Electric Car

SmD13x

Well first off, I do not know much about electronics, but I am in the process of reading.

To start off, I have to make an electric car that can travel anywhere between 5 and 10 meters in a straight line. I do not know the distance at first and I will be told the distance and will have to configure it somehow to go that exact distance. The car can only use 4 1.5v cells; 6v.

Here is the website that has the rules for this car I have to make. It is for science olympiad by the way. soinc.org/events/sample/ElectricVehicle_C08_v13%20_1_.pdf

Since I enjoy to program, I thought it would be cool to get a micro-controller like the Basic Stamp II and use that for this project. The thing is, I have never dealt with anything like this before and I'm not to sure where to begin. What I mean by that, is that I'm not to sure what I should buy. Like what motor should I buy and just what do I all need?? I don't want to start off buying the wrong items and not knowing what to do with them.

I found an article where a guy made an RC Car using the basic stamp. The thing I'm not sure about is that in this article he mentioned the Basic Stamp II couldn't output enough power for the motor, so he made an h-bridge. I'm just not sure on how to do all that yet..

Really the main thing I would like to know is what should I buy to start me off with this project. Motor brand and etc..

Anyways, If anyone has any advice or some type of different idea of what to do, that would be great, thanks...

Franklin

Some other poster was competing in this same event. You might use search.parallax.com to find the posts.

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- Stephen

SmD13x

Hmm...Well thanks for that very helpful reply. I'm assuming you mean this http://forums.parallax.com/showthread.php?p=689468, which really didn't help me, thats why I posted this.

Franklin

Well, first off you need to decide how you are going to control the vehicle. How are you going to set the distance, how are you going to keep it on track and so on. Once you have these items figured out then you would buy parts to make that happen. Have you a plan yet?

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- Stephen

SmD13x

Yes, I do have a somewhat plan. All I pretty much need to know are what items will work with the Basic Stamp II to get it working. I would just like to know what motor I should get. Right now I am in the process of reading about the Basic Stamp and its functions. The programming won't be the problem. I know a few different things that I could do for the distance. I'm pretty sure i will need an h-bridge so that i can control the motor, but again I'm new to this stuff so I'm taking guesses here on what I read so far.

Summary of Items I think I will need
micro-controller: Basic Stamp II
h-bridge: Not sure what I should get
motor: Again not sure what I should get

and of course the body and wheels which shouldn't be that hard. So if you can just tell me of what items you would use, that would be great. Thanks.

Franklin

I'd use continous rotation servos, several line following sensors and wheel encoders.

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- Stephen

SmD13x

Okay, thank you Franklin. The line sensors I can't use because you're not allowed any guidance at all. That will just have to be in the building of the base itself. Also, would I need an h-bridge for the servo? Or can the Basic Stamp II control it to go forward and back?

Oh, and should I just use
this
as the servo??

Post Edited (SmD13x) : 1/2/2008 8:16:56 PM GMT

hacktorious

http://mechatronics.eng.buffalo.edu/research/smartcar/Publications/Daniel_Project_June03.pdf

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Scott
If man made it, don't eat it!
Never under estimate the wisdom of nature!
www.POISONINGaNATION.com

Technic-R-C

Hello SmD13x,

Yes you do need an H-Birdge to control the DC motor.· You have two choices, you can either make one or buy one.· I suggest buying one with your level of knowledge.· If you want to make one i encourage you to try, but you might come up to some difficult coding situations and wiring problems.· Here is the list of H bridges that parallax sells (look for only H-bridges that control DC motors).

http://www.parallax.com/Store/Accessories/MotorServoControllers/tabid/160/CategoryID/35/List/0/Level/a/Default.aspx?SortField=ProductName,ProductName

I would suggest the HB-25 Motor Controller Two Pack·to control larger and stronger DC motors.· The HB-25 Motor Controller takes care of all of the dificult coding for you and it is a great choice for your project.· However it is also a little expensive.· If this is the case, you can purchase the pololu motor controller (link above).· This is another good H-bridge, but it is not able to control larger motors which might create a problem when you are driving a robot. (maximum of 1 amp for 2 motors)· The coding and help information (pdf file)is attached to each of the motor controllers web page.

In this project, you will also need to start learning code and wiring.· This can be accomplished by reading the "What's a Microcontroller" pdf book.·
http://www.parallax.com/Store/Books/EducationalTexts/tabid/181/CategoryID/66/List/0/Level/a/ProductID/139/Default.aspx?SortField=ProductName%2cProductName
This book, along with the accesories, will help you get started with wiring and coding your robot.

As for the sensors for your robot, i suggest looking at the parallax sensors and deciding which of them meet your needs.
http://www.parallax.com/Store/Sensors/tabid/86/Default.aspx

If you want an easy way out in completeing this project, i would buy the BOE bot kit
http://www.parallax.com/Store/Robots/RollingRobots/tabid/128/CategoryID/3/List/0/SortField/0/Level/a/ProductID/296/Default.aspx
All you have to do is add some sensors to it and configure the code for your project.
I would consider using encoders and·maybe GPS/navigation sensors that are built for the BOE bot.
encoder:
http://www.parallax.com/Store/Robots/RoboticAccessories/tabid/145/CategoryID/22/List/0/Level/a/ProductID/80/Default.aspx?SortField=ProductName%2cProductName
GPS and navigation:
http://www.parallax.com/Store/Sensors/CompassGPS/tabid/173/List/0/CategoryID/48/Level/a/Default.aspx?SortField=ProductName,ProductName

With parallax the possibilities are endless.

If you have any questions, feel free to ask. Good luck.

Regards

Technic-R-C





Post Edited (Technic-R-C) : 1/3/2008 1:10:11 AM GMT

Franklin

NO, if you are using servos (and the one you linked to is the correct one) you DO NOT need an Hbridge.

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- Stephen

Technic-R-C

Oops... My mistake, i was referring to the control of DC motors, i'll change that.

Thanks for the catch

Techinc-R-C

SmD13x

Again, thank you Franklin. I now have a good idea of what I am going to do.

Also, Technic-R-C thank you for the h-bridge recommendation. I'm going to try this with the servos first to see how those do, but if they don't work as well as I want, then I am going to use the h-bridge and DC motors. Another thing is, I would get that boe-bot since I am new to this, but it doesn't meet the requirements for this project. I am however going to use the boe-bot guide as a guideline for learning about this.

Again thank you everyone that helped, and I feel that this is going to turn out good