Thursday, December 24, 2009

Merry Christmas

For unto us a child is born, unto us a Son is given... - Isaiah 9:6

I saw this image on one the robotic sites that I visit regularly and saw it as a Modonna and Child (Mary and the Baby Jesus). Compare the image below and let me know what you think!

Merry Christmas! Hope you find something to fun to play with under your tree.

Tuesday, November 24, 2009

Happy Thanksgiving

Did a little Googling and found this cool Turkey-Bot at a blog called A Bit Dotty. The drawing is used with the artist and author's permission. Happy Thanksgiving everyone!

Saturday, November 14, 2009

Scribbler Robot Camps - Part Two

I am getting ready to do another set of Robot Camps for the Monroe City Schools. This time we will also run the camps at each of the Jr. High Schools. That will be six schools with about fifteen students at each school, plus a group of teachers.

This year I thought a maze might be fun to solove - so, I built one. Here is video of my Scribbler running the simple maze. Students will be asked to write a program to solve this particular maze. It shold be a fun excercise.

Saturday, October 31, 2009

Happy Halloween

Happy Halloween from Robotics Under the Stole. Check out this cool robotic pumkin!

Friday, October 23, 2009

Name that Bot!

What in the world do all these parts make? The new Parallax Stingray. The Stingray is a Propeller powered mid-size robot. I got one of the first 50 produced. It was really fun to put together and I look forward to posting more as I get it up running. Next step - sensors. See the assembled pics below from Parallax's website.

Photo - Stingray from above and side. Note the cool omni-directional tailwheel.

Monday, September 14, 2009

The Great Robot Race

This is a video from the P.B.S. Series NOVA. The episode is called The Great Robot Race. Though I do robotics on a completely different level, this is exactly why I find robotics so much fun!

Monday, August 3, 2009

Officially a Nerd!

Most people agree that you are officially an nerd when you get an oscilloscope. Well... I just got a Rigol DS 1052E, 50 MHz, 2 Channel Digital Storage Oscilloscope. I'm really having fun learning to use it. The manual is very good and has some fun Chinese to English translations! For example the warranty card is addressed to the "Honorable Customer."

Its an award winning scope because of its combination of low price and advanced performance at an entry level price. The 50-MHz portable oscilloscope provides a 1 Gsample/s rate, which puts it in the same category as big-name competitors. It then surpasses them by providing a full 1-Msample memory — as much as 40 times more than competing units.

The unit has a very bright, full color 5.7-in. liquid-crystal display, USB host and device ports, and a range of advanced triggering functions (such as edge, slope, pulse, alternate, and video) and mathematical signal-manipulation capabilities (addition, subtraction, multiplication, and fast Fourier transforms). All things you would expect in much more expensive scopes.

The real surprise is the price - the 50-MHz version is priced at just $595 (retail). I got mine on E-bay from mib_instruments shipped for free directly from Hong Kong for just $420 (plus $10 insurance)! I also have a soft case coming, which I ordered elsewhere.

The scope comes with power cord, two probes and a CD with the manual (in pdf) and PC interface software. Here are the specs:

Here is an online review from the EEVblog (Electronics Engineering Video Blog) on YouTube:

Thursday, June 18, 2009

Strange Coincidence

It is a strange coincidence that theme of our Vacation Bible School this year has a robotic mascot! Each year, we combine forces with St. Joseph's Roman Catholic Church and Christ Episcopal Church in Bastrop to do Vacation Bible School. We always use Concordia Publishing's materials.

This year, the theme is GADGET'S Garage and features the robotic mascot named Gizmo! Several year's ago, before I got seriously interested in building robots, we did another V.B.S. that had a robotic mascot. I made a 4 foot tall "robot" out of Christmas light and junk. The kids liked it. I ended up giving it to the local library. As I was posting this, it occurred to me that I might have a picture - so here it is too!
The basic idea of this year's theme is that in GADGET'S Garage they make new things out of old stuff. In robotics, that is called re-purposing. I guess I never thought of Jesus as a hacker!

Wednesday, June 17, 2009

Camp Fun

Here is one picture of the Monroe City School's Scribbler Robot Camp students playing with their robots. They were letting their robots follow each other around the line on the poster board. As you can see, the lead robot is lost and looking for the line. If I remember correctly, pictured from left to right are Brittny, Franz and Kaitlin. Those are the student's names - I don't remember what they named their Scribblers ;-). I hope that more pics will follow.

Friday, May 8, 2009

Addition to My Lab

Many of you who follow my blog will remember my post on my Robot Lab. I've just made a really cool addition to my lab thanks to my wife. Her business had some old glass door metal storage shelves that they were getting rid of and she got them for me!

I have been looking for something like this for a while, but these are better that anything I could have hoped for. They look like something out of IBM headquarters during the early days of computers.

