JeremyBlum.com

If you don’t read hackaday already, you should be, because it’s probably the best blog around.  Anyways, they’ve recently featured my roboclaw on their website: go check it out!

Here’s some of my other stuff that’s been on Hackaday:
http://hackaday.com/2008/07/14/deepnote-guitar-hero-bot/
http://hackaday.com/2009/05/17/nerf-centry-gun-with-image-recognition/

This is a project that I’ve been working on on-and-off for over a year now. A while back, a friend got me this robotic claw kit from thinkgeek, basically to make fun of my prosthetics research.  It’s simple enough…A wired controller is connected to the claw and has a few levers for eliciting movement from the arm’s various motors.  As you might expect, I got bored with picking up blocks rather quickly.  I instantly had the idea to pick up blocks remotely!  Oh what fun that would be!  To accomplish this I employed one of my favorite microcontrollers, the parallax propeller. Admittedly, the propeller is overkill for this project, but it’s what I happened to have on hand–It has 8 cores and I am only using one, but this is only v1 of the claw, and I hope to take better advantage of this chip in the future.  The propeller chip communicates with a small web server (also sold by parallax) via a serial connection.  I’ve even setup a network webcam, and embedded the feed in the control webpage, so I can easily control the claw from anywhere in the world!

Read on for pictures, source-code, a video, and a walk-through of the system!

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We didn’t win!  In case you haven’t figured it out, I’m talking about the Parallax Propeller Design Competition that we entered the DeepNote Guitar Hero Bot into.  That can probably be attributed the fact that 15% of the score was based on the practicality of the project.  We probably got a 0% for that…  Oh well, we still got Special Recognition from Parallax and a place on their website.  You can go check out the other project entries here; there are some extremely well done entries.  Here is our humble little page on the Parallax Site.

In related news, I’ve released all the source code, schematics, parts lists, etc. to the DeepNote “Build Your Own” page.  We don’t have any plans to release a full tutorial on how to build a bot, but with the information provided it shouldn’t be too hard to manage.  In fact, you won’t even have to program the darn thing because we’ve provided the source code!

We have successfully submitted the information for our DeepNote Guitar Hero Bot to the Parallax Propeller (the microcontroller we used) Design Contest.  The contest judges entrants on the following criterion:

• 30% Propeller Design Appropriateness Determined on applicant’s ability to use the Propeller’s unique architecture to achieve a working design. An entry which receives the highest mark in this category will utilize the Propeller to achieve a design not possible with a traditional microcontroller.

• 30% Originality Creativity of the project.

• 25% Professionalism This is based on the use of clear English in the Project Report, a quality design (if needed), clarity of explanations, quality of pictures and source code formatting/commenting.

15% Practicality Based on the project’s usefulness.

Check out all the competition information HERE

We got a whole lot done today. On the programming side of things, we’ve been working on getting the signals to go in through the microprocessor. There are a few things that the processor has to take care of…It needs to take in all signals simultaneously, and record their values (0 or 1) into a circular array so that they can be held in memory long enough to called after the necessary delay (the time it takes for the notes to reach the bottom of the screen from where our sensors are). Our processor (the parallax propeller) has 8 cores in it. 1 is dedicated to each of the inputs (5 total), another one runs the main program that executes the other cores, one more sends the signals out after adding a delay and processing (button presses and strumming), and the last is used use for debugging. We just about have the signal cleaning algorithm sorted out, and we are now working on adding a delay.

Onto the hardware side… Last week, We opened up the guitar and tested out connections using a multimeter and the “Game Controller” applet in the windows Control panel. Since the guitar is USB, you can plug it into USB, and analyze the button presses in that applet (Virtual buttons light up when you do different things on the guitar). They don’t make it easy. There are 5 buttons, each with 2 touch-sensor type things. When the buttons hits them, a circuit is completed and the button in the game is “pressed.” But, there are only 8 wires coming from the neck of the guitar. After a lot of wire tracing, we realized that some of the connections share a ground, while others don’t. Using the wrong ground results in only half the voltage drop (a drop from 2V down to 0V indicates a short and that the button has been pressed). After figuring out the pinout diagram (I’ll post it later) I was able to solder the appropriate wires onto connections for the guitar boards. I did this in such a fashion that the guitar will still work normally, but the wires will also be routed to the propeller chip that can virtually press the buttons. I soldered on leads that will allow the chip to activate the strum up and down, the whammy bar, and all 5 colored buttons. All of this will be contained inside the guitar. We will cut a hole in the side for a D-sub connection. There will also be a D-sub connection on the sensor bar on the screen. Wires will run between them carrying the information from the photodiodes, and in the other direction providing a 3.3V rail and a grounding wire.

Below are some pictures of the boards with new wires soldered on, and of our current prototyping board for the photodiodes and programming: