Articles by tag: design

Articles by tag: design

    Intake System Competition

    Intake System Competition By Evan and Austin

    Task: Compare build designs for the cryptobox intake system

    The block scoring system is going to be an integral part of the competition this year, and it will have to built sturdy. It’ll have to be reliable for us to have any shot of winning any matches. So we got to brainstorming. We spent a while at the whiteboard, drawing up various mechanisms and ways to pick up blocks. One idea was the idea of a block delivering system similar to those modern vending machines that have two degree of freedom movement. We began to design the contraption so that a conveyor belt could be placed on an up and down linear slide to position the blocks just right to make the different symbols. Another person came up with the idea to use our tank treads from Geb, our competition robot from two years ago, to push the blocks up a ramp and deposit them into the cryptoboxes. Neither of us could convince the other about what was to be done, so we both split off to work on our own models. Next week we will keep working on this build off of the century.

    Further Design of the Intake

    Further Design of the Intake By Evan and Austin

    Task: Design the grabbing systems further

    The sun came out and it was back to the field. We got started right away, both of us building our designs. Since the cryptoboxes were wider than the 18 inch sizing cube, we started by designing a fold out for the conveyor belt. This was entirely proof of concept, purely to see if it was at all aplicable in the game this year. We spent an hour or two gathering parts and put together an extending conveyor belt. This device would swing down, like the arrow suggests, allowing for more space to move the blocks back in forth, giving us accuracy in rune completion. This will be later attached to linear slides, allowing for an up and down motion.

    Intake Systems

    Intake Systems By Austin

    Task: Work on designs for the intake system

    Over the past couple of days we’ve experimented with a horizontally mounted track system that we had hoped would serve to move blocks through the entire length of the robot and into the crypto box. Immediately we noticed a few issues, the primary one being that the tread was static in terms of mounting and therefore wasn’t accepting of blocks when feed at an odd angle. To correct our feeding issue, we widened the gap between the tracks and added rubber bands in hopes of maintaining traction and adding to on demand orientation ability.

    Initial tests of our second prototype went fairly well, however the design suffered from some severe drawbacks; the first was its weight and size which would limit robot mobility and take up much needed space for other components, the second issue was that keeping the treads tensioned perfectly for long periods of time was nearly impossible and they would often sag leading to loss of grip, and finally the system was still fairly unpredictable especially during intake (blocks were flung occasionally). These finding lead me to believe we may scrap the idea in consideration of time.

    Aside from our track intake we’ve also been working on a gripper and slide system that shows promise.

    Narrowing Down the Designs

    Narrowing Down the Designs By Evan and Austin

    Task: Redesign our grabber systems

    In an attempt to get a working lift system before the coaches meeting we will be presenting at, a linear slide has been attached to the robot, along with a pair of grabbing arms. They work surprisingly well and aren’t as complicated as my idea. Plus the importance of speed has really taken hold on me this year. We need to be as fast as possible but my contraption is slow compared to the grabber arm. I think we'll be scrapping the idea for this grabber arm bandwagon everyone seems to be hopping on. While the grabber arm allows for quick pick ups and easy placement, our idea was only bulky and unnecessary because of our use of mecanum wheels which eliminate any need for a system to go side to side. Since the grabber was rudimentary, we’ll be making improvements and new iterations. We toyed with some materials earlier on in the season, and we’ll probably be implementing that into it.

    Slide Designs

    Slide Designs By Austin

    Task: Figure out slide mechanism

    After determining that the treaded channel was much too buggy to perfect with the time we had, we shifted attention to other scoring systems like grabbers, however before finding the right grabber we decided we needed to get the track for it completed first. We’ve had experience in the past with all sorts of rails from Tetrix kits that convert their standard channels into lifts, to the newer REV sliding rail kits which we also toyed around with in initial prototyping shenanigans.

    One of our key concerns was also wear and tear, in that we have had systems slowly breakdown in the past, such as our mountain climber and catapult, since they had plastic components that broke over time, we knew that long periods of use over multiple competitions would deteriorate the plastic components of either rail sets, and other rails that used full metal parts would simply be bulky and rough to fit in snugly with our robot. After a bit more research we settled on standard steel drawer slides from home depot, mainly because they were streamline and all around sturdy. The slides also provided us with easy mounting points for our future claw and attachments.

    We understood that whatever option we picked for slides would have to be easily repairable or replaceable during competition, should something go wrong. Since the drawer slide were easy to come by and needed little modification we could easily make duplicates to act as stand by and demonstration parts during competition.

