WEBVTT - Electronics 101: How Accelerometers Work 0:00:00.280 --> 0:00:02.920 Brought to you by the reinvented two thousand twelve Camray. 0:00:03.160 --> 0:00:08.880 It's ready. Are you get in touch with technology? With 0:00:09.000 --> 0:00:17.800 tech Stuff from how stuff works dot com. Yo, how's 0:00:17.800 --> 0:00:20.639 it going? Welcome to tech stuff. My name is Chris Polette, 0:00:20.640 --> 0:00:23.080 and I am a very weird editor here at how 0:00:23.120 --> 0:00:26.400 stuff works dot com. Sit Here across from me, as usual, 0:00:26.680 --> 0:00:30.800 is senior writer Jonathan Strickland. Slow down, you move too fast. 0:00:31.200 --> 0:00:35.440 You got to make the morning last Uh. Are you 0:00:35.479 --> 0:00:38.720 feeling groovy, Chris? I am? You know what else is groovy? 0:00:38.840 --> 0:00:42.559 What's that? Accelerometers? I like how you bridged that there. Yeah, 0:00:42.600 --> 0:00:45.600 it wasn't that. That was a really good segue. That's 0:00:45.680 --> 0:00:49.280 that's the tom Merritt segue where you get me mad 0:00:49.440 --> 0:00:52.440 by pointing out my segue. Oh nice, Yeah, tom Merritt 0:00:52.440 --> 0:00:55.240 always hated that, which is awesome, which why you always 0:00:55.280 --> 0:00:58.520 do it whenever soon anyway, So tom Merritt decide we're 0:00:58.520 --> 0:01:02.120 gonna talk about accelerometers to day. And accelerometers are in 0:01:02.160 --> 0:01:05.720 a lot of different products, um particularly a lot of 0:01:06.160 --> 0:01:10.680 handheld mobile gadgets, as it turns out, because they provide 0:01:10.680 --> 0:01:14.760 a handy guide to things like orientation and also just 0:01:15.080 --> 0:01:18.360 movement in general. So to understand what an accelerometer is, 0:01:18.400 --> 0:01:21.959 I guess we need to talk about what acceleration is. Okay, 0:01:22.040 --> 0:01:24.560 we can do that, Okay, Yeah, I just wanted to 0:01:24.560 --> 0:01:27.039 point out that we were going to make a return 0:01:27.120 --> 0:01:30.840 to our electronics one oh one. Yes, yes, a long 0:01:31.560 --> 0:01:33.720 return to electronics one oh one. This time we're talking 0:01:33.760 --> 0:01:38.120 specifically about accelerometers. And it's funny because, uh, um, on 0:01:38.319 --> 0:01:41.120 our first few podcasts on this in the series, we 0:01:41.160 --> 0:01:44.440 actually sort of went into a lot of different components. Um, 0:01:44.680 --> 0:01:46.959 and we we sort of recently went back into it. 0:01:47.080 --> 0:01:51.440 It's probably electronics to a one with the Arduino board. Um. 0:01:51.480 --> 0:01:53.960 But yeah, this is a component that you could actually 0:01:54.000 --> 0:01:57.280 hook up to them. They're not particularly expensive components, and 0:01:57.280 --> 0:01:59.200 they're found in all kinds of things, as you pointed out, 0:01:59.200 --> 0:02:04.320 including a lot of things you wouldn't necessarily think of, um, laptops, laptops. Yes, 0:02:04.840 --> 0:02:08.040 um yeah. I remember being uh sort of astounded when 0:02:08.120 --> 0:02:10.080 I heard that Apple was going to put a device 0:02:10.200 --> 0:02:14.680 inside their laptops that would detect when it the laptop 0:02:14.720 --> 0:02:16.919 had been dropped, so it could park the hard drive 0:02:16.960 --> 0:02:19.600 to minimize damage. And I thought, wow, that's cool. I 0:02:19.600 --> 0:02:23.160 wonder what that is. Of course, now they're almost in everything, 0:02:23.200 --> 0:02:25.400 so it's kind of hard to avoid accelerometers. But I 0:02:25.400 --> 0:02:27.560 think I think you're right. I think acceleration would be 0:02:27.600 --> 0:02:31.920 a good, um, good place to start. So acceleration is 0:02:31.960 --> 0:02:35.920 the time rate of change in velocity? Yes, it is, 0:02:36.040 --> 0:02:38.400 and uh and you you might say, well, what what 0:02:38.520 --> 0:02:42.120 was that was? Velocity? Velocity is two things. It's a 0:02:42.240 --> 0:02:44.320 thing speed and the