ausTIN CANs 2158 | 2023 Build Blog

[AndrewI]

Day 8 Prototyping

To start the meeting we started working down the list of improvements to try with the weed wackers. The prototype moved off the dolly and onto a kit bot with bumpers(some old bumpers that didn’t quiet fit but got convinced with a hammer). The first change was increasing the spacing between each axis and longer tread. This didn’t seem to change the dynamic at all which was good. The longer tread is a different style of tread which is significantly “floppier” it still worked but I think ideally we’d want to move back to the blue nitrile tread.

The next item on the list to test was adding a ramp. We played around with different ramp configurations but we couldn’t get any consistent results with two weed wackers. More weed wackers might push it up further or a less steep ramp might work better. This is probably as far as we’ll take the ramp idea.

The next idea that was tested was adding a bottom roller to see if that would help at all. We didn’t have a strong idea of what this would do but it was simple to try. The under roller makes everything less controlled and it looks like the robot is trying to juggle the cone. Don’t recommend.

Dual Over Head Rollers

The dual over head rollers got the space between the compliant wheels reduced from .5″ to .25″. This allows us to grab the cube between the rollers. If the power on the drill is let off the cube pops back out. We were careful not to use full power because we didn’t want to harm another cube.

The next iteration of the dual overhead rollers had great progress made today. This iteration uses two PVC rollers repurposed from our 2020 robot. Not even winning robots are spared from prototyping(it’ll get put back together once we learn from the rollers). This version also has two motors and the pivot that allows it to rotate 90 degrees in both directions. We worked on this a good portion of the day and I forgot to grab any pictures of it. You’ll have to wait until tomorrow to see it I guess.

The next idea comes from a reader of our build blog who messaged me and I’d like to thank them for it!

Talking and showing our work in the open created this idea. I’m not sure we’d have come up with this idea on our own. The next thing we started testing was combining the weed wacker with the dual over head roller. The weed wacker will center the game object and the dual over head roller will grab and control it. Now instead of the cone being in 2 orientations and an unknown position it will be in one smaller location and one orientation.

This prototype worked amazingly well. I was surprised. It seems to be able to intake cones in any orientation. Chassis speed is still a slight concern because we are using drills and can’t increase the speed enough relative to the chassis speed. We’ll attempt to solve that on the next iteration of the prototype which will include motors, a change of spacing to fit in our frame size of 26″ x 26″, and it’ll be driveable!

There were a few odd failures that happened while testing. We hope the next iteration will be much more consistent with motors powering everything and increased rigidity. I’d also love to test the difference the stiffer blue nitrile tread makes.

Want Your Own Weed Wacker?

If you’d like to join team weed wacker I have some measurements taken from our prototype that you can use to start your journey. These numbers aren’t perfect and I can’t guarantee what you will build will match the results we’ve had. As always you need to do your own testing, debugging and improvements! Let me know if you need any other measurements and I can grab them at the next meeting.

Dual Over Header Rollers

• 4″ diameter 1″ wide Green Compliant Wheels 10 per axle(need two axles)
• Floor to center of axle 9″
• Axles spaced 4.5″ apart
• Distance between first roller and weed wacker 9″
• Back roller was 5″ from the kit bot frame
• Rollers are 10″ wide

Weed Wacker

• Arm 17″ from bumper (20″ from kitbot frame)
• 11.5″ from floor to top bearing plate of weed wacker
• Weed wackers spaced 15″ center to center
• Bottom of weed wacker’s hub is 6″ from the ground.

Hub assembly

• Hex shaft 8″ or so
• 2 hex hubs
• 10 – 32 bolts and nuts to hold the hubs together
• 13″ of 1″ tread(blue nitrile seemed to be less floppy and possibly better)

Field Build

Our laser cut actual charging station parts today! We had to kick everyone out of the shop for an hour so we lost a bit of productivity but that’s fine. We cut the first of three sheets of 1/8″ aluminum for the charging station build. The next two sheets will hopefully be cut on Monday. We also completed our first grid section today. The other two sections have all of the pieces cut and just need to be assembled now. CAD for the frame rails was released today and the stock was cut down to size. Our frame dimensions ended up being 26″ x 26″.

This was screwed together I just forgot to take another picture….

First Charging Station Part

Next team meeting is Tuesday, can’t wait!

[roboticsqueen]

What were the measurements for the post placement? Directly centered?

[AndrewI]

This picture could clarify any measurements. I am thinking by “post placement” you are referring to weed wacker axles? If so yes we tried to center the gap created/between the weed wackers.

