Introduction

The ocean is divided into five zones. These zones go from the surface of the water (0 meters [m]) all the way down to 11,000 m, where there is no longer any light and the pressure of the water can crush a car. Although very little light exists at extreme depths, these deep zones are home to some of the world's most bizarre and fascinating creatures. Animals like viperfish, rat-tailed fish, and giant isopods, shown in Figure 1. Scientists can learn a lot by studying these creatures. But the zones where these animals live are very cold and dark, and the pressures are too high for humans to work safely. How do scientists gather information about deep-sea creatures? They rely on underwater robots to do the hard work.

Figure 1. This collection of amazing deep sea creatures includes a (a) viperfish, (b) rat-tailed fish, and (c) giant isopod.

But what are robots and how can they help us? Robots are machines often made to do jobs that are boring, repetitive, or dangerous for humans, like detecting leaks in gas pipelines, or getting rid of landmines. Robots can work in harsh environments, like the ocean or in space, unsafe for humans. An example of a space robot is the Mars Rover. This robot went to the planet Mars to gather information for scientists. An example of an ocean robot is the Tethys underwater robot made by the Monterey Bay Aquarium Research Institute (MBARI). This robot is designed to follow sea organisms while recording the physical and chemical properties of the water around them. Check out this video introduction to the Tethys underwater robot.

 
This video shows Tethys, an underwater robot that helps scientist at MBARI learn more about the oceans.

There are two kinds of underwater robots: remotely operated vehicles and autonomous underwater vehicles. Remotely operated vehicles (or ROVs) are connected to a cable that allows a human to control the robot from a ship or boat on the ocean surface or from within the robot. Figure 2 shows a ROV robot. Autonomous underwater vehicles (or AUVs) are controlled by computers on board the robot, and can operate without being connected to the surface. Because both ROV and AUV robots contain computers and electronic equipment, underwater robots need to be waterproof. This means that water cannot damage the equipment because it is inside a covering that prevents water from coming in.

Figure 2. This ROV robot operated by Harbor Branch Oceanographic Institution is 7.2 m long, 3.3 m high and 2.5 m wide and can explore to a depth of more than 900 m. Notice the scientist sitting in the acrylic sphere. (Photo by: National Oceanic and Atmospheric Administration [NOAA])

In this robotics engineering project, you will build an underwater robot, an ROV, that moves up and down using a motor, propeller, and a plastic clothes hanger. Before you start the project, you will need to figure out how and where to test the robot. Will you test it in a swimming pool or in a large container? (Note: Do not test it in a saltwater pool, as this can be dangerous.) If you decide to test the robot in a large container, make sure that the container is deep enough and large enough to hold the clothes hanger. Since the motor is a piece of electrical equipment, you will have to waterproof it by using a balloon to cover the motor and making sure that the edges of the balloon are glued to the surface of the motor (you can learn more about electricity from the Science Buddies Electricity, Magnetism, & Electromagnetism Tutorial). After putting these pieces together, you will have a cool robot that works underwater and is lots of fun to experiment with.

Terms and Concepts

• Robot

• Remotely operated vehicle

• Autonomous underwater vehicle

• Waterproof

• Motor

• Propeller

• Solder

• Buoyant

• Ballast

Questions

• What is a robot?

• What are the differences between an AUV robot and a ROV robot?

• What ways are ROV robots used?

• Why are underwater robots waterproofed?

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