Area 51 Robotics

Is This Blog Dead?

2008-11-28T19:09:00.002-05:00

I'm sure everyone who has looked in on this blog is wondering if it's been forgotten. The answer is no, not forgotten. I haven't been doing much robotics at home lately. I've been doing some robotics with a high school robotics team. So there may not be any significant activity for awhile, but I promise I'll be back from time to time.

Oh, yeah...

2007-06-14T17:16:00.000-04:00

Did I mention that the pictures are fixed?

Trouble in picture-land

2007-05-20T20:18:00.000-04:00

Still very little activity to blog, but I thought I ought to get on long enough to note that the pictures on this blog are broken. My fault. I changed providers and forgot to update the links. I'll get them back up soon. Sorry for the inconvenience.

Summer Break

2006-09-20T10:48:00.000-04:00

Sorry I've not posted, but now summer's over and my focus is returning to robotics. Dragonfly, Wolfbait and I are working to expand the high school robotics program to include activities outside of the six week FIRST build season. Meanwhile, my BHAG is still out there. Look for some good stuff soon.

Reading Break

2006-04-17T07:15:00.000-04:00

Progress on the BHAG has slowed due to a number of factors: 1) I tried to put together a kit to do part of the job and the finished kit didn't work; 2) in an unrelated problem, the transmitter/receiver pair in my existing setup, which was working, stopped working; and 3) Easter.

So while waiting for some new parts to arrive and time to put them together when they did, I've been thinking about ways to learn more about robotics. Unfortunately there are a limited number of books about robotics, and only a few of those are available through my local library. So I have been looking for magazines on the subject. There are two magazines I know of focused primarily on robotics: "Servo" and "Robot". I've looked through one copy of each of these magazines so I can't say I have a really good feel for the tone of each. If anyone out there cares to comment with their observations, feel free.

Servo (http://www.servomagazine.com/) is put out by T&L Publications, who also produce "Nuts and Volts" about electronics. From what little I've read, there does seem to be some electronics emphasis in Servo, but overall it seems to be a pretty balanced package.

Robot (http://www.botmag.com/) is published by Maplegate, who also publishes "RC Driver" and "FlyRC". It appears to me to be a bit flashier, perhaps in part because its board includes Adam Savage and Jamie Hyneman of MythBusters fame. This is a very new publication; currently issue #3 is on newsstands.

I should also mention a more general magazine of interest to technophiles: "Make" (http://www.makezine.com/), which is a project oriented publication for those who just want to build something cool.

The BHAG

2006-03-27T21:54:00.000-05:00

As I mentioned, I've been rather busy lately and haven't had time to post. Fortunately, at least one of the things that has kept me from posting about robotics is robotics. Let me give you a first glimpse of my BHAG, my Big Hairy Audacious Goal. My BHAG is:

A Robotic Blimp!

My goal is to build a blimp with control system that can navigate around a room without human intervention. One of the principle goals is that the system be CHEAP. I am using commercially available parts wherever possible to reduce the amount of development I have to do. Here's what I've got so far.

The blimp platform is a toy blimp by Huan Qi, sold here in the US by Raiden Tech (http://www.raidentech.com/rarecoblrcai.html). It's got two propellers which are driven by very small electric motors. The motors are mounted on a shaft which is also motorized to allow both motors to be tilted +/- 90 degrees. Each motor can be driven forward or reverse, so there are 6 possible commands for the transmitter to send to the blimp. The transmitter is powered by four AA batteries, and the blimp is powered by a capacitor which is charged using a plug built into the transmitter. $25 plus shipping.

To allow the blimp to be controlled from a PC, I used a commercially available I/O card and a simple home built board to connect the I/O card to the blimp transmitter board. The I/O card is the Elexol IO24, which I bought from Hobby Engineering (http://www.hobbyengineering.com/H1726.html). The things I liked about this card are: it has a USB interface, it supports 24 pins of input/output, it was pretty cheap. $70 plus shipping.

To connect the IO24 to the transmitter required a set of transistors. I mounted them on a circuit board with a current limiting resistor and a pull-down resistor. Don't look too close at this board; it shows off my very poor soldering skills. Hey, I'm an aeronautical engineer, not an electrical. The transistors and resistors came from an assortment, so I could tell you the exact price, but certainly less than $15.

