Portland Area Robotics Society

Regular Meeting Minutes

October 7, 2006, 10:30AM



1.      Presentations:

a.       Line Maze Design %G–%@ Roger Ray

2.      Table-top Line Maze challenge %G–%@ Monty Goodson

3.      News Reports

a.       Show-and-tell



1.      Jeff Steidls walker won 3rd place in the Robothon Walker competition! Congratulations Jeff.



Line Maze Competition

The competition this month is design a robot to turn at the third intersection on a line-maze map. The robot should detect and ignore the first two turns on the map, and take the third one, regardless of its direction. Further details were posted to the PARTS mail list.

Monty Goodson

Monty demonstrated his robot on the 3rd-turn line maze map.

Monty has been working on a simulation of his design using SCILAB %G–%@ www.scilab.org.

Line Maze Bot Software Design %G–%@ Roger Ray

Algorithms for path discovery and analysis.

Roger will post his example code and presentation on the Web in about a week.



Line maze rules allow 3 opportunities to run the maze. In the first two runs, the robot can explore the maze to record its topology. It can then plot an optimal course for the third run. Each run has a time limit. The robot should try to locate the end of the maze by the end of the second run.


In Rogers algorithm, the first pass is used to explore the maze. It chooses a random route, but tracks the coordinates of every intersection it sees. When an intersection (vertex) is found that has been visited before, it changes course and explores a new portion of the maze. The current version of Rogers code will stop searching when the end-point of the maze is located. Line Maze rules allow further exploration.


After the first pass, the robot calculates an optimal route to the end of the maze. It uses the distance between nodes, and the cost of turns to find a route it can execute in the shortest time.


In the second run of the maze, the robot continues to explore the maze %G–%@ hopefully reaching unexplored maze segments.


On the third pass, the robot executes the optimal route to the end point.


Show-and-Tell and News

Parallax has cut their prices in half on the Propeller chip.


Kevin attended the meeting and discussed his C# interface for a Roomba robot vacuum. See his posts to the PARTS mail list for details.