Author Archives: Grant Cox

Build Blitz 2015 – What a Rush!

Recycle Rush is here, and the 2015 Build Blitz team has tackled this complex engineering challenge head-on.  Our hope is that the educational resources, guides, and insights created during the past week will help all teams in their pursuit of superior performance.  Check out the highlights below!

Karthiks Strategic Analysis VersaFrame-Linear-Elevator-thumb Pinch Claw Design Process Interviews Simple Tote Puller (front) AM14U2 with VEXpro Upgrade 4-Bar Stacker Mecanum Thumbnail


Educational Resource: Karthik’s Strategic Analysis (and Live Google Hangout)

The first major event of the week was Karthik’s Strategic Analysis, an exclusive application of Karthik’s proven “strategy dictates design” methodology to this year’s game.  After taking a day to digest the rules and scrutinize its intricacies, Karthik was able to create a prioritized list of design goals intended to maximize a team’s scoring potential.

The Analysis continued that evening with a live Google Hangout alongside the President of VEX Robotics, Paul Copioli.  Karthik spent some time detailing his strategic priority list before he and Paul took questions from the FRC community.  The ensuing conversation was engaging, exciting, and (at times) surprising – if you watch one thing from this year’s Build Blitz, you won’t want to miss this!


Design Concept: VersaFrame Linear Elevator

VersaFrame Linear Elevator
CAD file (STEP, 5.76 MB)

Stacking Totes is one of the primary (and most versatile) scoring opportunities in Recycle Rush.  Whether you’re going for the 40 point Coopertition Stack or building stacks on Scoring Platforms, this is a year to go vertical.  A standard chain-driven linear elevator is an efficient way to accomplish this feat, and one Build Blitz team undertook the challenge of creating one entirely out of VersaFrame.  Two new VEXpro kits later, they succeeded.

Download a STEP file of the VersaFrame Linear Elevator here and visit the VersaFrame Gussets page to order the new parts required to build your own!


Design Concept: VersaFrame Pinch Claw

Recycle Rush features an element that hasn’t been seen in FRC for several years: multiple types of gamepieces to manipulate. One Build Blitz team took it upon themselves to overcome this engineering challenge by developing a simple pinch claw that can manipulate both Totes and Containers. The results were promising – check out the CAD file or drawings below to build your own out of VersaFrame.


Educational Resource: The Design Process and Recycle Rush

All successful FRC teams, without exception, implement and follow some sort of design process.  The Build Blitz participants are well-versed in their own versions of the engineering design process, having used it for years both on their own FRC teams and in their “real world” jobs or projects.  We sat down with each team to ask them a few questions about how they view the design process and how they are applying it to Recycle Rush.  The result was one of the most insightful and valuable posts of the week – check it out to find out how they’ve had to adjust their processes this year, how teams can get by without access to CAD, how to avoid common FRC design mistakes, and more!

Reliability and consistency are paramount. If you do ONE thing, every single match, without fail, you will beat the guy who does many different things poorly. Every time.


Design Concept: Simple Object Manipulators

Simple Tote Puller (front)This year, one Build Blitz team tried something new.  While custom elevators and linkages are great ways to help elevate the mid-tier of teams, we wanted to go even simpler.  How could literally a few pieces of hardware be attached to a basic robot frame and still create a solid contributor to a qualification or playoff alliance?

Forks Mounted on Drive BaseThe passive hook and plastic slider prototypes kicked this direction off with great success.  It turns out that a few pieces of VEX EDR metal and a sheet of polycarbonate are all that is needed to successfully move Totes around.  The second release was a set of forks made out of VEX EDR metal that could manipulate both Totes and Containers, achieving Karthik’s most important strategic goal.  These ideas are all about keeping it simple and effective, a crucial lesson for any team looking for a place to get started.


Educational Resource: Build Blitz 2015 Drivetrain Design Guide

ddgcover
PDF, 2.1 MB

Recycle Rush introduced a new element into the mix that has never been seen before in the FIRST Robotics Competition: a nearly complete lack of size requirements.  Thanks to this exciting new dynamic, creating a 2015 “Drive in a Day” that would suit all teams was no longer a feasible option.  Instead, the Build Blitz team put together a comprehensive Drivetrain Design Guide.  This year, there isn’t a “one-size-fits-all” drivetrain – the ideal drivetrain is the one that fits YOUR robot’s needs.