[Osby]

I might be not seeing things correct in the video. Does the tread on the weed wacker violate the frame perimeter rules posted in update #2. See G109h.

[AndrewI]

As it exists currently on that robot it would be in violation of that rule yes. It’s currently on a spare kit bot chassis for testing purposes. Tomorrow we’ll be shrinking it to fit with in our planned frame perimeter of 26" and testing everything again.

[AndrewI]

Day 11

To start the day we tested the dual over head rollers which are using PVC rollers from our 2020 robot. The PVC rollers didn’t work well, the first roller doesn’t seem to have enough grip to pull the cones in.

We decided to take a small break from our weed wacker prototype to explore using vectored intake wheels. Our team saw open alliance teams having great success with them. If we are able to center the cone reliably with out weed wackers our robot gets simpler and lighter.

Our first attempt used the dual over head roller prototype, the first roller was changed out for vectored intake wheels. Unfortunately for us the spacing on the first iteration was too tight, with a .25″ gap between the vectored intake wheels and the second roller. Too much compression means the cone didn’t center well. In the below gif the wheels were also on the wrong side which vectored the cone to the edge of the robot.

The second attempt used a different test bed with .5″ spacing between the vectored intake wheels and the back roller. This had slightly better results, it took in the cone easier but there was too much spacing between the vectored intake wheels on the shaft. This allowed the cone to get stuck between wheels. Tomorrow we will increase the number of wheels and play with the distance between rollers to see what works.

The buddy carry prototype got assembled on the swerve drive chassis today. We ran out of heavy and easy to secure things to add on the swerve drive chassis. Tomorrow we’ll find more heavy stuff to strap down and attempt to move around with a full weight robot on the forks. Our plan is to test driving up the charging station with a partner.

Charging Station

Tonight we attempted to bend some of the aluminum parts that we cut out on our laser over the weekend. This didn’t go well, the pieces kept breaking during the bend. There is some speculation that we might have gotten/used the wrong alloy for the first sheet of parts. We will be cutting a smaller piece out of our recently purchased(known alloy) to test tomorrow and see if we can bend it. Oh the joys of doing something for the first time during build season.

[eterna1c0d5]

How did you get the tread to stay on the shaft? Are there just screws through the tread and the shaft?

[AndrewI]

For the prototypes the tread is wedged behind the bolts that hold both hubs together. We haven’t invested time into finding a more permanent solution yet.

[AndrewI]

Day 12

Field Build

The alliance grid is almost complete. The last three grid pieces are assembled, they need to get bolted together and moved into place. There was good news on the charging station front today, we bent a small aluminum test piece and nothing broke. The charging station build is now full steam ahead again, the poly carbonate parts are being cut on the router. We are still waiting for our metal supplier to source us 1.75″ x 1.75″ aluminum square tube(which is taking surprisingly long).

Continued Prototyping

A group continued to test vectored intake wheels and their possible use to center the cone from the flange. The spacing is the biggest challenge right now. Too much space between the rollers and it won’t pick up the cone well enough, not enough space and you have too much friction to center cone. They tested .75″ of compression first, this had too much friction. They removed the grip tape on the PVC roller and retested. Still too much friction. Next was 1″ this was barely able to grab the cone, not enough compression.

Our next step is testing different spacings between .75″ and 1″. They will also be adding more vectored intake wheels to prevent the cone from getting stuck in the gaps between wheels. Another thing to try is adding a slippery material on the back PVC roller to reduce friction.

The buddy carry prototype today concluded their testing by carrying our 2022 practice bot up the 11 degree ramp(poor substitution for charging station). The practice bot didn’t have bumpers or a battery so it only weighs around 70 lbs. From a slow start the swerve drive chassis struggled on the lip. A little bit of speed conquered the lip and the two robots drove onto the ramp.

We are happy enough with the results currently that we will be starting to make the first real iteration of the buddy lift. We don’t expected to get the first iteration perfect. There will be a few problems that will pop up and we will need to solve but we’ve learned a ton from this prototype and its time to start refinement.

[jedgar6]

@AndrewI

To think I scoffed at a shifting swerve.

[chrisfl]

What were the dimensions for your smaller weed wacker? We have been having great success with the design and need to begin prototyping a compact version that fits the frame perimeter.

[AndrewI]

Glad to hear about y’alls success! The only weed wacker that we built that is smaller is the first version we made and we didn’t take a lot of measurements of it. The only real change was the spacing between the weed wackers. That was smaller at ~8" across(cone’s base didn’t fit through easily). I’d recommend changing that number to be larger than the cone’s base, maybe try 8.5" and see how it works? The other change would be the length of tread on each weed wacker. With 8.5" between the weed wackers I think 9.5" of tread per weed wacker would be a good starting number.

