Counting Rotations

MoMoney$$$;)0)
Member
Member
Posts: 16
Joined: January 14th, 2019, 6:38 pm

Counting Rotations

Postby MoMoney$$$;)0) » February 26th, 2019, 5:05 pm

Hey fellow users,

I was wondering if you guys know any good wheel rotation method, that's highly accurate (eg. for wingnut system). Also, I was wondering if any of you guys know the wheel rotation counter a lot of teams use, to have highly accurate number wheel rotations?

Thanks!

User avatar
LittleMissNyan
Member
Member
Posts: 45
Joined: October 24th, 2018, 1:28 pm
Division: B
State: MD
Location: AOCL (Away on Chromebook Leave)

Re: Counting Rotations

Postby LittleMissNyan » February 28th, 2019, 12:46 pm

Basically what our team does is we stick a small piece of tape on the wheel and count the number of rotations based on the piece of tape
Poyo! (^-^)

- Battery Buggy 9/3/5/5
- Game On 7/1/2/7
- Mystery Architecture 4/oof/NA/NA
- Aerial Scrambler NA/NA/2/NA

National Cathedral School/Oakdale High/Regionals/sTATES
Won Most Creative 2019!
Also a Builder Cult member

User avatar
invisiblebanana
Member
Member
Posts: 35
Joined: February 21st, 2019, 3:24 pm
Division: B
State: MA
Location: Belmont, MA

Re: Counting Rotations

Postby invisiblebanana » February 28th, 2019, 1:18 pm

Could you also put a mini ruler thing along the restraining rod and turn the wingnut to a predefined distance along the ruler?
"You can't see me"

InvisibleBanana's Userpage

User avatar
MadCow2357
Member
Member
Posts: 583
Joined: November 19th, 2017, 9:09 am
Division: C
State: RI
Location: Stark Industries Internship
Contact:

Re: Counting Rotations

Postby MadCow2357 » February 28th, 2019, 1:46 pm

invisiblebanana wrote:Could you also put a mini ruler thing along the restraining rod and turn the wingnut to a predefined distance along the ruler?

That is what I did last year. It works. Kind of.
MadCow2357's Userpage
Projected 2020 Events: Boomilever, Gravity Vehicle
Considering: Fossils, Machines, Sounds of Music, Wright Stuff
Builder Cult - builders rise up! :)
Dank Memes Area Homeschool
234.36
#BalsaManForever

User avatar
invisiblebanana
Member
Member
Posts: 35
Joined: February 21st, 2019, 3:24 pm
Division: B
State: MA
Location: Belmont, MA

Re: Counting Rotations

Postby invisiblebanana » March 3rd, 2019, 6:15 am

Could you elaborate on that a little please?
"You can't see me"

InvisibleBanana's Userpage

User avatar
MadCow2357
Member
Member
Posts: 583
Joined: November 19th, 2017, 9:09 am
Division: C
State: RI
Location: Stark Industries Internship
Contact:

Re: Counting Rotations

Postby MadCow2357 » March 3rd, 2019, 8:15 am

invisiblebanana wrote:Could you elaborate on that a little please?

Ight so I cut up one of those flimsy NECAP rulers, and attached that to the stopping rod. I spun the wheels till the wingnut reached a certain point on the scale, but overall it wasn't very accurate.
MadCow2357's Userpage
Projected 2020 Events: Boomilever, Gravity Vehicle
Considering: Fossils, Machines, Sounds of Music, Wright Stuff
Builder Cult - builders rise up! :)
Dank Memes Area Homeschool
234.36
#BalsaManForever

User avatar
invisiblebanana
Member
Member
Posts: 35
Joined: February 21st, 2019, 3:24 pm
Division: B
State: MA
Location: Belmont, MA

Re: Counting Rotations

Postby invisiblebanana » March 3rd, 2019, 8:50 am

Oh. Is the method itself not accurate or just prone to human error (like if someone turns the wingnut the wrong amount)?
"You can't see me"

InvisibleBanana's Userpage

mtownley
Member
Member
Posts: 6
Joined: November 3rd, 2018, 10:19 pm

Re: Counting Rotations

Postby mtownley » March 7th, 2019, 5:55 am

My son used an actual counter on his vehicle set to count the rotations for him. It was pretty accurate and consistent. Last year he just counted the revolutions as he turned the wheel. It helped this year with the counter on time since he wouldn’t lose track of the number.

