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Rights: The University of Waikato
Published 2 September 2010

Robots need to interact with their environment. Professor Dale Carnegie of Victoria University explains some of the vast array of sensors and how these enable robots to operate. These can include sensors that can detect the distance of objects, sound, motion, heat and levels of carbon dioxide. Information from the sensors needs to be combined to provide a correct interpretation of the environment

Point of interest

Why is a washing machine considered to be a robot?


Our robots have to interact with their environment, so even what you'd think would be a dumb washing machine, that has to sense the level of water that is inside it and has to sense how heavy the clothes are. Without sensors the robot is blind, it would get no feedback, no indication of what is happening in the environment. So the sensors are the only way that the robot can find out what is happening around it.

There is a huge variety of sensors, and sometimes we don't give our robot everything we possibly could because those sensors might be very expensive or it might take the robot so long to work out all the information coming from the sensor that the robot would spend all its time doing that and no time doing what it’s supposed to.

One of the simplest sensors that we have is an infrared range finder. With an infrared sensor, we are firing out a beam of light that we can't see. We fire out the beam, and it hits whatever the obstacle is and then it comes back, and we time how long that takes, and so from working out how long it took to hit the object and come back, we can work out how far away that object was.

Some robots need to hear. Our security robot, MARVIN, he gets his instructions by you speaking to him, so he has to hear. One of our robots is designed to detect people who have been trapped under rubble, so it might be from an earthquake or it might be from a terrorist activity. So some of our robots burrow down under the ground and they are really trying to detect if there is a human trapped under there.

So how do we do that? Well, we know that a human might be moving, so we will try to detect motion. A human is hot, unless they have been dead for a while, so we will try to detect heat. If the human is breathing, they will be consuming the oxygen, releasing carbon dioxide, so we can detect the carbon dioxide. And also if the human is conscious, they might be screaming for help, so we can put the equivalent of an ear on or a microphone there. And we need to make sure that it’s a human making the sound, not just rubble or falling bricks or anything like that, so we will carefully modify that sensor to make sure that we are listening for a human and not for anything else.

Yet we've got to be careful, because sometimes our robot will go down and what it will find is a fire. A fire will also produce heat, a fire will also produce carbon dioxide, so we need to make sure that we are finding a human and not something else. And in that case, we have to take that combination of all of those sensors and work them together.