    These positives came to form more than enough of a reason to continue prototyping our grabber that would eventually be attached once completed to the lift, which was now mounted to the robot and used a system of spools and pullies to extended above the minimum height for scoring in the top row.

    Building Competition 2017

    Building Competition 2017 By Evan and Austin

    Task: Find the best robot design

    The games have begun and it’s time to build. So that’s what Austin and I did. A war had been declared. Legions of the indentured collided on the battlefield. Millions were slaughtered during this new age armageddon. Austin had his army. I had mine. Two different ideas to do the same task: lift glyphs into their correct positions. A simple job but one that caused a rift in Iron Reign, an incurable rift between the forces of light and darkness.

    But then I decided to stop because his design had more speed than mine and speed is more necessary this year. My idea had been a lift that could move the glyphs back and forth but I realized that it would be a little too slow for the competition. Or, another solution would have had a side to side conveyor belt that moved glyphs back and forth to arrange them in the correct order, and then push them into the slots. This movement would have been separate from the four mecanum wheels that we are using in the chasis. His idea was simpler than mine, a conveyor belt that ran through the middle of the robot to bring the glyphs to the keybox, where they could be slotted in with the side to side movement provided by the mecanum wheels. So, like an outnumbered Supreme Court judge, I decided to join the winner so I could have a say in the early design. Once he got a prototype ofhis contraption working, it was able to pick up blocks effectively but it still needs improvement. It has issues with blocks at an angle, and it has trouble slotting the blocks into the keybox, but it's a nice step toward a working block system. We are currently planning to use the mecanum wheel base we used last year but this could change anytime. We left practice with a direction and that's better than nothing.

    Testing Materials

    Testing Materials By Austin, Evan, and and Tycho

    Task: Test Materials for V2 Gripper

    Though our current gripper is working sufficiently, there are some issues we would like to improve in our second version. The mounting system is unstable and easily comes out of alignment because the rev rail keeps bending. Another issue we've encountered is the cervo pulling the grippers so that they begin to cave inwards, releasing any blocks being held at the bottom. By far the biggest problem is our intake. Our drivers have to align the robot with the block so precisely to be able to stack it that it eats a majority of our game time. However, there are some advantages, such as light weight and adjustability, to this gripper that we would like to carry over into the second version.

      We tested out a few different materials:
    • Silicone Baking Mats - The mats were a very neutral option because they didn't have any huge advantages or disadvantages (other than not adhering well). These could have been used, however, there were other better options.
    • Shelf Liner - It was far too slippery. Also, when thinking about actually making the grippers, there was no good way to put it on the grippers. Using this materials would have been too much work with little gain.
    • Baking Pan Lining (picked) - It was made out of durable rubber but was still very malleable which is a big advantage. We need the grippers to compress and 'grip' the block without causing any damage.
    • Rubber Bands on Wheels - This material was closest to our original version and, unexpectedly, carried over one of the problems. It still requires very specific orientations to pick up blocks, which would defeat the purpose of this entire task.

    The purpose of this is as a part of our future grabber design, which will need to be relatively light, as our string is currently breaking under stress due to weight. The material must also have good direct shear and direct strength, as the grabber will have rotating arms that move in and out to grasp blocks. As well, we're replacing the tetrix parts with REV, as they're smaller and a little lighter, with the additional bonus of more mounting points.

    Designing the Grabber Further

    Designing the Grabber Further By Evan

    Task: Design the grabber design and make future plans

    The grabber has been evolving. A column made of a turkey baster and a wooden dowel attached to servo has come into fruition. The first drawings and designs are coming along, and some 3D printed parts have been thought up to allow the square dowel to become a hexagon. An adapter of sorts. The grabber and lift have been outfitted with a back board to stop blocks from getting caught underneath the backing bar. The back board is just some 1/16th inch wood cut to fit. The new turkey baster columns are in the first stages, so more info on them will come as more is discovered and progress has been made. The sketches will explain these designs better.

    Chassis Upgrades

    Chassis Upgrades By Austin

    Task: Upgrade our chassis

    Because our robot at this point has merely become a collage of prototypes that we compete with, there are often subtle improvements that need to be made. Starting with the wheelbase, Abhi has written a blog about the shields we printed to protect the glyphs from the gnashing bolts of our mechanum wheels, and we also tensioned all our set screws and motor mounts to make sure that our base was preforming in terms of the speed and strength we needed. As we add components to the robot things often are shifted around as well, after tuning up the drive train we focused on realigning our REV expansion hubs and their wiring so that nothing would be in the way of critical lift or drivetrain components.

