Electric Vehicle C

kenjarius
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Re: Electric Vehicle C

Postby kenjarius » Tue Apr 21, 2009 5:39 am

jazzy009 wrote:Hey we are switching to a computerized car. My partner went around to local electronic shops and the people had no idea what to use as the computerized part. Isn't it just a micro-processor? and do you know any (oddly) commercial place we could get one or from what device we could get it from...hopefully besides a computer.


For a microprocessor, you might want to check out parallax.com. They make the BASIC stamp, javelin (java based), and the propeller(Spin based). However my experience with them has not been the best. The Stamp is somewhat lacking in functionality and my propeller has exhibited strange unaccountable behaviors(other people have had no problems though >.>). The upside of using these processors though is that they are very user-friendly.

If you have had previous programming experience, you could try a PIC, AVR,...etc. These controllers generally use C and (in my opinion)should not be used unless you have had experience(yes that is important) or someone who can help you with it as the documentation is meant for professionals and can be very hard to understand.

and just as a strange side note micro-processors cannot perform recursive functions

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Re: Electric Vehicle C

Postby gh » Tue Apr 21, 2009 6:11 am

kenjarius: Recursion can be implemented on microcontrollers just the same as on a regular computer. Compiler limitations, or maybe limited space for a stack might prevent you from doing it on some platforms, but there's no huge architecture difference between your regular 8-bit RISC PIC or AVR and your desktop that would cripple your ability to use recursion. Except why would you need to use recursive functions on your EV, anyways?

Also, welcome to the forum. :D

Jazzy: You can not easily use a regular computer for your EV. Our computers are designed to interface with humans, not with motors and sensors. You try getting your laptop to turn your lamp on and off. For these things, we turn to microcontrollers, which are small, low-powered computers that contain all the stuff they need to run, and are made to well, control circuitry.

Anyways, the Stamp is great to learn on (refer to my rant a couple pages back), but lacks the hardware and software horsepower to read a really high-resolution encoder, which is a sensor that turns rotary motion into electrical pulses, and is pretty much what everyone uses for EV.

The Propeller is much faster than the Stamp, and is also has eight cores, so it can essentially do 8 different things at the same time. This ability is pretty useful on an EV, where you have the encoder reading, motor control, user input, a display, speed feedback, etc. all happening simultaneously.

I used a high-end (read: fast) PIC chip with a single thread of execution, but it had an extensive hardware interrupt system that basically allows the programmer to choose the priority at which various bits of code should be run. This way, I can have the encoder reading code subsume the motor control output code, since it's a lot more important that an EV doesn't miss any encoder ticks than making sure 500 times a second that the motor is turning.

Parallax also has the SX chip, which is just very very fast, so you can do things on it that would otherwise take specialized hardware like the Propeller's multiple cores or the PIC24's interrupt hierarchy to do. It does put a bigger burden on the programmer though, so that could be not so great for the complete beginner.
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Re: Electric Vehicle C

Postby starpug » Tue Apr 21, 2009 11:30 pm

Relative to my posts, on the image gallery. I've asked them to be removed because the builder, the team, and the school are, EXTREMELY, upset that pictures have been posted of the winning EV design here in Northern California. It was not my intention to cause any harm to their chances at Nationals, I thought that people would be able to praise the design and ingenuity involved in creating it.
There remain other pictures that have been posted by others and many more were taken when the device was being inspected. I have no control over those photos.
Again I regret ever taking those photos.
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Re: Electric Vehicle C

Postby sachleen » Tue Apr 21, 2009 11:44 pm

starpug wrote:Relative to my posts, on the image gallery. I've asked them to be removed because the builder, the team, and the school are, EXTREMELY, upset that pictures have been posted of the winning EV design here in Northern California. It was not my intention to cause any harm to their chances at Nationals, I thought that people would be able to praise the design and ingenuity involved in creating it.
There remain other pictures that have been posted by others and many more were taken when the device was being inspected. I have no control over those photos.
Again I regret ever taking those photos.


I'll say it again, I don't think you did anything wrong, your builder(s), team, and school are over reacting about it. If Loma doesn't win EV at nats, its because another school is better than them, not because somebody ripped off their EV design that doesn't even have anything super great that's worth 'stealing'...

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Re: Electric Vehicle C

Postby kenjarius » Wed Apr 22, 2009 2:44 am

gh wrote:
I used a high-end (read: fast) PIC chip with a single thread of execution, but it had an extensive hardware interrupt system that basically allows the programmer to choose the priority at which various bits of code should be run. This way, I can have the encoder reading code subsume the motor control output code, since it's a lot more important that an EV doesn't miss any encoder ticks than making sure the motor is turning 500 times a second.