[jbarry987]

How do you address the pick up of cones parallel to your top rollers?

[AndrewI]

Day 13

Assembly and Field Build

The competition robot assembly began today. The swerve modules were mounted to the new drive rails. Next the frame was squared up and secured. The top brain pan and bottom belly pan were cut on the router and are ready to be installed. Electronics will start going in on Saturday.

The alliance grid was finished tonight. Manufacturing will be working on the cable protector and barrier next. Charging Station parts are getting laser cut on Friday.

Scheduling and Prototyping

Today we had a discussion in the CAD team about the schedule and where we stand. Currently CAD zero subsystems complete. If we were to unrealistically say we’d get CAD complete and ship the first version by next week it would take manufacturing about two weeks to complete the parts and assemble. That would put us around week five for a functioning robot. We have a week one competition so we need time before then to program and drive the robot.

It is impossible to keep all of our same goals for the first version of the robot and complete CAD in a week. So we talked about which items we could remove from the first version of the robot. The current plan is to finish the buddy carry, and the arm for the first version. The team agreed to hold off on refining a floor intake for the first version.

We plan on making use of a released intake(not floor intake) for the first version. We will continue to prototype a floor intake but it won’t hold up progress on the entire robot. This will allow us to get a robot to programming faster, and allow us to start practicing sooner.

With our schedule cleared up the prototyping group continued to test vectored intake wheels. They increased the number of vectored intake wheels on the front shaft. This improved the prototype significantly. It was able to some times center the cone now. The position of the back roller still causes too much friction and the cone will get stuck sometimes.

Next we took an old prototype and put it on the table to simulate replacing the back roller with a smooth surface. This worked amazing well to center the cones. On top of the table is a piece of poly carbonate to reduce friction. This worked well enough so we’ll probably end up exploring removing or changing the location of the back roller more on Saturday.

That brings us to the next problem we’ve discovered with the vectored intake wheels. Currently our prototype requires the game piece to be close to parallel to the robot in order to intake.

This is a significant down grade in performance over the combined dual weed wacker or even the dual overhead rollers. The combined dual weed wacker was able to intake cones in all orientations besides tip pointing towards robot.

We’d like to see this performance with the vectored intake wheels. So we are exploring ways to increase the angle the vectored intake wheels can intake. On Saturday we will be trying 4″ vectored intake wheels to see what that changes. Saturday is a long meeting and we have a big list of things to try. See you afterwards!

[Potttaaatttooo]

What type of vectored intake wheels did you guys use for these vids? TTB ones/3DP ones (where theyre all plastic) or do they have rubber rollers. Also what material was the back roller as well? Is it just PVC?

[AndrewI]

Great questions. We 3D printed all the vectored intake wheels besides the used on the table top test. We got the files from here. I don’t have a brand or source for the vectored intake wheels used on the table top test, but those wheels have rubber rollers.

The back roller is just a 2" OD pvc pipe. It was covered in black gaffers tape at first but we removed that to reduce friction.

[AndrewI]

Day 15

Prototyping

Today our prototyping was focused on iterating upon the vectored intake wheel prototypes. While testing the 2″ vectored intake wheels we discovered that if we lowered the back roller there was less cone material to get stuck on.

The back roller was moved and we put the 4″ vectored intake wheels on. Okay lets be honest these wheels were probably designed for drive base uses… Any ways we got to testing. It worked good as long as the cone wasn’t pointing in towards the robot or perpendicular.

While testing the perpendicular cones we noticed the vectored intake wheels were still vectoring the cone to the center. It just doesn’t always intake the wheel. It is funny / odd to see the cone moving sideways by just the edge.

Next we added a piece of plywood underneath to adjust the spot the cone is hitting the vectored intake wheels at. This seemed to increase the chance the cone would get grabbed into the rollers and centered.

A third roller was added to the bottom to try and encourage the cone to get grabbed. Unfortunately we used too small of wheels and the third roller doesn’t make contact with the cone at the right spot. It needs to be closer.

The 4″ vectored intake wheels have great potential. On Tuesday we will try fixing the bottom roller to hit at the right place. We’ll also try adding a compliant wheel in between the left and the right sets of vectored intake wheels. One of these will hopefully solve the issue of the cone not getting grabbed when perpendicular.

What if the cone is facing towards the robot? Well we are not sure how to solve that yet. Its likely we’d be able to translate the drive base and reorient ourselves so its not pointed directly towards the robot. Another thing that might work is driving into the cone and pushing it by the tip. We’ll try these out and see how they work if we are able to solve the issue we are having with perpendicular cones. If not well back to weed wacker I guess.