direction it's moving in it. And 0:02:44.360 --> 0:02:47.239 it has two vectors, speed and direction. You cannot have 0:02:47.320 --> 0:02:50.960 velocity without both of those. Oh man, I'm suddenly transported 0:02:51.000 --> 0:02:55.080 back to my physics senior physics class in high school. So, 0:02:55.080 --> 0:02:59.079 so acceleration is the time rate of change in that 0:02:59.800 --> 0:03:03.079 she aange and velocity so um, in a way you would, 0:03:03.440 --> 0:03:05.639 And you measure it by saying it's a distance over 0:03:05.680 --> 0:03:09.360 time over time. Yes, so it's it's measured in feet 0:03:09.360 --> 0:03:12.200 per second per second or meters per second per second. 0:03:12.280 --> 0:03:16.240 So for example gravity, gravity's force of acceleration is at 0:03:16.400 --> 0:03:19.880 thirty two ft per second per second or nine point 0:03:19.919 --> 0:03:23.040 eight one per second per second. So yes, are you 0:03:23.160 --> 0:03:25.760 using the just curious are using the same texas instruments? 0:03:25.800 --> 0:03:29.519 Power point presentation that was one of my main sources. UM. 0:03:29.639 --> 0:03:31.600 The only reason I mentioned that is if you really 0:03:31.600 --> 0:03:37.040 want a uh basic introduction to accelerometers and the things 0:03:37.040 --> 0:03:38.880 we're talking about, that's a great place to start. It's 0:03:38.880 --> 0:03:41.160 free and you can find it online. It's really you know, 0:03:41.360 --> 0:03:44.720 and I trust Texas. It's a it's a PDF format 0:03:44.800 --> 0:03:48.880 and it's clearly it was obviously a slide show, yes originally, 0:03:49.200 --> 0:03:52.120 and you can go through and it's quite quite simple 0:03:52.160 --> 0:03:54.000 to follow along. It does get into a little more 0:03:54.000 --> 0:03:57.760 technical detail than what will cover here, mainly because um 0:03:57.800 --> 0:04:01.280 it uses some really handy graph fixed to explain which 0:04:01.320 --> 0:04:03.480 Chris is showing off to me to the benefit of 0:04:03.520 --> 0:04:05.760 no one out there. But it has some really handy 0:04:05.760 --> 0:04:09.960 graphics to explain things like measuring acceleration and observing acceleration, 0:04:10.200 --> 0:04:13.720 which obviously in an audio podcast we cannot take advantage of, 0:04:13.760 --> 0:04:16.720 so we'll be skipping over that stuff. So accelerometers are 0:04:16.720 --> 0:04:21.920 really all about detecting a change in motion, and uh 0:04:21.960 --> 0:04:27.479 there two basic types of accelerometers. There's a kind that 0:04:27.560 --> 0:04:32.480 will just uh detect um a dynamic change in acceleration, 0:04:32.880 --> 0:04:37.240 and then there's the static acceleration. Now static acceleration, you're thinking, well, 0:04:37.279 --> 0:04:40.400 how can you have something that's static and accelerating at 0:04:40.440 --> 0:04:44.000 the same time. Yes, because static basically the definition of 0:04:44.000 --> 0:04:47.040 static is it is not changing. Yeah, an acceleration is 0:04:47.080 --> 0:04:49.919 a change in time, uh, the time rate of change 0:04:50.000 --> 0:04:53.360 in velocity. So how can you have static acceleration? That's 0:04:53.400 --> 0:04:57.760 really talking about measuring um the amount of stack acceleration 0:04:57.839 --> 0:05:01.840 due to gravity. Yes, so gravity is going to have 0:05:01.920 --> 0:05:05.440 this constant poll. Uh. And like we said before, three 0:05:05.520 --> 0:05:09.039 two ft per second per second is the standard um. 0:05:09.120 --> 0:05:12.839 That's the acceleration of gravity. So on Earth anyway, So 0:05:12.960 --> 0:05:17.040 that's that's always going to be there as long as 0:05:17.080 --> 0:05:19.880 whatever the devices is on Earth. I mean, granted, if 0:05:19.880 --> 0:05:23.160 you take that device into outer space that changes or 0:05:23.200 --> 0:05:25.800 you go to a different planet, then that will change 0:05:26.040 --> 0:05:27.920 the They will