Wow, you just outlined the basic structure of what I use on my program for my EV :P
Just out of curiosity, did anyone here have any success using steppers? North Hollywood here in Socal used one, but their vehicle didn't do that well.

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Re: Electric Vehicle C

Postby nickfastswim » Wed Apr 22, 2009 5:36 am

tehkubix wrote:
starpug wrote:Relative to my posts, on the image gallery. I've asked them to be removed because the builder, the team, and the school are, EXTREMELY, upset that pictures have been posted of the winning EV design here in Northern California. It was not my intention to cause any harm to their chances at Nationals, I thought that people would be able to praise the design and ingenuity involved in creating it.
There remain other pictures that have been posted by others and many more were taken when the device was being inspected. I have no control over those photos.
Again I regret ever taking those photos.


I'll say it again, I don't think you did anything wrong, your builder(s), team, and school are over reacting about it. If Loma doesn't win EV at nats, its because another school is better than them, not because somebody ripped off their EV design that doesn't even have anything super great that's worth 'stealing'...


tehkubix is right on this, you did nothing wrong. Just because some other teams can see pictures of a really good EV design doesn't mean they will suddenly gain knowledge of how to make a good EV. Anyone can open up a computer and look inside but does that mean they know exactly how to build one and make it work? Probably not. Those pics are just pics of the final result, they don't show the full story of how the EV was build, programed, calibrated, etc..
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Re: Electric Vehicle C

Postby SiegeLord » Wed Apr 22, 2009 7:59 pm

nickfastswim wrote:tehkubix is right on this, you did nothing wrong. Just because some other teams can see pictures of a really good EV design doesn't mean they will suddenly gain knowledge of how to make a good EV. Anyone can open up a computer and look inside but does that mean they know exactly how to build one and make it work? Probably not. Those pics are just pics of the final result, they don't show the full story of how the EV was build, programed, calibrated, etc..

That doesn't matter. Even if they were pictures showing the detailed workings of the car, they still would be fine. This is a Science Olympiad, and in science all you do is share ideas, in order to further understanding and technique. Winning is secondary to what you learn from trying your own designs, and seeing other people try theirs. Cutthroat competition where everything is secret, and people are threatening to sue everyone hurts the very goals of Science Olympiad, which it looks like the Mira Loma team needs to review @ http://soinc.org/mission

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Re: Electric Vehicle C

Postby rocketman1555 » Wed Apr 22, 2009 8:06 pm

SiegeLord wrote:
nickfastswim wrote:tehkubix is right on this, you did nothing wrong. Just because some other teams can see pictures of a really good EV design doesn't mean they will suddenly gain knowledge of how to make a good EV. Anyone can open up a computer and look inside but does that mean they know exactly how to build one and make it work? Probably not. Those pics are just pics of the final result, they don't show the full story of how the EV was build, programed, calibrated, etc..

That doesn't matter. Even if they were pictures showing the detailed workings of the car, they still would be fine. This is a Science Olympiad, and in science all you do is share ideas, in order to further understanding and technique. Winning is secondary to what you learn from trying your own designs, and seeing other people try theirs. Cutthroat competition where everything is secret, and people are threatening to sue everyone hurts the very goals of Science Olympiad, which it looks like the Mira Loma team needs to review @ http://soinc.org/mission


I still want to know how they plan on suing for something like this. Its not technically an invention because at least 1000 other devices to do the same thing in pretty much the same way have been built across the country
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Re: Electric Vehicle C

Postby andrewwski » Wed Apr 22, 2009 9:56 pm

I don't see anyone saying that they are filing a lawsuit against anyone. Where's that coming from?

There really would be no grounds anyway - taking pictures is perfectly legal as described before. And let's say hypothetically somebody copied your device down to the very last detail. Unless you have a patent on it, there's no grounds there either.

I don't see what the issue some people have with pictures are. It's not like they're taking your code or something. I could put up pictures of my EV (and I will, as soon as I get them from a teammate) and I guarantee you nobody could build my EV as well as I could. Note, I did not say nobody could build a better EV than me. Mine wasn't that great - fell just shy of 197 at regionals and had only been in the lower 198 range during tests. It was fairly crude and imprecise compared to the ones that place at states. But it was fine for regionals, and I could have made another if we went to states. But since it was my design, and I had spent weeks testing and modifying it, nobody had the inside-out knowledge that I did - so they couldn't tweak it properly, couldn't fix what went wrong, etc.

