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Welcome to Week 3

Week three of Begin Robotics looks at feedback control and how it is important in robotics. Watch Professor Richard Mitchell explain more.
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Welcome to Week 3 of Begin Robotics, where we consider feedback. Feedback for control and feedback for interaction. In Week 2, we looked at the anatomy of a robot, so we know about sensors, how the robot can perceive its environment. We know about movement, how you can get the robot to drive around. For the classically-minded, cybernetics comes from the Greek worked for steersman. The equivalent Latin word gives you governor, or government, the people who like to think they’re in control. How does the steersman control things? Answer?
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He looks to see where he’s going, and if he’s not on course, perhaps because of wind or tides, he adjusts the rudder, or the steering wheel, or whatever he has, to get back on course. That is the principle of feedback control, and we’ll explore that and see how it actually works in practise. Specifically, we’ll apply these ideas to mobile robots. So we’ve got our mobile robot here on the screen. What we’ll see is, how do you drive the robot at a particular speed. How do you ensure when it starts to go uphill, that it still drives at the right speed? Because gravity will try and slow down, or if it’s going downhill, gravity will speed it up.
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We will use proper feedback control. We will show other examples of feedback control. For instance, we’ll use the Grimblebot self-balancing robot, which doesn’t fall over, because it uses ultrasonic sensors to detect when it leans too far. You’ll see the Baxter robot, and how that can work with a human, and how I can use the Baxter and try and get it to pick up golf balls, and then let the robot pick its own gold balls up itself.
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But this idea of feedback control has lots of other applications. In your own home, for instance, you have a central heating system. That is a feedback control system, which ensures your house is at the right temperature. Your body temperature is controlled, unless you’re ill, by feedback, because if you’re too hot, you sweat to cool down, if you’re too cold, you shiver to warm up. And this idea of feedback control for temperature equally applies to the whole Earth.
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If you believe the Gaia theory, for instance, then the Earth is a self-regulating cybernetic system which has ensured that, for the last 3.6 billion years where we’ve had life, that the temperature of the Earth has remained constant enough for life to exist throughout that time. And then we’ll investigate haptic devices. These allow you to feel things in a virtual world, things that aren’t really there. We will use a robot-looking like device, which you grab hold off, which moves subtly, and then you can feel things. We’ll also demonstrate the virtual drum kit, where you hit something that’s not there, but you can start to hear the drums.
In the video above, Richard takes you through some key topics for Week 3.
We know about the robot and its anatomy.
  • It has sensors to perceive its environment.
  • It has motors which can drive its wheels.
We may want the robot to drive at a particular speed or in a particular direction.
  • But how do you ensure the speed is correct?
The answer is that we use feedback for control.
  • But feedback can be used to control more than speed –
  • We control ERIC’s rock and even temperature.
What’s more, feedback has other uses which we will also explore this week.
We’re keen to hear your thoughts as you progress through the course. Please use the comments section below to communicate with other Learners. From the 6 July for 4 weeks (until 2 August) the course will be facilitated by Ahmed Ashlam, from the Department of Computer Science, University of Reading. He will be supporting the discussions found at the end of each Step during this time. You can ‘follow’ mentors to see their responses to other Learners; you just need to view their profile and click the ‘Follow’ button. By following a profile, any comments made will appear in your activity feed, which you can filter by selecting ‘Following’.
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