While the guide was created with the 2015 game in mind, it touches on many “evergreen” fundamentals of drivetrain design that will also apply to future years.   Explanations  for angle of approach, “Crayola CAD”, and an introduction to proper speed and gearing calculations are all included (just to name a few).

When you’re firing up your drivetrain for the first time, and you’re testing to see how it transitions over the bump, remember one thing: center of gravity & weight play BIG roles in the way it will perform.  Test your robot in “real life” configuration.  Fully loaded, including any game objects it might be carrying.

This field has one other obstacle designers need to consider: PARTNER ROBOTS.  This is especially important if you’re not crossing the scoring platforms.  Make sure you think about traffic flow before you build an “aircraft carrier” robot and expect to drive it around with impunity — you have two partners who may also have aircraft carriers!


Educational Resource: Claw Design Guideclaw-cover

Recycle Rush features another element that hasn’t been seen in FRC for several years: multiple types of gamepieces to manipulate.  More than ever, proper claw (manipulator) selection and prototyping is crucial to teams’ success.

This guide will help teams learn about a few common manipulator styles and choose the claw that works best for them.

“Due to the nature of competitive robotics, nearly every game involves some sort of object manipulation. Whether it’s picking up an object and placing it on a goal or gripping onto a field element, claws are an extremely common method of object manipulation that most teams consider at some point during their design process. Claw designs can be as varied as overall robot designs, but most fall under one of three categories: roller claws, pivot/pinch claws, and passive/fixed claws. The purpose of this design guide is to introduce these three primary styles and to help teams evaluate the best manipulator for their needs.”


Design Concept: AM14U2 VEXpro Upgrades

The Recycle Rush Scoring Platform features one of the sharpest approach angles in recent FRC history.  If traversing this short but challenging bump is part of your team’s strategy, then proper drivetrain analysis, design, and testing are essential to ensure a smooth transition.

With a few minor modifications, the 2015 Kit of Parts drivetrain can be easily adjusted to use VEXpro 6″ Traction Wheels and belts. This upgrade allows your drivetrain’s wheels to maintain full contact with the ground through its entire journey, reducing the risk of frame damage or becoming stuck.


Design Concept: 4-Bar Stacker

This 4-bar stacker was designed to stack up to two Totes on the Step – ultimately using this to assist in gaining Coopertition points. The concept of a 4-bar is common in FRC designs due to its simplicity and effectiveness, qualities which are readily apparent in this design. Powered by a VersaPlanetary Gearbox and Mini CIM motor, this linkage can be paired with a pinch claw or other manipulator to stack Totes with ease.


Design Concept: Mecanum Drivetrains

One of this year’s desired drivetrain design traits, as identified by the Drivetrain Design Guide, was side-to-side (holonomic) motion. Thanks to a complete lack of defense and the necessity of precision alignment for maximum scoring, being able to strafe sideways is a no-brainer for Recycle Rush.

While many teams are often hesitant to bet on a mecanum drive due to its weak performance under defense, these unique wheels actually fit the bill nicely for this year’s challenge. The Build Blitz team put together two options for creating a Mecanum VersaChassis, using both the classic Single Speed Double Reduction Gearbox and the new for 2015 Single Reduction Clamping Gearbox.

Linear Elevator is Complete!

The previously showcased Linear Elevator is complete! A few minor modifications have been made since the initial video – most noticeably, a constant force spring was added to aid with raising heavy Totes. This elevator is perfect for mounting your favorite object manipulator onto, and can integrate well with many different base robot designs.

VersaFrame Linear Elevator
Click to download CAD file (STEP, 5.76 MB)

Keep an eye on the VersaFrame gussets page tomorrow, where you’ll be able to purchase the new gussets and build your own VersaFrame Linear Elevator!

The Design Process and Recycle Rush

One of the primary benefits of the FIRST Robotics Competition is its emphasis on the engineering design process during build season.  All successful FRC teams, without exception, implement some sort of design process. These processes are not a mystery – there are many resources online for teams looking for help.  The VEX EDR Curriculum and Karthik’s Strategic Analysis are both great places to start.