But, under this logic, I suppose we should ban spectators from building events as well? Because god forbid somebody else knows what your design was...

How about we let the issue die and focus on actual Electric Vehicle stuff.
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Re: Electric Vehicle C

Postby sachleen » Wed Apr 22, 2009 10:53 pm

I could even post my code, you wouldn't get much out of it. It just reads the value from the encoder and compares it to what it should be based on months of testing and tweaking. Even if you had the pictures, code, and spreadsheets I have, you still wouldn't be able to recreate my car because you would still have to test it yourself and find the various distance/encoder ticks/time relationships yourself. No matter how good of a builder you are, I still haven't found a substitute for the testing and tweaking.

You can check out the spreadsheet I used for EV as well as the source code for the VEX controller on it:

Electric Vehicle Spreadsheet | RobotC Source Code

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Re: Electric Vehicle C

Postby nickfastswim » Sun Apr 26, 2009 7:20 am

tehkubix wrote:No matter how good of a builder you are, I still haven't found a substitute for the testing and tweaking.


This applies to all the building events and any engineering work in general. I have never built any SO building event and had worked right away just as I expected it to. I actually spent at least 3x more time testing and fiddling around with the design than building it. From what i recall my simple EV took 5hours to build and then I spent about 22hours over a period of 2 weeks before competition debugging, and testing.
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Re: Electric Vehicle C

Postby Dark Sabre » Sun Apr 26, 2009 8:59 pm

To repent for being unable to take pics of some regional EVs, here are some state EVs:
[gallery]Electric Vehicle[/gallery]

The one with the massive breadboard on top won.

And yes, I really need a DSLR so I can get a telephoto lense.

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Re: Electric Vehicle C

Postby packer-backer91 » Sat May 09, 2009 4:22 am

because most of use are done for the year (unless you are going to nat's, than good luck) how did every one do this year
its alright to give scores because this will not be a Div C event next year. for the 4 time my partner and I have done great at Regional’s (with a score of 199's) then bomb out at state and get 5th (this year we got 196.75 at Michigan's state)
how did everyone else do? (I think I will add the video's I have some time to YouTube now that I know that it will not be an event anymore) Every year it seems that I do poorly at state (but this year I had a reason to be mad I never got a second run to correct the 2.5 cm I was off to the Right because the judge did not stop the timer like It says in the rules)
So overall how did everyone do this year?
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Re: Electric Vehicle C

Postby MontyBuilder » Thu May 14, 2009 10:40 pm

I'm new to the event, and our teachers are making all of us do EV to see whether or not we get make SO in the first place.
I don't know much about electrically stuff, stuff, stuff and stuff, but I have been successful in Scrambler for the past 2 years and I'm trying to incorporate some of my knowledge of how that runs into this event.
How is this design

You have a threaded rod with wingnut breaking system.
YOu have a button, that when pushed, starts the device, and when pushed again, stops the device. You place this button at the end of the threaded rod so that when pressed will channel an electrical current all the way around to a motor on the other side of the EV.
tHIS MOTOR WILL SPIN the wheels and thus the threaded rod (attached to the wheels) will also turn.
Because the threaded rod is spinning, and the wingnut cannot spin too, it must slide down the rod, just like a scrambler brake.
Eventually, the wingnut will slide all the way down to the button that started the whole procedure, push it, and turn the electrical current off, as well as stop the car at a certain distance.

Comprehend?!
Is that OK?
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Re: Electric Vehicle C

Postby Dark Sabre » Fri May 15, 2009 12:05 am

If you have done scrambler with wingnut breaking before, yeah, that would be a easy and effective way to do it.

I would recommend using two separated swtiches, one to start it and one to stop it. I say this because you need a "permanent" switch (doesn't return to original position after you release it) for the starting one, which tend to be harder to flip (okay for your hands, but hard for your wingnut), but you can use a "momentary" switch for the stop switch, which tend to have very light/easy actions. I say momentary just because that's the type of switch, the switch will actually be held down by the wingnut, so the electrical change will not be momentary.

So use one of these for the wingnut to press:
Image

You should definitely read the "Motor braking" bullet here:
http://scioly.org/wiki/Electric_Vehicle#Electrical_.26_Electromagnetic_Braking

The setup that gh's diagram shows should work well for you...
Image


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