[chbot] droid hackfest - Sunday?

Morris skibear at gmail.com
Thu Jun 25 07:35:06 BST 2009


Who is keen on doing some robot hacking on this Sunday and next Sunday?
10AM till lateish?

If possible discuss on chchspace at googlegroups.com (sign up if you
haven't - http://chchspace.nztech.org/)

Options:
* You could bring your own robot bits
* I could help someone that want to do the electronics/mechanics but use
python and an arduino for control.
* You could help me (see below!)
* Just come along and do some other stuff! (Normal chch creative space).
* I have second hand motors and batteries I can sell for what I paid for
them - $1 each. I have about 10 each of : 20W motors, 7.2Volt 1500mAh
NiMH batteries, and 12Volt SLA/VRLA batteries which were 800mAh new but
I guess wont be near that now.
* I would love some criticism of what I have been doing!

Following pdf has excellent information and links to projects using the
WL520gU for hardware projects:
http://mightyohm.com/files/wifiradio/Jeff_Keyzer-Hacking_the_Asus_WL520gU.pdf

Cheers, Morris

Developing a wifi remote controlled robot that can be controlled by a
GUI. Using browser e.g. Internet Explorer on Windows, or Safari on
iPhone). General design can be used to control any actuators or read
many sensors (e.g. USB devices!) but is only suitable if you are not
trying to make a "micro" sized robot (and is not good a good fit if you
want robot to be alive for many hours without recharging -- unless you
use a car battery!).

Progress on the following design:

1. Dumb Duemilanove/Arduino microcontroller
    * So far have used pyduino (running on the router) to do PWM control
of an LED, and reading a micro-switch. Just done using command line
using example.py that comes with pyduino to select input/output pin and
watch results.
    * ATMEGA328 connected to router using USB (FTDI serial
communications).
    * Installed firmata onto arduino (standard sketch that comes with
arduino.cc build tools). www.firmata.org 
    * Running pyduino to control firmata code.google.com/p/pyduino
Treat microcontroller as dumb device (no C code required!).
    * Super simple to read analogue inputs too (haven't yet tested).
    * There is firmata code for controlling servos too (I want to get
that going soon but I would like help).
    * Later on will be <$10 using cheaper ATMEGA chips with veroboard or
simple PCB. Current board is $65 but only one evening's work to get it
up and running using USB so worth it!
    * Later can use cheap serial connection ($5 USB, or maybe connect to
interal 3.3V serial port of the router)

2. wireless router running Linux and Python scripts.
    * Router is to be the main brains of robot. Currently testing Python
scripting (controlling an Arduino - fun!) but intend to use Python web
server for GUI interface and Ajax (so can control robot from web page
using mouse and keyboard).
    * Asus WL-520GU wireless router USB 2.0. Costs $86 from
http://www.cbcnz.com/product_info.php/products_id/146191 on corner
Fitzgerald and Kilmore - they have them in stock. Maybe a little cheaper
from AKL. 
    * Running OpenWRT Linux from www.openwrt.org - Kamikaze 8.09.1
version using kernel version 2.4 (tftp the file
http://kamikaze.openwrt.org/8.09.1/brcm-2.4/openwrt-brcm-2.4-squashfs.trx into the unit).
    * Running Python installed to a 1GB USB stick (because I wanted the
full version not python-mini and standard 4MB flash not big enough for
full version).
    * wireless working well.
    * super easy to add and remove packages from the unit using opkg.
    * the internal flash is mounted as a flash drive and you can just
edit individual files or upload them.
    * USB is not true 2.0 speeds due to 200MHz CPU hitting 100% at
relatively low speeds.
    * Kernel 2.6 available but broadcom driver is apparently not stable
so wifi performance bad.
    * Haven't started on web server stuff - but not expecting anything
difficult. Could also use the internal luci (Lua script) web server if
have to.
   * Using USB hub so can also plug in USB memory and Duemilanove at
same time.

3. Electronics
    * What I intend to work on this Sunday! Any help or criticism would
be appreciated.
    * Or I would love to just use the router and Duemilanove with your
electronics&mechanisms (then I can work on Python control control code
or web server instead!)
    * Planning to wire up motor driver electronics Sunday - got $10
L298N dual 3A motor driver which is super simple to use.
    * Got 7.2V and 12V batteries but no proper chargers yet. (ideally do
using arduino!)
    * Got some switches and other sensors.
    * $8 USB sound card (still to arrive from AKL) - need simple
amplifier for speakers (maybe use microphone?).
    * Intending to play with a USB webcam (maybe use microphone?).

4. Mechanics
    * Tried motors and wheels. Goes fine with 12V and fast with 24V!
    * Currently just hacked together badly (wire and random junk).
    * Investigated places to get Aluminium framework "meccano
compatible" for a flexible framework that can be quickly cut and
screwed. Would be best if can share costs.
    * Got some Servos and intend to use some mecanno to make an arm.


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