Portland Area Robotics Society

Regular Meeting Minutes

May 5, 2007, 10:30AM


1.      PDXBot Update %G–%@ Larry Geib.

2.      Line Maze Challenge %G–%@ Monty Goodson

3.      Pico Sumo! A Sugar cube with wheels. Zac Wheeler.

4.      Robomagellan %G–%@ Robert Shearer

5.      News & Reports

a.       Show-and-tell


1.      See PDXBot.07 update below.


A vote of the attending club members approved an expenditure of club revenues for PDXBot.07 expenses. The vote was 15 for, none against.


PDXBot.07 update %G–%@ Larry Geib

Two Weeks to PDXBot.07!!

See www.pdxbot.org for complete details! Download the poster and display it in you place of work or business. Register your robots.


The Saturday venue is at Holliday and 10th Ave %G–%@ Portland DoubleTree inn. The RoboMagellan contest is Sunday in the Portland Park Blocks.


There will be two event stages. The Boise Robotics group will attend with a display of rover robots and near-space vehicles. First Lego League and Vex robotics teams will attend and display. There will be tech-demos from club members. Portland Dorkbots will sponsor an art bot competition. Lots of vendors have signed on to sponsor the event and offer products.


We need volunteers who can help with event administration, registration, displays, AV operators, and many other roles. Please contact Larry Gieb or visit the PARTSevents Yahoo group to volunteer. We are also looking for several video cameras that we can use with the event projectors. It would be great if we could locate a video transmitter/receiver for a roving camera.


Line Maze Challenge %G–%@ Monty Goodson

See www.anastasia.com/robot for Roger Rays maze solver algorithms.

Zac Wheelers Pico Sumobot

Zacs robot is 12mm on a side. See his website at http://poor-robot.com/pico


The robot is based on the Atmel ATtiny44 microcontroller (QFN package) and an Allegro A3901 motor driver. He is also using a reset monitor IC %G–%@ ADMG7B %G–%@ to reset the microcontroller before the battery drains too far. The battery is a 20mAh lithium polymer battery from Full River. The sensor is a sharp GP2S60 IR reflector. There are two of them pointing downward. Zac has plans to mount side sensors on a future design.


Conan A RoboMagellan design -- Robert Scheer & Jim Remington

Conan is ancient Gaelic for little wolf.


Robert and Jim started with a Tamiya TXT-1 monster truck chassis, but abandoned it in favor of a custom design. Their new chassis is designed to be more robust and accommodate better wheel odometry for navigation.


Conan features

Dead-reckoning navigation %G–%@ No GPS, yet.

Subsumption software architecture.

Double-precision math

CPU capacity for moderate image processing

wireless networking communication


Conan the robot is based on the following components:

        Super Droids 4WD chassis.

        4 24v 75W DC motors with timing belt drive.

        Dual bearing wheelshafts.

        Wheelshaft encoders

        Custom PWM driver PCBs

        Mavric 18 microcontroller

        Inertial measurement unit

        Mini ITX Linux PC for high level control. Ubuntu OS, customized.

        RS232 to motor controllers and IMU.

        USB to sonar and Camera

        4Amp-hr 8-cell lipo battery.


Subsumption software architecture is a method of organizing the robot programming so that various logic functions can override one another to control the robots motion. A collision detector can override a navigational program, for example. Conans main program is a sequence of statements that tests conditions from its sensor and navigation programs. The order of this sequence establishes the priority of robot control tasks.


News and Show-and-tell

Mark Medonis is working on a DC-DC boost converter for 18V at 1.5A from a 12v supply. Mark also recommends www.all-battery.com as a supplier for batteries and chargers.


Touch screen displays %G–%@ www.simmetry.com.