1. Lego Balancing Act by Chris, Don & Kris Alma College NSF Mindstorm Workshop June 2005

2. Overview Processor cooperation to accomplish a task Compensate for unreliable communication Reinforce basic mechanics

3. Problem – A Balancing Act (1) Construct a see saw to be populated with 3 bots: 2 servant bots assigned to opposite ends of the see-saw; each attached to a cog rail to permit forward and backwards movement only; each has a storage area to hold weights 1 control bot in the center attached to the pivot point via a rotation sensor

4. Problem – A Balancing Act (2) Control bot determines whether the see-saw is perfectly balanced. If not, sends a message to a servant bot to move either forward or backwards. Servant bot may receive messages with < 100% reliability (natural and/or artificially controlled unreliability)

5. Problem – A Balancing Act (3) Task Levels (all using pre-built system) Easiest: Give all communication routines, unequal weights Hardest: Handle variable starting positions, movable fulcrum, no provided code

6. Problem – Alternate version Control bot stationary on one end with moving counter balance bot on other end. Counter balance bot moves in response to requests from control bot. Control bot is moving up and down burning building “saving” people (light sensor detects “floors” of building each as a black line)

7. Save me!