NSF-GK12 Program at Chelsea High School

Basic knowledge of programming such as logic statements (AND, OR, IF … ELSE, and FOR, DO, and WHILE loops) and commands needed for robot movements.

1. One Blindfold
2. One cane (a meter stick)
3. Robots
4. Computers for programming
5. Maze for robots with stable walls

Ask students whether a bicycle can move by itself.  What is required for a bicycle to operate? Guide the class discussion towards who controls bicycles, cars, and airplanes. Ask students to define the role of a controller in a system.  Ask students whether a controller can be non-human.  Guide the discussion towards examples of computer controlled systems such as auto-cruise in cars and auto-pilot in airplanes. Ask students to come up with more examples of the systems that use controllers.  Also, establish the point all systems need a controller in order to operate and execute a task.  Ask students to define a controller. 

Write the definition of control systems on the board and draw a control system block diagram. Explain the steps (input, control, and output). Ask students to describe the input, controller, and output of bicycles, cars, and airplanes.

Ask students for a volunteer.  Blindfold the volunteered student and give him/her instructions to walk to across the room (e.g. go 3 steps forward; turn left 90 degrees; go forward 2 steps).  Ask class to identify the input, output, and controller of this system. 

Call for another volunteer and blindfold him/her.  Give him/her a cane (or a meter stick) and ask him to find his/her way from one side of the room to the other without giving him any directions.  Ask class to identify the input, output, and controller of the new system.

Ask class to describe the differences between the two systems: blindfolded student following directions versus blindfolded student with a cane in hand. Guide the discussion towards the point that the second student benefited from a sensor (cane). Next, draw the open-loop (feed-forward) and closed-loop (feedback) control diagrams on the board and ask students to identify which diagram corresponds to which blindfolded student case and why.

At this point establish that there are two types of control systems: open-loop and closed-loop.  Explain the advantages and disadvantages of the two types of controllers using a heater example:

1. Open-loop heater controller (no thermostat):  
   • Heater on for 30 minutes
   • Heater off for 30 minutes
2. Closed-loop heater controller (thermostat):
   • Heater on if temperature is < 65 degrees Fahrenheit
   • Heater off if temperature is > 70 degrees Fahrenheit

Design a maze for robots with stable walls.  Have students program their robots to complete the maze without the advantage of having sensors. After letting them struggle with the error complications, equip the robots with touch sensors (whiskers) and have students re-program their robots to complete the maze. Again, ask the students to identify the type of the controllers they used and which one works better.

Have students to complete this evaluation sheet.