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
Thanks for having us again @Tyler_Olds Always nice to be on the show. Compliments to you and Greg for getting all the useful informative content out there.
Week 3 Recap + Plans week 4
Hello everyone, here is another update of what progress we’ve made since week 3. This week we have been working on every subsystem and some other interesting stuff.
We will tell you about:
- Complete assembly
- Backpack robot
- Scouting tool
[Week 3 Recap | Team Rembrandts Building Season 2022]
This week we finished our first prototype robot. It has every subsystem on it to complete a full cycle with two balls and we quickly saw a lot of good things happening, but also a few problems that occurred.
Our main problem right now is our intake. We saw that the balls don’t go inside our robot as fast as we wanted, and sometimes not at all. We tested a lot with the spirals, the mecanum wheels, different compressions or just no compression at all and just have a bouncy intake, but we haven’t found the sweet spot yet.
Since the unwritten rule is “touch it own it”, and we want an intake that can collect every ball in < 1 sec, we have to make some adjustments.
We did notice that having an intake that doesn’t bounce while collecting works better since it has constant grip on the ball and thus collects it faster.
One of the good things we saw is that our shooter works perfectly on the drivetrain. We tested everything correctly and the results show us exactly that.
When testing the shooter we wanted to shoot the balls in a way they don’t collide in mid-air. Until we came with the idea to shoot the first ball in the upper HUB and the second ball in the lower HUB. This is a really solid way of shooting.
- This way of shooting has a shooting time of < 1 sec.
- The accuracy is extremely high, since the balls will never collide. Not in mid-air and already inside the upper HUB.
- The above two reasons make a 20 cargo RP very likely to achieve.
Intake & Outtake Cycles Week 3
Get your seat ready for this fashion because it will blow your mind! This week we also finished our very first “backpack robot”. We can now use this for multiple things:
Our software department can now already start working on the driving paths for autonomous, instead of having to wait for the final version of our robot.
We can also use it as a general robot to show other people/teams what our robot looks like.
Since we have to travel all the way to amerika, we want to make our robot completely modulair, so we bring every robot part with us in our own luggage. It saves us a lot of costs and time to get our robot with us.
This year we are also focussing more on strategy. So a few members have been busy making a scouting tool. We want to take scouting very seriously this year since we think it can make a very big difference. It is fully under development at the moment so there might be a lot of changes later on. (We took inspiration from team 5012, thanks for that:) Our current progress:
- We will scout every match that will be played and get as much data from it as possible.
- With that date we can clearly see a team’s performances and even progression throughout the competition.
- With that team data we can predict if an alliance is going to win or not. This can change your strategy for that match. For example: shooting Lower HUB instead of Upper HUB to achieve the extra RP.
- We’re also scraping data from The Blue Alliance to obtain more match data.
- After all matches are played we can make a pick list based on the collected data with the best possible alliance combinations.
The upcoming weeks we will be busy working on the assembly of the rev2 robot. We made the necessary adjustments to perform better on every subsystem. Our materials are ready for assembly and we are very curious about the new results. Testing, testing and more testing!
Credits for this post go to @Teis_Joepman
He’s a new user to CD and can only post 1 embedded item per post… I’m just copy pasting!
This is now my favorite thing I’ve seen for this season thus far. Can you speak more to this? While I think it’s “just a matter of flywheel tuning”, I would imagine there is a lot that happened in the background to support this success.
Yes, this was only possible because of the way our software department was able to tune the flywheel by using the Sysid tool.
When we starting shooting, quickly changing the setpoint by a push of a button showed decent results in terms of creating multiple ball paths. But, as the Sysid tool testing finished, the shooter had been tuned to a settling time of less than 0.5ms, with a way less heavy bump in velocity when a ball was shot. After coding an automatic detection of the 2nd ball hitting the flywheel, we were able to quickly change velocity and create a second ball path while shooting the two balls.
After some testing with multiple sets of velocities and speeds of shooting, a demonstration was done “with extreme differences in setpoints” which showed the robot hitting both hubs at the same time. This idea was then further investigated and shows great potential.
