Mousetrap Vehicle C

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Re: Mousetrap Vehicle C

Postby Paradox21 » January 13th, 2010, 6:18 pm

winneratlife wrote:P.S. I ended up scoring around 70 in the test according to the rules. Is that good?

At an invitational a few weeks ago I got 1st with a score a little under 5. 2nd, 3rd, and 4th had scores of 31, 54, and 112 respectively. One team scored a 1054, so I assume they just barely missed the 7 meter mark and otherwise would have gotten a 54, so... yeah.
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Re: Mousetrap Vehicle C

Postby winneratlife » January 15th, 2010, 5:24 pm

Paradox21 wrote:
winneratlife wrote:P.S. I ended up scoring around 70 in the test according to the rules. Is that good?

At an invitational a few weeks ago I got 1st with a score a little under 5. 2nd, 3rd, and 4th had scores of 31, 54, and 112 respectively. One team scored a 1054, so I assume they just barely missed the 7 meter mark and otherwise would have gotten a 54, so... yeah.



UNDER 5!!!
Nice...
Anyways, what ruins me is the distance score. My vehicle curves on the way out, but then comes straight back, and that really ruins me. So I would've gotten third...but I assume you're from MN? That means I'll really fail the invite next week if I don't fix it...

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Re: Mousetrap Vehicle C

Postby Paradox21 » January 16th, 2010, 1:57 pm

winneratlife wrote:
Paradox21 wrote:
winneratlife wrote:P.S. I ended up scoring around 70 in the test according to the rules. Is that good?

At an invitational a few weeks ago I got 1st with a score a little under 5. 2nd, 3rd, and 4th had scores of 31, 54, and 112 respectively. One team scored a 1054, so I assume they just barely missed the 7 meter mark and otherwise would have gotten a 54, so... yeah.



UNDER 5!!!
Nice...
Anyways, what ruins me is the distance score. My vehicle curves on the way out, but then comes straight back, and that really ruins me. So I would've gotten third...but I assume you're from MN? That means I'll really fail the invite next week if I don't fix it...

My vehicle is actually very different. I had a great distance score (about .5 cm) but the vehicle itself runs relatively slow. I am working on it...
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Re: Mousetrap Vehicle C

Postby winneratlife » January 16th, 2010, 2:33 pm

How do you get it to go straight? Trial and error?

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Re: Mousetrap Vehicle C

Postby Paradox21 » January 17th, 2010, 5:38 pm

winneratlife wrote:How do you get it to go straight? Trial and error?

Hmm, I would suggest parallel axles, a rigid frame, and straight, equal sized wheels. If you have Electric Vehicle experience it helps enormously.
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Re: Mousetrap Vehicle C

Postby winneratlife » January 17th, 2010, 5:49 pm

Well...
My frame is good, my wheels are equal, but I can't get the axles to be perfectly parallel. It also seems that the axles are bending slightly because they are too thin? I'm not sure what's going on, but it won't go straight!

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Re: Mousetrap Vehicle C

Postby Paradox21 » January 17th, 2010, 5:55 pm

winneratlife wrote:Well...
My frame is good, my wheels are equal, but I can't get the axles to be perfectly parallel. It also seems that the axles are bending slightly because they are too thin? I'm not sure what's going on, but it won't go straight!

Hmm, if you can't get parallel axles, maybe you could try building something that will allow you to adjust the angle of one of the axles. Then you have to be able to tighten it back down again so it will never move. I believe that has worked for people before. My axles are just parallel, I never had to adjust them.
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Re: Mousetrap Vehicle C

Postby beaverkid » January 17th, 2010, 8:24 pm

There's a new FAQ on the national web page:

01/17/2010 - 18:49 In 3b, the term “run violation” is used. Do you mean a competition violation?

Yes, it should be "competition violation".

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Re: Mousetrap Vehicle C

Postby Balsa Man » January 19th, 2010, 6:05 am

Paradox21 wrote:
winneratlife wrote:How do you get it to go straight? Trial and error?

