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Dave W
06-10-2005, 04:39 AM
I run a "Technology Club" for a middle school in my area.· This past year, I talked the principal into buying 2 "What's a MicroContoller" with the homework board for our club.· The kids played with them for a short while, but quickly lost interest.· They built and ran the projects in the book which comes with the kit, but those are really boring projects.· I've been racking my brain for something the kids can do which will not require additional money and which will keep them interested.· There is another consideration:· I have about 10 kids in the club, but only 2 computers.· One of those PCs is running Windows 95 and, therefore, may not be suitable for the Stamp Editor.· That PC is an old (I mean really old) IBM PS2 computer.· It is not built on a Pentium processor.

Okay, with that background, here is my idea for at least approaching a project to hold the kids' interest.· Do any of you recall the DOS days when clubs were formed to challenge the hot-shot programmers?· One of the events those clubs sponsored was a programming challenge wherein the competitors would each write a TSR (terminate and stay resident) program.· When these programs were launched, the object was for one of the programs to find and crash the other one while still remaining active itself.· The surviving program was the winner.· I suspect that this activity was the beginning of virus writing.· I have described this only to give everyone an idea of what I am looking for.· Since I have far more kids than I have computers, I need some way of dividing the kids into teams and then challenging each team to create something.· It must be something that 6th to 8th graders find interesting.· Afterall, this is an after-school activity and they have been sitting in class all day.· So this must be something which is really fun.· The fighting progams is only a thought.· Another idea I had was to write a program which did some sort of interesting function.· Assign each team to write a program to do the same thing.· The winner would be the fastest and most efficient program.· There would be a timer of some sort to measure the progam's performance.· The tough part is that the program must do something which the kids will find interesting and challenging.

So far, I have not come up with anything that I feel would fit this challenge.· I don't even know if the combatting programs is possible on a stamp.· Is it?· There is only one more meeting left this school year.· I'm doing research now so that by the time the next school year begins, I will know what I want to with the kids.

Anyone have any ideas?

Dave W

Don Leuenberger
06-11-2005, 02:07 AM
I know how you feel about keeping kids that age interested, its tough. They need something visual and with some worthwhile goal in the end, in my experience (dad, scout leader). How about dividing them into teams to build metal detectors. Then they have to search an area of the school yard for a coin or something and the winning team gets a bag of candy or some other bribe. Here is a link to another post that explains how to build one.

metal detector thread (http://forums.parallax.com/showthread.php?p=467256)

It would cost a little in parts and a bag of candy but I don't think it would be that expensive. There's not much programming there but maybe you could spiff up the requirements to include leds or something.

Don

Beau Schwabe (Parallax)
06-11-2005, 02:28 AM
DaveW,

If you choose to go this route, I would be interested in the results.

As I am the one that did this project ( Thanks Don for the plug ), it was before I was a Parallax employee.
This project was more of a proof of concept for myself, I keep thinking one of these days I will build a larger scale coil design
and take it up to the "big lake" (Michigan) during a summer vacation.

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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Dave W
06-11-2005, 02:56 AM
Thanks for metal detector idea.· I'll need to study it some more, but on first glance, it looks as though I would have to build it.· I can't use soldering irons with these kids and I doubt that the detector would stay assembled·with the push socket breadboards·when used in the fields outside the school.· Also, the programming is fairly simple.· So that isn't a challenge for 10 kids.· I want to give it some more thought to see if I can make a project that kids actually build and then put to use.· It looks like this does meet my cost goals.· I may have some suitable transistors lying around or I can use the ones which came with the Stamp kit.· But those are pretty cheap in any case.· I would need to buy some magnet wire, but I'm sure I can afford that.· Now I just have to figure out how to turn this into something a little more challenging for the kids.· I do like the idea of a search contest with the prize going to the team that finds the most (valuable??) metal.· I might be able to use this idea like a scavenger hunt where the kids have to find metal objects which are really litter around the school.· That way, I could entertain the kids and teach them about a clean environment at the same time.

Is this design sensivitive enough to detect coins?· Again, that would certainly be motivator.

