Mousetrap Vehicle C

Paradox21
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Re: Mousetrap Vehicle C

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

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.
When it comes to the future, there are three kinds of people: those who let it happen, those who make it happen, and those who wonder what happened.

winneratlife
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Re: Mousetrap Vehicle C

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

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...

Paradox21
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Re: Mousetrap Vehicle C

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

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...
When it comes to the future, there are three kinds of people: those who let it happen, those who make it happen, and those who wonder what happened.

winneratlife
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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?

Paradox21
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Re: Mousetrap Vehicle C

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

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.
When it comes to the future, there are three kinds of people: those who let it happen, those who make it happen, and those who wonder what happened.

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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

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.
When it comes to the future, there are three kinds of people: those who let it happen, those who make it happen, and those who wonder what happened.

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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

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
Len Joeris
Fort Collins, CO

winneratlife
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Re: Mousetrap Vehicle C

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

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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