Hmm, I would suggest parallel axles, a rigid frame, and straight, equal sized wheels. If you have Electric Vehicle experience it helps enormously.


Yes on EV experience!. Three factors that affect steering, two of which are not so obvious. The obvious one is axles parallel when looking down from the top; if they're not, that puts a turn in. Its easy to make a jig for your side rails that sets the distance between the two axles exactly the same distance. Next is wheel diameter; if there is a difference, that will induce turning - toward the smaller diameter wheel. Again, pretty easy to make sure wheel diameter is the same (or in trial and error approach, to sligtly reduce diameter of the wheel its turning away from. Both these factors.....show up more if they're in the axle that's to the front. The front (which ever way you're going) has most of the steering effect, and the rear follows. I'll bet there is a significant difference in steering behavior going out and coming back.
The last factor comes from the fact that three points define a plane, and the vehicle has four wheels. Unless your axles are exactly parallel, looking at the vehicle end-on, one of the wheels will be somewhat up off the floor. It may not be apparent; may look like all four are in contact, but one will be more lightly loaded. Again, the steering effect this induces will mostly be seen when the axle w/ the lightly loaded wheel is at the front. There are a couple ways to.....factor this out, though dealing with this issue/effect is the hardest. The easiest is to set up a way that when you attach your chassis platform to your wheel side rails, both axles, with wheels in-place, are....there, and you attach (glue) the rails to the plate with all four wheels firmly on the ground. Of course, if you later adjust wheel diameter, it will throw things off. The harder approach is to put some kind of flexibility (i.e., suspension) in. One option - take a close look at the drive axle end of a radio controlled race car - is to have one where it can pivot- looking end-on, the ends of the axle can move up and down (EV from last year...). The other is to have one end of one rail flexible enough that the end can move up and down.... No details on this, though, till later in the season....:-) it can be done, and it does work
Getting it to run perfectly straight is, of course, not necessary - a little bit of curve in each direction, as long as you can stay in the 1.5m lane, and the behavior is consistent- you can adjust starting position along the start line to get back to the center point.

Len Joeris
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Re: Mousetrap Vehicle C

Postby winneratlife » January 19th, 2010, 3:21 pm

Balsa Man wrote:
Paradox21 wrote:
winneratlife wrote:How do you get it to go straight? Trial and error?

Hmm, I would suggest parallel axles, a rigid frame, and straight, equal sized wheels. If you have Electric Vehicle experience it helps enormously.


Yes on EV experience!. Three factors that affect steering, two of which are not so obvious. The obvious one is axles parallel when looking down from the top; if they're not, that puts a turn in. Its easy to make a jig for your side rails that sets the distance between the two axles exactly the same distance. Next is wheel diameter; if there is a difference, that will induce turning - toward the smaller diameter wheel. Again, pretty easy to make sure wheel diameter is the same (or in trial and error approach, to sligtly reduce diameter of the wheel its turning away from. Both these factors.....show up more if they're in the axle that's to the front. The front (which ever way you're going) has most of the steering effect, and the rear follows. I'll bet there is a significant difference in steering behavior going out and coming back.
The last factor comes from the fact that three points define a plane, and the vehicle has four wheels. Unless your axles are exactly parallel, looking at the vehicle end-on, one of the wheels will be somewhat up off the floor. It may not be apparent; may look like all four are in contact, but one will be more lightly loaded. Again, the steering effect this induces will mostly be seen when the axle w/ the lightly loaded wheel is at the front. There are a couple ways to.....factor this out, though dealing with this issue/effect is the hardest. The easiest is to set up a way that when you attach your chassis platform to your wheel side rails, both axles, with wheels in-place, are....there, and you attach (glue) the rails to the plate with all four wheels firmly on the ground. Of course, if you later adjust wheel diameter, it will throw things off. The harder approach is to put some kind of flexibility (i.e., suspension) in. One option - take a close look at the drive axle end of a radio controlled race car - is to have one where it can pivot- looking end-on, the ends of the axle can move up and down (EV from last year...). The other is to have one end of one rail flexible enough that the end can move up and down.... No details on this, though, till later in the season....:-) it can be done, and it does work
Getting it to run perfectly straight is, of course, not necessary - a little bit of curve in each direction, as long as you can stay in the 1.5m lane, and the behavior is consistent- you can adjust starting position along the start line to get back to the center point.