Dave W

Gadgetman
06-11-2005, 05:09 AM
Get ahold of a couple of small DC motors, some transistors that can be used to drive them(A good chance to teach them about H-bridges, too) and a couple of light sensors.

There's a lot of things that can be made with that...
Line followers, 'flowers' that turns to face the sun...

Strip a couple of old Floppy drives for the steppers. Connect them directly using transistors and you can teach them how the steppers work.
(How to step them with a program, ramp-up, ramp-down, half-stepping)

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Don't visit my new website...

Philip Gamblin
06-12-2005, 07:02 AM
Along the lines of a previous suggetsion, I built a "box bot" to demonstrate some programming for my daughters. My brain was an OEM BS2 ( it was cheaper) that I used to drive a couple of servo motors that I hacked for continous rotation which were hot glued( be sure to use the Hi Temp) to the bottom of a Radio Shack plastic enclosure. A one inch furniture caster took up the rear position as a tail dragger. I'll post some photos if you're interested. Once you have a running boxbot, groups can program to best perform a task. I glued additional proto boards onto the box for ease of prototyping. You can use the boebot guide for examples.

Dave W
06-12-2005, 10:30 AM
Yes, post some photos, Phillip.· I don't have a clear picture of what it is that you did.· So the photos will help.· Thanks.

Dave W

Cogburn
06-12-2005, 08:04 PM
You might try building an incubator based on the BS2 for the temperature control.· Use an old ice chest for the incubator box and a light bulb for heater.· You would need a solid state relay but those are around $12.00.· Hatch some eggs- the kids love that.·

You might also build a weather station - anemometer is easy using count command and temp is straightforward too.· Download StampDaq (free)and the kids·can see the temperature changes on an excel spreadsheet·graphed in real time.·

Build something for the classroom- servos are cheap.· Try building an alarm that will sense when the classroom is too loud- program BS2 to make the servo wave a "flag" that says "QUIET" and maybe also sound a buzzer.

Build some mousetrap cars or some CO2 racers and build a timer using·some photogates.· Program BS2 to·declare the winner of·a race.·

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Showing up to school doesn't·mean you are a student any more than crawling up in an oven means that·you are a biscuit.

Philip Gamblin
06-13-2005, 11:54 AM
Not sure if I properly attached the photos. Assuming they did the "bot" is a radio shack plastic enclosure, with two servos and a one inch furniture caster for the tail dragger. The nice thing about the OEM board is that you can easily put the 220 protection resistors in the breadboard. They should be visible in the photos. The wheels were scavenaged from a surplus toy drive. Everyting is hot glued together. With care I have had it together over a year. When something does fall off simply hot glue it back. The battery pack is not connected but I use a 4 AA pack on the battery snap. We'll need to work on your power supply to set up a different pac for the servos. A nine volt would probably go quickly.

Post Edited (Philip Gamblin) : 6/13/2005 5:02:13 AM GMT

Dave W
06-13-2005, 08:56 PM
Thanks, Phillip,

The pictures help a lot.· I'll be using the homework board which includs a small breadboard area.· I think maybe I'll use some of my NiMH AA digital camera batteries to power this.· They should run it for quite a while and they can be recharged.

A question for you:· You mention 220 ohm protection resistors.· What are they protecting?· I see 12 or so resistors in a row which look like 110 ohm resistors.· Are those the resistors you are talking about?· You don't have a schematic, do you?· It looks simple enough that, if you just describe it, I can take it from there.

By the way, I'll be out of town and not checking my email or forums from June 15 through June 24.· So, if you don't hear from me, that is why.

Dave W

Chris Savage
06-13-2005, 09:19 PM
Philip Gamblin said...(trimmed)
The nice thing about the OEM board is that you can easily put the 220 protection resistors in the breadboard. They should be visible in the photos.

Philip,

·· About those resistors...I see them on the board, but it looks like only one is connected to anything.· I see this mentioned in the previous post, but the other thing is you have a ribbon cable coming off the back side of the OEM Module.· All those lines are connected directly without any resistor protection.· I also took a second closer look at the resistors...Red, Red Brown would be 220 ohms, but they don't look that color.