    Any jettisoning bolts that have been catching components while moving, and any sharp edges have all been ground down to ensure that any motion is smooth and that there are minimal catching hazards during operation. Because of the earlier mentioned prototype state our robot was in, many of the key components laid outside of the 18 inch cubic limits and so these components we brought in and neatly fastened to the internals of the robot bearing in mind ease of access for future updates to components. This entire push for cleanliness was the result of upcoming scrimmages and practice matches that we would be participating in.

    Stopping Glyph Damage

    Stopping Glyph Damage By Abhi

    Task: Stop Destroying Glyphs

    Since damaging field elements is a huge no-no, we needed to fix this, we decided to create a 3-D part to protect the glyphs from our wheels

    Model:

    During the first attempt, I had just self taught Creo hours prior to construction. As a result, I was not very precise nor efficient in my design. Nevertheless, we recognized that there were some basic shapes we could use for construction such as a semicircle for the bottom half and two rectangles on the top part. We decided to use measurements that were estimated from a singular mechanum wheel. This culminated in the design below.

    Result:

    The part itself is made out of nylon as usual. Our main issue was measuring the wheel accurately to create a functional part. The two parts hampering the design was that the U-shape must be off the ground slightly, and that the shape's semi-circle would not have the full radius of the wheel. So, we iterated through various designs of the U-shape, changing the height off the ground by ~1mm each time. We also varied the radius, until we realized that we could measure the width of where the semi-circle segued into the rectangle and get the estimated diameter of the semi-circle.

    Wheel Protector Correction

    Wheel Protector Correction By Abhi

    Problem: Wheel Guard Innacuracy

    Refering back to the design of the wheel guard, we decided it was time to actually mount it on the robot. At first, it seemed like the part was perfect for the robot since it fit just snug with the screws on the wheel. However, upon mounting, we discovered the following:

    Turns out that the part is acutely shorter than the real height of wheel relative to the horizontal axis superimposed upon the vertical plane. As a result, a second and better trial for modeling needed to be conducted. For this run, I chose to measure the dimensions directly from the robot rather than a spare wheel.

    Correction:

    As seen above, the corrected version of the part looks and works much better. Though there is a slight margin of error in the success of the part due to the dynamic nature of the density of the field tiles , the part should be reliable for the most part

    How to make a part in PTC Creo Parametric

    How to make a part in PTC Creo Parametric By Abhi

    Problem: How to Make a Part in Creo Parametric

    PTC Creo Parametric is one of the best software to 3-D model tools that we can print out. I will detail how to create a part in Creo for both our team and any other teams who need help creating a piece. For this demo, Creo Parametric Academic Edition was used along with a pre designed model of the part.

    To begin the model, create a new part. Make sure you are making the part in the right dimensions since the 3-D printer needs special requirements. For the 3-D printer that Iron Reign has, we chose to make all of our dimensions in millimeters. You can change this configuration by going into File>Prepare>Model Properties >Units.

    Once your program is set to go, go under Model and press Sketch. This will create the base diagram which we will raise to make our part. Once the sketch menu appears, you will have to choose a plane on which we will draw. For this sketch, we will draw from the top plane since we want to raise it from the bottom. To do so, press on the top plane and press sketch. If the view is still in an isometric format, you can change the view by pressing the button indicated in the video.

    Once the sketch is set up, we need to draw two concentric circles with the right dimensions. To find the dimensions, I refer often to the premade part. Once I have made the system, I set up centerlines vertically to be able to draw better. Next, I cut off the top two parts of the circle since we will put rectangles on them.

    Next, select a line chain to draw two sets of rectangles with the bottom edge fused with the half circle. At the end, you should have a U shaped part. Now, we can draw another centerline along where we want the screw holes. After doing so, we can use the circle tool to make two holes in the rectangles.

    We now need to extrude this part to the right size. After pressing the extrude took, we can change the size on the arrow. After doing so, we need to place two high radius thin circles on either sides. These are placed as weight pads so that when the part prints, it doesn't curve on the printing bed.

    At this point, we can do some optional things to make our part..well lets say prettier. We can use the round tool so the edges look nicer and the screws are easier to place inside. After doing so, we can use the render tool to color all the edges. At the end, you will have a complete part to print

    End result:

    We hope you learned from this tutorial and are able to apply this to any future parts you make!

