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TableBot Design – Bench Notes
- April
- 15
I spent the afternoon working on a simple robot. It’s great! This first pciture shows my initial build of the manual’s Square-Bot, and Felix the cat investigating. I quickly tore that apart, and moved on to a robot designed to operate the TableBot parameters as outlined by Camp Peavy. The TableBot competition is:
- Phase I: Build a robot that goes from one end of a table to the other and back.
- Phase II: Have the robot push a block off the ledge of the table.
- Phase III: Have the robot push the block into a shoebox mounted at the end of the table.
My first go focuses more on learning the programming of the VEX microcontroller. The VEX brain is made up of two PIC 18F8520 microcontrollers. The programming system is made up of EasyC by Intelitek, and MPlab. I found it quite handy for getting (re)started in C programming.
You can see a few features in this bot by clicking on the picture to the left.
Receiver
The receiver is not active on this bot. I’m programming it to be autonomous!
Light sensor
There is a light sensor at the front (left), mounted on a servo. I worked on code that would turn the sensor left and right, looking for the brightest light source. It wasn’t easy, as I didn’t have a good bright flashlight, and it was REALLY sunny outside. Also, my coding is quite rusty. I found myself doing things out of order, and getting weird results. I decided to stop messing around with it, and focus on the TableBot design goals.
Table Edge Switch
After tuning my programming skills on the light sensor, the table edge switch came together nicely. I wrote the first have of TableBot Phase 1: Move to edge of table. It does this nicely. The kids were amazed when I set it on the coffee table in front of the TV, activated it, and it buzzed up to, and stopped at the edge. “Wow, how’d it do that, Dad!?!”
Success!
Beeper
The digital outputs of a PIC microcontroller are readily available for use on the VEX controller. I popped a Piezzo speaker into an output, and set my program to beep on start and exit. If you look closely, you can see the black circle beeper hanging out of digital output 15.
To interface, I used a RadioShack Beeper I found in my junkpike, part number 273-065. It is rated to 12vdc, but works fine on the voltage supplied. Negative lead goes in the “far right” pin, ground and the positive lead on the far left.
Next
The next step is to program the second half of TableBot phase one. Return, or just turn away from the edge and continue on.
More elaborate sensors might be in order, with this current wheel configuration. I can forsee a wheel going off before the sensor does. Perhaps better if two sensors were outside and ahead of both front wheels, and logic to consider what to do based on the feedback of each sensor.
The VEX Robotics Design System
- April
- 10
In highschool I worked for Rhino Robots of Champaign Illinois. Production was in a machine shop, where we created most parts and assembled the Rhino XR-1 robotic arm. The arm was targeted towards education and expermentation. It was a great experience.
In the 90’s Lego came out with their Mindstorm set, that featured motors and a controller allowing for “the average kid” to get into robotics. I was fortunate enough to participate in the North American Beta Test for the product. I walked away with a free mindstorms set, and had good fun tinkering with it.
I have good fortune to receive a VEX Robotics Design System. The VEX system is a Erector-style construction system with the requisite wheels, motors, controllers and other acessories to make functional robots.
I got to know them by building the squarebot in the manual. “Starter Kit” is a good name for it. I believe this enough to get you started, and that will be about it. In building a basic rover, I managed to to use most of the beams and screws. Anything more advanced may require more of these components.
The controller is an impressive 6 channel fm transmitter and receiver that interfaces to the VEX controller module. Two dual-axis joysticks on the front take the first 4 channels, and two more channels in the form of buttons on the bottom. The transmitter has an lcd display, allowing you to adjust many paramaters. From the outset, the design looks excellent.
Ok. Maybe that’s enough for just now. I plan to blog my VEX adventures here. If amateur robotics is of interest to you, then I hope you subscribe to my blog… good stuff to follow.
Kayakbay launches with first Podcast
- March
- 24
As a computer geek, I find myself sitting at the keyboard for 8 to 12 hours a day. This is not good.
Not good for the body and not good for the mind.
What’s the verb? Computing? Hacking? Keyboard pounding? Well you know what I mean. My back hurts because my leg muscles are weak. My hands hurt from the button pushing. I’m irratable from all the thinking (and coffee).
I need release!
Enter kayakbay. Kayakbay is a blog, mainly podcast, about two things:
- Kayaking
- Relaxing
Take a minute to visit Kayakbay.com. We’ve posted our first podcast. Hope you like it!
New Gear Podcast
- February
- 5
I’ve upgraded the podcast station with some new gear. What do you think of the new sound? The new station includes the following gear:
It was a little tricky to get the MultiMix to interface with my PC, and CastBlaster exactly the way I wanted it. But, with help of documents at alesis.com I was able to pull it off.
Music today by by:
Courtesy of music.podshow.com
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Podcast with Retro Audio Gear
- January
- 30
Homebrew Podcasting gear, retro-style! Today we test an audio setup using the Shure M67 microphone mixer, and the Electro-Voice D054. If you could podcast in the early 80’s this might be the gear you would have used. The Mic goes in the Mixer, and the Mixer goes in the Mic-In on my PC Sound card. Much of the poor audio quality can be attributed to the sound card and perhaps some on the old M67.
The Shure M67 was actually made form 1968 to 1987. What a run! I suspect mine is more along the lines of the 80’s, and not the 60’s. I suspect the Microphone is from the same era as well.
Songs by:
Courtesy of, once again, music.podshow.com
My friend Don confirms that I’m not dreaming about seeing guys sing into similar microphones on TV. Here’s Tony Bennett singing into a small hand-held dynamic microphone. I bet it’s a Shure or Electro-voice.
The kids love listening to the podcasts in the car. I’ll be sure to do some more with them! Liz likes it too. Perhaps I’ll be able to justify buying a mic stand.
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If anyone is actually trying to subscribe to the RSS feed with a podcasting reader, I must apologise. The file names were incorrect, messing up the Juice aggregator, and maybe others. Well, now that I think of it, I bet I’m the only one that suffered. But it’s fixed now!
Podcast with Liz
- January
- 27
Podcasting with Liz -
More fun testing with an old dynamic mike into the Advantage One Mike mixer by Biamp. It works! I couldn’t find an image of the D054. But it looks just like this image of an Electro-Voice RE55. How do you like the sound quality of the retro microphone?
Songs by:
- Natives of the new Dawn
- Brain Buckit
Liz is interested in Podcasting and Blogging for business. So, I thought I’d put her on the microphone and see how she likes it.
It seems to take me about an hour and a half to do everything. More time preparing content, and then writing this blog entry, than actually making the podcast!
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Hope you like it!
Here’s the station we’ve been using. You can see the makeshift mike stands that Liz likes so much.