I broke a what?!?!

I've busted a lot of stuff over the years - mostly the poorly constructed and therefore delicate projects I'd built, but also plenty of electronic components, hardware, circuit boards, etc. I've even broken and bent a few small tools.

But until yesterday I'd never snapped off half a pair of needlenose pliers so cleanly it looked like they'd been sawed apart. How's that even possible? (Sure, my finger strength is unparalleled, but I wield it gently. :)

I'd post a picture, but I can't be bothered to dig 'em out from under the pile of Robosapien discards clogging up the trash. Trust this random guy on the Internet, though - it really happened.

Maximum information, minimum post

I've been planning for a while to write up some research I worked on in 2011 involving intrinsic "motivation" for robots. We got a workshop paper out of it, and I presented the results to the ECE department last year. I also planned to extend it into my thesis project.

But... the lab went through some advisor round-robin and the project fell apart, and I just don't feel like writing it up into a full post anymore.

In a nutshell, our robot learned a policy for a POMDP to learn about objects in a space by manipulating them with its arm, then assigning object classification probabilities, with Shannon information gain across all objects as the learning reward.

Here's the AAAI workshop abstract, with a link to the full PDF:
http://www.aaai.org/ocs/index.php/WS/AAAIW11/paper/view/3960

Here's a fun picture of the robot!

Cricket, the toy robot that never was

I decided earlier this year to build a robot as a gift for a young relative. I've always found Braitenberg vehicles interesting and wanted to create a mobile robot with simple sensors and the ability to switch among several Braitenberg-type "personalities" (light-following, sound-avoiding, etc.).

Thus Cricket was born.

Cricket with, well, some things working.

Turns out I underestimated the chaos of the target environment, with multiple even younger siblings running around. Only a totally bombproof gift would work - which Cricket is not.

That, plus some irritating bugs I don't feel like ironing out, means Cricket is now abandonware. But not forgotten!

Testing the light pods.

Full details and more pics after the jump.

Hot glue FTW!

How did it take me so long to discover hot glue?!?!?! Everyone else smears it on their robots and projects, but somehow it never occurred to me to try it. As an inveterate epoxy user - what a revelation!

Sure, it can get messy. But the adhesive power, the (literal) flexibility, and the absolute trifle of time it takes to set up are mind-bottling.

I just built a set of contact bumpers for a small robot in about 10 minutes, including time to mount them on the robot itself. With epoxy I'd still be waiting for the bumpers to set up, then I'd have to mount them tomorrow and wait another day, and it'd still be fairly brittle.

Now I'm on the prowl for anything that needs gluing - just like way back in the day when I discovered duct tape. Thanks, hot glue gun! 

Neural networks part 2: Evolving a "living" robot

In my first post on neural networks, I discussed training the network using gradient descent - a pretty straightforward optimization method. This project took a completely different approach: evolving the network's weights with genetic algorithms. 

Our project team designed a virtual agent (robot) that learned to avoid obstacles while acting autonomously to "work" and "eat", maintaining its own internal conditions in proper balance like a living animal.

The virtual robot (green circle) navigates from the green "health" waypoint to the red "work" waypoint while avoiding the gray obstacles.

We started in simulation, planning to implement the working system on a physical robot, but ran out of time to get the hardware side functioning. C'est la vie robotique! We did make sure our virtual agent would use the same motor commands as the real robot, so the simulation wasn't completely disconnected from the real world.

Full details, including the multilevel control architecture we developed, after the jump.

Neural networks part 1: Teaching Canyonero to drive

Artificial neural networks (ANNs) are modeled after natural neural networks (brains and nervous systems) and though they don't work exactly alike, both a brain and an ANN can learn arbitrarily complex tasks without being told exactly how - they just need data about the task and their performance.

A generic artificial neural network.

ANNs have been applied to a lot of artificial intelligence and machine learning problems, from autonomous vehicle driving to recognizing handwritten address on envelopes to creating artificial intelligence for video game agents.
  
I won't go deep into the math behind ANNs here; there are great sites on the web (and it's not really difficult, there's just a lot of bookkeeping). 

Instead, I'll take two posts to describe a couple of neural net projects I've worked on. First up: a mobile robot called Canyonero that learned to compensate for its own mismatched wheels.

Canyonero, with a camera in the front and a netbook running an ANN.

PIC + pyserial + Windows

I use PIC microcontrollers fairly often since I'm familiar with them and they generally have the features I need. That's a pain when I need to program a PIC board, then talk to the code over a serial port. I need Windows to burn the firmware, but I've never bothered to learn Windows serial port programming. 

Then I realized the pyserial library for Python is cross-platform. Sweet! One download and one "import serial" later I was burning firmware and talking to the PIC over USB serial, all from inside Vista.

PIC serial comms to the left of me, Python to the right, here I am, stuck in the middle with you...

(Well, almost... there's some weird version conflict where the pyserial version I downloaded doesn't like the Python version I have. Lucky I found a sketchy-looking forum post with some random dude's replacement for a key pyserial file. Copy, paste, run, and done. Sure, I can't close the serial port without getting an error, but it opens and handles data just fine. Thanks Internet!)