    Designing the Jewel Thief

    Designing the Jewel Thief By Evan

    Task: Design a part to remove the jewel

    The jewel thief, the mechanism for knocking off one of the jewels, was going to be one of the tougher parts of our bot to integrate, based on the chassis we began with. But, with a little engineering and some long thought, we came up with a few ways to implement it. First, we began with a side mount, and it was alright for the angle, but we switched our autonomous plan to begin pointing forward, presenting me with a new problem. The part we had used before would simply not work. We tried a modified version of the pusher we'd made, but it didn't fully suffice. It was impractical and would require more than a little wire extention for the servo. We finally decided that a frontwards approach should be taken from the side. Instead of a single middle forward facing prong, a two bar prong sticking from either side, meeting in the middle, and providing a platform for a potential relic placer. While not completely finished, we intend to have it done by the first qualifier, fully functional. It should allow us to knock the jewel off during autonomous effectively and efficiently, although that’s all to be seen.

    Relic Recovery Strategy Part 1

    Relic Recovery Strategy Part 1 By Austin

    Task: Determine building strategy for Relic Recovery

    Any well-versed team understands that, depending on the competition for the year, a robot will either be modified to compete or be built from the ground up. In any case, however, a robot often starts at its chassis, and teams have multiple companies that provide solutions to the common robot chassis’ needs and specifications. To name a few: AndyMark® has its standard kits that include all the parts and electronics needed to build a very basic frame that includes a few mounting points for the rest of the robot’s components, Tetrix has its standard kit that provides all the parts for an entire robot if used properly (however, we’ve discovered drawbacks to be mentioned later), and even REV has thrown its hat in the ring with new motor and battery types to add to the highly adjustable REV rail chassis kits. For rookie teams there is no lack of options for starting your robot chassis. However, as a team gains experience they find the flaws that come with each kit and move towards creating robots that harness equal amounts of parts from all companies. Here’s what we’ve learned about each company:

    AndyMark: overall, AndyMark is a great supplier for all the standard parts you’ll need, however we wouldn’t recommend buying their overall chassis kits because they can be on the pricier side and come with few replacement parts and too many unnecessary parts. Most of our gears, wheels, pulleys, motors, and batteries come from AndyMark in batches of parts that we keep on hand to prototype with or replace failing parts. This keeps us from paying for parts we don’t need and having what we do need on hand. The overall quality of their parts is high, but they do decay quicker with use, especially when running the robot at multiple competitions without proper repair time.

    Tetrix: Tetrix is highly standardized in all dimensions, making the connections between parts easy to grasp for basic builders who haven’t developed a mental 3D idea of what they’re working towards. Tetrix kits don’t include electronics. However, their brackets, channels, and joints are very useful for making connections between various components of your robot, so keep plenty on hand for quick fixes and prototyping. Our biggest concern with tetrix are their designated nuts; we find that they often are shaken completely off respective bolts, which can lead to mechanical failure and penalties. To combat the issue of robots quite literally shaking themselves apart, we recommend using nyloc nuts. They have a small amount of nylon in them that grips the threads of bolts making them almost immovable without a pair of pliers.

    Rev: Iron reign loves our Rev rails. The ability to have a mounting point at any incident on a bar is amazing, and often allows us to pull off the crazy designs we create. Rev has created a system that is beyond flexible, meaning that the limits of your designs have expanded. For those who want a chassis that is easily maneuverable, Rev rail is extremely light as well. While Rev is expanding into providing parts like AndyMark, we find that they are still in development but we eagerly await upgrades.

    Overall, Iron Reign wanted a robot chassis that was stable, maneuverable, and modular to our needs, so this is our compromise that we’ve applied to all aspects of our robot;

    - AndyMark FRC Standard Omni-Wheels: we chose these because of their dependability and maneuverability. They provide standard motion as well as strafing for fine-tuning movements in front of cryptoboxes. While we had to print custom mounts, and modify tetrix channels for the necessary axels, the wheels pared nicely with the rest of our components once mounted.
    - Rev Rail: our entire upper chassis is made from interconnected Rev Rails that serve as a smooth, easily adjustable, and light support for the massive omni wheels that rest below it. The rails provide plenty of room for future expansion, and can take quite a beating (we learned this the hard way by dropping our robot off a table).
    - Tetrix Channels and Brackets: these are the middle men, the parts we change to fit those awkward angles and fittings, such as the axels for our wheels. Overall never a bad idea to have extras on hand.
    - Hardware: we always use standard hardware sizes, but we make sure that the corresponding components are snug fitting and streamlined to minimize unnecessary snags and sharp edges.