CAD

CAD worked on refining the arm and buddy climb today. The arm got all the important positions documented in our engineering notebook. Note only the last photo showing the substation interaction has an intake one it.

The “choo choo” mechanism which will power the first stage of the arm was completed today. Behind it you can see the start of the winch gearbox for the second stage of the arm. We copied/borrowed/stole the geometry from the every bot intake. We’ll use this for driver practice until we perfect the floor intake.

Down left, up right

Charging Station

The charging station build managed to get another sheet of metal laser cut today. The last one will get cut tomorrow. More pieces were bent today. We struggled to bend the long 48″ piece, our brake isn’t rated for the length and thickness but it struggled through. The 1.75″ box tube came in and those parts started getting machined. We are probably still a week or so out from having the charging station finished.

Driver Practice

Don’t have a finished robot yet? Same here. However we aren’t letting that stop us from getting driver practice in. We have a drive base that works and the past week we’ve been doing drills aligning to spots on the grid. Today we upped the ante. If you have a spare 2 x 4 and drive base laying around you can start doing some driver practice!

The goal is for the driver to just gently touch the pole and head back to the other side of the field and touch the pole on that side. Then repeat, moving down the grid each time. We time these runs to see who is the fastest.

Next team meeting is on Tuesday, we’ll be busy thinking about more prototypes in the mean time!

[AndrewI]

Day 18

The meeting started with a quick team recap from the sub group leads. Next we announced our primary and secondary driver for the season. Together people interested in practicing for driver have had 453 timed practice runs since we started back in November. We’ve selected the two main drivers so they can make the most of our limited practice time.

Quick Prototyping Update

Today we figured out a few things that with the 4″ vectored intake wheels. First thing was lowering the 4″ vectored intake wheels created new problems. We raised the floor instead of lowering the vectored intake wheels. This caused the 4″ vectored intake wheels to push the cone away.

The next thing we tried was adding a compliant wheel in the middle of the vectored intake wheels. Our thinking was that this would better grab the cone and pull it in. This didn’t fix the problem of grabbing the cone.

The final most important thing we learned is that our back roller is too low. The back roller makes contact with the cone’s edge preventing the cone from being grabbed up into the intake. We added more space between the two. This drastically increased how quickly the cones would be grabbed. But the prototype lost all of the compression against the cone so it doesn’t center or hold the cone at the moment.

To fix the loss of compression we will be relocating the back roller, moving it higher up. In order to do this we have to reconfigure our prototype’s setup. We’ll also remove the green compliant wheel. These two items should return the centering and holding of the cone.

The Arm prototype started it’s assembly process today. The main pieces of the arm were put together. It was discovered a shaft was missing, so that got added to the list of things to manufacture. Next steps are adding the plates that hold the arm to the robot’s chassis.

Charge Station

We completed an audit of the charge station parts list, we found a few pieces that are missing from our manufacturing process. A completed charge station is at best a week out still. At some point I’ll write down how we use Trello to track/handle our part workflow. Until then, this picture will have to hold you over.

[MachoStoopid]

What kinds of driver trials did yall do? Ive been toying with the idea of making gear runners in the off season like how 118 did (link)

[AndrewI]

Day 19

It felt like a slow day today. Everyone was working but things are in progress / in the middle still. Progress is being made on multiple fronts, just nothing to show from it today.

The bumpers got their mounting system attached. This year we have 3D printed spring latches that hold the bumper. Its very easy to unlatch and remove the bumper. We are only on iteration 5 of our bumper mounts

We tested the 4″ vectored intake wheels a bit more today. This prototype is hard to get the performance we want out of it. The back roller positioning is problematic, too low the cone gets stuck perpendicular, too high the cone doesn’t get picked up. We are going to let this prototype take a break for while.

We started looking at the dual over head rollers again. They are working on another iteration that uses 2″ compliant wheels instead of 4″. This reduces the weight and makes the intake smaller. Here is a slow motion video from the side with 4″ compliant wheels.

The wiring on the competition robot is coming together. Probably another day and a half of work left on it. So hopefully it will drive on Saturday. Then we need to expand the frame perimeter of the practice bot to match our competition robot.

Tomorrow will be a busy day, we have a large amount of parts that are queued up for the CNC router. If they get cut in time we’ll start seeing some more progress.

@MachoStoopid We ran a few of the skills at home courses before the season started. Since kick off we’ve been practicing cycles from the substation to the grid. We don’t have documentation of the courses, its on my list of things to make.