Category Archives: Build Blitz 2014

Team Copioli: Intake Design

Team Copioli put a large emphasis on acquiring balls off the floor. It was decided that the most convenient way to pick up the ball was to have it go over top of the bumper, and not have to design in any breaks in the bumper. Our past experience led us to prototype a roller claw, as they have been very effective in past FRC challenges. The prototyping was instantly successful, so we moved straight on to CAD.

Here are the final specs:

  • Top roller, 12 fps linear speed
  • Roller being powered by a BAG motor through a 10:1 VersaPlanetary
  • Rotation of the shoulder joint powered by a Mini CIM through a 3-stage 300:1 VersaPlanetary
  • Roller using 3x 3.25” VersaWheels, torque being transferred through a series of VersaHub
  • 3.25” Wheels have a built in hub, also the grippiest against the ball
  • Structure is made out of 1×1 VersaFrame, using stock VersaGussets, and some modified with hand tools

100 01-04-14 03.11.52

At first, we attempted a roller claw similar to 1114’s Simbot SS from 2008, but the geometry didn’t work out the way we wanted.

118 01-05-14 01.17.11

Here, we used VersaHubs to transmit the torque. We’ll get into the ‘why’ of that more below, in the Q&A.

current-intake roller

This is the final version of the intake (for now) showing the roller and some gears we have on the arm. We’re not planning on using the gears for their intended purpose. If we have time, we’d like to try putting encoders or potentiometers on them in the future.

_401p Sunday Progress

The intake, integrated into the drivetrain.

To get some insights into the how and why of this design, let’s talk to James Tonthat, who was the lead engineer on this subsystem.

Q:What did prototyping tell you?

Before we even started prototyping, we began with some Crayola CAD to figure out measurements that might work. Just some simple shapes in SolidWorks, but once that started working out, we started to put them together with what we had around. It took about an hour to dig parts up, but we clamped together the VersaFrame and played around with the dimensions – and when we showed it to Paul, he said it was “money in the checkmate bank”…so back to CAD we went for a more formal documentation.

Q: How did you decide on pneumatics vs motors for the actuation of the mechanism?

Usually, with a longer build season, you’re able to figure out what pneumatics you want & can order them – the lead time is long, but that’s okay when you have six weeks. Since we only have 3 days, we’re limited in what we can use- and, quite simply, we have more motors on hand. Using motors also allows us to be more flexible on where the intake arm can travel – if we haven’t completely figured out the final configuration, it makes it really easy to change around. Pneumatic systems would be more difficult to rearrange. We also, don’t want to add all the overhead of having pneumatics – extra tanks, manifolds, etc – we chose to keep it neat, tidy and light.

Q: How did you decide on the roller speed?

A rule of thumb that’s fairly popular in the FIRST community – however fast your drivetrain goes, have your intake rollers go a little bit faster than that – as fast as you can, actually, while still gripping the game object. One of the most important parts of the game is to capture the game object as quickly as possible. The faster you can do that, the quicker you can score – and the more matches you can win. By setting the linear speed of the roller faster than the drivetrain, you can guarantee that as you drive up onto a ball and capture it, it won’t roll away from you. Once you touch the object, you own it.

Q: What about this breakthrough you had with the VersaHubs?

We got to a point with our initial design where we had packaging issues – Since we’re going over the bumper, the new 20” rule makes us work in a very small space. Our initial idea became really awkward and cumbersome. We weren’t sure we were going to be able to make what we had – an axle with a belt to a gearbox – work well, so we rethought the exercise. We moved the motor & its mount, and used something creatively – the VersaHubs – and we got a much better solution. We had a lot of time invested in the original intake, but this new one made a lot more sense. It’s going to be much faster once it’s built than the first idea we’d had.

Q: How modular is this design? How will it fare in a competition environment?

Part of the Build Blitz challenge is making something that will be competition worthy. For a team that’s actually competing, anything that goes outside the frame perimeter is going to get beaten up during matches – FIRST is a contact sport. The intake is one of the most important mechanisms for this game, and so it needs to be easily fixable & replaceable. If this intake gets damaged, we could swap out pieces or even the entire mechanism during competition. Even if this particular roller design doesn’t work out, we have contingency plans – sprocket and chain, belts, pneumatics – that we can work into design if we need to. For the case of an actual FIRST team, they could also swap out and adjust the entire mechanism with only a few fasteners between events if they needed to adjust their performance.

_intake gearing - minicim - 300to1 - 12v

Intake arm joint

_intaking gearing - bag motor - 10to1 - 12v

Intake roller

Team JVN: Aren’s “Sweet Spot”

Often, strategy is determined based off of scoring calculations, observations based on experience, or just plain gut feel. However, sometimes they come from something a bit more inspired.