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

Philip Gamblin
06-14-2005, 12:33 PM
There is really not much going on with the hardware. What is wired though, are photo resistors with caps which, with the current program cause it to follow a light or "photovore" functionality . Simply loading a different program creates a "photo phobic" behavior. The resistors are actually 220 ohm and are simply current limiting for all of the available I/O. Only 4 I/O lines are in use, two lines for the servos and two lines for the photo resistors. The ribbon cable goes "below the deck" to provide power and control signals for the servos. The first iteration of this project used the infrared emitter/reciever ( same as the BOE bot) pairs for touch free object detection and included LEDs for visual confirmation of channel activity. I also built up a small audio amp for morse code output driven directly by a Stamp pin. The tranlucent·8 pin dip on the breadboard is·a light sensor which is sold by parallax and is simply stored·on the board.

Post Edited (Philip Gamblin) : 6/14/2005 10:01:56 PM GMT

Dave W
06-15-2005, 06:51 AM
Philip, I'm curious about the function of following a light. From your photos, it looks like you used 2 simple photo resistors and have them bent toward the floor. Does that mean that you can only use the robot on a bright floor? Also, with 2 photo resistors so close together, how does the robot know which way to turn. Suppose I was 10 or more feet away and shone a bright flashlight at the robot. If I moved from one side to the other, would the robot change directions to follow the light? What I'm having trouble with is understanding how photoresistors only 4 or 5 inches apart can detect a measureable difference in the amount of light striking each detector from a light souce on the other side of the room. If each detector had properly designed lenses in front of it, then I could understand how it works. I suppose that one could use a laser pointer to direct the robot. That would work, but one usually assumes a more ordinary light source. Also, with a laser point aimed at one of the detectors, all the robot could do is make a sharp turn toward the illuminated detector. It would not be possible for the robot the direct itself to get a balance between the 2 detectors. So, in effect, the operator is steering the robot by giving the appropriate detector enough exposure to get the robot headed in the right direction.

What is the explanation for your case?

Dave W

Philip Gamblin
06-15-2005, 09:23 AM
All of your questions are exactly what make it an interesting platform. It is a very simple RC circuit built around the RCtime command. In the "photovore" mode,· light in front = RCtime results are roughly equal and the bot moves forward. A differenence of X magnitude, the bot turns right or left. All of the behaviors are software adjustable. Right now it kind of hops, but the motion could be made smoother through software tuning. That's where the kids come in. everybody has a base program and the same hardware. Better programs make a better behaved bot. It could be a line follower, soccer bot, or sumobot..... whatever. I don't know what is over their heads, but they could write the "real" program, pseudo code, flowchart etc. A program can be written in notebook, the only time needed at the PC is program entry and download time. I would have attached the code but it is not on this machine. The program explanationsand examples are in the (thanks to Parallax) freely downloadable BOEbot documentation.

Post Edited (Philip Gamblin) : 6/15/2005 2:27:56 AM GMT

Dave W
06-15-2005, 09:42 AM
Philip.

What I was getting at is that there would not be any measureable difference in light intensity at the 2 sensors unless the guiding light was pretty close to the robot. I'm envisioning a common flashlight being on the other side of the room and shining on the robot. How would it know which way to move unless you carefully positioned the beam so that one of the photo resistors was illumintated more than the other? Just being to one side of the robot wouldn't do that unless you were pretty close. Or am I missing something here? I understand that the BS2 can measure light using an RC time constant. I'm just trying to get a picture of how sensitive such a steering mechanism is. Certainly, the kids can experiment with it and they might surprise me with some ingenious method of controlling the robot. I was thinking of setting up an obstacle sourse and, without any remote control by kids, have them write a program which would move the robot in fixed increments that would get it through the course. If a method can be used to detect light beams (small flashlights) at each turn, that would be another challenge. I don't know about lines on the floor. I suppose we can do that as long as the tape or whatever we use can be completely removed when we are through. Anyway, I've got the whole summer to think about it. Thanks for your help.

This is probably my last post until June 25 when I return from my trip.

Dave W

Philip Gamblin
06-15-2005, 09:57 AM
the line following I did used the infrared sensors with black electrical tape on white posterboards joined together nor was I particularly successful.

Post Edited (Philip Gamblin) : 6/26/2005 9:30:42 AM GMT