Thanks to Woot.com, we will be getting a TV sooner than expected. Since there is no room elsewhere in our new apartment, our desktop computer will reside in the entertainment cabinet hooked up to the TV. The cabinet we found is absolutely perfect, size wise. The only problem will be ventilation. I noticed the Xbox fans spinning up faster than I’ve ever heard them go, and I know these units are prone to overheating, so I have devised a cooling scheme involving computer case fans mounted into the back of the cabinet, sucking air through the front and exhausting out the back.
Here is the cabinet
entertainment cabinet
Here is a sketch of the ventilation system. The irony is that I just threw away all my spare computer fans. But I have the microcontroller and speed controllers.
sketch
Depending on the power draw from the fans, I might just be able to speed control them with PDM right out of the microprocessor. But if they draw too much power for that, I’ll have to use the motor controller boards (cheap anyway). The cool thing is that I’ve already coded a microprocessor to patch thermistors readings out the PWM channels, and controlling motors in response using a separate motor controller. I think this is a really cool application, I’m excited. Also, I should be getting a full Solidworks 2011 soon, which makes it easy (easier than 2010) to do a nice fluid dynamic analysis. This will determine optimal fan placement to maximize airflow. The airflow analysis setup will actually be tricky since the computer has fans (of unknown CFM) in it, too.
He is using “comedic summary.” Missionaries never told me I was going to hell, and when I was a missionary I never told that to anyone. That’s the kind of judgement God forbids most people from making. But there is a bit of true doctrine in there LDS people will recognize.
I already knew Jesus Christ from my childhood, but when I heard similar doctrine from the missionaries I wondered why I wasn’t better off ignorant. Its a natural question. Just like all legit questions there is an answer, and it didn’t take long at all for me to figure it out. Do you know?
The website has undergone a visual transformation. Most of the content is the same, but a different interface is much cooler I think. I have added more examples of my design work in the “portfolio” section, and added a few Powerpoints and another philosophy paper in the “school work” section. The portfolio additions aren’t formatted nicely, but its all up there. The overhaul is aimed at making it easy for prospective employers to see my work.
Please take a gander (GregKelley.org) and give me ANY feedback by commenting on this blog poast. It will possibly help get me a job!
Holly made a pot of potato soup on Wednesday. She calculated that it cost about $3, and we’ve been eating it every day, adding milk, potato flakes, ham and red pepper flakes to make it stretch until payday. Sometimes its fun being poor. Especially since Holly can make things taste soo good. And she’s done a really great job building a food storage and freezing dinner left overs. So, we haven’t been able to shop for a while now, but we’re doing just fine because of the bounty we have been blessed with. I don’t wish to paint a dire picture of poverty, we are just between school and job, and want to be as frugal as possible since there is no income. We always live so comfortably, and have everything we need. Life is good.
I took my last examination today. It was a philosophy final. Last week I took a fine arts final (which was a joke), turned in my final nanocomposites paper, presented the engineering design project to a Boeing representative, and gave the final advanced CAD presentation. That’s it! I am half expecting something to happen to stop me from actually getting my diploma. It is just too good to be true.
It is often said, and generally expected that serving a full-time church mission is the hardest thing to accomplish. This has never been true for me. Maybe I had an especially easy mission, it was Baltimore, MD. It is probably middle on the difficulty scale of locations. But the difficulty is usually psychological, social, sometimes spiritual. Well, school is definitely the hardest thing I have ever done. I’m not a fabulous “book learner” even though I think I have an aptitude for the subject. I started at Tacoma Community College in 2003 with one math 90 class. I eased into my formal educational career, beginning in earnest with college level classes in January 2004. The last 6.5 years have been very difficult. It is the longest continuous effort I have ever made on a single thing.
There are still loose ends I have to take care of at school. Still obligations, almost deadlines. I have to be sure the engineering design project gets shipped to the client. I have to collect all my belongings from the ASME office, ASME shop, and the student access shop.
And now I stand on a precipice. I had to look up how to spell that. Turns out a precipice denotes a place of great peril. That’s not how I mean it, but precipice seems like the right word. I mentioned this yesterday and someone asked which way I would fall. I don’t know. Holly and I are hoping a job will place us in the Puget Sound area, around family and schooling for her. We will stay in Pullman for now, while the job search continues, and move for sure sometime in August.
Its 3/14. At almost two o’clock today it was 3/14 1:59.27. At that moment, the earth’s average circumference was 3.14159265 times its average diameter. Also, amazingly, the average diameter of the Earth’s orbit around the sun was 1/3.14159265 times the distance Earth traveled since 3/14 1:59.27 last year.
Weird huh?
Pi day only happens once a year, but its magnitude is a function of no variables, time least of all. if there is one mathematical constant you know, it should be Pi.
With this in mind, I present Pi cup. Pi cup was created in the company of Holly and her parents - Dave and Faye - when they treated us to a fun filled afternoon in The Dancing Paintbrush in Poulsbo.