One of the defining moments of Team JVN’s weekend was a calculation done by Aren Hill that we’re affectionately calling “Aren’s sweet spot.”

arenssweetspot

From the beginning, the team assumed that doing a “layup” motion from against the wall (or ~20″ back) would be the most effective way to consistently score in the high goal. It would be repeatedly testable and possible to replicate in match conditions, two things that are crucial for a basic robot design. A former robotics driver and drive coach, Aren wanted to see if there was a way he could make it even easier on the driver. A quick 2D “Crayola CAD” easily laid out the parabolic path a ball would take upon leaving the robot, and revealed something interesting. Since the goal opening is taller than the ball by one foot, the previous mentality that you need to shoot precisely to score from the field turns out to be somewhat false. The above image shows this path – the vertical line in the middle is the field wall, with an opening for the goal. As becomes apparent, if you peak your parabola just below the top of the goal, you actually have access to a very wide starting range to score from (87 inches, or 7.25 feet, in this example). Increasing the power of your shot makes the parabola shallower, widening that “sweet spot” starting range. At this point, the prototyping kicked into overdrive. We had the opportunity to go out to Greenville High School, where the Robowranglers had been building the practice field that they will use for this season. The prototype was pulled back from the wall about 7 feet, starting angle was raised, and surgical tubing was increased. In a word… success. http://www.youtube.com/watch?v=3s2Ivy6nH8k After seeing that, we never looked back. All future iteration served to refine that design and widen the applicable sweet spot. Tune in to the robot reveal at noon on Tuesday to see how we did!

Team Copioli: Building a Simple Robot

One of the goals for Build Blitz was to give the teams with very few resources some design ideas that were very simple, yet had the potential to have a significant impact on a match. From the outset on Team Copioli, we thought we would make a priority list, and only focus on the top 3-4 items on the list. We recognized our own resource limitations (mainly time), and wanted to showcase the power of simplicity. However, as the process has gone on we’ve had very quick success with our prototypes, allowing us to pursue more of the items on our priority list. As such, while our robot is still very simple to construct, it’s definitely not as simple as it could be, or as we had initially envisioned. We didn’t want to abandon the idea of simplicity, so we’ll take this blog post to talk about what we would build, if we were going with the simplest approach.

Let’s revisit our priority list from yesterday. For full details (and the complete list) take a look at this blog post. If we chose to remain simple while still maintaining competitiveness, we would focus on only the first five items.

1. Drive. Obviously, we would need to have a driving robot.

2. EJECT! EJECT! EJECT! Being able to release a ball is a must, otherwise you run the risk of choking your own alliance.

3. Receive from the Human Player. This the most basic way to enter a ball into play, and allows you to have the potential to be part of an assist.

4. Score Low. This only requires a somewhat controlled release, and gives you the potential to convert assists into actual points.

5. Pick up off the Ground. Our final priority. This greatly increases your assist potential, as you can now pick up any ball that’s been released by an alliance partner (or their human counterparts).

Combining just these 5 relatively simple tasks, would make you a strong asset to any alliance, even at the highest level. This type of robot could be a first round pick at most Regionals, and a second or third round pick at the Championship.

Remember, it’s better to do 5 things at 8 out of 10, than 8 things at 5 out of 10. “The jack of all trades is the master of none.” Simple can win championships. In fact, I’m in the building with one of those simple World Champions right now. unnamed

Team JVN: The Power of Prototyping

Team JVN started out with a strategy session that went surprisingly quickly. Once we began analyzing the game, we realized that due to the nature of the game cycles, it is pretty easy to determine the possible flows a match can take. (Well, at least as far as we think!) We discovered that the highest scoring cycles all included some way to elevate the game balls, even if it’s only over the truss and not more complicated/difficult movement. We began talking about putting a launcher of some kind on the robot, perhaps something that can intake the balls from the floor; add in a catcher and you have an extremely robust scoring machine. It also means that you become an attractively versatile alliance partner, which is obviously desirable.

One of these all-in-one machines could truss or catch, score by launching into the high goals, pick up another ball without catching it in the air, and so on. Our team felt this was a good path and decided to move forward prototyping a launcher/catcher robot. A catapult-style launcher would fit in well with our initial intentions of planting our robot on the goal wall and doing a layup-type movement. The catcher component would help show how viable truss-catching actually is, and would give us a feel for the new 20″ outside perimeter rule for 2014.

Our first prototype, the catcher bot, was surprisingly large. It actually inspired our confidences in the ease of making something that could both catch effectively AND toss a ball to another catcher bot. Given the potential scoring importance of assists in this year’s game, this was a particularly important discovery for us. The second prototype, our catapult launcher, had a ball airborne within the first two hours of the build. This was also particularly confidence-inspiring for the team. We utilized an old 2005 kitbot chassis that we had laying around into the base for our robot. We sent team members Charles Wensel, Carlos Perez, and Randy Larsen on our first Home Depot run for some 2×4’s and used those to create a tower. We added VersaFrame parts for the arms, added surgical tubing for tensioning, and voila – our catapult was working like a charm. But all of that was just the beginning.