    While these are the typical components that make an Iron Reign base, we have seen other teams get extremely creative with raw material, although this usually requires heavy machinery such as laser cutters and lathes. Overall, we are a team that uses what companies provide and modify it to fit our needs (which has worked well for the past years of competition.) For smaller start up teams we recommend a similar approach of learning each system and its advantages over the course of multiple years, and finding what you feel works best for your needs.

    How to Assemble parts in PTC Creo

    How to Assemble parts in PTC Creo By Abhi

    Task: Learn how to Assemble parts in Creo Parametric

    In addition to making parts to print in Creo, it is sometimes useful to combine multiple parts to make a model. For example, we can make a robot model by assembling parts in Creo. We have conducted a video on how to do so.

    For this tutorial, we first created two simple parts which fit snugly inside one another (done before the video). Then, we created a new assembly file and uploaded the bigger part first. We placed the smaller part and did the assembly by matching the sides of the cylinder. That is how we ended up with a cylinder with its hole plugged in the end.

    Reflections

    We hope to use Assemblies to make models for various structures in our robot in the near future. We hope this tutorial helps you with your endeavors!

    Gripper v4, Octopuckers

    Gripper v4, Octopuckers By Tycho and Abhi

    Task: Design a new piece for intake

    Version 2 of our gripper arms worked much better than our original. Due to their silicone material and trianglular shape, we definitely had more control over the glyphs than our one degree of freedom grabber arms. However, we still had issues we needed to address. When glyphs were taken in, since the silicone surface did not have much mobility and compressibility, glyphs would often fall. Due to slight changes in glyph size, the bigger glyph would determine the space between the grabbers, meaning the other glyph would be mobile despite us wanting its control. This is when we develoepd the first version of our new rotators.

    The first edition of our rotatory mechanism allowed us to play with ninjaflex printing and flexibility. They were 15mm extrusions designed to stack on one another on a REV rail or similar rigid structure. Since Ninjaflex can bend, we got more grip on the glyphs. It was definetely a well designed model but had many issues. First, each fin of the fan was very thick. Though it was able to grip glyphs well alone, the system was not able to grip much better when stacked together. We decided we needed more surface area contact with glyphs during intake.

    This led us to create a new model with thinner fins and thin tabs at the end. The thin flaps allowed more grip area with the glyphs allowing us to work better. Though good in theory, when we went to print out the part, we discovered our 3-D printer didn't allow printing vertically of surfaces less than 1 mm. Since this idea didn't work, we started thinking of the idea of suction cups. This led us to our current design.

    The design worked very well. We decided to name them Octopuckers since they had suction cup shape and there were 8 fins to a pucker. The surfaces of the octopuckers which would contact the glyphs were large and had a large area. Since this was heavier than the bridge connecting them to the center, the branches bent easily allowing for a grippy surface which was also flexible. After testing it on a small scale, it seemed to work well so we will continue development and implement it on our next edition of the grabber arms.

    REVolution Pulley

    REVolution Pulley By Tycho

    Task:Build an Army Worthy of Mordor

    This GT2 pulley has rounded teeth that engage nicely. GT2 pulleys and timing belts are the most common in use with 3D printers - but those are usually of the 2mm pitch variety. We didn’t think our printer would be able achieve the fine detail accuracy needed to print at that size, so we went for the 5mm pitch belts. On our printer we can take this part off and use it right away with only the most minimal cleanup. This is a 24 tooth pulley.

    REVolution Simple Dual Rail Plate

    REVolution Simple Dual Rail Plate By Tycho

    Task: Power to the REVolution

    The dual rail plate allows you to couple the rotation of two REVrails together. The distance between the holes should be based on how you are coupling them together. This model is designed to use GT2 5mm pulleys and a 46 gap timing belt.

    REVolution Basic HingePlate

    REVolution Basic HingePlate By Tycho

    Task: Power to the REVolution

    This is our most used hinge plate. The 4 holes can take M3 screws to attach to a REVrail on one side at the end.

    REVolution Narrow Inside Washer

    REVolution Narrow Inside Washer By Tycho

    Task: Power to the REVolution

    This washer is a stackable spacer that can be used to adapt standard bearings/sprockets/pulleys to thinned base plates.

    REVolution Thick HingePlate

    REVolution Thick HingePlate By Tycho

    Task: Power to the REVolution

    This is our most used hinge plate. The 4 holes can take M3 screws to attach to a REVrail on one side at the end.

