CADS

When you are starting up a FIRST robotics team it is fair to say that you are making things up as you go.  Sure, you can read how others have done it, but everyone has different circumstances.  You have to go with your strengths.

Our fledgling team has several, including a really great work space.  One of our sponsors is a place called Machine Tool Camp.*  They refurbish huge, complicated CNC** machines.  But as a...well a hobby I suppose, they have created a Maker's Space.

Our robotics team will be the first real users of the work space as it by happy coincidence is being finished off just in time for us.

It is what I call Robot Building Disney Land.  In addition to the necessary creature comforts (bathroom, coffee machine, kitchen) it has computer work stations and most importantly for our purposes a serious metal fab shop.

Rookie FIRST teams do not, as a rule, finish high in the standings.  So our goal will be to exceed the low expectations of first timers and to look darned good in the process.

So, if you have access to software and computerized milling equipment that will allow you to do fancy, complex and artistic metal fabrication, what do you do?

You start a pre-build season series of classes for students and coaches.  Lets make fancy stuff out of hunks of metal!

And I have to say, some of these kids are Scary Smart.
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* Of necessity my blogging on FIRST robotics will have a bit less anonymity than my usual bill of fare. Being as I am semi retired I guess that is OK.

** For the uninitiated CAD is Computer Assisted Design.  CNC is Computer Numerical Control. The first term is essentially designing things on computer.  The second refers to feeding the design parameters into a computer that can control metal fabrication machines and build the part for you.

Christmas 2015

"I wonder what normal families do for Christmas?"

I asked that on Christmas Day.  I'm guessing for instance that our ongoing tradition of setting up a Christmas tableau on the neighbor's lawn under cover of darkness is a bit atypical.  This year we had a jousting theme with one participant being Santa Claus riding a snow blower and wearing a Jason mask...

I like the old Pontiac hubcap used as a shield.  Oh, also note the poor gnome stuck in the intake...

Of course we do give presents.  I found some really swell Amish themed pint glasses at the surplus store.

But I was out done by one of our lads who fancies himself a writer.  He came up with a five page manifesto feverishly hammered out on a manual type writer.  Chock full of cryptic allusions to plots and conspiracies of course...

As to presents for me, I did pretty well considering my Naughty score for the past year.  I got a couple of swell outfits for Bill the Squirrel and some sausage guaranteed to be made from genuine feral pigs.

Ah, but these are trifles.  The biggest gift was the presence of the younger generation(s).  All are doing fine.  And with a new baby in the house for the first time in 22 years the mood is definitely changed.  Rocking, bouncing, mugging to try to induce precious smiles.  Old songs that have lain dormant for a quarter century are haltingly recalled, then after a rusty line or two come back in perfect execution.

I hope you all got some good swag from the big  guy in red wearing the hockey mask.  I treasure all my presents including a shoulder full of warm spit up.

The Christmas Squirrel Speaks

Hey, its Christmas.  No blogging!

Christmas Shopping?

Hey, I'm not very good at shopping.  I can only stand doing it for short periods of time and at stores where I can find interesting things to look at.  Not buy usually, but look at.

The local Guy Stuff Store is usually fun.

I am not sure how this works.  Does it give Fido a squeeze or an electric shock if he barks? Seems to me that would actually increase Dog Anxiety.  I also wonder if there is a human version.

Mealworm Frenzy. Kind of says it all.

I am puzzled by this one.  Tarsal is a medical term that refers to the ankle.  So basically this stuff is called "Big Foot".  I don't want Big Foot to feel I am intruding on his territory.

This at least might have some practical application.

Ten Cents worth of History

It didn't belong there.

I was at a college surplus sale.  You go there to pick up slightly out of date computer equipment and sturdy yet clunky storage shelves that you usually regret buying.  I got a few things; a coffee maker for a buck, a phone for the cabin, nothing great.

So why was there a box of bowling trophies?  I already have too much kitschy stuff laying around but trophies sometimes get re-purposed as awards for my robotics competitions.  So I grabbed the best one.  Heck, it was only ten cents and I think you will agree, its a beauty.