Len Joeris
Fort Collins


Can you please tell me how to make the "jig"? Invite Saturday, final testing tomorrow night, so sometime tonight would be good.

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Re: Mousetrap Vehicle C

Postby Balsa Man » January 19th, 2010, 4:03 pm

Well, details on how best to make a jig (to align axles parallel) would depend on how your vehicle is designed. Part of the problem - part of being a competitor - is figuring out how to build the tools you need to build the device you want. I'm assuming you're using some sort of rails through which the axles go, and those rails attach to the sides of some sort of plate/board - the chassis plate. If not, Don't know what to suggest. Each rail will have two holes through it, one for each axle. Those holes need to be exactly the same distance apart. EZ way is to be able to drill them together (as in literally, taped together). If, while you have them taped together, you cut one end, so at that end, the end of the rail is the SAME distance from the axle hole on both. Then take a piece of board. Glue a strip down one side (a little longer than the wheelbase of the vehicle). Glue another strip at EXACTLY 90 degrees to it- bummping up against it. Put one rail up against the long, side strip, with the accurately cut end up against the shorter strip. Glue the chassis plate to it. Then put the other rail on, with its accurately cut end also up against the shorter strip while you glue it on the chassis plate. If you build this simple jug carefully, you will have parallel axles. If you don't, you wont.... That's the thing about jigs, if made accurately, they help you. If not, they don't.

Good luck!; pretty late in the game to be building...
Len Joeris
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Re: Mousetrap Vehicle C

Postby winneratlife » January 19th, 2010, 4:39 pm

Nah, mines built. But, I like your idea of getting a fixed rail and drilling 2 holes in it...

I'm using Lego's with the holes drilled out (there's a little circle in the center). So, if I can line up some big pieces, it should be uniform. Hmm...

Well, maybe I'll fix it for regionals. But there's no way I can put that together before Saturday. Thanks anyways.

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Re: Mousetrap Vehicle C

Postby packer-backer91 » January 21st, 2010, 8:23 pm

I was wondering if anyone can give me a rough estimate of the weight of anyone’s vehicle it's my goal to get mine to weigh under 250g. Also as a guess for a great score for this event is under 20 is that close to anyone else’s actual runs.
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Re: Mousetrap Vehicle C

Postby winneratlife » January 22nd, 2010, 11:56 am

Tested Wednesday night! Got it down to 26! Invitational tomorrow!

Under 20 is really good, it would've taken 2nd at paradox's invitational ((s)he got under 5).

EDIT: Got it down to 9.6 distance at invite? Huh? Apparently my testing location is on a hill?

EDIT 2: 9.6 distance = 4th? What? I got lane bonus too... Unless my speed was really that bad...

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Re: Mousetrap Vehicle C

Postby inycepoo » January 26th, 2010, 3:02 pm

NYC Metro regionals are in two weeks, and I've yet to figure out a stop-and-reverse mechanism for my vehicle yet. I have both mousetraps in place with lever arms, it runs straight (built vehicle out of robot parts salvaged from my Sumobot trial event), and it stops right between the 7m and 8m line, but I don't know how to make it reverse :\ Can anyone give me advice how to make this work? I'll be willing to help with Trajectory, Mission Possible, Sumobot (NYS trial) or Ecology in exchange for any suggestions here, please. Thanks :]
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2010 New York City Metro Regionals:
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