Very cool, thanks. I thought they were the stealth wheels.
We’re shooting with approximately 40mm depending on if we’re going to shoot with a grippy material on the hood. Then it might be around 42mm
What gear ratios do you use for your shooter and intake gearboxes? Are you using MAXPlanetary systems?
I generally avoid using Planetaries of any kind on high speed applications because it adds inefficiency and generally you need so little reduction that it can easily be achieved with a single belt, chain, or gear stage.
Shooter is 1:1 with 2 NEOs. (Tuned and powered down with software)
Feeder is currently 5:1 but will most likely go to 9:1 with a NEO.
Usually we use the MAX Planetary gearboxes for prototyping and then try to design it for belts and pulleys in the final design without using additional gearboxes. This is usually more lightweight and works for us since we some nice productions partners to lasercut custom parts and 3D print every pulley we like.
I think this year for the feed through we’ll be ending up with a MAXPlanetary gearbox since we don’t have the space to package a pulley and belt with a reduction.
Friday & Saturday Week 2
Here’s a quick update on our progression so far. The original goal we made on Monday of week 2 was to have a complete robot done by the upcoming Sunday.
Sadly we ran into two issues. Our shipment from VEX Robotics in the UK didn’t get delivered on time. It’s been held in Eindhoven since Wednesday due to insufficient paper work from VEX, is what UPS has been telling us…
They had no contact info and there was no total invoice value with the shipment so it was a clueless box for Customs which alarmed some red flags… We paid for priority shipping since they were important parts for us but sadly we still didn’t receive the package yet.
The other issue we ran into is that we forgot to upload ALL the sheetmetal parts that were needed to assemble the drivetrain. We do all our sheetmetal lasercutting at the Cromvoirtse, one of our partners. So too bad we couldn’t CNC router our own sheets and have to wait until Monday to pick up the last parts.
Luckily we were able to get some work done! We’ve assembled the entire intake and shooter so far. We’ll be running tests with those tomorrow.
Today they adjusted some hood angles and tested different PID settings to see what shot worked best.
Here’s a quick compilation of some shots:
Complete Hanger Prototype
We’ve assembled a mock-up prototype to test our hanger principles of a pneumatic climber.
Various tests can be seen in the video below:
Sunday’s Plan of Approach
See if we can get the intake tested on a different drivetrain we have if we can match the needed height requirements.
We dialed in the PID values for this shooter. Tomorrow we’ll be testing the shooter with the adjusted hood angles and different PSI Cargo.
I really like the hanger design. Passive deployment, and a simple extend, drive, and retract. What size is the cylinder, and where did you source it from?
Yep, in CD and the YT website
Sorry about the black screen. Made a mistake with exporting the video from premiere pro.
You guys not missing out on any footage. Its just that my project timeline got increased and it exported the last spot without videos in black
Tried trimming it in YT editor but didn’t worked
Edit 1; oops I saw I edited it the wrong way haha. It’s only black currently. I’ll fix it asap
Edit 2: It’s uploading and verifying now. Deleted the old, added the new. Here’s the new link:
They’re just regular pneumatic cylinders. It’s 40mm bore with a stroke of 200 operating at 60psi.
One on each side.
You can get it from various vendors. Theoretically it should be enough to lift the entire robot but yesterday we noticed sometimes it wasn’t when it was placed off-center of the robot. We’ll dig into that deeper today!
so I noticed early on in your prototyping you said you tested compliant and stealth wheels and either didn’t make much difference. I see in the end you switched from blue complaints to orange stealth. any particular reason you went that way? is it as simple as it matches your teams aesthetic? we are looking at using pretty much the same shooter set up and were planning on the blue compliant wheels. we don’t have any stealths on hand to prototype with so can’t quite see for ourselves.
We have tried both compliant and stealth wheels indeed. We didn’t see a lot of performance difference between the compliant and the stealth wheels.
We indeed ended up switching to the orange stealths due to team aesthetics mostly. I think you’ll be fine with compliant wheels as long as you use 4 or 5 of them as a big drum.
We ended up compressing our shooter with ~40mm and with 4" stealths.