    REVolution Pillow Block

    REVolution Pillow Block By Tycho

    Task: Power to the REVolution

    This is a standard pillow block. We had to add adhesion pads to the ends because the nylon would curl away from the print bed. But these are easily cut off with a hobby knife.

    REVolution 15x20 Tooth Sprocket

    REVolution 15x20 Tooth Sprocket By Tycho

    Task: Power to the REVolution

    This is our REV0lution 20 tooth sprocket for #25 chain. This took a lot of trial and error to get right, because it was the component most sensitive to our print settings. We had to inset the tooth profile quite a bit because any extra material created by perimeter settings would cause the gaps between teeth to be too small for the chain to fully engage, and because nylon is so slippery, this would radically increase the likelihood of the chain slipping. Or you would have to make the chain super-tight and that would increase the friction at the bearing. It still requires a pretty tight chain. And it requires a lot of post-print cleanup. The lip where the lowest layers spread out on the build plate have to be trimmed with a hobby knife - all the way around. And then the chamfers at the tip of the teeth have to be rebuilt. We used a reciprocating sander to do this. Nylon is one of the hardest materials to sand effectively, but fresh 220 grit paper will eventually do the job. We only need 2 sprockets for our new Glyph System, so it was worth the effort. This would be the first component that we would recommend replacing with a regular flat aluminum sprocket if you have the means to accurately broach a 15mm square hole in it. Or switch over to timing belts entirely - the timing pulley works fine right off the print bed.

    REVolution Rail End Cap

    REVolution Rail End Cap By Tycho

    Task: Power to the REVolution

    End caps are stops placed at the end of a REVrail. Five of the holes are for M3 bolts that can be screwed into the standard holes in the cross section of the extrusion. We highly recommend tapping these holes and then using threadlock to retain the bolts. So far we’ve only had to use a single bolt since we haven’t experienced very large forces The other 4 bolts are for attaching to a bearing on the far side of an attachment plate.

    REVolution Thin Bearing

    REVolution Thin Bearing By Tycho

    Task:Build an Army Worthy of Mordor

    This is the standard bearing / bushing that allows a REVrail to rotate inside a plate. It is typically coupled with a glide washer and two stops to bind it to an attachment plate or pillow block.

    REVolution Rail Stop

    REVolution Rail Stop By Tycho

    Task: Power to the REVolution

    This stop can be placed anywhere on a REVrail to trap mounting plates inside bearings. They are usually used in pairs.

    REVolution Custom Dual Rail Plate

    REVolution Custom Dual Rail Plate By Tycho

    Task: Power to the REVolution

    This shows customized version of the Dual Rail Plate. This is for our 4th generation rolling gripper system. The small ears are designed to hold a long M3 bolt that have a stack of mini ball bearings on them. These ball bearings squeeze our timing belts together, forcing them into a more oval shape, but still allowing them to glide. This reduces friction quite a bit. Otherwise we had to put a lot more tension between the pulleys to get the belt to fully engage. This plate also has grooves to attach servo pulled wires to control the plates angle one of the REVrails and it has a flange to mount our beater guards.

    REVolution Narrow Bearing Washer

    REVolution Narrow Bearing Washer By Tycho

    Task: Power to the REVolution

    Washers can be used as spacers. They are also used to smooth out the rough top layers. Keep the bed very clean and smooth and the bottom surface of parts should be very slippery against other nylon. Put these in between the rough top bearing surface of one part (with rough surface facing rough) and the smooth bottom surface of the next part, and the friction will be substantially reduced.

    REVolution Inside Washer

    REVolution Inside Washer By Tycho

    Task: Power to the REVolution

    This is an inside washer. It will fit entirely inside the standard plate hole. We don’t use these much, but they can be useful as spacers.

    Introducing Kraken

    Introducing Kraken By Abhi and Tycho

    Task:Design the robot model

    We have finally completed assembly modeling Kraken, Iron Reign's Relic Recovery robot. Named after the sea creature due to the robot's OCTOPUCKERS, Kraken stands as a fierce competitor in FTC.

    To the chassis, we added the glyph system mounting. We first designed a linear slide replica and constrained that to a small TETRIX U connector piece which attached to the REV rail base. On the other side of the linear slide was a TETRIX bar attached by distance and coincident contrains. Onto this, we mounted the grabber system, and assembly done with a combination of normal, distance, and coincident contrains.

