WEBVTT FILE 1 00:00:00.000 --> 00:00:02.750 Measure. Analyze. Learn. 2 00:00:03.000 --> 00:00:06.250 The "Propeller Powered Pendulum" is one of the advanced 3 00:00:06.250 --> 00:00:09.250 projects in our 'Engineering Projects with Vernier' book. 4 00:00:09.250 --> 00:00:11.750 It's one of several that involves instrumentation 5 00:00:11.750 --> 00:00:14.000 and control of a system. 6 00:00:14.000 --> 00:00:17.250 In this project, we had asked the students to build a system 7 00:00:17.250 --> 00:00:20.750 with our rotary motion sensor here, and an arm with an 8 00:00:20.750 --> 00:00:25.000 electric motor mounted on it with a fan blade, a propeller blade. 9 00:00:25.000 --> 00:00:28.250 And the propeller can provide some 10 00:00:28.250 --> 00:00:32.250 motion and positioning of the arm. 11 00:00:32.250 --> 00:00:35.250 In each chapter of this book we offer a project 12 00:00:35.250 --> 00:00:40.250 which is meant to be a relatively straight forward task. 13 00:00:40.250 --> 00:00:44.250 And then, we offer more complicated challenges. 14 00:00:44.250 --> 00:00:47.750 For the project in this book, all we ask the students to do is, 15 00:00:47.750 --> 00:00:50.500 to write a program, using LabView, 16 00:00:50.500 --> 00:00:53.250 to make this arm move like a pendulum. 17 00:00:53.250 --> 00:00:58.000 That is, give it a little kick so it keeps running like this forever. 18 00:00:58.000 --> 00:00:59.750 Much like you would give your 19 00:00:59.750 --> 00:01:02.000 younger brother a push in the swing. 20 00:01:02.000 --> 00:01:04.750 You have to give a little push, or else they'll stop swinging. 21 00:01:04.750 --> 00:01:07.000 So, that's really not too hard to do. 22 00:01:07.000 --> 00:01:10.750 We have a sample program here, "VI" they call it in LabView. 23 00:01:10.750 --> 00:01:14.000 Let's give it a try. 24 00:01:21.000 --> 00:01:23.000 Notice that the fan only comes on when 25 00:01:23.000 --> 00:01:24.500 the arm swings in one direction. 26 00:01:24.500 --> 00:01:28.500 So, we get the effect of keeping this going. It should go forever. 27 00:01:28.500 --> 00:01:30.250 I'm going to go ahead and stop this now. 28 00:01:30.250 --> 00:01:35.000 And, let's take a look at the code. 29 00:01:35.000 --> 00:01:38.750 It's relatively simple code, it's LabView code now. 30 00:01:38.750 --> 00:01:42.250 It's basically a loop, and we're continually checking the 31 00:01:42.250 --> 00:01:46.000 position of the arm from that Express VI on the left, 32 00:01:46.000 --> 00:01:49.000 which reads the position of our rotary motion sensor. 33 00:01:49.000 --> 00:01:51.000 And then, we just make a decision on whether or not to 34 00:01:51.000 --> 00:01:55.750 turn the motor on, depending on what the arm position is. 35 00:01:55.750 --> 00:01:57.500 So that was the project for this chapter. 36 00:01:58.000 --> 00:02:00.500 The challenge, and the extreme challenge, from this chapter 37 00:02:00.500 --> 00:02:03.750 of the book have the students take this concept further. 38 00:02:03.750 --> 00:02:06.250 Instead of just turning the fan on and off, 39 00:02:06.250 --> 00:02:09.750 we actually have them control the power level for the fan, 40 00:02:09.750 --> 00:02:13.500 so that you have better control of the position for the arm. 41 00:02:13.500 --> 00:02:17.250 In the extreme challenge, we actually have them make a PID, 42 00:02:17.250 --> 00:02:21.750 a proportional integral derivative controller for the arm position, 43 00:02:21.750 --> 00:02:25.750 which is a classic engineering project. 44 00:02:25.750 --> 00:02:28.250 Chapters of engineering books are devoted to this. 45 00:02:28.250 --> 00:02:31.750 But basically, they have to have a program that takes the arm 46 00:02:31.750 --> 00:02:35.000 from this position to 40 degrees and holds it steadily, 47 00:02:35.000 --> 00:02:37.500 and does that most efficiently. 48 00:02:37.500 --> 00:02:40.500 The whole concept of tuning a PID controller is a great one 49 00:02:40.500 --> 00:02:42.500 for students to experiment with. 50 00:02:42.500 --> 00:02:45.000 If you have any questions about any of the projects in our 51 00:02:45.000 --> 00:02:48.750 'Engineering Projects with Vernier' book, check out our website.