You mention mid-air collisions and possibly shooting 1 high and 1 low. Did you run into that problem a lot? I see video of a bunch of shots in posts 63 and 75 but very few mid air collisions. Do you have more footage of the dangers of shooting the balls too fast? Were the mid-air collisions reduced if you waited a little longer between shots? Was the collision usually from the balls actually hitting each other before the hub or from the 1st bouncing off of the hub?
Is this just a strategy for matches that points aren’t super close? If so why not just do both lower?
Thanks for the insight! Looking forward to seeing this beast run cycles on a field.
(Repost because of bad video link)
Shooting the balls directly after each other often causes one to fall out or to be misdirected by the second ball. We don’t have many video’s of this. But you can see the effect of 2 balls colliding in this link:
Creating a different ball path for the second ball reduces this problem as they land side by side:
Waiting longer between shots reduces this danger by a lot, as you don’t need to worry about collision. But, as our requirement says both balls within 1 sec, we didn’t pursue this.
We instead decided that we wanted to use the concept of shooting one ball in the upper HUB and one in the lower HUB, as the first version, and try to tune the 2 ball paths so that it is consistent later. We haven’t been able to do this yet. When we finetune it into 2 consistent ball paths, we might switch back to 2 balls in upper HUB.
I love your concept of switching between the two shots in hopes for reducing bounce outs. I’m curious as to the mechanism you are using to change between these two shots in such a short time. Do you have a hood angle adjustment you are making as well as a change in flywheel speed?
We make changes in the flywheel velocity, with the help of Sysid
Thank you! I am really quite surprised that you are angle to hit both shots without changing a hood angle. Fantastic work!
Thank you for all the information your team has posted! Our team has taken great inspiration from your robot!
Here is our throughput testing
And after some changes to our polycarbonate “walls” https://youtu.be/C0vx6ZWyUGo
Sorry for the radio silence… We had a little miss communication in the team on who would post the update and they both they the other did it
So here’s some late updates!
Week 4 Climber Update
ASSEMBLY & TESTS PNEUMATIC CLIMBER
First of all, we started with the assembly of the second revision of the pneumatic climber. The main thing we wanted to test was how the climber would behave with the flexing polycarbonate and the new hinge design. After the climber was assembled, we mounted it on the robot and put it to the test. These are the main things we noticed during the tests:
The polycarb hinge does prevent the sideways bending in the hinge point, but still flexes which is what we want. The flex in the hinge can be seen in the pictures below.
We designed two different 3D printed mounting blocks for the hook, one that could hinge and one that could not. We haven’t been able to test the hinging one properly, but as the robot is just barely off the ground, the hinging hook will probably make the robot touch the ground.
The screws and that mount the climber to the drivetrain are hard to reach, so taking into consideration the modular design we want to achieve, we want to look into rivet nuts for easier mounting.
MOTOR DRIVEN CLIMBER
While we were busy with the assembly and tests of the pneumatic climber, a new version was already being designed. This design was based on a motor driven telescopic climber that was already designed in the off-season and was based on a west coast products climber. We also implemented a brake system based on the one 2910 used in 2021. The climber will use constant force springs to deploy and a NEO with a REV gearbox to retract. We will start with a 1:25 gear ratio as a moderate start and increase speed if needed. We went for two stages to make the system as compact as possible. The spacers for the hook are made out of TPU with various wall thicknesses, we will test which amount of flex works the best. Another thing that has been designed is a clamp to attach the climber to the shooter for extra strength.
There are a few reasons why we wanted to also design and manufacture a motor driven climber next to the pneumatic one:
- First of all, the weight, the pneumatic climber would shift the CoM up by 15cm.
- Usage of less space, extra air tanks aren’t needed for the motor driven climber. The overall size of the system itself will also be smaller.
There are also some disadvantages, for example that the motor driven climber will not be able to climber after T=0.
The next steps will be to assemble the motor driven climber and to do more tests with both versions of the climber. After the tests, one design can be chosen with which we want to continue. Then we can make some final perfections on the design and send it to production after this week.
4BAR POLY INTAKE - WEEK 4 Rev1
We started with Assembling the Rack and pinion style intake and made sure it was assembled totally. We noticed there was some flexibility in the rack which meant the compression to the ball wasn’t that great. The design was meant for cylinders with a stroke of 60 mm and a thickness of 16 but to make the flexing less we eventually used bigger ones with a thickness of 20 mm.