I teach the eight and nine year olds in Sunday school now. Today was my first Sunday, and I have to say it was pretty awesome. I thought I didn’t like strange little kids. Turns out they’re all strange but I do like them anyway. There was a time when all the little kids are together, from ages 5-11 (or something like that). The leader announced the topic for today was the atonement of Jesus, and asked if anyone knows why we need Jesus. The little kid in the row behind me, he was probably seven, said “so that we can be forgiven of our sins and be resurrected.” The teacher called him to the front and made him say it louder. On the way back to his seat the teacher said “Very good! Somebody has been listening to their parents and Sunday school teachers!” He said very casually “That’s all I have to do in life.” I might have been the only one to hear his comment, he sat right behind me and said it quietly.
Well, that kids on the right path I’d say. He sounded like he decided on that himself, which is inspiring.
I don’t think children are so wise that we can learn from them. I think we can learn from them because they are ignorant of almost everything in the world. They’re very basic humans, and mature humans can forget some of the basics. If you lose hope in the goodness of humanity you can turn to this group. At least the ones in church on Sunday.
You’ll see a couple instances of these model-fabrication visuals throughout the blog and site. I like seeing designs come to life - especially if I’m the one fabricating. So, v1.5 does away with a lot of electrical tape, and is a more engineered chassis.
I put a few Antennae on with a double servo gimbal so they move around, this freaked Holly out. I took it off. Had to introduce an external 5V regulator which could output more amperage to the radio to power the servos. The TrexJr motor controller board has a 5V out to power the radio, but it is limited to 50mA, enough to drive the radio receiver, but not servos.
Here is the chassis design, followed by the fabricated piece.
Here is a picture of my use of zip-ties to mount the motors. The rounded plastic pieces constrain the motors vertical freedom, and the zip ties hold the motors in place. Like so:
Tankbot 1.0 incorporates a lot of electrical tape to hold it together. But, it is pretty resilient. This is the result of a 1-day build. I think I’ll have a more engineered iteration soon using the electronics and hardware I already have. Tankbot 1.2 will have a light and wireless cam. Here is Holly behind the controls.
I interrupted her homework but it was worth it.
Here is Holly’s fine controller abilities demonstrating Tankbot’s maneuverability.
I can put a 5V regulator between the battery and receiver, and hook up some servos to the receiver. The motor controller board outputs power to the radio receiver but only about about 50 mA of juice, so not enough to power servos. That’s a pretty easy upgrade. But eventually, when I get some more tank tread, and make a legitimate chassis, I can put more electronics in there. The following diagram shows a tankbot version I have in mind. So, the only thing I’m not sure about is the serial data line out of the micro-controller. Can I just split it and send to the servo controller and motor controller? Do I daisy-chain the servo controller and the motor controller? Will the two boards getting commands from the microprocessor get confused about whom should be receiving which commands? Plus, how do I program? I took like one java programming class like 4 years ago. Also, will the micro-controller allow a mixture of programmed operation and real-time control from the radio?
This document frame was a christmas gift from my cousin Laura, and will soon house different 8.5×11 than the one below. But until then, it is home to a Christmas gift from Dave, Holly’s dad.
I redeemed this gift certificate about a week ago and something magical happened. I found a reason to put a lot of pictures into my blog post. The box arrived today while I was out, so Holly opened it and this is what she found:
Any guesses? It should be noted here that I have searched the internet for parts just like this for a couple years now. All the ones that have been offered were either too weak/small/cheap, or too large/expensive. I’ve tried to think of a way to make them myself, all to no avail. And then, on my favorite robot supply website, I saw a little flashing red “NEW” next to an icon depicting these bad boys. got ‘em.
It gets better…. see the plastic parts go together in like so manner:
And then, when you least expect it…
they go together some more.
YUP! Tank tread. And when you add a pinch of misc. robot parts you get the the makings for a cool toy.
The bulk of the gift was this dual channel motor controller circuit board. This takes several control signal inputs and translates that to motor power output. It can take an analogue input (potentiometer, 0-5V, pictured), PWM signal (square wave from an RC reciever), or commands through a serial data line (micro-processor or computer). It can mix channels for differential drive output, so basically controlling a tank-style drive system, and it also has a bonus motor output, and a few other bells and whistles. It is pretty much the absolute minimum needed to control the motors on a tank-bot. I’ve built a tank style robot before (The Claw) but due to its rubber tread, it gets derailed on carpet which is no fun. These plastic tank tread are great on carpet. I will experiment with studding them with hex bolts for better traction. I also realized after assembling the tread that I will need more. They are too small, and I would like to give them geometry similar to The Claw, in order to climb obstacles. I’ve got all the electronics for a very fabulous robot, and now I’ve got a key piece of hardware. I will figure out how to make aluminum hubs for the tank so I don’t have to keep buying plastic ones, and I can use them for idler wheels.