still be static, it'll just be a 0:05:27.960 --> 0:05:31.280 different force because you know, not all planets have the 0:05:31.279 --> 0:05:36.280 same gravity as Earth. Right, So where did you want 0:05:36.320 --> 0:05:38.120 to go from here? Well, I was gonna talk If 0:05:38.160 --> 0:05:41.320 you're telling you about dynamic acceleration, then what you're measuring 0:05:41.520 --> 0:05:45.400 is how fast or how how much how much change 0:05:45.440 --> 0:05:49.080 is undergoing in the velocity of a particular object over 0:05:49.600 --> 0:05:52.400 uh an amount of time. So um, that would be 0:05:52.440 --> 0:05:57.039 something that would give you readings on uh, how quickly 0:05:57.160 --> 0:06:00.840 something is changing in velocity, uh, for stuff like our 0:06:00.880 --> 0:06:03.400 handheld devices, and that would be a good example that 0:06:03.480 --> 0:06:07.680 might be, um, the the laptops, Like it tells you 0:06:08.240 --> 0:06:12.600 that it's changing very quickly from stationary to moving really 0:06:12.640 --> 0:06:14.800 fast and that needs to shut down the hard drive. 0:06:15.200 --> 0:06:18.480 Although really I would say that the accelerometers that are 0:06:18.520 --> 0:06:21.240 in laptops are probably similar to the ones that are 0:06:21.279 --> 0:06:25.840 on things like, um, the iPad or other tablet devices 0:06:25.880 --> 0:06:30.240 also smartphones, which are the static ones, and that's where 0:06:30.320 --> 0:06:33.159 where it's uh. The reason for the stag accelerometer is 0:06:33.200 --> 0:06:36.520 to kind of measure the difference uh that's going on 0:06:37.120 --> 0:06:40.280 due to gravity, so that you can determine the orientation 0:06:40.560 --> 0:06:44.800 of that particular device. Yeah. Now they do make accelerometers 0:06:44.839 --> 0:06:48.320 will measure things in two axes. Basically you're you know, 0:06:48.440 --> 0:06:52.960 horizontal in your vertical and then just oversimplifying again obviously 0:06:53.000 --> 0:06:55.040 if you tilt it, you're still measuring in two axes. 0:06:55.200 --> 0:07:00.120 But but there are three axes axis accelerometers as well, 0:07:00.320 --> 0:07:02.880 so you can you can measure a lot more effectively 0:07:02.920 --> 0:07:08.680 as you could imagine within a three D space plane. Yeah, So, um, 0:07:08.720 --> 0:07:12.080 it depends on your application. UM, for something like a 0:07:12.200 --> 0:07:16.040 Nintendo WE remote, you're definitely gonna want a three axis accelerometer. 0:07:16.280 --> 0:07:21.440 Same thing with the other various motion controlled game controllers 0:07:21.480 --> 0:07:23.840 that are out there. But it depends. You know, you 0:07:23.880 --> 0:07:26.160 may not necessarily need that if you can, if you're 0:07:26.160 --> 0:07:32.120 measuring acceleration on something that is moving on a flat plane, UM, 0:07:32.160 --> 0:07:34.200 to access would be fine, to access should be fine, 0:07:34.320 --> 0:07:36.800 or you could. I read one guy that suggested that 0:07:36.840 --> 0:07:38.560 if you really needed three D and didn't have a 0:07:38.600 --> 0:07:41.440 three D, you could mount to two D basically one 0:07:41.680 --> 0:07:43.840 and at at a right angle from the other to 0:07:43.880 --> 0:07:47.720 measure the third axis. But that you know, And and 0:07:47.720 --> 0:07:52.720 while there's the static and dynamic accelerometers, there's also the 0:07:52.720 --> 0:07:56.640 there's also another major division, which is analog versus digital. 0:07:57.320 --> 0:08:00.400 So an analog accelerometer is going to have an tinuous 0:08:00.480 --> 0:08:04.840 voltage output that's proportional to its acceleration UH, and then 0:08:04.920 --> 0:08:08.840 digital accelerometers will use UH well, most of them use 0:08:08.880 --> 0:08:12.800 pulse width modulation for the output, which has a square 0:08:12.840 --> 0:08:17.160 wave of a particular frequency, and the amount of time 0:08:17.640 --> 0:08:20.800 the voltage is high will be promoted proportional to the 0:08:20.840 --> 0:08:25.320 amount of acceleration. So you know, again you're talking about 0:08:25.600 --> 0:08:29.440 measuring this and in terms of electricity, in terms of voltage, 0:08:29.760 --> 0:08:33.160 and that's what tells the sensor, Hey, this thing is 0:08:33.200 --> 0:08:36.640 moving in this particular way. It's the change in voltage. 0:08:36.679 --> 0:08:39.600 So you've got you've got the accelerometer and you've got 0:08:39.640 --> 0:08:43.080 a sensor that together are telling the device what this 0:08:43.160 --> 0:08:49.480 information actually means. And uh, then within these these major categorizations, 0:08:49.480 --> 0:08:55.600 we have several different ways of actually registering acceleration. Yes, 0:08:55.760 --> 0:08:58.280 so we can talk about some of those. For example, 0:08:58.400 --> 0:09:03.640 there are capacitive alerometers. Now that's where you're talking about 0:09:03.760 --> 0:09:09.240 change in capacitance across the surface. Now, capacitance is materials 0:09:09.240 --> 0:09:13.840 ability to hold an electromagnetic charge. Well, you know, like capacity. Yes, 0:09:14.200 --> 0:09:17.240 so it's an easy pneumonic device. Yes, and you one 0:09:17.400 --> 0:09:22.040 very common form of capacitance involves having these parallel plates 0:09:22.040 --> 0:09:24.880 that are a certain distance apart, and then if you 0:09:25.000 --> 0:09:29.959 change the distance, that changes that the capacitance of those surfaces. Uh. 0:09:30.040 --> 0:09:36.120 The distance has a a very strong correlation with the 0:09:36.160 --> 0:09:41.319 capacitance of those um plates. So if they move closer together, 0:09:41.400 --> 0:09:44.000 the capacitance is going to change. So if you create 0:09:44.080 --> 0:09:48.760 a an accelerometer that will allow these these parallel plates 0:09:48.800 --> 0:09:51.880 to either move closer together or move further apart than 0:09:52.000 --> 0:09:55.120 The accelerometer can measure that change in capacitance and then 0:09:55.160 --> 0:09:59.560 interpret that through the sensor as a various form of acceleration. 0:09:59.559 --> 0:10:03.000 It may be the tilt of the device, the orientation 0:10:03.000 --> 0:10:06.160 of that device. That's how you would see it. When 0:10:06.200 --> 0:10:10.840 you like turn your smartphone sideways and it automatically changes 0:10:10.880 --> 0:10:14.599 the view. That's how you perceive this. But on the 0:10:14.640 --> 0:10:17.360 back end, it's all being done through this change in voltage. 0:10:18.200 --> 0:10:24.120 That's just one version, though there's also piezo electric accelerometers 0:10:24.240 --> 0:10:27.880 rather which now you may not be familiar with piezo electric, 0:10:28.400 --> 0:10:32.760 uh that that term we're specifically talking about a an 0:10:32.760 --> 0:10:36.800 interesting phenomenon. There's certain there's certain elements, there's certain kinds 0:10:36.800 --> 0:10:40.800 of materials that when they are when their shape is 0:10:41.160 --> 0:10:46.440 changed in a certain way, they will emit um electricity 0:10:46.600 --> 0:10:50.760 or if they are uh subjected to electricity, their shape 0:10:50.760 --> 0:10:54.400 will change yeah um and and basically in some cases, 0:10:54.679 --> 0:10:58.800 like the application of stress will make this make this 0:10:58.840 --> 0:11:03.160 effect happen. Um cistals are often used. Crystals and watches 0:11:03.240 --> 0:11:07.600 are a very common way of of h illustrating this principle. 0:11:07.640 --> 0:11:10.880 That's how they work. They actually do change shape and 0:11:11.480 --> 0:11:14.360 uh when stress is applied, and then they will admit 0:11:14.360 --> 0:11:17.640 electricity or vice versa, which kind of interesting. UM. So 0:11:17.960 --> 0:11:20.040 this would be a piece of electric crystal that would 0:11:20.040 --> 0:11:22.240 be mounted to some sort of mass and there'd be 0:11:22.280 --> 0:11:28.760 a voltage output UM whenever acceleration changed. There's also piezo resistive. 0:11:29.679 --> 0:11:32.800 Those are surfaces that have some sort of electrical resistance 0:11:33.280 --> 0:11:37.040 and that will change relative to whatever acceleration is uh 0:11:37.240 --> 0:11:41.480 is placed upon that object. UM. There's some that involve 0:11:41.760 --> 0:11:48.439 magnetic fields, the magneto magneto resistive resistive accelerometers. Yeah, those 0:11:48.480 --> 0:11:50.640 will change in the presence of any sort of magnetic field. 0:11:50.679 --> 0:11:55.439 There's also the Hall effect accelerometers, which they detect motion 0:11:55.480 --> 0:11:59.120 by sensing changes in magnetic fields, but only in corridors. 0:11:59.720 --> 0:12:06.000 I'm kidding, I walk alone. Uh. Anyway, There's also the 0:12:06.000 --> 0:12:09.800 there's UM some that detect changes in heat, and the 0:12:09.920 --> 0:12:15.199 changes in heat and become interpreted as changes in acceleration. 0:12:15.880 --> 0:12:18.319 And Yeah, there's all these different kinds that are out 0:12:18.320 --> 0:12:20.719 there on the market. So the kind you use is 0:12:20.760 --> 0:12:25.800 really dependent upon what sort of device or um. Uh, 0:12:25.840 --> 0:12:29.640 what's our purpose accelerometer is going to have? UM? So 0:12:30.320 --> 0:12:34.439 it's it's an interesting world. I mean, it's interesting kind 0:12:34.480 --> 0:12:38.880 of um uh component that can be used in lots 0:12:38.880 --> 0:12:41.559 of different applications. Uh, it's I think it's actually pretty 0:12:41.600 --> 0:12:44.160 clever to use it in things like smartphones and tablets 0:12:44.440 --> 0:12:47.760 as a way to help, uh, determine the orientation of 0:12:47.800 --> 0:12:49.760 that device so that it gives you the proper view. 0:12:50.080 --> 0:12:52.840 I mean, it's also used useful in things like let's 0:12:52.840 --> 0:12:56.800 say that you have a device that has UM a 0:12:56.840 --> 0:12:58.599 camera in and you're using it for an augment and 0:12:58.679 --> 0:13:05.599 reality purpose. The accelerometer might help the the your processor 0:13:05.720 --> 0:13:08.000 in your in whatever device you're using. For example, I'm 0:13:08.000 --> 0:13:10.160 just gonna use smartphone because I've seen that most frequently 0:13:10.160 --> 0:13:12.839 in smartphones. Let's say you've got a flat map out 0:13:12.880 --> 0:13:15.679 on a table, and you've got your augmented reality application 0:13:15.760 --> 0:13:18.040 running on your smartphone, and it creates this three D 0:13:18.520 --> 0:13:22.360 virtual realm that's that sits on top of that physical 0:13:22.400 --> 0:13:24.880 map that you're looking at through the lens of your 0:13:25.000 --> 0:13:28.600 smartphones camera. The accelerometer might be feeding information to the 0:13:28.640 --> 0:13:33.640 CPU that helps the the smartphone. No how you're holding 0:13:33.640 --> 0:13:37.560 your phone so that it's displaying the three D model properly. 0:13:37.920 --> 0:13:40.840 Because if it doesn't know the right orientation, then you 0:13:40.920 --> 0:13:43.280 might be looking at let's say it's a building. You 0:13:43.360 --> 0:13:45.040 might be looking at a building and it's tilted at 0:13:45.040 --> 0:13:49.120 a really weird angle because it hasn't the phone is 0:13:49.200 --> 0:13:52.480 unable to figure out how it's positioned in relation to 0:13:52.600 --> 0:13:54.959 the map. Now, some of that is done by the 0:13:55.040 --> 0:13:56.880 camera itself. A lot of that actually is done by 0:13:56.920 --> 0:13:59.480 the camera itself, but the accelerometer may also feed additional 0:13:59.520 --> 0:14:02.400 information to the CPU in order to get the most 0:14:02.400 --> 0:14:06.560 accurate results. So that's just one example. I mean there's 0:14:06.559 --> 0:14:09.800 plenty of others. There's things like, uh there, I remember 0:14:09.920 --> 0:14:13.760 there was a um, I think it was an iPhone 0:14:14.040 --> 0:14:18.120 app that came out shortly after the iPhone debut, which was, uh, 0:14:18.200 --> 0:14:20.960 it would measure how long in the air your iPhone 0:14:21.000 --> 0:14:22.200 was when you would toss it up in the air 0:14:22.200 --> 0:14:25.320 and catch it, which to me sounds like a terrible, 0:14:25.440 --> 0:14:28.440 terrible idea. It sounds like a great way to to 0:14:28.960 --> 0:14:37.160 create Apple iPhone turnover, Apple turnover. Uh. But yeah, I 0:14:37.160 --> 0:14:41.520 mean cars. Cars. Yes, that's a very obvious use, especially 0:14:41.520 --> 0:14:43.680 for things like even even if you're not talking about 0:14:43.880 --> 0:14:47.680 within a car itself, like like for for the end driver. 0:14:48.120 --> 0:14:50.000 Let's say that you want to do things like test 0:14:50.080 --> 0:14:53.880 a car for the stresses that it will undergo when 0:14:53.960 --> 0:14:57.120 it's in a crash situation. You use accelerometers in that 0:14:57.200 --> 0:15:00.480 as well to kind of and accelerames within crash test dummy, 0:15:00.120 --> 0:15:03.760 since you can determine if the forces that a human 0:15:03.840 --> 0:15:08.000 would uh would experience within a test or within a 0:15:08.000 --> 0:15:11.720 crash situation rather if they would be you know, strong 0:15:11.840 --> 0:15:14.160 enough to cause injury or even death. In fact, we 0:15:14.200 --> 0:15:17.200 have how crush test dummies work at House of Works 0:15:17.200 --> 0:15:20.680 dot com that goes into more detail on that. Yeah, yeah, well, 0:15:20.720 --> 0:15:23.880 I mean you can there. They were also talking recently 0:15:23.920 --> 0:15:29.040 again about how UH car manufacturers have been putting boxes 0:15:29.080 --> 0:15:33.880 in cars for years now to gather information, uh, sort 0:15:33.920 --> 0:15:36.960 of like the boxes that you see in airplanes. UM, 0:15:37.040 --> 0:15:39.880 that will tell you more or less, you know, the 0:15:39.880 --> 0:15:43.200 information that it collects all kinds of information, but basically 0:15:43.200 --> 0:15:46.360 the speed at which you were traveling. Um, you know, 0:15:46.840 --> 0:15:48.440 it will give you an idea the direction you were 0:15:48.480 --> 0:15:52.080 headed in. So if they need that information for to 0:15:52.240 --> 0:15:55.640 determine what happened in an accident, UH, they could pull 0:15:55.720 --> 0:15:59.000 that from the their uh the box and they can 0:15:59.280 --> 0:16:01.440 you know, they use these these instruments to tell but 0:16:01.480 --> 0:16:05.960 you know, an accelerometer is not necessarily enough depending on 0:16:06.040 --> 0:16:09.080 what you want to do. And that's that's actually interesting. 0:16:09.080 --> 0:16:11.240 I mean they are everywhere now, but you're starting to 0:16:11.240 --> 0:16:15.920 see certain applications for which UM accelerometers are being augmented 0:16:15.960 --> 0:16:19.800 with gyroscopic devices, things like the the WE remote when 0:16:19.840 --> 0:16:22.960 they and introduced the motion plus the six excess controller 0:16:23.000 --> 0:16:26.360 for the PS three. Yeah, yeah, yeah, these are elements 0:16:26.360 --> 0:16:29.680 where the gyroscope also plays a big role in determining 0:16:29.720 --> 0:16:32.720 the orientation and the pitch, the role the yaw, all 0:16:32.760 --> 0:16:35.440 that kind of stuff that also gets that also gets 0:16:35.520 --> 0:16:38.480 uh measured by the gyroscopes, which, by the way, we 0:16:38.520 --> 0:16:40.760 have an article how gyroscopes work and how stuff works 0:16:40.840 --> 0:16:43.800 dot com. Yes, and when when we wrote about the 0:16:44.120 --> 0:16:46.920 space industry, which it's come up a couple of times 0:16:46.960 --> 0:16:51.120 about the gyroscopic controls that they used to use back 0:16:51.120 --> 0:16:53.600 when we were trying to reach the moon. Uh not 0:16:54.040 --> 0:16:57.640 us personally, No, we