    As on our robot, this linear slide system is supported by a small TShaped piece with two aluminum bars. This required tangency constrains with the inside of the T piece along with angle offset to the REV rail base.

    Finally, we attached the jewel thief mechanism via subassembly, We first attached servos to either side of the custom designed pentagon piece. Then, these servos were constrained to the REV rail base and partly to the phone mount bar extruding out.

    All of this went over our amazing chassis design. To see more info on the chassis assembly, refer here

    What's next?

    We hope this chassis provides an alternate testing mechanism for sizing of our future prototypes. Another version of the chassis is underway based on changes to our robot.

    Chassis Model

    Chassis Model By Abhi and Janavi

    Task: Use Creo Parametric to CAD the chassis

    After making significant development on our robot, we decided to model it. So far, we have developed the chassis of the robot seen below

    To develop this, many types of contraints were used.

    The entire model is dependent on this tetrix bar. The bar was constrainted using the Default feature since it was the base of the model. To this, the lift motor was attached as well as the battery box. These two were constrained by the Distance feature to the end of the bar.

    Four REV rails were attached to the TETRIX bar. These supported the wheels and their motors. They were constrianed through the Coincident to the bottom of the tetrix bar and Distance to the side of it.

    There are custom designed motor mounts constrained to th side of the REV rails using Coincident and Distance measurements. To this, there are TETRIX wheel mounts attached onto which the mechanum wheels are attached. On the outside, wheel guards were attached. The motors that drive the wheels are attached to REV motor mounts which were constrained to the underside of the REV rails. Attached to the motor is an axel which connects to a sproket to turn the wheel.

    The REV hubs were the hardest to constrain in this model because they didn't have typical sides. To mount them, we used a combination of Distance, Coincident, and Angle Offset features. The final part of the model was the phone mount which was simply constrained using coincidents.

    The next steps of this robot is to complete the robot model. This chassis was actually reused from last year. Due to licensing issues, we had to redevelop this model. We hope to experiment with this model to make space for the new, larger gripper arms.

    Creo Parametric, a Learning Journey

    Creo Parametric, a Learning Journey By Abhi

    Task: Learn Creo Over Time

    Over the course of this past season, I have been learning how to use Creo Parametric to learn 3-D modeling. Since this is Tycho's last year on the team (so far he has been our main modeler), I decided to learn from him so the modeling legacy would continue.

    The first project I was tasked to design was the wheel guard on the robot. As a very early learner, I ran into many issues. For example, I used to eyeball all my dimensions. This clearly didn't work out as evidenced by my epic fail of the first form wheel guard. However, after experimenting with the constriants, I jumped all the early hurdles and learned the basics.

    My first assembly project was to CAD the conveyor belt we hope to eventually mount the grippers onto. As someone who had never dealt with assemblies before, I felt like someone going through a maze. Even assembling basic parts like an axle hub to the axle, it took me 10 minutes because I struggled changing dimensions and such. This project, though very basic, seemed impossible to me. However, after working through it, I was able to become more familiar with constraints to apply to the next biggest task, the robot model.

    So far this is what we have constructed of the robot chassis. After training on the conveyor system, I was able to complete the chassis easier. By doing this, I have dealt with more constraints and have been moving faster.

    Next Steps

    After learning a lot so far from Tycho, I hope to finish the model soon and continue growth on the model. The only thing remaining on the model is the vertical bars connecting the lift and the lift itself.

    Friction Coefficients of Various Materials

    Friction Coefficients of Various Materials By Ethan

    Task: Test Friction Coefficients of Various Materials

    Introduction:

    Iron Reign has used many different materials in years past. In those years, we usually preferred materials which were more durable. We started with ABS, but while hard, it was relatively brittle. We attempted to use Filoflex and Ninjaflex, and they were more durable, but too soft. Finally, we had used nylon for the past seasons, as it was extremely durable but also was hard enough to get the job done.

    However, our needs have changed. In this challenge, we have to consider not only durability, but also how well the material works with other materials. And, the most important dynamic we must consider is the interaction with the foam blocks and the gripping material, since it is the major point-scorer.

    The coefficient of friction determines the power of the force in the opposite direction of motion. While friction is determined by ƒ=µn, we can ignore the normal force when using the same object repeatedly.

