shot only reach
the top of the goal)
-Keep the ball on the shooter for shots
Bonus for shooter:
-Hit from 20 feet back
Unfortunately, we did not get to test the shooter much on
Thursday, since almost the entire day was spent trying to make the changes to
the robot. Since the field for practice matches closed at 4:30, which was
when we finished, we did not get to play around with the shooter on the field,
but got to begin to play with it on the small practice area. While we did
get to play around on the practice field, we did realize the black tubing was
far too weak for the energy output compared to the energy input/the friction
within the bands made the bands not return as quickly as the other thinner
walled bands. Before we could really replace the bands, it was about time
to go.
Friday morning was a bit more interesting, as there was the
driver's meeting and everything else. After the night before, we went
ahead and changed the surgical tubing out from the shooter and went back to the
thinner walled stuff. This worked extremely well, but now the winch had
trouble winching back, and would stall just before latching. After
looking at it, we realized the churro we were using was bent, which definitely
is not a good thing. After seeing this, we went ahead and pulled our
extra hex shafts from the practice robot (which we brought along for some
reason as a just in case we needed parts), since they are a lot sturdier. After
burning a decent amount of time with this, we went ahead and tried it again,
but again realized it was having trouble. Because matches were happening,
we had to just decrease the amount of tension and shoot from much closer.
After a while, we realized the way it was wrapped for the
competition bot was different from the way the strap was wrapped for the
practice bot. After seeing this, we realized the strap was constantly
pulling on the middle from the sides of the catapult, rather than pulling
straight down on the sides from the sides. Because it was pulling on the
middle from the sides, there was a quick angle change, meaning the force was no
longer radially perpendicular to the rotation of the axle, so that the two
motors would have to work harder and harder by a factor inversely proportional
to the sine of the angle between the strap (spanning from the side to the
middle of the catapult) and the axle. This was an easy fix, since it was
just changing the way the strap ran on the catapult, so that the winch was
pulling on the sides rather than the middle, so that the sine of the angle
between the strap and the axle would stay nearly perpendicular. Once we
changed that, the winch worked perfectly again.
While the winch still worked well, we also remembered how
important the radius of the "spool" is, as that was the original
reason we couldn't use the yellow strap. Since the radius is more
important than the angle of the strap with the axle (although both are
important), and it is harder to pull back the further back the surgical tubing
is pulled (or it is easier to pull back if the tubing hasn't been pulled back
much), it doesn't matter so much what the angle is between strap and bar when
the catapult is beginning to be pulled back, but rather toward the end, when
there is the most upward force. Because of this, we went ahead and
mounted the strap to the axle a little further in, decreasing the radius, but
keeping the angle between the strap and the bar nearly perpendicular as the
catapult was beginning to be latched. This allowed for smoother operation
with the winch, and, finally, the winch problems are solved.
Finally, after seven matches or so, we had the shooter winching
back and shooting consistently. Saturday
was a similar day to the end of Friday, in that we just made sure the latch was
okay and continued to shoot consistently, although from much closer up. By the eliminations, we finally realized we
had to re-tension the surgical tubing, and get it back up to the power it was
supposed to be, and, since the winch was now working.
Requirements met by end of Regional/first test:
-Shooter winches back consistently and effectively
-Shooter shoots consistently
-Had continuous hit range (did not miss shots due to ball being
too high)
Bonus trait of shooter by end of Regional/first test:
-Can now hit from 20 feet back after re-tensioning
The ball still stays on the shooter while shooting, but can be
knocked forward when nudged, or when the robot abruptly stops. Also, while the shooter still works, the surgical tubing seems to be way overstretched. After looking up how much surgical tubing is supposed to be stretched/the most efficient amount, we found it to be about 150% the original amount, so that would be something we may possibly change.