User avatar
MadCow2357
Member
Member
Posts: 583
Joined: November 19th, 2017, 9:09 am
Division: C
State: RI
Location: Stark Industries Internship
Contact:

Re: Counting Rotations

Postby MadCow2357 » March 7th, 2019, 6:37 am

mtownley wrote:My son used an actual counter on his vehicle set to count the rotations for him. It was pretty accurate and consistent. Last year he just counted the revolutions as he turned the wheel. It helped this year with the counter on time since he wouldn’t lose track of the number.

What counter did you use? My axle spins at 1030 rpm so the counters I was looking at wouldn't work, with max rpms of 350.
MadCow2357's Userpage
Projected 2020 Events: Boomilever, Gravity Vehicle
Considering: Fossils, Machines, Sounds of Music, Wright Stuff
Builder Cult - builders rise up! :)
Dank Memes Area Homeschool
234.36
#BalsaManForever

mtownley
Member
Member
Posts: 6
Joined: November 3rd, 2018, 10:19 pm

Re: Counting Rotations

Postby mtownley » March 9th, 2019, 9:52 am

MadCow2357 wrote:
mtownley wrote:My son used an actual counter on his vehicle set to count the rotations for him. It was pretty accurate and consistent. Last year he just counted the revolutions as he turned the wheel. It helped this year with the counter on time since he wouldn’t lose track of the number.

What counter did you use? My axle spins at 1030 rpm so the counters I was looking at wouldn't work, with max rpms of 350.


It was a rotary counter with a max of 350rpm. I'm curious why a 350 wouldn't work for counting since when you are winding the wheel, you are not rotating it at 1030rpm. As it unwinds, it obviously can't keep up with 1030rpm, but it wouldn't matter b/c the counter doesn't have anything to do with stopping the motor. We just reset the counter to 0 after each run and rewind. Maybe there's something I'm missing? Our season is over. My son's car got first in Regionals, but he won't be going to State in the event.

User avatar
MadCow2357
Member
Member
Posts: 583
Joined: November 19th, 2017, 9:09 am
Division: C
State: RI
Location: Stark Industries Internship
Contact:

Re: Counting Rotations

Postby MadCow2357 » March 9th, 2019, 12:59 pm

mtownley wrote:It was a rotary counter with a max of 350rpm. I'm curious why a 350 wouldn't work for counting since when you are winding the wheel, you are not rotating it at 1030rpm. As it unwinds, it obviously can't keep up with 1030rpm, but it wouldn't matter b/c the counter doesn't have anything to do with stopping the motor. We just reset the counter to 0 after each run and rewind. Maybe there's something I'm missing? Our season is over. My son's car got first in Regionals, but he won't be going to State in the event.

I'd like to use a mechanical counter, but because the motor and braking system are on the same axle, the only way I can wind is by reversing the motor current the opposite way. Like, I have to turn the motor on to wind for braking. I don't think I would mount the counter on my vehicle either, since it would add significant width to my vehicle. And kudos to your son for getting first!
MadCow2357's Userpage
Projected 2020 Events: Boomilever, Gravity Vehicle
Considering: Fossils, Machines, Sounds of Music, Wright Stuff
Builder Cult - builders rise up! :)
Dank Memes Area Homeschool
234.36
#BalsaManForever

shrewdPanther46
Member
Member
Posts: 420
Joined: October 9th, 2017, 6:25 pm
Division: C
State: NJ

Re: Counting Rotations

Postby shrewdPanther46 » March 9th, 2019, 4:31 pm

MadCow2357 wrote:
mtownley wrote:It was a rotary counter with a max of 350rpm. I'm curious why a 350 wouldn't work for counting since when you are winding the wheel, you are not rotating it at 1030rpm. As it unwinds, it obviously can't keep up with 1030rpm, but it wouldn't matter b/c the counter doesn't have anything to do with stopping the motor. We just reset the counter to 0 after each run and rewind. Maybe there's something I'm missing? Our season is over. My son's car got first in Regionals, but he won't be going to State in the event.

