Electric Vehicle C

[Coach Marz]

The answers to all your questions could probably be found within this post. It might take a while but if you read through it and edit it a little you should find anything you need. You can find everything you need at a Home Depot. You just need to be a little inventive. Good luck

[andrewwski]

A sighting device would be used to line up the vehicle so that it's pointed straight along the center line.

You really don't need to measure the track yourself. Only if you doubt the distance they tell you would you want to.

I don't know if Home Depot would have everything, but you could also check a local hobby shop. And Radio Shack. Depends on what type of vehicle you want to build.

I built a 2nd place EV in about 2 weeks last year...so it's definitely possible.

[Paradox21]

I built a third place vehicle in 2 days. If you are serious about it then you should definitely be able to finish in time.

[jazzy009]

I built a third place vehicle in 2 days. If you are serious about it then you should definitely be able to finish in time.

Whoa. I did too. what a coincidence.
if youre going for a pure mechanical vehicle though it will take a little longer, you just have to devote a lot of time to it and you will finish.

[rman]

Took 3rd with a score of 196.68 yesterday at regionals. I can't believe there were 2 teams that did better. Last year nobody broke 195.

I was just short of 3 cm off (only a few millimeters distance wise, most of it was drift to the left), and apparently 300 ms for the time score. However I know my time score was not off, as I used a timer circuit to run the vehicle. I'll attribute it to reaction time of the person using the stopwatch.

Given a little more time to toy around with it, I probably could correct the drift and get within 1 cm. But I'm happy with what I got.

I didn't see the winning vehicles but I sure would have liked to. Saw a lot that didn't do so well though. One didn't go anywhere, one veered right to the left; one kept going past the finish line, rotated about 160 degrees, and came back a few feet; quite a few only made it about halfway down the track.

I have been wondering about the time score for this event as well as "it's about time". Many of these vehicles use the crystal oscillator of their microprocessor to keep track of time and the vehicles are capable of timing accuracy measured in milliseconds (or better). Then the Event Coordinators and their helpers use hand held stopwatches that have an ultimate accuracy, due primarally to the human attached to them, measured in 10ths of seconds at best to time the run. This would all be OK I guess if the event coordinator recognized the inherent limit in accuracy of the stop watches and didn't attempt to attribute more accuracy then they are due. It would seem to me that a time error when measured with 3 humans with stopwatches has a statistical significance of no better then perhaps a few 10ths of a second. If we are trying to be scientific about our measurements then we should consider any time within this statistical significance to be the same.

In other words you cannot say that someone's vehicle was off by 0.03 seconds when your timing accuracy is no better then 0.3 seconds. Any time within this accuracy should be considered zero and scored as such, otherwise the winner is likely to be picked by random chance rather then due to a better time score.

[Paradox21]

According to wikipedia human visual reaction time is .18 to .2 seconds. But if we assume that it takes them .2 seconds to realize the vehicle has started, and .2 seconds to realize it has stopped then the time should still be accurate. Obviously there still is the possibility of human error, but if three stop-watches are used (as is recommended) then the relative error should be insignificant.

[rocketchicka]

We worked on our vehicle until 10:30 the night before comp and on the bus there. We finally got it done enough so it had a chance to work and we got 5th surprisingly. Turns out it was the deciding points on wether or not we went to state!

[rman]

According to wikipedia human visual reaction time is .18 to .2 seconds. But if we assume that it takes them .2 seconds to realize the vehicle has started, and .2 seconds to realize it has stopped then the time should still be accurate. Obviously there still is the possibility of human error, but if three stop-watches are used (as is recommended) then the relative error should be insignificant.

Anyone who has timed swimming events knows that you are lucky to get the three timers to be within several tenths of a second. Sometimes the errors from one timer to another are nearly a second. With a sample of only three timers there is no way that you are going to get better then a few tenths accuracy. Since the rules require recording time to 1 hundreths of a second it would seem that they are recording data to at least on more significant figure then the accuracy of the data. At the very best the data should only be recorded to 0.1 second because anything better then that is not statistically meaningful.

[Flavorflav]

According to wikipedia human visual reaction time is .18 to .2 seconds. But if we assume that it takes them .2 seconds to realize the vehicle has started, and .2 seconds to realize it has stopped then the time should still be accurate. Obviously there still is the possibility of human error, but if three stop-watches are used (as is recommended) then the relative error should be insignificant.

Anyone who has timed swimming events knows that you are lucky to get the three timers to be within several tenths of a second. Sometimes the errors from one timer to another are nearly a second. With a sample of only three timers there is no way that you are going to get better then a few tenths accuracy. Since the rules require recording time to 1 hundreths of a second it would seem that they are recording data to at least on more significant figure then the accuracy of the data. At the very best the data should only be recorded to 0.1 second because anything better then that is not statistically meaningful.

I have not timed swimming events. I have, however, timed Olympiad events, and I have never seen a timer off by anywhere near a second without said timer knowing there was a problem. I agree that the last digit is not significant, but I think "several tenths" is exaggerated.

[fleet130]

Note: It is standard practice to record values to a precision with 1 uncertain digit. In this case, you may consider the "10ths" digit is the first uncertain digit , but the rule writers obviously felt it is the 100ths digit.

Having supervised this sort of event for many years, I can attest to the fact that timers are almost always within a few 100ths of each other. 10-20% of the time they are identical. Timers are usually aware when they have significant error and those times should not be used.

By eliminating the slowest and fastest results from 3 timers, many errors are eliminated. Using just the center time produces much more accurate results than combining them.

Without a doubt, there are errors in the system: however, stopwatches are the only viable method in the Science Olympiad environment.