After the prototypes were complete, we began JVN’s favorite part – the iteration of our designs. Those on ChiefDelphi or that have worked with John over the years have heard his “Design is Iterative” mantra many, many times. And for good reason – it’s an incredibly important part of the design process. The subteam – and later, most other team members – spent the majority of their afternoon and evening testing the launcher, recording the results, and attempting to find the correlations. For example, we noted the direction the ball was launched (e.g., “ball launches straight up”). Then we tweaked the robot in some way, such as tilting the robot forward to simulate changing the hard stop position. We then recorded the results – “ball now launches more forward” – and repeated this process over and over to understand the launcher’s behavior. As we tested the launcher, the structure itself began to change. We began to change the parts of the robot that we felt might affect these key components, and eventually ended up creating a more versatile and adjustable robot overall. Specifically: adjustable peg lengths for the ball cradle, adjustable hard stop length, adjustable pivot point for positioning, adjustable pivot height, adjustable surgical tubing strength, adjustable starting angle for release, etc. When the robot changed, our results changed as well. Now our results were more like, “Launches straight up. Adjust nylon strap to change actual hard stop position. Now launches more forward.”

To understand the robot further, we changed only one variable at a time to really nail down the correlations between each variable and the final output. We kept it simple by using basic tools (such as a tape measure) to track and record how much a nylon strap needed to move, or an angle meter to record the starting angle, etc. This isn’t complicated to do, but so many teams get this wrong by not properly dedicating the time and effort to this task. Small prototyping efforts can yield hugely important results later in the build season. By being efficient in our prototyping processes (and by utilizing some cool maths that we’re referring to as “Aren’s Sweet Spot” that we’ll bring up in a later post), we had an extremely consistent high shooter robot by the end of evening. It appears the final robot will end up looking very similar to the prototype design since we were pleased with its overall performance. There’s still a lot ahead of us, not to mention a small mountain of CAD work. We’ll keep you updated!

Team Copioli: Drivetrain Design

Team Copioli considered a variety of drivetrain configurations. Even though we finally settled on one, we’re presenting all 6 configuration examples, along with details on the gearing for the community to see. All options are West Coast Drive for using the VersaFrame and 6 wheels.

First, the two wheel options:

1. 4″ VersaWheels

4wheelside
2. 3.25″ VersaWheels

325wheel side

We also considered three different drivetrain options:

1. 3 CIM Ball Shifter – including gearing with 3.25″ wheels or gearing with 4″ wheels

2 cim in ballshifter 325in wheels
3cimballshifterspeeds 325in wheel
3 cim ball shifter speeds 4in wheel

2. 2 CIM Dog Shifter – including gearing with 3.25″ wheels or gearing with 4″ wheels

wcpds
wcp shifter 325in wheels speeds
wcp shifter 4in wheels speeds

3. 3 CIM Single Speed – including gearing with 3.25″ wheels or gearing with 4″ wheels

wcdss
wcp single speed 325in wheel speed
wcp single speed 4in wheel speed

Our team decided to go with the 3 CIM Ball Shifter, except we’re only going to use 2 CIMs. (We’ve already allotted two CIMs to the launcher, so we only have 4 available for our drivetrain.) Why not just use a 2 CIM ball shifter in this case? Good question. The 3 CIM Ball Shifter is designed to be mounted right into a West Coast Drive, thus it’s a natural contender for the VersaFrame. We’re going with 3.25″ wheels, for compactness.