Traditionally it is baseball that is considered to be the sport that defines the character of America.  I won't argue the point here.  But if you specifically wanted to understand Middle America, that chilly flyover land seldom seen on the news, I think bowling could stake a rival claim.

People bowl on teams.  They wear slightly silly uniforms.  Unlike baseball you can eat a cheeseburger and fries while participating.  Until recently you could smoke.  Bowling is a game that is rooted in small town tradition but present in larger places.   It tends to be an older person's game but kids do it also.  For years it was one of our Christmas family traditions.

There is an entire set of non visual features of bowling that are every bit as distinctive as baseball. The rumbling progress of the ball with the sudden crash of impact on the pins.  The tactile rush of air from the little hand dryer built into the ball return.  The faint smell of cigarettes that while ever diminishing will probably never vanish entirely.

So, my dime's worth of American history?

Feit's Lanes was a classic small town bowling alley/bar in Park Falls Wisconsin.  I found a couple of images of it.  Here it was in its heyday:

It is actually for sale now.  Looking over the prospectus I had a hard time reconciling the pictures. But with the old facade apparently sheared off and replaced with something unfortunate, this is Feit's today:

The information that accompanies this says that the bowling alleys were torn out years ago making a larger space for bands, gatherings and so forth.  I saw this photo and just got sad.

For over sixty years Feit's Bowling alley and bar was run by a Robert A. Feit.  You can probably imagine him in your mind.  Tubby guy with a crew cut.  Always talking. He likely had a million stories, none of them true.

But you would be wrong.  Very wrong indeed.

Robert Feit was born and raised in Park Falls.  In 1946 he came back to marry his sweet heart and settle down.  But for a few years he was a member of the United States Marine Corps First Raider Battalion, also known as Edson's Raiders.  Wounded, many times decorated, he saw some of the most ferocious fighting of the Pacific War, as a member of a truly elite military formation.

I bet he kept the crew cut.  The years do tend to leave their mark on our once trim waists.  But the stories... I bet most of the ones we would actually tell you were true.  But he didn't talk that much and the stories he wouldn't tell you were the truest ones.

Robert Feit 1926 to 2007.  Semper Fi.

One Pound Prototype Robot

When I first started doing the middle school combat robotics course we had one and three pound weight categories.  This paralled the categories used in "official" competitions.  But the one pounders, known as ant weights, were never very exciting.  With that small a weight allowance you just could not build much beyond a simple pusher.  Or at least you had a very difficult time doing anything fancier such as adding a powered weapon.  So we have been all three pounders for several years now.

But things are changing.  As I started looking around at ways to move beyond simple hacked servos for robot drive I came across these:

Ebay has a ton of them for sale, with prices in the four or five dollar range once you factor in postage. So cheaper than a servo, but they still need something to control them.  A solution suggested itself...

Here is your basic - roughly one pound - robot.  Nothing more than a couple of  hacked servos, a battery and a radio receiver.  Not particularly zippy, but to be fair it seemed to have an excess of duct tape on one wheel that was catching...

I think we can do a little better than that.

Below are a pair of the bright yellow gearmotor/wheel combinations from China via the miracle of ebay.  The fact that they come with perfectly fitting wheels is a big help, fashioning sturdy, reliable hubs can be pesky and time consuming.

The little green circuit boards soldered on to the motors are my solution to the issue of control.  They are just the electronics pulled from servos.  Sure, why not?  I have a big box of them that have come to grief over the years of doing the event and they appear to have plenty of extra capacity.  So long as you run them at 6 volts they are unlikely to go up in smoke.  The slender wires act as sufficient resistance that I don't see any way to "over amp" them even if you did try to push an immobile object with them.

Here is the above platform with the servos swapped out for China Gear Motors.

Way faster.

As with my Proto3 robot a few thoughts on practicality.

Weight: above was, with battery, about one ounce under a pound.  There is room for improvement of course, the frame I borrowed had been heavily baptized with glue, and was larger than needed anyway.