    Procedures:

    In this, we created an inclined plane that rotated around the base so that we could change its angle slowly from 0 à 90. The coefficient of friction is equal to the tan(ɵ), where ɵ is equal to the angle of slippage. We had to overcome some hurdles, most notably the higher center of gravity of a standard foam glyph, so we cut it down to one-inch of height so that it wouldn’t slip. Another way to restate the tan(ɵ) is the opposite/adjacent of the triangle formed by the incline.

    We slowly increased the slope’s angle until the block slipped, then recorded the angle of slippage to calculate the coefficient of friction, µ.

    Data:

    Surface

    Opposite Edge

    Adjacent Edge

    µ

    Standard Polycarb

    8.925

    8.125

    1.098

    Sandpaper (120 grit)

    9.5

    8.25

    1.152

    1-layer Ninjaflex, no ridge

    10.925

    5.5

    1.986

    1-layer nylon, no ridge

    10.25

    6.125

    1.673

    Nylon ridged

    6.75

    10.5

    0.643

    Drip Silicone Sheet

    6.25

    8.6

    0.727

    Full-Thickness Ninjaflex

    12.2

    less than 1

    Immeasurably High

    Results:

    We found, as we expected, that the Ninjaflex sheets have the highest coefficient of friction. The most important thing to do to further increase the coefficient of friction is increase the area of the contact. While we obviously can’t increase the surface area of the block, what we can do is increase the contact points between the sheets and the glyphs. The main way we can do this is decreasing the quality of our prints, counterintuitively. The reason for this is that the decreased quality creates little fibers that stick up from the print which create more contact points.

    The meaning of the coefficient of friction is how easy it is to slide an object across a surface, and as it gets higher, it gets harder to push across the surface. When the coefficient becomes greater than 1, it becomes easier to lift the object vertically than slide it horizontally (This can be qualitatively confirmed by touching the test block). And, for the conveyor belt, we need a high coefficient of friction.

    In the future, we should test multi-layered prints, as that ought to further increase the number of contact points. We also plan to impregnate the prints with fine garnet dust, which will hopefully make the sheets more abrasive, and therefore have a higher coefficient of friction.

    A critique of this experiment could include that the actual type of friction in the robot game is kinetic, or rolling, not static. In this case, the friction would be higher than rolling friction but lower than kinetic. This is due to the grippers pushing the blocks in, increasing the normal force. However, most coefficients of friction are proportional, so we can extrapolate from the static friction we gained to assume that the material with the highest coefficient of static friction will also have the highest coefficient of kinetic/rolling friction. In the future, we will also test kinetic friction with a spring scale.

    References:

    This source serves to prove the higher coefficient of friction of Ninjaflex – our experiment varies as we leave the 3-D printing artifacts on the sheet. As well, this measures a different type of friction than ours.

    https://ac.els-cdn.com/S2212827117300793/1-s2.0-S2212827117300793-main.pdf?_tid=0b998c36-02ac-11e8-bb23-00000aacb361&acdnat=1516980039_4970d0ef82d6f5d0a8bdd886b6005602

    Conveyor Belt V2

    Conveyor Belt V2 By Abhi

    Task: Develop Conveyor System 2

    After analyzing the lack of speed from our last competition, we decided to continue the journey of attaching the gripper arms to a conveyor belt as previously designed. To do so, we realized that we needed to utilize the REVolution system to make the grippers work better. Also, we needed two points of attachment for our robot after seeing that one didn't work with the first version of the conveyor. To figure out how to do all this, we went to our best tool: Creo Parametric.

    The assembly began with an assembly of two REV rails through distance and coincident constraints. To this, we mounted two bearing holders with bearings inside on either side of the bars. Inside, the plugs holding the REV rails were attached with coincident constraints. This combined assembly was added to the final assembly and was set with a default constraint. To the inside of the plugs, REV rails were attached using coincident constraints. Next, a copy of the bearing assembly was added and attached to the REV rails attached to bearings.

    For the next part of the assembly, we had to make a couple of subassemblies. First, we attached a Sprocket hub that we custom designed for the REVolution system and attached it to a 35 Sprocket from Andymark. The other end was plugged into another hub. This sub-assembly was replicated 4 times so that it could fit on all of the conveyor belt pieces. Also, we had to make a similar subassembly for the 25 sprockets since those are what our motors were designed to do.

    Finally, we mounted two motors on the insides of the REV rails. The sprocket attached to this motor would connect to the REV rails so that the whole system could actuate. This was constrained using coincidence.

    Next steps...

    We really liked how this model turned out. By starting to build it based on the model, we realized how useful Creo is to our design process. We hope to use it again soon for determining how to mount the grabber arms to the belt system.