So that's the first phase of my project. The hardware is for this phase is together and tested. The software is mostly written and as an engineer, I'm proud to say that it is written in Fortran. Now on to the challenge: how will the blimp know where it is in the room?

FIRST

2006-03-27T06:46:00.000-05:00

For those of you who have read this blog back to its beginning, you may recall that the blog and our family's foray into robotics all started when my daughter, Dragonfly, got involved with her high school robotics team, which builds a robot for the FIRST robotics competition. Last year Dragonfly was deeply involved in the team, and Mermaldad got only slightly involved, helping the team solve some problems near the end of the build season and cheering for them at the regional competition.

This year we were involved once more, with Dragonfly just as busy and Mermaldad getting a little more involved, although work commitments kept him from being there as much as he'd have liked. Even Wolfbait got involved a little. Since he was still in middle school and thus not officially part of the High School Team, he was named a volunteer and enthusiastically admitted to the build sessions.

One of the things that I really like about FIRST is that it's not only about the robot. Sure, the robot is the most tangible product of the students' effort, but FIRST offers many awards for teams in a variety of areas. The highest award, considered even more prestigious than winning the competition itself is the Chairman's Award. The Chairman's Award goes to the team that "best exemplifies and demonstrates the values that FIRST emphasizes".

The FIRST world revolves around the concept of "gracious professionalism". We compete against the other teams, but they are not our rivals, they are our colleagues, and we treat them with respect and courtesy. Teams are encouraged to help each other out. In fact the structure of the competition, where each round is played 3 on 3, means that the team you played against last round may be the team that you play with the next.

Last year, when we went to our first FIRST Regional Competition, we had a pretty good idea what to expect from the game. What we didn't expect is the enthusiasm of the students. Teams had cheering squads, were dressed in wacky outfits, and brought along mascots. The announcers include a DJ who plays music all day long. It's a lot of fun to watch!

This year our team's robot didn't fare all that well in the standings. At the end of the competition we were ranked in the mid-30s out of 42 teams. This is slightly better than last year's performance, but I believe the robot was a much better machine. Our last 3 matches were plagued by a problem with the controller, something out of the team's control. It was disappointing, but all part of the competition. The really nice thing was that near the end of the competition, one of the sophomore students came to me and the team advisor and said (and I paraphrase), "We ought to divide the team up in two and have our own mini competition using all the parts from the last three years. I think we'll learn a lot from building more. I learned so much more this year, when I had to build stuff myself than last year when the seniors did everything." To me, that's what it's all about.

Not Dead Yet

2006-03-27T06:42:00.000-05:00

It has been so long since the last post to this blog that even loyal readers may have concluded that it was dead. It has been sleeping quite soundly, but is not dead yet. A combination of Christmas activities, a major project at work for Mermaldad, the FIRST robotics build season and regional competition, and actual robotics work at home all contributed to our delinquency. Having reached a brief lull in these other activities, I'll try and catch up with a few posts.

Floatin' on Air

2005-12-09T20:44:00.000-05:00

More true robotics coming up dear reader, but for now, a little technology-related diversion. Here's a picture of yours truly running an event for our engineering day for Young Astronaut Clubs. My professional society organizes this day every year. The event shown here was inspired by an experiment we did it physics lab back in college. The pipes are 1" PVC. Along the top are tiny holes, 1/4 inch apart. It's hooked up to an electric leaf blower. When the blower is turned on, it's like air hockey, except on a rail instead of a flat surface. The students' challenge was to make a sail powered vehicle to go down the rail as far and as fast as possible. It was a challenging task, but some of the teams did very well.

We're Smokin' Now!

2005-10-08T10:00:00.000-04:00

Been awhile since my last post. With summer activities leading right into school activities for Dragonfly and Wolfbait, we haven't had any time for robotics lately. In fact, I tried something shortly after my last post and haven't even taken the time to get some pictures and write it up, until now.

