Let's Make Robots!

DAUGFOETUS

Navigates via accelerometer

This is only complete in so far as it is a completed intermediate step in the development of another machine, but as a test platform I won't be developing it any further*.  As it stands, DAUGFOETUS is about putting into practice the methods and code that OddBot so generously generated in my tip/walkthrough on using the MMA7361 outboard on an Arduino.  The platform is for my K-9 WIP, not posted yet (thus, the name refers to a pre-nascent dog.  It's is also kind of a shout out to our homie Kariloy who has a brilliant knack for coming up with long, esoteric robot names.)

The base is 6mil Sintra, the motors are 6v 72rpm geared sets from eBay and the motor mounts are custom aluminum.  The motor controller is a Hex A00331 L298-based unit, which I'm loving.  I bought three of them for a hair under U$12.  They work brilliantly.  The wheels are Banebots 3 7/8" hard 50 shore.

Lesson Learned #1: As you can see in the video, figuring out the values for the sensitivity variable is of great importance.  The platform responds to each forward impact (I didn't code for when it backs into anything) but it also responds to bumps in the floor, shakes of the "stalk" on which the sensor is mounted-just about anything.  This was not optimal mounting for the bot-essentiallly I zip-tied the DuPont wires connecting the accelerometer to the Mega together.  That probably accounts for most of the false impacts that it reacts to. (For K-9 I'm actually breaking down and having a PCB made to mount the MMA over an ATTiny 44 so that I can use the ADCs in the ATMel Chip to talk to the BeagleBoard via serial.)

Lesson learned #2: a castor in the front of a bot is a losing strategy in any situation where rugs come into play.

Lesson learned #3: if you aren't going to put a power switch on a platform this size (ie, you're using the battery plug to determine the on/off state) don't engage the battery harness while the robot is in your lap and you're wearing flannel pyjama bottoms.

 

 

(*Also, I just got tired of seeing the same bot jump to the top of the queue without any content updates.  For that reason, I provide the following counter, which will allow me to change only it whenever that other, unnamed machine mysteriously is updated without updating anything:)

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for some reason this reminded me of my favorite way to get into a robots head space so to speak . imagine your in a big cardboard box and you have got to get around , "Ho no i've bumped in to something ,better go back. whats this way? " you have got me thinking more about internal sensing not just accelerometers but gyros ,weal encoding position sensing in general  , battery condition sensing . ive put a lot of focus on the external conditions for my bots ,

ya got me thinking, well you and a few others :)   

P.S. on Lesson learned #3:

Don't engage the battery while the robot is on your lap not even when you are not wearing anything.
Tires and body hair don't match very well!

basile

Never approach a robot naked. Especially one with tracks or a gripper.