I'd like to use a mechanical counter, but because the motor and braking system are on the same axle, the only way I can wind is by reversing the motor current the opposite way. Like, I have to turn the motor on to wind for braking. I don't think I would mount the counter on my vehicle either, since it would add significant width to my vehicle. And kudos to your son for getting first!

why is that the only way you can wind what stops you from just turning the wheel mechanically

User avatar
MadCow2357
Member
Member
Posts: 583
Joined: November 19th, 2017, 9:09 am
Division: C
State: RI
Location: Stark Industries Internship
Contact:

Re: Counting Rotations

Postby MadCow2357 » March 9th, 2019, 6:27 pm

shrewdPanther46 wrote:why is that the only way you can wind what stops you from just turning the wheel mechanically

Because of the motor's internal electromagnets (I think that's what they are referred to), it makes turning the wheel much harder - in fact, this was very important in my buggy's braking last year (regenerative braking?). While turning the wheels manually is possible, it would:
1. Be a pain, and my hands would fall off after continued testing.
2. The duration of the time needed to wind it manually could possibly make us go over the 8 minutes of run time, which would definitely not be a good thing.
Sad thing is, I cannot even put the motor on my other axle to allow for manual winding, at least in this current configuration.
MadCow2357's Userpage
Projected 2020 Events: Boomilever, Gravity Vehicle
Considering: Fossils, Machines, Sounds of Music, Wright Stuff
Builder Cult - builders rise up! :)
Dank Memes Area Homeschool
234.36
#BalsaManForever

User avatar
Tendan
Member
Member
Posts: 11
Joined: January 27th, 2019, 5:37 pm
Division: C
State: PA
Location: Here

Re: Counting Rotations

Postby Tendan » March 9th, 2019, 8:07 pm

MadCow2357 wrote:Because of the motor's internal electromagnets (I think that's what they are referred to), it makes turning the wheel much harder - in fact, this was very important in my buggy's braking last year (regenerative braking?). While turning the wheels manually is possible, it would:
1. Be a pain, and my hands would fall off after continued testing.
2. The duration of the time needed to wind it manually could possibly make us go over the 8 minutes of run time, which would definitely not be a good thing.
Sad thing is, I cannot even put the motor on my other axle to allow for manual winding, at least in this current configuration.

If the motor is restisting rotation because of the electromagnets, it is probably being short circuited. This could be caused by the braking system you were referring to (an eddy current brake). If you are using an eddy brake again, disengaging the brake should be all you have to do to get it to rotate pretty freely.
If the motor isn’t being shorted, the problem is more likely high inertia and/or high friction in the motor or other parts of the buggy. You could try and fix this in a few ways, including:
1. Replacing the problem part(s). If the part you replace is the motor, your buggy might be able to accelerate faster, since the motor won’t have to overcome as much inertia before moving.
2. Disconnect the motor from the axle. If you are using a coupler with set screws, you could loosen the set screws and make you distance setting with the motor disconnected. Then retighten the set screws before the run. This might not work, depending on your configuration.
I hope this helped. Good luck with your buggy!

shrewdPanther46
Member
Member
Posts: 420
Joined: October 9th, 2017, 6:25 pm
Division: C
State: NJ

Re: Counting Rotations

Postby shrewdPanther46 » March 9th, 2019, 8:36 pm

Tendan wrote:
MadCow2357 wrote:Because of the motor's internal electromagnets (I think that's what they are referred to), it makes turning the wheel much harder - in fact, this was very important in my buggy's braking last year (regenerative braking?). While turning the wheels manually is possible, it would:
1. Be a pain, and my hands would fall off after continued testing.
2. The duration of the time needed to wind it manually could possibly make us go over the 8 minutes of run time, which would definitely not be a good thing.
Sad thing is, I cannot even put the motor on my other axle to allow for manual winding, at least in this current configuration.

If the motor is restisting rotation because of the electromagnets, it is probably being short circuited. This could be caused by the braking system you were referring to (an eddy current brake). If you are using an eddy brake again, disengaging the brake should be all you have to do to get it to rotate pretty freely.
If the motor isn’t being shorted, the problem is more likely high inertia and/or high friction in the motor or other parts of the buggy. You could try and fix this in a few ways, including:
1. Replacing the problem part(s). If the part you replace is the motor, your buggy might be able to accelerate faster, since the motor won’t have to overcome as much inertia before moving.
2. Disconnect the motor from the axle. If you are using a coupler with set screws, you could loosen the set screws and make you distance setting with the motor disconnected. Then retighten the set screws before the run. This might not work, depending on your configuration.
I hope this helped. Good luck with your buggy!

Your brakes should only engage when your limit switch is closed... there is no reason for turning the wheel to become more difficult. you are probably wiring incorrectly or something as Tendan mentioned if you really are having issues turning the wheel...


Return to “Battery Buggy B”

Who is online

Users browsing this forum: No registered users and 2 guests

cron