So here it is, the H-bridge implemented on a circuit board. I soldered one up and started on the second--one for each rear wheel--and then decided to try the first one out. I hooked it up and turned on the power. One nice thing about the power supply with the load resistor (see June 1, 2005) is that when there's a short, there isn't a big puff of smoke. Nevertheless, the circuit quickly heated up and began to smoke. I shut off the power immediately, but I'm sure my MOSFETs are cooked. I guess I need to do some tests before applying power to circuits in the future. Of course, it doesn't help that my soldering looks like the amature job it really is. I don't see anything, but I might have shorted something with a bead of solder. Back to the drawing board...

Introducing...The H-Bridge!

2005-07-10T21:20:00.000-04:00

At this point, our first robot has motors to drive the wheels, a spiffy frame, and nothing else. We're going to need a way to distribute power to the drive wheels, under the control of the processor. The first step in this is to create an H-bridge. An H-bridge is a circuit that allows one to send power to a device forwards and backwards. In fact, an H-bridge has four operating modes: coast, forward, backward, and brake. I could try to explain the H-bridge, but other sites, such as http://www.robotroom.com/HBridge.html, do a fine job, so I'll leave it to them.

Here's our H-Bridge. It is based on the International Rectifier RFZ44N power MOSFET. Playing with these MOSFETs taught me something interesting. Unlike a "traditional" transistor, which is current-based, MOSFETs are voltage-based. When you supply a voltage to the gate of a MOSFET and then disconnect it, the gate remains energized and power keeps flowing from source to drain. So in my H-bridge are four pull-down resistors to force the signal low when power is not being applied. Also note the diodes to keep the motor from pumping current where it doesn't belong. We chose the MOSFET because it is the same one used by the manufacturer of the cordless drills, so we know they can handle the current. The one issue is that the RFZ44N requires more than 5V to close, so we'll need to use another transistor to switch on the RFZ44N.

Sunday night's all right for picking

2005-07-10T13:28:00.000-04:00

whoo-hooo my first post, Anyways back to business being a 13 year old I don't have a lot of cash lying around. Many first time robot builders don't want to invest alot of money into a robot until they are sure that is what they want. To reduce costs we do things like buy at discount outlets, garage sales and search trash heaps. Monday is our trash day so Dragonfly and I ride our bikes around the neighborhood on Sunday night looking for prime targets like fans, tape players, microwaves and old remote control cars. Besides getting the electronic components its amusing (and a heck of a lot of fun) to tear out the devices innards. Usually if you can get a microwave it has at least 3 switches, a circut board and display panel and a motor for the turntable. Robot parts are everywhere you just need to know where to look.

}-Wolfbait-{

Nice ride huh? You might notice I've found a CPU and have it in the wagon. Lets hope it works.

Back from vacation...

2005-07-03T20:57:00.000-04:00

Just back from vacation. Haven't done anything lately, but I ran across another blog by another robotics newbie. See http://www.robot-newbie.blogspot.com/

Nothing Here, but Something Cool Elsewhere

2005-06-11T10:17:00.000-04:00

Nothing much has happened lately at our house, robotics-wise. The kids were finishing up their last week of school and getting ready for an end-of-school party at the house. I've been trying to get the yard in shape for the summer. So I've spent the last week just dreaming of robots. The other day I saw a sidebar in Consumer Reports about single-use (disposable) digital cameras. The summary was what I always thought. What an expensive way to get digital pictures! But in my robotics frame-of-mind, it finally dawned on me: these things would be really cool to hack. Imagine, a relatively low resolution camera for $10-$20. So I looked around on the internet and found that indeed, there is a community of single-use digital camera hackers that have been doing this for at least two years. My favorite is here. I also ran across a group of amateur radio operators (hams) who used such a camera to take pictures from a weather baloon at over 32,000 feet. How cool is that?

A Non-Event

2005-06-03T22:55:00.000-04:00

This will be a short post because of all the things that didn't happen. The modified power supply was a big success or a big disappointment, depending on your perspective. We took the newly modified power supply out onto the driveway, away from any structures in case it caught fire, and plugged it in. With a small DC motor attached, we turned it on. The event was recorded on video, in case something disasterous (but nevertheless cool) happened. Instead, the power supply worked as intended, the motor an the internal fan spun up, all the binding posts showed the correct voltage, and the load resistor does not appear to get particularly warm. So my apologies, dear reader, no video of electronics being transformed into a smoking pile of slag this week!

I need more power, Scotty!