The Build Blitz participants are well-versed in their own versions of the engineering design process, having used it for years both on their own FRC teams and in their “real world” jobs or projects.  We sat down with each team to ask them a few questions about how they view the design process and how they are applying it to Recycle Rush.  The varied answers offer an exclusive insight to the core of what it takes to succeed in competitive robotics.

 

What is the most important step in the design process you use for FRC?

“Brainstorming.  You need ideas.  Without ideas, whether they’re off-the-wall, outside-the-box, or just ‘normal’, you won’t even have a place to start.”

“Understanding the problem.  Make sure you start from scratch and take time to understand what’s actually important, forming a list of requirements.  Karthik’s Strategic Analysis can help with this.”

“Separating what I WANT to do from what I NEED to do.  Many times, a glamorous idea will jump out at you right away, but you need to avoid limiting your creative vision by jumping to this conclusion.  For example, in Recycle Rush, building as many giant stacks of Totes as possible immediately comes to mind – but when you step back and look at the game as a whole, there may be other ways to achieve higher scores.”

Most teams have created a design process based on historical assumptions of FRC games.  With the major changes in Recycle Rush, what parts of your design process needed to be changed this season?

“With changes to the playoffs and how teams are ranked, you may have to think differently about your match strategy.  Being the best partner you can be is crucial.  Since the ranks are based off of average score, it’s very likely that the #1 seed will be the best scorer.  However, the best PARTNER will be the #1 pick by that seed – not necessarily the second-best scorer.”

“With the standard bot sizes thrown out the window, an important constraint has been removed. Defining your constraints is an incredibly important part of engineering.  The removal of such a basic constraint does allow for creativity, but can be overwhelming.”

“This game’s non-defensive nature has completely changed our build philosophies.  You no longer need to be crazy robust.  This is an entirely new way of thinking about complexity and how it relates to robustness.  You still need to emphasize consistency, but that no longer means being robust enough to survive a hit from a cinderblock.”

“You’re no longer limited by many of the traditional rules.  You can do whatever you want – which could be dangerous.  Teams need to be able to predict and judge what they are capable of.  Now, more than ever, there is a high risk of overreaching.”

What mistakes in the design process do you commonly see FRC teams making?

“Getting to the ‘end’ and just sitting there, complacent with their result.  Design is an iterative process – it may take only 5 more minutes of iteration to score 5 more points every time.”

“Jumping to the ‘how’ too fast before evaluating the ‘what’ or the ‘why’.  The answer to ‘how do you score in Recycle Rush’ should not be ‘with an elevator,’ it should be ‘by stacking Totes.'”

“Not realistically understanding their team’s capabilities.  This game, more than ever, will be won or lost in the build season.  Don’t overreach – you will not succeed.  However, don’t underreach either – you will be leaving points on the table by not being everything your team can be.”

“Overestimating what their team can do.  This applies to robotics games in general beyond FRC.  And, I suppose, to life in general.”

“Going straight to design without prototyping.  It’s important to prove the viability of a system before going deep into CAD.  If you make the world’s best CAD file for a robot that doesn’t end up being able to compete, you won’t have time to step back and create a better system that actually works.”

How can teams without professional engineering mentor support improve their design process?

“Take advantage of the community in general, whether it’s Build Blitz, Robot in 3 Days, Chief Delphi, or something else.  There is absolutely no shame in researching what others have done before you.  Be cautious, though.  Try to parse out the noise by looking to those who tangibly succeed (win) consistently, or to those who are highly respected by the community. The Simbot Seminar series is a great example.”

“Every decision you make should have a ‘why’ associated with it.  Try to avoid choosing things arbitrarily.  If you don’t have a good reason or can’t come up with one, keep investigating until you can find something that does have that solid ‘why’.”

“Make sure you HAVE a process. Watch out for the ‘Ready-Fire-Aim’ syndrome.  If you implement some sort of process, whether it’s the VEX EDR CurriculumKarthik’s Strategic Analysis, or something else, you will already be a step above those who jump right in.”

For teams without the ability to use CAD, how would you recommend that teams structure their process to make up for this missing resource?

“Spend even more time on accurate physical mockups.  For example, if you’re trying to pick up Totes from the floor, make sure you have the actual Totes, you start them in the correct layout, your carpet is as close as possible to competition field, etc. Most CAD starts with ‘Crayola CAD‘ anyway; you should try to do something similar in the physical world.”

