Automated Backhoe

Greetings,

I have posted pictures of my most recent automated creation on brickshelf:

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=170126

Be sure to check out the "backhoe.wmv" video (2 mb).

The Automated Backhoe took 60 hours to build. Contruction/acquistion started in
August 2005. It was first displayed at Supertrain 2006, Calgary, Alberta,
Canada. It features the Lego Technic Backhoe #8455 automated using the Control
Lab Interface, programmed using Robolab.

Features:
Six motorized pneumatic switches control outriggers, shoulder rotate, shoulder
lift, arm lift, bucket tilt, and front bucket lift and tilt. There are two style
of switches, one style moves slower to control centering. Yes,
that is a lot of pnematic hose.

Eight small compressor pumps arranged in a dual style configuration designed by
Jennifer Clark in her JCB JS220 Excavator:     
http://www.telepresence.strath.ac.uk/jen/lego/jcb.htm
Compressor is powered directly with a 9V train controller with a large
pneumatic cylider with electric pole reverser pressure cut-off switch.

Tread-link and chain-link conveyors to return black beans to pit. The
mountain/pit divides into four sections for transportation purposes.

Four custom LED for headlights and tail-lights. Yes, I plan on addin a flashing
LED for the dome light. Other LEDs indicate conveyor and switch movement.


Comments:
I wanted to be able to control the extension of the cylinders thus the slower
motorized electric switches with touch sensors. Unfortunately the reaction time
of control lab / robolab was too slow to stop the switch in the off/centered
position when touch sensor was triggered. I then attempted to 'time' the switch
back to the center postion. Unfortunately it seems that the CLI or Robolab
occasionally goes 'stupid' or 'slow' so that the motors would turn on for
several seconds longer that the program specified causing eractic arm movement
(switch moved to opposite open position). In the end I removed all attempts to
center the switches.

The backhoe ran for about 19 hours during the train show. After the first couple
of hours a black bean got caught between a gear and the chain-link causing the
chain-link to break. After a few modifications the backhoe ran for another 16
hours with only a minor failer. A bean jambed the conveyor but a little wiggling
by hand fixed the problem. I am very pleased
with the reliability of this machine. My previous long-running displays (marble
machines) typically failed every couple of hours.

I decided to use black beans after estimated the cost of buying black/grey 1x1
round plate would exceed $30 USD. Total cost of black bean was $3, I could eat
them, and I could care less if I lost some.

Thanks to my uncle and aunt, Elden and Sarah for providing a cheap laptop and
getting it too me just in time!

Thanks to Riverbend Elementary School for lending me the Control Lab. If anyone
has a control lab they would like to sell please contact me. I am will to pay
$80 USD.

Roy Nelson (legoroy)