Now all my robots, equipment or whatever I put in them can be out of the dust and at the same time where I can see them and show them off. It is a combo storage space and display case. Super cool, eh?

Saturday, May 2, 2009

Robot Camps Underway

Last week (April 27-30), we held the first to the Monroe City Schools' Robot Camps. It all began at Wossman High School and I think the students had a great time. I know they learned a lot about their Scribblers! Each of the students left with their own Scribbler Robot, a workbook, a USB adapter and cable, a padded lunch box for storage and a flashlight (for light following)!

This week (May 4-7), we will be a Neville High School.

Jodie Moorhead from Instructional Technology is my partner in running the camps and he got some great pictures and video. I will try to post some of them later.

Friday, February 6, 2009

Monroe City Schools' Robot Camp

I am working with the folks in Instructional Technology at the Monroe City School District to conduct a Robot Camp at three High Schools this spring.

We will be using Parallax's Scribbler Robot and will introduce about 50 students to robotics and programming. We will hold 3 one week camps at each of the three high schools.
I will post more information as we firm up our plans.

Monday, January 5, 2009

Scribbler Encoder Success!

Happy New Year! On January 3, 2009, my buddy erco announced, "Success! I made several test runs with the finished encoders today, and it's quite rewarding to see the Scribbler actively correcting itself to drive a straight line. I posted a video... which shows the robot driving a small square and ending up pretty close to where it started. I have finished the encoder hardware installation to my satisfaction, but my software is very preliminary."

Here are photos of erco's encoder installation. As he explained, he built it on a tiny piece of single-sided perfboard in a non-standard way as you can see in the photos. The board is a tight fit between two molded ribs in the top body shell. The encoder sensor is mounted in a raised position on the non-copper side so that it can stick through a mostly square hole in the case. All other components are mounted on the copper side so that he could flush-mount the non-copper side to the housing inside using a drop of hot melt glue. The Optical gap between encoder and wheel is ~0.150. erco aligned the sensors to read the outer rings of his encoder wheels, and mounted it horizontally from axle in the top body shell. Each encoder circuit has 3 wired connections: +5V, ground, and output. He disconnected photocells on the front of the Scribbler to use the encoders. Photocells are also mounted in the top body shell on a small green PC board under a black plastic light shield. Nothing was removed, erco just unsoldered the green wire from P4 on the circuit board to disconnect all 3 photocells. The green wire becomes the ground connection for both encoders. He connected the left encoder output to pad P3 and the right encoder output to pad P1 on green photocell PC board. Stamp-wise, the left encoder is IN2 and the right encoder is IN0. The +5V connection is taken from the 6-hole "Hacker Port" header on main PC board.

See erco's impressive video below. With the pattern on the floor, you can clearly see the Scribbler keep itself running straight and it returns almost perfectly to where it began.
Photos and video courtesy of erco.

Thursday, January 1, 2009

Piezo Film Vibra Tab Mass as Encoder

Another experiment in the Scribbler wheel encoder project that erco and I are working on.

This slightly dark video is a proof of concept video using the Piezo Film Vibra Tab Mass Sensor as a possible wheel encoder on the Parallax Scribbler. It uses the Scribbler's wheel spokes to trip the Vibra Tab as the wheel rotates. It is like a playing card in the spokes of a bicycle wheel.

The Scribbler's wheel has 8 spokes on each side, actually 8 high spots and 8 low spots. That is 16 positions for one turn of the wheel. The wheels are 3-1/8" in diameter (approximately). The circumference is computed with the formula, circumference = pi times diameter, or C= π d. The circumferece is 9.82" or 9-13/16". For each 16th a turn, the wheel has travelled 0.614" or 5/8".

An issue might be the time the Vibra Tab is bent during contact with each spoke. I don't know yet if it sends one message when it bent or continuous messages.

But, as the video shows it does work (at least in concept).

Parallax Scribbler Encoder Project

A friend of mine, erco, from the Parallax Forums and I are working on an encoder project for the Parallax Scribbler. A wheel encoder keeps up with the turns of a wheel. It "counts" the rotation speed by reading teeth (like a gear), notches, or black and white stripes with an optical or mechanical reader. By doing this, you can tell how fast a wheel is turning and how far it has turned (for example, if the wheel turned once and you know its circumference - you know how far you have traveled). This lets you measure the distance the robot has traveled and lets you correctly keep it running in a straight or curved direction. The thread of our discussion on the forum for this project is here.

As a benchmark, my buddy, erco, wrote a simple test program to show how the Scribbler runs forward and backward through a range of speeds. This is a video of my Scribbler running the test program. This shows the difficulty of the Scribbler running straight consistanly through its speed range. Prior to the test, I reset the Scribber with its original program. There is no correction via the Scribbler Program Maker GUI by the calibration routine. The calibration routine lets you make a single correction to one motor to equalize its speed to match the other motor.

As you can see, the Scribbler does not run very straight without some sort of correction.