“Plywood and 2×4’s work great.  However, VEX EDR, VEX IQ, or other construction systems are inexpensive ways to make accurate small-scale mockups quickly.  Think about it – every episode of Mythbusters starts with a small-scale mockup before they move to the real thing.”

“I’ve seen some teams be successful using large sheets of paper or whiteboards for 1:1 robot drawings. It’s a throwback to classic drafting techniques and helps to visualize everything.”

“Get CAD.  At the very least, experiment with some free 2D sketch tools like SketchUp Make (formerly Google SketchUp), PTC Creo Sketch, or DraftSight (from the makers of SolidWorks).  Additionally, both SolidWorks and Autodesk have free or discounted options of their professional CAD suites for educational use.  Even using 2D ‘Crayola CAD‘ will save you enormous amounts of time in the process as you try to lay everything out.”

Any final pieces of advice for teams, either about the design process or about Recycle Rush?

“Be the best team YOU can be.  The goal of any FRC team should be to build EXACTLY as complex or as powerful as they can without overreaching.”

“Reliability and consistency are paramount.  If you do ONE thing, every single match, without fail, you will beat the guy who does many different things poorly.  Every time.”

“Never underestimate the power of prototyping. You don’t know what you don’t know – it’s much more difficult to try and predict how something will perform than it is to simply build a mockup and test it.”

“Savor the opportunities granted by Recycle Rush.  There is nothing more fulfilling than coming up with a creative solution to a complex problem, and this game is FILLED with complex problems.  We should consider ourselves fortunate that FIRST has given us this complexity to work with.”

Simple Object Manipulation – We’ve Got a Container!

Pushing a Recycle Rush Container 5" from the Ground The first project from the Simple Object Manipulation group showed two ways to move and score Totes with ease.  Totes are only one portion of the game, though. Karthik ranked manipulating Recycling Containers as his top priority, second only to actually driving around the field.  It was time for the Simple Manipulators group to tackle this high-value game piece.

After some manual testing (pushing the Container from various heights by hand), we determined that they can actually be pushed fairly smoothly without tipping over – as long as you keep all pressure approximately 5″ from the ground (or lower).

 

This discovery made the design and prototype very straightforward.  By attaching a few pieces of VEX EDR metal to a pre-built drive base (sound familiar?), we were able to push, guide, and score both Totes and Containers with ease.

Forks Mounted on Drive Base (close)  Forks Mounted on Drive Base  Recycle Rush Forks (alone)

AM14U2 Upgraded to 6″ VEXpro Traction Wheels

The Recycle Rush Scoring Platform features one of the sharpest approach angles in recent FRC history.  If traversing this short but challenging bump is part of your team’s strategy, then proper drivetrain analysis, design, and testing are crucial to ensuring a smooth transition.

With a few minor modifications, the 2015 Kit of Parts drivetrain can be easily adjusted to use VEXpro 6″ Traction Wheels and belts. This upgrade allows your drivetrain’s wheels to maintain full contact with the ground through its entire journey, reducing the risk of frame damage or becoming stuck.

Click here to download a CAD file (ZIP, 21 MB) of the upgraded drivetrain to visualize the changes, and keep an eye out for detailed instructional drawings and BOMs coming soon!

What is the -Simplest- Way to Move a Tote?

The goal of Build Blitz is, and has always been, to provide educational resources for medium-level or inexperienced teams who may need some additional help to get going.  The concepts explored thus far (4-bar stacker, linear elevator, and pinch claw) are solid subsystems that can combine with a variety of other systems to form a complete robot.  These are intended for teams looking to seed or be a solid pick by a seeded robot.

However, we wanted to know if we could go even simpler.  For teams just getting started with absolutely minimal resources, how can literally a few pieces of hardware be attached to a basic robot frame and still create a solid contributor to a qualification or playoff alliance?

The Passive Hook

Theory: Drag a Tote from the top using a passive hook.  The robot can drive up to a Tote in the Landfill and use its natural lip to drag it across the field.  To dislodge, the robot can either drive over the Scoring Platform (if its drivetrain allows) or just turn sideways and slide the hook off.  Angled sides of the rake will assist with this dismount.

Simple Tote Puller (top)  Simple Tote Puller (close)  Simple Tote Puller (front)

Testing: The prototype was built using three pieces of VEX EDR metal clamped to an existing drive base.  It ended up working very well, dragging the Tote along with ease when in the “long” orientation.  The “short” orientation did not work as well with this initial prototype; this will be something to work on for the next iteration.

