Instruction Guide: Ball Sorter

Submitted by Randy Steele on 26 February, 2012 - 10:37

This lesson ties together all the learning to date. The students must design a ball sorter robot that will acquire a ball from a Ball Stand and deposit the ball in a Red or Blue Container, depending on the color of the ball.  The robot must repeat the action autonomously for 10 iterations.  Students are expected to use My Blocks to develop their program.  A second light sensor, or color sensor, is recommended for this challenge.

This "Problem Solving with Programming" pdf  from the "Challenges" page in "NXT Video Trainer 2.0" discusses the incremental design.  This approach of breaking a large task down, and then incrementally designing/testing one piece at a time is a great antidote to most students' compulsion to jump right in at try to write a complex program all in one step. 

This Advanced Flow Charts PowerPoint describes using Process Blocks to design a hierarchical flow chart of a program.  Each My Block in a student's program would be a Process Block in their flow chart.  Insisting on a hierarchical flow chart as part of the Planning step before NXT-G coding (Prototyping) begins will greatly aid in the software design.  

Ball Sorter Challenge

This challenge is laid out in the Ball Sorter PowerPoint:

  • The layout is on a 4 foot square arena
    • The Ball Stand is a solid rectangular structure to aid in using the Touch or US sensor to help position the robot
    • The Red and Blue Containers are 1 foot square walled containers with solid sides to aid in using the Touch or US sensor to help position the robot
    • The track lines are high-contrast to the background to allow line following to help align the robot
  • Randomly place a red or blue ball on the Ball Stand at the beginning of the challenge, and then again after each ball is removed by the robot
  • You can decide whether or not to allow the Sound sensor to be used (not strictly autonomous, but may allow for differentiated instruction)
  • If a second light (or color) sensor is not available and line following is not used, repeatability may become an issue.  This can be addressed by modifying the rules (fewer iterations, periodic manual repositioning, etc.) 

Have students document the steps of the Engineering Process (restate challenge in their own words, identify related web sites, etc.) that they use in developing their robots. This Engineering Process Log Word hardcopy file may be used to document these steps in writing, or this electronic version may be used for a softcopy.