Engineers use robots to do tasks that might be harmful to humans. One common example is working with hazardous chemicals. A hazardous chemical is one that could cause a negative health effect, such as cancer, lung damage, skin irritation, or even death. If a mixture contains at least 1% of a known hazardous chemical, it is classified as a hazardous material. Consequently, many common household solutions, such as paints, cleaners, inks, and dyes can be considered hazardous. An acid is sometimes considered a hazardous chemical, because it can cause severe burns if it gets in your eyes, nose, or skin. Not all acids are hazardous, however. Some acids, such as vinegar and lemon juice, are used in cooking to give foods their distinctive flavor.
This challenge is to build a sensor-controlled robot to test for acids. A robot of this type would be very useful if you were dealing with the possibility of dangerous acids in an area.
In this project, you will design and build a mobile robot for testing the pH of a solution. Use a ceramic coffee cup or other relatively heavy container to hold the solution, since a lightweight container, like a Styrofoam® cup, might tip over. Have the robot approach the cup, stop when the touch sensor comes in contact with the cup, and then lower the pH Sensor. After a few seconds have your robot raise the pH Sensor, play a sound, and then back away from the cup. Your program should compare the pH value of the solution with a pre-defined limit. If the pH is less than 7, have the robot scream. If the pH is greater than 7, have the robot say “good.”
We recommend using orange juice or cola for the acid in this project and water with a little baking soda added to it for the base. If you use any other acid solution, use caution as they can be toxic, corrosive, or irritating to the skin, eyes, lungs, or mucous membranes. Handle those solutions with care. Do not allow the solutions to contact your skin or clothing.
You are strongly encouraged to use the Engineering Design Method and your creative imagination when tackling this challenge.
Sensors and Equipment
This project features the following Vernier sensors and equipment.