The Plastic Slider

Theory: Slip a plastic sheet underneath the Tote and drive away with it. Since the Tote is sitting on top of the sheet, it now moves with the robot! To get the tote off, pull the ‘rug’ from underneath the tote.

Plastic Tote Slider

Testing: Similar to the hook, this was accomplished by clamping a spare Delrin sheet (though Lexan would also work) onto a pre-built drivetrain.  (Fans of FRC Team 148 may recognize the X009 concept used here). This test worked, but not as well as we would’ve liked.  The sheet actually had a smaller footprint than the Tote, meaning that the Tote occasionally caught the carpet and slipped off of the sheet.  The next version will feature a larger sheet (#MeasureOnceCutTwice), and we’ll also see how this theory applies to a Recycling Container.

These concepts are true applications of the KISS principle to Recycle Rush.  Admittedly, these robots (by themselves) will probably not be the highest-scoring robots at an event.  However, consistency is key in a helpful alliance partner, and the simplicity of these robots will be a primary contributor to that consistency.  This is a mindset that will help all teams (rookies or veterans) in their quest for Recycle Rush success.

Day 1 – Great Strategy, Upgraded Drivetrains, and a Claw!

Day 1 of Build Blitz has come to a close, and we have some great beginnings to share.

Karthik’s Strategic Analysis

Karthik spent his first few days of this build season creating a strategic priority list for Recycle Rush.  His analysis weighs the difficulties of key tasks against their rewards – and the results may not be what you expect.

He then took to the internet in a live Google Hangout, where he and fellow Build Blitz team member Paul Copioli broke apart the game even further.  They even had time to answer some questions from the FRC community.

 

AM14U2 UpgradesAM14U2 3 CIM Ball Shifter Concept 1

This year’s Kit of Parts drivetrain, the AM14U2, provides a solid foundation for teams to get started with.  We’ve started developing some ways to take this drivetrain to the next level.  Our first version incorporates our most popular shifting gearbox, the 3 CIM Ball Shifter, and some 6″ wheels to help traverse the Scoring Platforms.  Guides and CAD models will be coming soon!

Drivetrain Design Guide & Philosophy

Today’s work on the Drivetrain Design Guide focused almost entirely on the Scoring Platforms.  This is the first game in a long time to have a bump in the field, especially one of this magnitude (16 degrees). It does a great job of bringing several key design requirements (like angle of attack or ground clearance) into the spotlight – teams need to be very careful about taking these into consideration when designing their drivetrains.

Recycle Rush Bump Transitions Recycle Rush Bump Clearance

Pinch Claw Design

Earlier today we posted a video of the first pinch claw prototype test.  By the end of the day, the initial CAD for that simple claw design had been completed.  It now picks up both Totes and Containers, using a linkage to lock into place when holding a game piece.  Tomorrow, we hope to build one out of VEXpro parts (other than Versa2x4) for final testing.

CAD Pinch Claw (Iso View) CAD Pinch Claw (Top View, Open) CAD Pinch Claw (Top View)  CAD Pinch Claw Holding Tote CAD Pinch Claw Holding Container

Check back tomorrow for updates on the Linear Elevator, the 2015-Specific Drivetrain, and some information on Simple Game Piece Manipulation!

 

Pinch Claw Test #1 – Keeping it Simple!

The Build Blitz team is hard at work on their seven areas of focus to help teams succeed at Recycle Rush.  The first to have a working prototype was the Claw group!

Simplicity and reliability were the overarching mentalities that drove this claw design. The goal for this particular test was to determine a jaw angle that would acquire Totes in an imperfect orientation. Simulating real-world conditions whenever possible can help to avoid a common frustration: seeing a prototype that worked excellently in a perfect lab environment fall short in the field.  This particular prototype succeeded in its goal of acquiring (and stacking) a misaligned Tote!

Wooden Claw Prototype - Surgical Tubing     IMG_0607 Claw Prototype 1 - Engineering Drawing

In its current design (which, to be fair, is three 2×4’s bolted together), the pinching claw can only pick up Totes.  However, with slight modifications, the team is confident that it will be able to pick up Recycling Containers in future versions.