Hello All.
Team 233 The Pink Team is proud to present “Vector”, our take of the rollable boat hook climber.
During the off-season our mechanical student lead CADed this climber while working with me as I taught him the design process, advanced CADing techniques, and how to perform some design calculations. I am very proud of Max’s efforts and the final results. I would like to post all of the design material and a tutorial on how to build and configure this climber at some point, but for now this will serve as the CAD release so it may be used during season if needed.
Some info on the climber. It can still be improved and we have plans to do so after season when we have more time to test those changes. We attached this climber (in a partially finished state) on our off-season robot and it work fairly well, even though it was completely 3D printed.
The climber takes roughly 3 sec to deploy or retract 60” and is designed to lift 190 lbs with 1 climbing unit on a 40-amp breaker, this is while using a Kraken or Falcon motor. It weighs roughly 10 lbs. It is not the cheapest thing to build, I would estimate that it costs roughly $500 USD in (COTS) excluding machining costs or metal procurement.
This climber was designed to be mounted on any single face of the climber and be able to hold up a robot from that face only. This has not been tested yet though, so I don’t recommend it.
Certain aspects of this climber takes some inspiration/research from other boat hook climbers that can be found here:
I will try to answer any question that may be asked here about this on December 28.
The solenoid actuated ratchet is really neat. I’m about to buy one to play with. Do you have a link to the one you used? The Amazon reviews on one I found via searching that model number weren’t promising.
Thanks for your comment.
So the reviews for the one we purchased are mixed but it appears to be so because of user error or they were looking for it to do something it was not designed for. in general, solenoids are very hard to mess up on because they are very simple and reliable, you just have to apply the correct voltage and adhere to their duty cycle and you should be fine.
Have you guys tested the solenoid? I question whether the rated 600g push/pull would be sufficient to toggle the ratchet under load. It would seem that an unlatch & unspool sequence could start to flirt with the thermal limitations of the solenoid.
Why not use a servo and linkage since budget isn’t a concern?
Thanks for the Comment! You bring up some good points.
I would not say that budget is not a concern for us . right now it is very expensive to build but we have plans to reduce the cost by $200+ dollars and reduce the weight and part count ect. Our concern for this 1st version was to achieve the function we wanted along with our requirement list and worry about reducing cost through improvement later on.
as for the solenoid, you are right that there is 0% chance that it would be able to actuate under load.
this is solved by the following software/physical sequence to extend the climber:
powering the climber to retract just a little, this will take the load off the pawl.
while doing step 1, power the solenoid to lift the pawl, allowing the ratchet to rotate freely when extending.
reverse the motor direction to extend.
when the solenoid is powered off, the pawl will engage with the ratchet and prevent un-spooling.
if retracting, you do not have to power the solenoid at all as it is spring loaded and will prevent un-spooling if power is lost or you stop climbing
we choose the solenoid for many reasons,
it is lighter than a servo
it is simpler than a servo and more reliable
its size is smaller than a servo
it is easier to control than a servo
when the robot is disabled and power is cut from the robot, the solenoid will default into its locked condition, the ratchet and pawl are positioned in such a way as to be over center so to speak so the pawl gets pressed deeper into engagement with the ratchet when load is applied.
solenoid is more robust.
the servo had several disadvantageous aspects to it that lead us to choose the solenoid.
unfortunately we ran out of time to test the solenoid in a fully integrated state where it was controlled by the robot. the prevention of un-spooling was tested with around 70lbs since the prototype was made from plastic. and it worked just fine, we wanted to put it through a very thorough testing before release, but had to cut it short due to time constraints. we will continue to test it and improve it in the future and release those changes when we make them. but for now i will say you would be taking a slight risk if you are expecting this to be a flawless mechanism, we simply have not had the opportunity to test it to the point where i would be comfortable saying it was 100% reliable or has no potential issues.
I will try to upload some that i have when i get back from my vacation for the holidays on the 2nd or 3rd, unfortunately the device and videos are at my place which i am not at right now.
Here is a video I have of the climber in our off season comp. I forgot i still had it on my phone. it is the only one i have as i was running around that day like a chicken with my head cut off lol.
Unfortunately, it is of the one where we had the current limit set way to low in software and had a brand new student operating the robot for the first time, so its full capabilities are not shown off.
likewise, it has the ratchet and pawl removed and the guide plate is just a block of wood as the new students had just finished assembling it and the drive base on the day of comp and ran out of time.
I have also added in some pics of the first revision too.
With only the starting configuration as a limit (42" tall) and no vertical extension limit, how tall of a boat hook could you theoretically fit onto a robot?
well…, you could try to adhesive bond multiple boat hooks together to get a longer one than is sold: Revolve Boat Hook – Revolve USA
But Vector is only designed to accommodate 1 full boat hook, the extension length from bottom of the mech to the top of the fully extended state is ~71", and fully retracted is ~ 10.5". you could try to edit the cad to make the spool bigger, but that would require you to changed nearly every parts sizes to accommodate it. you would effectively be re-CADing the whole thing.
I just added more to the folder. also the guide plate is still a WIP.
I want to reiterate that this climber has not been thoroughly tested enough for season use and the current guide plate design is still very much an untested design with some slight issues to resolve. we would feel terrible if somebody used this for this season thinking it was a plug and play solution with no issues right now.
while I know what it will take to solve those issues, we don’t have the time to devote to it right now to do that, and all of our students who would be learning and making those design changes are fully committed to our season right now.
I hope that answered your question, please let me know if you have any more!
. right now it is very expensive to build but we have plans to reduce the cost by $200+ dollars and reduce the weight and part count ect. Our concern for this 1st version was to achieve the function we wanted along with our requirement list and worry about reducing cost through improvement later on.