RoboCUBE by Colin Bacon

Robocube from Colin Bacon M.Sc.


Hi(from Norway)

Robocube is a robot based on a concept Integrating the Basic Stamp micro-controller (from Parallax),
with multiple PIC micro-controllers (from Microchip) and Lego Technic (from Lego), to enable an easy
construction of a wide variety of highly complex and versatile roaming robots.  My approach is to
re-use and build on existing good designs and the Basic Stamp, PIC and Lego Technics really offer
this to me in this project.  

The robot is made of 2 main parts:
1. The application Board (PCB): 
This is where the lego components snap into place. I realy hate cables and so to avoid them, all
Lego sensors and the two motors snap into Plated Through holes on the PCB. The Application board
also contains the other parts suchs as the power supply connections and IR sensor, IR LED's, speaker
& servo connectors. Lego Technics enables you to put some real character to the BOT.

2. The Cube controller:
The BOT has been named RoboCUBE,because the 'brain' is based on stacking a BS2 and many PIC
microcontrollers on top of each other in a very compact 3cm Square PCB's to form a cube (well
almost). The aim is to get this down to 15mm cubed using SMD devices in the next versions. 

Each connected PIC micro-controller is responsible for a separate function within the BOT,  such as
motor control, Infrared proximity detectors and IR remote control. This "plug and play" design
concept enables me to to keep extending the functionality in small simple steps. All controllers
communicates with the stamp via a two pin Serial interface,  based on the same principles as an I2C
interfaces where device code is transmitted and ack's are sent back (I'm now actually working on a
pure I2C version, but had some problems with the slave device).

The combined micro-contoller 'Robocube' is designed to be easily unplugged and reused on any other
application board or project, without too much additional effort.

   
The Infra Red proximity sensor & combined Remote control unit is really cool. It is controlled by a
PIC16F84. The I2C stlye Master/Slave architecture enabled me to use the IR sensors and IR LEDS for
multiple functions.  The Basic Stamp sends a device code to the slave PIC controller (which is
ACKed), then a function code. If a the function code (12) is sent,  the IR proximity sensors starts
counting the number of flashes received from the two IR LEDS. Depending on the number of successful
'hits' (from 100 (38Kz) flashes on right and then left) the bot can determine the distance from an
object. When it the result reaches 98 hits, you know that you are very close to an object. With this
modulating approach you don't get any problems with other IR sources in the area and is very
reliable.

If the function code (11) is sent,  the PIC slave checks for an IR remote control device command
(e.g from Sony video remote control). Once it picks up the signal,  the bot goes into 'command mode'
allowing you to control the bot with any IR TV remote control. So far I have left, right, forward,
back & even control the servo on the back that controls a gripper(See my website for videos of
this). 

The next steps in my project is to get the same PIC controller to check for Light intesity (code 13)
from Cadmium Suphide senors and check for bumper detection on the RBn port with (interupt on
change), triggered by the two Lego senors on the front. I'm also playing around with transmitting IR
pulses from the bot to communicate with other bots and creating robot zapping games.      

The Lego motors are controlled via a seperate controller board with a sn754410NE. This works really
well and is very simple to interface.

The project has taken me about 6 months to get this far. But then I only can spend a few hours a
week on this (we all know this problem!). I'm a professional electronic/Mechanical designer so
producing the mechanical design to fit the Lego parts and creating PCB's was not too much of a
problem. However, it was a bit tricky making the double sided boards though. If anyone knows any
good proto-typing companies then let me know! 

The Robocube controller was also more complicated then expected. The problem is finding good
electronic & robot part suppliers in Norway. The stacking connectors caused the most problems,  as
the soldering must be extremely accurate, with very low profile solder (no big solder blobs) and I
had a real problems finding Pin Headers with long legs (any ideas?). 

Cost? about 100 with Lego parts.

There are more details, pictures and videos on my web page http:\robocube.webhop.biz Email: robocube@thebacons.info


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