Welcome back students. It’s great to see you again. Today, we’re going to talk about odometry. Odometry sounds crazy, is the robot’s ability to integrate internal measurements, like it’s wheel rotation, other stuff, to figure out how far it’s gone. Before we do this, I want to make a human odometry experiment with you. Okay, so next quiz, get up your feet. Close your eyes. Walk forward five steps. Turn around 180 degrees and walk forward five steps again. Open your eyes. Did you manage to get to the same spot? Well, while you were doing this, your own brain performed odometry, integrate the motion from your muscles and your senses, and figure out where you are. And just like me, you’re not perfect. You’re probably a little bit off. You’re not really perfect. Robots aren’t perfect either, but robots constantly take sensor data from inside and calculate how far they’ve gone. Now, robots are a little bit different. They use the rotation of their wheels, they use inertial measurements. Inertial measurements are magnetometers, and gyroscopes, and accelerometers. And putting this data together into a coherent belief of how far we’ve gone is what this next lesson will be all about.