Design of the 4-bar intake started parallel on the rack and pinion style intake. It started with a quick sketch showing the points to attach the arms to the drivetrain and wheels. After this the designing of the actual intake took place. For the designing of the intake a few points were important:
Figure 1 Sketch movement 4-bar intake
First, we thought it was important to look at flexibility and came up to the conclusion that 5mm thick polycarbonate would do the job. But we wanted to be sure that the intake was as steady as possible in the in and out position. For the out position the flexibility must be from side to side but it must also absorb a hit from the front and don’t lose any compression on the ball. That is why we chose to make sure the polycarbonate arms were designed to have a hard stop on both positions by slamming the arms on each other.
For the actual actuation of the intake cylinders of SMC were used which is 16 mm thick and has a 50 mm stroke. To make sure the cylinder doesn’t damage while the intake is out, we made sure to have the cylinder in resting position when intake is out.
For the first prototype we made sure to have the possibility of testing a Neo and a Neo 550. This by 3d printing holders for both motors.
After designing the first prototype the production of the 4-bar intake could begin. It was done by printing a 2d drawing on 1:1 scale and glue it on the polycarbonate protection foil. After cutting the polycarbonate with an iron or ribbon saw the centre holes can be drilled on the correct sizes and assembly can start.
What is important to do:
- The 2D drawing must have centre marked holes in them to make sure the centre of the holes aligns perfectly to the Cad drawings.
- Glue the 2D print on the protection foil and not on the Polycarp itself, otherwise the paper can’t be removed that easily.
- Make sure al holes that need to be drilled are drawn in drillable sizes.
Pros and Cons of a 4-bar intake:
- It is a small packaging system
- Flexibility and rigidness can be optimized in own preference
- Quick in-house prototyping and iterations
- The use of the saw can cause imperfections
- Placement of arms and attachment points must be perfect to get the job done
- Motor must be on the intake itself
Rev1 POLY 4BAR INTAKE - INITIAL TESTS
SUNDAY WEEK 5 UPDATE
Shooter Rev2 Up & Running
New design with the NEOs mounted down low and a long belt running up.
Current design status of the intake:
Current intake built & tested:
What did we change?
The side plates that hold the axles are stiffer/thicker than REV1 of this intake. Current design has 8mm.
Added a crossbar to increase stiffness
Increased compression to 230mm from carpet to center of the VIW shaft.
Ended up with 1 neo on 1 side so far.
Current design has 2 solenoids, 1 for each cylinder. Eventually we’ll run 2 cylinder on 1 solenoid.
Currently the back of the cylinder is bolted with a bolt through the drivetrain side rail. This works kind of “okay” for now but we’re thinking of going for a better solution > Rot end ball joint on the back of the cylinder.
Added spacers on the cylinder shafts to create a hardstop on the retract side. The cylinders were a little too long but adding spacers we were able to adjust the compression. This is something we’ll design for in the final design as well.
4Bar Rev2 Intake
Test Run 1 Robot Rev2 (Codename: Moffel) - Week 5
Test Run 2 Robot Rev2 (Codename: Moffel) - Week 5
Disclaimer/Side-note: Don’t mind the shooting angles. We just wanted to test intaking and outtake. We’ll dial in the shooter later and rework our upper hub to make it more durable and fixed on the ground so we can slam into it.
When trying the vectored wheel intake we have been having problems with the ball bouncing off of the bumper and then back out when we run at it fast, have you seen this? My guess is that we need to lower our wheels closer to the floor a little bit, but wanted your perspective.
What speed are you running your Neo at? Any gearing?
Where did you get your Vectored wheels? Do they have special grippy rollers or anything else specific that you have found necessary to make this design work?
We did indeed see similar issues with them bouncing off, this was resolved by increasing compression to the floor and double checking the distance to the bumpers.
The intake is currently geared at 2:1 reduction off a single NEO.
The vectored intake wheels we are currently using are the 2" ones from VEX. One other thing we found important was to have the compliant wheel in the middle of the roller larger then the mecanum wheels, for this we are using a 3" compliant wheel from AndyMark.