What this would mean for compliants I couldn’t give you a proper answer since we didn’t test enough with it.
What are you aiming for mostly, LOWER or UPPER?
Edit: here are the STEP files for our shooter layout if you want. Of course we’d love some pictures and videos if you guys end up running something similar!
Looks like you’re lifting on the retract stroke of the cylinder. Don’t forget to take into account the lost area caused by the piston rod when calculating your potential lifting force.
Looks like with two 40mm pistons @ 60psi you’d be creating about 230lbs of force or so. Definitely should be enough for lifting a robot. But if you’ve got a significant sized rod on your cylinder, that force could be reduced significantly.
We are primarily aiming for lower, but also hoping to hit upper, all from the fender.
We had a different design going, it would shoot out one side to go high and shoot out the other for low.
its a long story, but in short, we wanted to dump cargo into the low, and shoot high, but saw your prototype and decided that was much better. We borrowed your prototypes cad and made our own (although it pretty much looks the same in the end).
So heres roughly what it looks like now
This is our mockup assembly so ignore the mess lol
Also sorry for the cell phone screenshots of cad, im replying to this while stuck in traffic after our meeting
A student on our team did a similar analysis for Power Up, but just for the Alliance scores. I really like breaking that down to individual robots.
The charts are eerily similar!!
So far so good!!! We have tested quite a bit with our 80/20 test rig that we built and we decided to start with 6" wheels and 2" of compression. Tonight was the first night we were able to use the Falcon 500’s with your design of side panels after testing with an impact gun. The students wanted to have some fun and tested at 100%. Obviously this would never happen in a match, but is cool to see (the inner teenager in me saying that).
FRIDAY - WEEK 3
It has been a while since we posted an update… sorry about that! The last weeks most of our team members were having exams and school work.
Sunday Week 2 Testing
We’ve been testing with various different variables on a 4000 rpm PI controller.
- CARGO with 3.0, 3.5 and 4.0 PSI.
- Different alignments on the fender: left, right, from the middle
- Shooting with a cargo between the bumper and the fender
- Again smooth polycarbonate vs. ribbed rubber
You can see all the different tests on our youtube channel. (https://www.youtube.com/c/Teamrembrandts/videos)
This was the last test run we’ve done for the day:
What did we learn?
Shooting from the fender into the LOWER and the UPPER can be done with a 2 position hood. But when there is a CARGO in between your bumper and the fender, you might get in trouble. It can be done with a 3 position hood but we don’t like the added complexity for now. For rev1 we’re sticking with a simple 2 position pneumatic adjustable shooter.
We’re still liking the ribbed rubber, which seems to increase shooting consistency.
With 40mm of compression we see hardly any difference between the different PSI shots.
Intake Rev1 Testing & Rev2 CAD
Sadly the drivetrain wasn’t done in time due to a production mistake on our end.
We focused mainly on testing the shooter which meant we have no progression on the intake in the last week.
We’ve been working on the actuation part of the intake. It will be powered by a pneumatic cylinder.
The extending stroke will push a rack down inside a tube > retracting the intake within the frame perimeter. The intake arms have a laser cutted pinion down that rotates since the rack pushes down.
On the extending stroke there will be a spring that counterbalances the weight of the intake. This means we can use smaller bore cylinders > less air pressure/volume needed.
On the retracting stroke we make use of the weight of the intake itself. The gravity of the intake helps overcome the spring force.
See the movements in the CAD below. On the right we have a functional model of a cylinder with spring and a bag with 750 grams of weight. Approximately the weight of our intake.
Rev1 Robot Is Alive!
We got the robot up and running. Need to do a final check up tomorrow and fixate the intake at the right angle to test with intaking cargo as well.
Here are some screenshots on the current sub system development.
Plan For The Weekend
Final testing of Rev1 development robot.
Finalize CAD of Rev2 development robot.
Start preparing materials for the upcoming new revision.
4481 Team Rembrandts is continuing their 2019 championship run with incredible progress demonstrating their ‘backpack’ robot and also their secondary robot for the Rapid React challenge. https://youtu.be/mZXx-_ed5EA