Adaptability: OK.  I think enough weight could be spared to allow for either a four wheel version or a simple weapon running off the 6 volt drive battery.

Effectiveness:  It was not as effective a pusher as I would like, probably the gearing is set for speed over torque.  Four wheel drive would help a lot, and also make it easier to handle.

Challenge to Learning ratio: again I have to worry about making this too easy.  It was not at all difficult to toss this together in a few minutes.  Other than pulling the servo guts out and doing a little nimble soldering work, I don't see how the urchins would be kept occupied for very long.

Cost: feasible.

I am looking at several other options as well.  Some time into next year I may have to revisit this.

Three Pound Prototype Robot

Although my middle school combat robotics class has been both successful and fun for many years now I have been tinkering with the idea of a technology upgrade.  In part to keep it more interesting. And in part because we can.  Electronics in particular have gotten so much more affordable recently.

But anything I would do would have to fit the spirit of the class, which is cheap and fun.  It would also have to be within the dubious skill set of middle school students.  And would have to be feasible within the somewhat cramped confines of our Machines Behaving Badly combat arena.

So eliminating any elements that would be too complex, too expensive or perhaps too speedy for a confined space, what's left?

Some of the Minions who come over to help with the event suggested this motor, widely available on ebay.

They claim to put out 1000 rpm at 12 volts and come well recommended for durability.  But still, at about ten bucks including shipping, they are not quite the bargain of our hacked servo drive systems. Or at least they did not look to be, then I found a bag of 18 similar motors that I ordered years ago and never got around to using.  I should clean the workshop more often.

428 rpm at 9 volts sounds good, we will actually be running at 9.6. Assuming two per robot, if I toss in the ones I already have we are down to an affordable price per machine.

I made some hubs out of plastic squares from the surplus store.  Just tighten that little set screw...

Motors with attached hubs/styrofoam wheels going on.  I am using cheap and easy cable ties and hot glue here, but there are nice mounting screws on the front of the motors.

And...the finished product.

If you are keeping track of such matters, that is a standard 9.6 volt RC car battery.  I don't doubt that the system could handle more voltage but these are cheap and sufficient.  That is a standard Futaba FM 75mhz receiver, it runs with the free Vex transmitters I have been using.  The green board is an older model Scorpion speed controller.  This could be the rate limiting problem for us.  I have to do some ebay prowling and tinkering, but most of the ultra cheap speed controllers have suspect reliability.  And even the cheapest equivalents to the above unit are around 35 bucks.  Of course it is quite possible to swap speed controllers from one machine to another for a season or two as we build up stock.

On to the testing.

Speedy enough?

Yep.  The controls are a bit glitchy due to a conflict between the on board mixer of the transmitter arguing with that of the speed controller, but that is fixable.

How about pushing power?

If you can push a tool box around you can push another three pound robot.  Keep in mind that the box has a lot of friction from its surface area and that my tossed together robot does not have anything on the wheels to enhance traction.

So, lets pass judgment on the prototype.  We need to make it fit the budget which at present is about 20 dollars a machine.  If I scale the class size back from 24 to 20, and toss in the 9 robots worth of motors I already have, then assume I can get some kind of bulk deal somewhere, I figure motors will be around 200 dollars.  The cheapest speed controllers that look up to the job are about 35 each.  If we swap from one machine to the next, lets say we need six.  I might be able to shave a bit off the cost there as I plan to shop a few of the cheaper "mystery electronics" controllers from ebay.

Other costs should be fairly minor.  We will need more 9.6 volt batteries but our stock is good there as is our "in event" charging capacity.  Wheels, hubs, electrical connectors all are minor issues.

The prototype as shown above is only 1 pound 9 ounces so there is room for armor, weaponry, decor, etc.

One problem I note is that this is a little too easy.  Tossing together Proto3 took an hour or so of tinkering.  My charge is to keep the kids engaged for six or seven sessions of two hours each.

Another option I have considered is reviving the earlier dual path event, having one and three pound machines in their own brackets of course.  To that end I also tinkered with a Proto1 robot.......