Steve's Things

So, even though I’ve built a wide variety of crap over the last few years, all of them with varying utility, I’ve decided to build a quick robot. With oodles of free time and the feeling of having to go back to work on the horizon after what feels like an eternity of holiday (1 week) I quickly grabbed a bunch of stuff I had sitting around and put this guy together with all the grace of a kindergarten macaroni art sculpture.

Ugluino Being Built

Based off of an Arduino Nano, this guy works just fine. I don’t like using Arduinos for the following reasons.

• Perceived lack of control of what’s going on inside
• Feels like cheating since it’s so easy
• Arduino UI is kind of shitty, especially for larger source files.
• When dealing with AI routines, making it difficult to use multiple files is a minus

Anyways, i plugged ahead and quickly pounded this out with the following IO

• Input – The only one, the Echo pin on the ultrasonic sensor
• Output – Trigger on ultrasonic sensor
• 4 Digital output – for controlling direction on SN754410 Quad half h-bridge driver. These go to two gear motors which are attached directly to wheels
• 1 PWM out for duty on motors
• 1 attached servo out of the servo to turn the sensor

The back end of the Ugluino

Most everything worked out swimmingly until I fucked around with some wiring and produced a short. I hooked the robot on to the USB supply on my computer, I noticed after a few second that the power to the unit wasn’t running… hmmm POOF! Well, as it turned out, there was a problem with the wiring to the ultrasonic dealy and it blew what I beleive was a zener diode

I wasn’t able to figure out exactly what it was, I suspect that it is a zener diode that selects between main power and USB since it is on the output of the VReg. I could be wrong. Since I didn’t have any more Arduino Nano’s I simply tried to fix it and soldered a wire across the offending gap. The device seems to work fine…? Anyways, if anyone know what that part was on the Arduino Nano v3.0, I’d like to know ’cause I couldn’t find the 3.0 Schematics and the design has moved those parts around.

Anyways, The robot moves around based on a very simple algorithm.

1. Stop Moving
2. Scan from 40Deg Right to 40 Deg Left in 10 deg increments
3. return appropriate movement from a function that analyses it
4. execute proper movement (Forward, Backward, Right, Left, Hard Right and Hard Left)
5. rinse
6. repeat

It seemed to work reasonably well. I’d like to build a more sturdy version for shits and giggles so that I can play with the algorithms. I’m probably gonna build one with a PIC18F2685 instead of an Arduino. Also, instead of a single sensor, I will use IR proximity sensors to detect low lying objects. Moving the sensor with the Servo make the robot seem more intelligent than it actually is like it’s ‘looking around’. I quite like that. 🙂

Anyways, it’s my first post of the year, considering it’s January 1st and 3:52 am as I write this. maybe I should go to bed. Here’s a video of it getting around.