autonomous go-cart
Mr. Richard
Posts: 51
Hi, I am new to microcontrollers and the like and I was wondering if anyone has experience with this.
I a High school teacher who just bought a BS2 board of education kit. My teaching partner wants students (me) to make an autonomous go-cart. I can build a line following robot and would like to do the same thing on a larger scale. The plan is to use a steel frame, two DC motors independently driving two wheels using one or two car batteries as a power source. I will use two swivel casters in the front.
Can I control 12-volt motors with a BS2? If so, what do I need to do?
What size motors should I look at to drive a steel frame cart (about 250 pounds with frame, batteries and rider?
Thanks for the help
Josh Richard
Technology Education Teacher
Spring Grove Area High School
I a High school teacher who just bought a BS2 board of education kit. My teaching partner wants students (me) to make an autonomous go-cart. I can build a line following robot and would like to do the same thing on a larger scale. The plan is to use a steel frame, two DC motors independently driving two wheels using one or two car batteries as a power source. I will use two swivel casters in the front.
Can I control 12-volt motors with a BS2? If so, what do I need to do?
What size motors should I look at to drive a steel frame cart (about 250 pounds with frame, batteries and rider?
Thanks for the help
Josh Richard
Technology Education Teacher
Spring Grove Area High School
Comments
Have you considered starting with something on a smaller scale, such as modifying an RC car for autonomous use? It would be a good prototype for something bigger down the road.
You would be able to implement the basics of your system, with an eye towards scalability. It would also allow you time to adequately research & design your go-cart, while still learning new skills and technology.
I wonder what people really mean with this "autonomous" stuff, anyway.· I know how the dictionary defines it, but its usage is quite another matter: see, it's not independent and it's not under control either (it's A and not-A, simultaneously.)
"Autonomous" go-cart??· I ain't gettin' in it!· [noparse][[/noparse]Your Board of Education have a big personal-injury liability contingency budgeted?]
Anyway, I figure that one of these pedal cars (pic attached) would make a great R/C car platform, "autonomous" or otherwise.· Though their turning radius isn't phenomenal, they still have Armstrong steering.· And they have space aplenty, too.
My thinking was to have a rider holding a kill switch to stop all power if needed. This would help add to the safety factor. Could I add a freshmen kit that would seek out 9th graders?
Thanks for the thoughts
Josh Richard
In place of the line follower, you might consider a GPS system (where the vehicle follows a preprogrammed coordinates) or a beacon system. One group is working on a RC car which when placed in a hallway will seek a beacon located in a classroom, avoiding walls and working its way around obsticles. It is a lot of algorithm work and logic, but most -if not all- of this stuff has been done before (usually connected with the D.O.D., of course!). One group is using a Motorola HC11, but I am sure when they see how easy the Parallax Stamps are to work with, they will change their design (one group already has changed over to the BS2pe). Good Luck.
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Matts Persic
14231 Komedal Rd., NE
Bainbridge Island, WA 98110
United States
mattspersic@comcast.net
+1 206 931-1653 USA
+44 (77) 93827641 UK
http://www.parallax.com/detail.asp?product_id=29144
-ACfishing
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·
-Robert A. Heinlein
Thanks for checking up on me
Josh
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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!
Managing high voltage/current is dangerous and I never managed to find a mosfet controller that can do it.· Try using SCR's with pulse width modulation·instead (never tried it before so i'm not sure exactly how to do it or how well it works).···
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Post Edited (Lightfoot) : 1/16/2007 5:08:28 AM GMT
Edit: i see you want to build a line following robot its still cool, are you buying a go-cart or making one?
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<i>Happy]
Post Edited (Batman) : 1/17/2007 12:35:28 AM GMT
Lightfoot,
Have you looked at the HB-25? I plan on using them. I will start with small motors so I don't kill a freshmen.
Batman,
The project will use a few different classes. A CAD II class will do some research and design some frames. The winning two or three will be sent to an advanced metals class where the plans will be read and fabricate a frame. The Power Technology class will take the frame and make a rolling chassis. The electricity/electronics class will do the electrical work, and the machine automation class will do the stamp work. All said and done, my goal is to have about 30 to 40 students handle some part of the project. I will have one or two choice students to follow the entire project and know all the parts.
The two issues is the lack of time and funds. Students will be working on this in addition to regular class assignments. The other issue is cash. I need to put all budget requests in a year in advance, so if I need different major parts, I will be sending kids to their uncle’s friend’s scrap yard!
