The cascading lift to place the hook was a Redline on a 16:1 Sport gearbox. The actual climbing was two CIM motors on a 24:1 gearbox and a 0.7" diameter spool
There is. Unfortunately I don't remember how it's implemented- since it's a cascade elevator it might just be the lowest tube has a bolt through the bottom to stop it once it hits the bushing.
Fantastic work!! Team 7448 here is glad to see some ideas like this, coming from rookie year last year we are looking up at teams like you guys for inspiration and this gives tons! Thank you!
Which motors are you using ? I was actually preferring banebots... But There is some problem with base motor and gear box... There are just two bolts between the gear box and motor, and that's not enough to hold them. So, do we need to replace the base motor ( like bldc) with same gear box? Do you have any idea?
Hey! Matthew Preis my team just started frc and have no experience I was wondering if you and maybe some of your team could come to my school and teach us about how the robots work and some strategy and other things for a day? My school is Higher Ground Academy Secondary in Saint Paul MN Thanks
We'd be happy to find someone who can help you out! You can get in contact with the University of Minnesota robotics team by email at robotics (at) umn.edu, but I would also recommend you contact the MN FIRST regional leadership to get in contact with a local team or mentors that have robotics experience: firstuppermidwest.org/contact-us/
We used modified pvc T junctions to mount pulleys for the bottom two stages, as well as cut notches in the bottom of the pvc pipes for the paracord knots to rest in without rubbing along the pvc.The inner diameters of the pvc tubes on our final version were 0.5 inches apart, giving the paracord some space even with the thickness of the pvc.
@DeltaForce3537 Here is a picture showing what we did: lh5.googleusercontent.com/qzSFJsTDLL8L1TY530Y2b9697Xhgx3k9vywS4c2pZTg7FED4jZSopWVjvSN5guKeTIbw2oiSJpUSxxgcjCyzVPYxH7ABGouIH06FNelgS-E3ss7wPek=w1280 The red lines are cuts, the scribbled out part waste material, and the blue circle is where we mounted a bearing inside the T junction on a bolt across the diameter. There are, I'm sure, many other ways to mount a bearing and/or reduce friction, but this functioned fine for what we had available.
@DeltaForce3537 Ah, apologies for the link issue, I will describe as best as I can (please bear with me if I am describing things that are obvious; it isn't particularly complicated, I just want to make the description as clear as possible). The unmodified PVC T-junction is, unsurprisingly, shaped like a T and can connect up to 3 PVC pipes by fitting them snugly into its channels. We rotated the T-junction 90 degrees so that it looked like a sideways T (kinda like "||=") so that there is a channel going to the bottom, a channel going to the right, and a channel going up. When I say "bottom", "top", or "right" in the rest of this description I mean in this "||=" orientation. We modified it by cutting off the top channel of the T-junction, making it look more like an upside down L, and then used the right channel to mount a bearing. We did this using a bolt running through the diameter of the right channel and some spacers (we eventually 3D printed them but cut up surgical tubing actually worked pretty good for our prototypes) to keep it centered. The PVC pipe for the stage will go in the bottom channel, and the rope will run around the bearing so it isn't rubbing along the bare PVC end. If you plan on going underneath the trench or are worried about height for another reason, cutting down the upper left part of the T-junction to make space for the T-junction of the next stage to nest will help reduce height and bulkiness. You can then have one T-junction pointing to the right, the next pointing to the left, etc if necessary so that they can nest easily. Hopefully that description helps! Best of luck to you and your team
Did you buy a winch to draw up your robot for the climb function or make one yourselves? If you bought it, where can I find it (if it is a relatively cheap one)? If you made it, how?
The winch is made of a rod with a round exterior and hex interior that fits around the hex shaft of a CIM motor, and has three water jet cut flanges that fit around the hex shaft, one on either side and one in the middle, spaced apart by the aforementioned round exterior hex interior rod. The flanges have a hole in them for the paracord to tie to. The CIM's short hex shaft was extended with churro, held in place by the round/hex rod and a bolt running through its center hole to the tapped end of the CIM hex shaft. The middle flange keeps the paracord running around the right side of the robot separate from the paracord running around the left side, essentially allowing the winch to pull in both directions at once.
We have two winches on the robot, one which powers the telescoping hook deployment mechanism (“the lightsaber”) and one connected to the hook itself which actually winches up the robot to climb. The former winch has a rod with a round exterior and hex interior that fits around the hex shaft of the redline, and has two water jet cut flanges on either side that fit around the hex shaft, which have a hole in them for the paracord to tie to. The redline’s short hex shaft was extended with churro, held in place by the aforementioned round exterior/hex interior rod and a bolt running through its center hole to the tapped end of the redline shaft. The latter winch has a similar setup except with a CIM motor instead of a redline, and there are three flanges instead of two-one in the middle and one on each side, spaced apart with the round/hex rod. The middle flange keeps the paracord running around the right side of the robot separate from the paracord running around the left side, essentially allowing the winch to pull in both directions at once.
How is the AndyMark redline motor working as far as consistency? Last year both of ours failed because of poor heat distribution. The end result was that the copper holding the brushes basically melted off and caused our robot to malfunction...
You have to be pretty careful with these, and not stall them under too much load. We only use Redlines/775pros for either low load or mostly free spinning applications where they don't see sustained current draw. motors.vex.com/ has some great information about how quickly these motors burn out under load (the Redline is very similar to the 775pro)
so is it legal for someone to use your design? I see you list the cad files online, does your robot comply to all this years rules? I am no longer a mentor, a local company took over, I am curious though.
We try to make the robot legal for this year's game, because otherwise it's not very useful as a teaching material. Some things do slip through, notably size constraints (we stick out about 1/4" front and back) and a few other minor details.
We used the KoP Chassis (6 wheel config) because ease of assembly was the main factor for the drive train. Given the length of our robot (32") and the desired 6" wheel diameter (to traverse the field berms), 4 wheels per side would be a tight fit. Having the drive motors in the middle also helps keep our center of gravity in the middle of the robot.
Thank you this was helpful. We were thinking along the lines of what your team was thinking and did a Pugh analysis in which a drive train of this style came out on top.
We used a solid pvc flange bolted through a metal plate on the bottom of the robot. We also added a crossbar from the top of the telescope motor mount to the frame for extra support.
they are from thriftybot but I believe they are sold out, if you want a 3D-printable solution I would recommend this chief Delphi thread www.chiefdelphi.com/t/frc125-2-printable-mecanum-aka-v-i-w-release-2019-2020/369139
We use pneumatics to actuate the intake (0:13) and the control panel spinner (1:46), and to stop balls from entering the shooter (0:25). They are a relatively simple way to actuate mechanisms that have 2 fixed positions. You will need space for the compressor and air tanks, and will have to watch out for leaks.
What's very interesting and awesome is that our teams current design is so similar to yours! Sadly we don't have the resources to build it in 3 days, but I'm definitely going to take this back to my team to improve ours before it's built. Awesome job!