2005-06-01T22:10:00.000-04:00

School's winding down for the mermals. For Dragonfly, my high school student, this means finals. Even for Wolf Bait, my eighth grader, there are projects to finish. The only thing he's building right now is a model of Gutenberg's press for extra credit. Not content to sit idle, mermaldad had to tinker with something. Besides, if we're going to build a motor controller, we're going to need a good power supply to test the circuit with. Sure, a couple of batteries would be easier, but no one ever accused me of taking the easy route (even when it makes sense).

So let's adapt a power supply. I found a nice website at http://web2.murraystate.edu/andy.batts/ps/powersupply.htm which describes turning a PC power supply into a hobby supply. I already had a PC power supply laying around, given to me by a friend. Even better, it already had a switch and cooling fan built in. So all I really needed was to connect the power feeds to some binding posts and hook in a load resistor (switching mode power supplies must have a load). I left the unused power connectors in case I ever need them to test out computer components. Here's a picture of the finished power supply:

Here's a close up of the binding posts area. The label on the power supply conveniently had the four supply voltages arranged such that I could put a binding post next to each one. The cable tie holds the load resistor against the case for heat transfer.

Hmm. I suppose it would've been smart to be sure the power supply works before doing all these modifications, wouldn't it?

It begins...a little history

2005-04-21T22:24:00.000-04:00

It was not too long ago that Dragonfly, my high school freshman daughter announced to me that she had joined the robotics club at school. I didn't even know the school had a robotics club. As an engineer with NASA, I knew there were high school robotics competitions. Our NASA center sponsors a bunch of teams, and I had thought a few times about getting involved, but like many things, I hadn't figured out when I'd have some time to do it.
Dragonfly has a history of being interested in everything. But she doesn't have time for anything more, so some things end up not getting much of her time. I decided to hang back a little to see if she was truly interested.

The robotics club exists to field an entry for the FIRST robotics competition. The students have six weeks to build a robot, using a mix of parts from FIRST and from anywhere else. Then the robots get shipped off to the competition. The competition is quite different from the robot competitions you see on TV. The focus is much more on what the robots can do other than beat each other to a pulp. This year's challenge involved moving PVC tetrahedrons into or on top of tetrahedral goals. The robots compete in teams of three, forming a new alliance each round. The competition is something to behold. Imagine a basketball arena full of the school geeks. (As an engineer, I use the term geek in the positive sense; I'm proud to be one of 'em.) Some of these robots are really advanced and can do lots of stuff.

'fly's team didn't do really well. It's only their second year, and they're still learning. But they did better than their cross-town rivals, so they're feeling pretty good. On the way home, she says to her mother and me, "(Sigh), now I've got to wait another year to do this again."

Here's where I see an opportunity to play and pretend it's for the childrens' educational benefit. "You know, we could do some robot building at home during the off season." I look around at the faces. Dragonfly and Wolf Bait, her little brother, are grinning wildly. My wife is not looking displeased. So far so good. I know I'm going to have to tread a fine line here. I'll be able to build robots with the kids, as long as I don't fall too far behind on the other household projects, like the trim that needs staining, and the rec room that needs...well, everything. I guess my daughter isn't the only one who is interested in everything and has time for nothing.

Getting Started

2005-04-02T22:02:00.000-05:00

Let's get started. This is a journal of our efforts in building robots. We're starting out as amateurs, so we don't have any great wisdom to impart. As we learn things, we'll post them here and hopefully help someone out. The web is a rich resource, and we've learned a lot from what others have posted. Hopefully we can return the favor.

You may have noticed the "we" in the paragraph above. No, no delusions of royalty, and it's not an editorial we. I refer to myself and my two kids, my partners in these experiments. More about us later. Let's have a look at our first robot.

Well, it's not really a robot yet. It's a vehicle right now. The point of this robot is to learn how to build one...and to have a little fun as well. Yes, those are cordless drills, and yes, the frame is a toilet seat. The motors come from a local discount chain, for $20 each. The frame was something we had laying around. The rear wheels are from the local home center and are for a lawn mower.

The 18v motors in the drills are powerful. Squeezing the triggers by hand can easily cause the vehicle to do a "wheelie". We'll need to put mass up front to counter this.