Anyone,
I have a 4 channel RC plane controller, can I send a signal from that to the stamp and control the cart? In my mind I can send a signal to the stamp and have the stamp react and control the motor controllers.
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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!
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- Stephen
You asked:
"I have a 4 channel RC plane controller, can I send a signal from that to the stamp and control the cart? In my mind I can send a signal to the stamp and have the stamp react and control the motor controllers."
Sure, why not. Here is an overview of what it looks like:
Remote R/C······· Local R/C······ ·············· ·PBASIC·Stamp
Transmitter -->·· Receiver·· -->··Fetch CMD······ Identify········ PULSOUT to
(Chan. 1-4)······ (Chan. 1-4)···· · via PULSIN·-->·Channel -->· proper·HB-25
Hope that helps.
Regards,
Bruce Bates
I looked into the first robotics. , it is a really cool thing. The schools I talked with have a $20,000.00 budget. 60% of time spent is fund raising. I prefer to do something that has a smaller budget and gets more kids involved. I am looking for getting more "that's cool" per dollar spent. If I could find some extra cash laying around the district, I would be more interested in larger competitions.
·
I just bought 7 vex kits from Radio Shack and am creating a contest for students. We are looking to the first as a guide.
·
Bruce,
I'm glad to know that my mind connects to reality sometimes.
·
Thanks for the help ypu folks are great
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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!
couple of things.
first off a RC plane trasmitter on 72Mhz range (assuming this is in the USA) is not supposed to be used for anything ground related by FCC laws.
you can buy plane style contollers and RXs on 75Mhz (surface freq) or depending on the TX a 75Mhz frequency module.
I have a Futaba 9c plane controller that I have a 75Mh module to run my RC monster truck. Then i switch modules to fly the planes.
if you are going to control somthing this big with RC I would look into a PCM modulated RC setup
http://www.futaba-rc.com/faq/product-faq.html#q102
also kill switches (note the plural)
I would have at least 2 kill switches on the system. one a physical battery disconnect that you pull off or hit a BRB (big red button) to disconnect all power to the kart. also a remote kill that stops the motor functions. I would use a seperate remote in case of a main TX/RX failure.
I dont know much about stamps (yet) but I do know RC (avid flyer for 5+ years and into cars for more then 13) and I know what a 13lb rc car doing 30 feels like hitting your ankle
I am looking forward to seeing this project work out. keep us updated and POST PICTURES [noparse]:)[/noparse]
Post Edited (Unstable) : 1/20/2007 5:31:33 PM GMT
In refrence to the frequencys, could I simply switch cristals in the transmitter and reciver?
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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!
http://www.futaba-rc.com/faq/service-faq.html#q2
here is a link to a basic futaba 4 channel. you can select a surface frequency for it. with 4 servos
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXEFJ4**&P=0
or if you only need a 2 channel setup (typical RC car "pistol" setup)
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNHS1**&P=0
this is what I use
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXHMD2**&P=0
with one of these for the RC truck
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXH259**&P=0
its pricey but will do just about anything you want it to.
the "bot" faq on the futaba site.
http://www.futaba-rc.com/faq/faq-bots.html
Post Edited (Unstable) : 1/21/2007 7:25:47 AM GMT
The long answer is besure both the transmitter and reciever are retuned. We switch crystals all the time when flying RC airplanes and have never had any problems with the FCC or other peoples controllers.
My RC airplane uses a 7 channel radio transmitter/reciever and it is neccisary to swap out compontents.
It was requested that I remove the name of the hobbyist-vendor who supplied the Radio/Receiver named in my Autonomous-Toy-Boat-Project. The device is well within FCC power and frequency requirements. (Especially in kit form.) However, can not be officially advertised as an assembled unit without paying an absorbent fee. At $12.95 USD each assembled, including transmitter, and the cost of components alone being nearly 80%, not including assembly, obviously was not being done for the money. Rather for the love of electronics and bringing to the table affordable technology to microcontroller-hobbyist .
However, now that the ‘WANNABE-FCC-POLICE‘ have reared it's ugly-head, the individual is now scared to death by the apparent sheer delight this individual has in supporting an air of apparent illegal intent with unjustified innuendos including dictating FCC law to those with the most innocent of intentions.
Certainly anyone having illegal motives would not be publishing the information in a public forum! I have complete faith in the current law enforcement system. Personally, I would like to see this individual crawl back under the rock from where he once hailed and leave us amateur hobbyist free to experiment without fear of being under the microscope of such self-proclaimed authority!