Intake
Requirements for the intake:
-Pick up the ball quickly
-Spit out the ball quickly
-Actuate/move outside of the frame perimeter
-Be sturdy/able to take hits from other defending robots
Bonus for the intake:
-Keep the ball held on the shooter
-Pick up from a wide range
The intake worked well, except for the second and third
matches. With the physicality of this
year’s game, we did not realize how semi-ineffective the rivets on the intake
were. After the second match, we
realized a large portion of the rivets were entirely knocked out and broken,
which caused the intake to flop around during the match. Unfortunately, we had matches close to each
other, so we ended up getting to replace some of the rivets with bolts, but not
all of them, so some more of the rivets holding it all together were knocked
out. Also. the chain slipped a couple of times, but, luckily, it was in the same matches as when the rest of the intake wasn't working.
In terms of the worries of picking up over inflated balls, as
almost all of the balls were inflated to pressure rather than size, the intake
did just fine, and the motors did not stall at all. At most there were two times where the robot
had small amounts of trouble picking the ball up, and just needed a bump,
either from a wall or another robot to pop the ball the rest of the way in.
For the shooter, we will need to add something extra to the intake
to try to keep the ball somewhat contained.
Requirements met after regional/first test:
-Can quickly pick up balls from the ground
-Can quickly spit balls out onto the ground
-Extends out of frame perimeter to get balls
-Loads ball directly onto shooter
Bonus traits for the intake met:
-Can pick up smoothly from the sides due to the side rollers
Need to work on something to keep the ball contained and stable on
the shooter, so the ball stays even if the robot is hit. Also may need a second motor, so that if the chain slips on one, there is a back up to still drive the intake.
Drive Train
While the drive train works, we need to make the robot have a higher top speed/be faster, based on the style of play. Also, due to what happened, we found we need to increase the friction of the wheels, because, often times, the wheels would just start slipping. Overall though, pretty much it was solid, except for those two things. In terms of the wide, square, or narrow debate, the robot was just fine in terms of stability, and tipped over forward a total of once (immediately got back up by putting the intake down. For maneuvering between robots, everything would most likely have been easier if the bot was square, because it would have a slightly smaller footprint in the width department, but would still be easy to turn and have a large enough intake.
Catcher
Thursday, we went ahead and added the catcher, as well as the yellow straps on the catcher. Pretty much, it did everything we could ever ask for. As a human player, I was able to throw to the robot from between 12 and 15 feet away, which made it easy when defense was beginning to be played against us. As the goal was just to make the human player job easier and allow the human player to have a larger range for error, the catcher was doing exactly what it was built for (and, it made the top half of the robot look like the top half of a lawn chair).
Regional Summary
In terms of requirements set and completed for our final product, every requirement set was completed and done by the end of the regional, and it is just a matter of adding the things that would be nice for us to have, but the final product is definitely finished and working as it is supposed to work.
Overall, we ended up as 29th seed at the end of qualifications and ranked 12th in OPR for the regional, including the first 5 matches where we were not working. Once we were working, we were one of the obvious top teams, which is why we were picked second overall, meaning we were at worst the fourth best robot at the regional, and, pretty much showed, we were at least one of the top three robots out of 45 there.
While we ended up getting eliminated in the first round, partially due to the alliance partners (easily defended and had trouble with mechanisms when defense played on them), we did with the Quality Award. The Quality Award, as described in the FIRST Administration Manual for this year's game, "celebrates machine robustness in concept and fabrication". This, of course, is a huge award for us in terms of showing that the engineering design process has worked very well for us, and, for the sake of the engineering design process, is one of the more important awards in judging the build season as a whole.
In terms of things to do once we get back, to improve performance for the Arizona Regional, we need to change the gearing so it goes faster, change the wheels, figure out a ball retaining device, and (preferably) figure out a new way to mount the surgical tubing (and add lights, although it probably would more so add a cool factor rather than enhance performance). While the latch has been working alright, it would also be nice to see if there is a different latch we could make that would not wear down as quickly, although it is okay for now.
Approximate times of working Thursday: 8:30 AM - 8:00 PM
Approximate times of working Friday: 8:00 AM - 7:00 PM
Approximate times of working Saturday: 9:00 AM - 1:30 PM
