Electric Vehicle C

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Re: Electric Vehicle C 2009

Post by gh » February 6th, 2009, 11:00 am

I recall that this was answered last year in the SOInc.org FAQs section for EV (I think I sent it in, heh) and it was determined that capacitors, inductors, and other components that could be considered storage devices were OK.
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Re: Electric Vehicle C 2009

Post by fleet130 » February 6th, 2009, 11:37 am

I think it went something like this:
'Para. 2.c.1 - Does this paragraph apply to devices such and capacitors and inductors that store small amounts of energy derived from the allowed batteries?

No. Paragraph 2.c.1 refers to additional energy that is not derived from the batteries which propel the vehicle. Additional storage devices, such as springs, weights and even batteries may be used as long as energy derived from them is not used to propel the vehicle in any way. Any batteries used for these purposed would be included in the 4-cell/1-battery pack limit in paragraph 2.b.

It should be obvious that to propel the vehicle, electrical energy from the batteries must be converted to another form. Energy from the batteries may be transferred to intermediate storage devices/forms as long as all energy which propels the vehicle is derived from the batteries.
Remember, this is a new year, new rules and new people interpreting the rules and answering questions. Anything said last year may not hold water this year.

Note: The above Q/A is talking only about "capacitors and inductors that store small amounts of energy derived from the allowed batteries".

It's still up to the contestants to show all energy used to propel the vehicle was derived from the batteries. This year's rules clearly state in Para. 2.a that all electrical energy used for any purpose must come from the batteries. Para. 2.b covers energy use for purposes other than propelling the vehicle.

The only person who can answer this with any authority is the one who will be judging it at your tournament.
Information expressed here is solely the opinion of the author. Any similarity to that of the management or any official instrument is purely coincidental! Doing Science Olympiad since 1987!

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Re: Electric Vehicle C 2009

Post by rman » February 7th, 2009, 2:52 am

I guess I have just seen too many second tiers from coordinators who had a very subjective feeling about the interpretations of the rules. Sometimes the coordinator is more interested in appearances then actual function. I saw someone posting about having their trajectory almost being decond tiered because the event coordinator thought that a spring used in the trigger was actually powering the ball. As I recall the event coordinator had essentially made up his mind without even asking the kid what the spring did. Without any real guidance as to what would be considered more then a simple filter cap some competitors might believe that they couldn't use caps or inductors at all. I like the idea of allowing anything that is gets it's power from the batteries. That avoids any subjectivity in size or use of the inductors or caps, wish it was in the rules.

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Re: Electric Vehicle C 2009

Post by fleet130 » February 7th, 2009, 4:50 am

rman wrote: I like the idea of allowing anything that is gets it's power from the batteries. That avoids any subjectivity in size or use of the inductors or caps, wish it was in the rules.
Isn't that what the rules say?
Para. 1:...construct a vehicle that uses electrical energy as its sole means of propulsion...
Para. 2.a: Electrical energy used for any purpose must be stored in common, commercially available batteries...
Para. 2.b: The allowed batteries and/or additional non-electrical energy storage devices may be used to operate other functions...
Unfortunately there is no way to immunize event supervisors against lack of knowledge. You will have to deal with each one individually.
Information expressed here is solely the opinion of the author. Any similarity to that of the management or any official instrument is purely coincidental! Doing Science Olympiad since 1987!

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Re: Electric Vehicle C 2009

Post by rman » February 8th, 2009, 3:31 am

fleet130 wrote:
rman wrote: I like the idea of allowing anything that is gets it's power from the batteries. That avoids any subjectivity in size or use of the inductors or caps, wish it was in the rules.
Isn't that what the rules say?
Para. 1:...construct a vehicle that uses electrical energy as its sole means of propulsion...
Para. 2.a: Electrical energy used for any purpose must be stored in common, commercially available batteries...
Para. 2.b: The allowed batteries and/or additional non-electrical energy storage devices may be used to operate other functions...
Unfortunately there is no way to immunize event supervisors against lack of knowledge. You will have to deal with each one individually.
As you quote, in 2a. It says that electrical energy used for any purpose must be stored in the batteries. 2b. it says that the additional energy storage devices must be non-electrical. I might think that a reasonable interpretation of those rules would be no capacitors or inductors since both of those are electrical energy storage devices, and any electrical energy used for any purpose must be stored in the batteries. I don't believe that this is what the rules intended, but it's hard to say for sure. I am assuming that a cap or inductor/transformer that is used primarilly for a purpose not related to storing energy to propel the vehicle or to actuate something (like a simple RC oscillator, or filter cap in a power supply, or an inductor in a DC to DC converter) would be ok. But I am thinking that if you actually stored enough energy in a cap so that you could propel the vehicle or operate a brake or clutch with it, then you might get into trouble.

In reality the deciding factor will probably have more to do with the physical size of the cap then it's ability to drive the vehicle. A very light and slow vehicle could almost certainly be sucessfully powered by a "supercap" small enough to not draw any attention, while a huge electrolytic filter cap being used by a fanatical beginner circuit designer to simply decouple the motor from a DC to DC converter might get a second tier.

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Re: Electric Vehicle C 2009

Post by gh » February 8th, 2009, 6:32 am

rman wrote:I am assuming that a cap or inductor/transformer that is used primarilly for a purpose not related to storing energy to propel the vehicle or to actuate something (like a simple RC oscillator, or filter cap in a power supply, or an inductor in a DC to DC converter) would be ok. But I am thinking that if you actually stored enough energy in a cap so that you could propel the vehicle or operate a brake or clutch with it, then you might get into trouble.
But the entire idea behind a DC-DC converter is to charge up an inductor and chop it, then use the spike to charge up a capacitor. The DC-DC controller would vary that so the output voltage is constant, and that would be what many are using to give their motors a constant voltage. Anyways, I think any judge who has knowledge that inductors and capacitors are energy storage devices would also probably know that they store relatively miniscule amounts of energy, self-discharge fairly quickly, and for the most part derive energy from the batteries.

As a sidenote, I'm not regulating the voltage to my motor at all. I'm running them straight from the battery, then using feedback from the encoder to determine speed, I adjust the speed of the motor in software. This makes the timing far more resilient to environmental variables. However, I think if I did regulate it, it would probably improve consistency.
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Re: Electric Vehicle C 2009

Post by andrewwski » February 8th, 2009, 2:03 pm

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.

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Re: Electric Vehicle C 2009

Post by packer-backer91 » February 8th, 2009, 4:36 pm

I was reading the rules through again and was wondering on the part on distance score, it says "These distances are measured to the nearest mm the distance is measured is measured from starting line to tip of the vehicle's pointer, perpendicular to starting line (point to line)" I was always under the assumption that it was going to be measured from the pointer of your vehicle to the center of the target distance but that makes me think that they measure from pointer strait to the line of target distance. Also in finish line score it says that it is measured point to point (meaning center of line to your pointer).
Does anyone know if that is what is meant by in the rules (I have always just naturally measured center to center). Just want to know, working on improving my variance left or right but if they don’t measure that way I don’t need to worry.
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Re: Electric Vehicle C 2009

Post by andrewwski » February 8th, 2009, 5:10 pm

Distance score is from the line (they give it in terms of the starting line, but you could measure to the finish line and subtract).

Finish line score is from the pointer to the center of the finish line (the point where the center line and finish line meet).

So your left/right drift won't affect your distance score, but it will affect your finish line score.

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Re: Electric Vehicle C 2009

Post by packer-backer91 » February 8th, 2009, 5:43 pm

thanks thats what i thought it ment
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