I'm sorry for those who may now not have the benefit of obtaining such a harmless Radio/Receiver device as it will no longer be available for purchase. Unfortunately, commercially available radio-control systems (Such as Futuba) can run into the hundreds of dollars and unnecessary for most experimental applications especially for simply interfacing the basic-stamp with ground based vehicles.
Thanks for listening!
-J
P.S. I feel must apologize for my apparent disgust and perhaps disregard for levity, however I feel attention must be drawn to this type of ‘fear mongering’.
Post Edited (jhoyoza) : 1/30/2007 4:23:53 PM GMT
I was not threatening anyone, just stating the laws as they are.
I figured as Mr. Richard was doing this project in a school enviroment that he should try to stay within the confines of the law, and to do that he need to know that such laws exist. I don't know what happened with your project, or why, but this is more then a problem with interfereing with someones profit.
I have seen a RC plane TX that had the crystal swapped out interfere with a plane 2 channels down from it. and that was staying within the same 72Mhz range. changing all the way to 75Mhz can have a larger impact. and we are not talking about a "toy boat" here but a large sized RC vehicle that will be operated around people. anytime there is the potential for injury a little "fear mongering" is needed.
Thank you.
<crawls back under his rock>
I saw no threats in what Unstable had to say. I always appreciate knowing more than one way to look at an issue. Now I know that I can quickly test a system (when there are NO planes flying around) by changing crystals then can invest in a proper system when I see it al work.
I currently have two 4 channel ground systems and was looking to move up to a 6 channel system.
Next·raido question. The 4 channel controller I have has a spring to return three out of the four channels to center. Is there a way to add a spring to the fourth channel?
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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!
A knife switch attached to a string still has my vote for a kill switch.
Yes, you can do the spring return BUT that largely depends on the controller you use. It also largely depends on your access to small springs.
Reason for this is because different controllers have different spaces inside. My RC airplane is a traditional box style controller and my T-Maxx has a controller that fits in your fist with a steering wheel uptop.
I assume you are using the traditional box style transmitter?
Post Edited (AIman) : 2/1/2007 5:13:33 AM GMT
I have a hitec laser 4 transmitter ..http://www.hitecrcd.com/Radios/laser4.htm
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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!
i saw an article in a magazine recently (don't remember if it was Servo or Robot or Nuts and Volts) but basically the left and right gimbals are the same just the one axis has a ratchet instead of a spring and bar (if you open it up it you will see what I mean) you can either fabricate a return bar or I am sure you can get one from hitec and use any small spring (depending on how hard you want it to center.
think in one of my radios it acually had the parts internally just not attached.
1) If the joystick (pot) is in direct contact with the front of the controller then you will need to check the back of the pot to see if you can do something there.
2) If the back of the pot is closed, can you open the pot and work from the inside?
3) If you can't access the pot then can you replace it?
4) Can you duplicate how the other pots function with the spring attachments?
Welcome to hacking
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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!
As far as ground and air frequency's for RC equipment, the biggest reason to not use air channels on ground equipment is that to someone else using a plane, or chopper another airborne RC vehichle is readily apparent. When air frequency's are used on the ground, many times the first indication to another RC'er in the area is when they lose control of whatever they are flying, ergo bad things can happen. That of course, and the whole FCC thing, but·safety is why the FCC thing is there. A 3-5lb gas powered plane can do serious damage when they get out of control, its why the automatic liability insurance with an AMA (Model Aeronautics) membership.
On the subject of switching crystals, most modern radios have no issues and are FCC legal to switch crystals in the same band. (IE channels) The serious issues come into play when you change bands without retuning the transmitter and receiver set. (IE 75mhz to 72mhz) Check with the manufacturer of your radio, but channel switching generally isnt an issue. Again, the main concern is safety, large jumps in frequency without retuning can allow the transmitter and receiver to drift in opposite directions, so the immediate danger to band changing is drastically shortening your control distance.
Safetys, Most new PCM <read> digital radio and receiver combo's will allow you to program a "default" position for all channels on the receiver end. So when signal is lost or degrades to the point of loss of control, everything on the receiver end goes to this user programmed default. This could be motors off, brakes applied etc etc so loss of contact gets a little less scary.
Flying a JR XP8103 digital, and 652 on the rare occasions I get the chance, love em both.
Hope this was some help and not too late to be of use. Oh, and if I didnt say it outright, older radios tend to have more issues with drift, and once you hit a certain age you have "Narrow band" and "Wide Band" narrow is preffered for less interferrence.
Good luck
Chris