Mike & Justin: First Thoughts

We’re lucky to have Mike & Justin in-house for the Build Blitz to help get their unique perspective on the event. We believe they’re both a great representation of the pulse of the FIRST community, and sat down with them to talk about their initial reactions. Q: What did you think about the brainstorming activities for each team? A: Team Copioli was in the conference room for a much longer time. They focused on pure strategy, planning thoroughly before execution. They talked through the details in-depth before they decided to get started. Team JVN did talk through strategy but focused less on the game and more on the robot strategy. They definitely took a more hands-on approach. Q: We’ve got two very different management styles leading each of these teams. Any thoughts on how they’re working so far? A: It’s no secret that Paul Copioli is a very dynamic personality and a strong leader. In the Team Copioli discussions, the entire team had input but it was obvious that Paul was leading and directing the discussion. Team Copioli strongly utilized Karthik, their sideline reporter, as game strategy is one of his strong suits. John V-Neun isn’t as vocal, but it’s clearly obvious that he is equally as passionate about the success of his team as Paul is about Team Copioli. Grant, Team JVN’s sideline reporter, has a strong role in ensuring the documentation is as complete as possible; he’s been doing a great job making sure their ideas have been captured. Team JVN hit the ground running – they did less talking through the issue but have been actively prototyping their ideas. Q: How is the prototyping different by team? A: Team Copioli currently has 4 people actively CAD-ing their robot. Team JVN has John CAD-ing, but the rest of the team prototyping. It’s a sharp contrast! We feel like Team Copioli is really treating this like the three-day challenge it is, whereas Team JVN is looking at it in the full six-week perspective. We feel like Team JVN may end up with a more prototype-looking robot and Team Copioli will have a much more refined, professional-looking robot. Q: What are your thoughts on the overall Build Blitz? Is the event playing out the way you thought it would? A: There’s no secrets! I knew that the general idea was to be as transparent as possible, but we’re overwhelmed by the mass documentation. It seems different than a lot of normal kickoffs – this isn’t the same as hunkering down with your team. Sometimes we feel like less is shared that way. Here at Build Blitz, they’re obviously working hard on emphasizing teaching others their brainstorming, prototyping, and building process. It’s an excellent look into the brains of JVN, Paul, and Karthik and to understand their past FRC successes. This is going to advance the FIRST community. Stay tuned – we’re just getting started and there’s still 66 hours to go!

Team Copioli: Aerial Assist Priority List

Team Copioli has been working diligently on creating our priority list – which in fact is completed well in advance of our anticipated schedule. We’re working well together and have finally hit a groove. Although Aerial Assist has thrown some interesting challenges our way when you consider our abbreviated build season, the brainstorming went relatively smoothly and we’re ready to get cranking on the prototyping work ahead of us.

We set our priorities as follows:

1. Drive! – Our team feels strongly that this always needs to be number one. If you cannot move, you cannot play this game offensively or defensively. (There is an option for a stationary passer, but it’s really too restrictive for our liking.) There’s a lot of opportunities for strategic movement around the field, and so we want to ensure our drive system is robust.

2. EJECT! EJECT! EJECT! – If a ball gets stuck in your robot, your entire alliance ceases to be able to score any points. This is very bad. Every team in FIRST needs to be able to release the ball if they plan on carrying it… otherwise they’re taking a pretty severe risk that they could be hindering their alliance partners. It’s better to be safe than sorry, especially when the stakes are high.

3. Human Players – Receive & Possess – We decided that receiving and possessing a ball from a human player is a basic functionality all teams need to have. Most teams will overlook how difficult this task can be, so we want to put particular focus on the human player role. You can’t do anything with a ball if you can’t possess it, and we believe this is the easiest way to acquire it. We thought about last year and how difficult it was for teams to slot-load frisbees from the human player station.

4. Score Low – We sat down and figured out that the low goal, with one pass and a truss, equals an easy 21 points. The high goal, with one pass and a truss, equals 30 points. The math doesn’t lie – low goal scoring is 70% of high goal scoring. However, it’s important to factor in that scoring low is much easier than scoring high. We think a robot that gives up the option of scoring high can still end up a top tier robot in this game. This was an interesting discovery.

5. Ground Pick-Up – If a ball ends up on the ground and no one can pick it up, your alliance comes to a grinding halt. We also thought it was valued more highly than attempting to truss, because it certainly gives you more options on the field. There’s going to be many more opportunities to pick up from the ground, so we felt it was an important capability.

6. Trussing! – …that being said, obviously we’d like the capability to truss. Big points, and we think it will be easier to do than scoring high – it requires less accuracy, for one. The goal has a 36″ opening and the balls are 24″ themselves – that doesn’t leave a lot of wiggle room for the robot to shoot. Also the points aren’t reliant upon a goal being scored – it’s just 10 points on the board no matter what.

7. Catching the Ball – Trussing isn’t reliant upon a partner, but the scoring is the same. So we placed “catching the ball” lower on the priority list than trussing for that reason: it’s a more difficult task. Not to mention the accuracy that is involved… that could also be difficult to dial in.

8. Score High – To be honest, this is low on the list given the difficulty. It’s not easy to be a very high-scoring robot in this game, and the value of those high-scoring options seems lower once you consider the ease of the other options. It’s notable enough to be on the list, but very low.

Now we’re set to start our prototyping, and our CAD team is going to crowd into Paul’s office to get to work. More coming soon!

Team JVN: Late Start

If you tune in right at noon today, you may notice that it looks like Team JVN isn’t jumping off as quickly as Team Copioli. The truth is, they’re not. As many of you know, John V-Neun is the Lead Engineer for FRC team 148, the Greenville HS Robowranglers.

He promised the students on 148 he would finish running kickoff with them, before jumping into Build Blitz with TeamJVN. The result of this promise, is that TeamJVN will spend a few hours with the students of Greenville High School following the typical Robowrangler process before starting on their own (stupidly fast) pace. Only a few hours left!