never tried. Well I tried, but 0:16:57.760 --> 0:17:01.160 my cardboard box never actually took flight. But yeah, so 0:17:01.200 --> 0:17:04.680 I mean between the two of them, uh, an accelerator 0:17:05.240 --> 0:17:10.880 axcet acceleramat Earth everything and a gyroscope can be very 0:17:11.040 --> 0:17:14.360 very accurate in terms of what measurement can you know 0:17:14.480 --> 0:17:17.480 the measurements that you can take on on uh, what 0:17:17.520 --> 0:17:22.040 direction and what velocity? Yeah, actually, actually acceleration is going 0:17:22.080 --> 0:17:25.679 on to give you a much more accurate response in 0:17:25.720 --> 0:17:28.040 your electronic gear and some other things that you have 0:17:28.080 --> 0:17:31.520 to consider with an accelerometer. We talked about the number, uh, 0:17:31.760 --> 0:17:35.320 the the access number like how many Yeah, so we 0:17:35.359 --> 0:17:37.879 had that in there, but there's there's more than just that. 0:17:37.920 --> 0:17:41.639 You also have to consider the maximum swing, which is 0:17:41.760 --> 0:17:45.520 that's how much force the accelerometer is is essentially uh 0:17:46.000 --> 0:17:51.720 rated to to measure. Now for something like your smartphone 0:17:51.840 --> 0:17:54.040 or your tablet, it doesn't have to be particularly it 0:17:54.040 --> 0:17:57.200 doesn't have to be able to withstand huge amounts of 0:17:57.200 --> 0:18:01.560 of of acceleration. We think of acceleration often in terms 0:18:01.600 --> 0:18:05.160 of the Earth's gravity. So, frank example, if you've ever heard, 0:18:05.160 --> 0:18:07.480 oh man, he was pulling six gs on that turn, 0:18:07.960 --> 0:18:11.560 that's six times the acceleration force of Earth's gravity that 0:18:11.560 --> 0:18:15.600 that person was was experiencing. And um, you know, if 0:18:15.640 --> 0:18:17.840 you're on the Space Shuttle, you might be experiencing ten 0:18:17.960 --> 0:18:20.800 g's which, by the way, uh, if you do that 0:18:20.840 --> 0:18:25.200 for too long. Um, it will kill you because as 0:18:25.320 --> 0:18:27.720 as you experience these these higher g s, you will 0:18:27.720 --> 0:18:32.320 actually have the blood forced from your head and uh 0:18:32.440 --> 0:18:36.240 down your body, and that can actually deprive your brain 0:18:36.280 --> 0:18:39.320 of oxygen. Which is why if you ever watch a 0:18:39.359 --> 0:18:42.679 test pilot or you ever go through test pilot training 0:18:42.680 --> 0:18:45.800 for supersonic flights, they often are told that they have 0:18:45.880 --> 0:18:48.480 to uh, they have to sort of strain so they 0:18:48.520 --> 0:18:51.480 force blood back up to their brain to avoid blacking out. 0:18:51.600 --> 0:18:54.000 So it's it's like where you actually hear I'm going 0:18:55.920 --> 0:18:59.080 where they're they're really trying to force blood back up 0:18:59.080 --> 0:19:01.760 there so that they can withstand these g's that are 0:19:02.600 --> 0:19:07.040 uh they're undergoing for the purposes of a supersonic flight. Um. Actually, 0:19:07.080 --> 0:19:10.639 I saw a great MythBusters where Adam Savage totally blacked 0:19:10.640 --> 0:19:13.520 out because he was doing a supersonic flight and they 0:19:13.560 --> 0:19:16.639 did this really powerful turn and uh and it was 0:19:16.800 --> 0:19:18.920 it was too much for him. And you know, let's 0:19:19.160 --> 0:19:21.359 let's be honest, the dude it was the first time 0:19:21.400 --> 0:19:23.720 going on a on a flight like that. I mean 0:19:23.760 --> 0:19:26.520 I would have happened to me, just probably faster because 0:19:26.520 --> 0:19:30.160 I think Adams in better shape than I am, so um, anyway, 0:19:30.160 --> 0:19:32.560 for your accelerometer, you have to have it. You know, 0:19:32.760 --> 0:19:34.720 you have to figure out how much force it's going 0:19:34.760 --> 0:19:38.400 to be able to to measure. And for something that's 0:19:38.440 --> 0:19:41.159 simple like smartphone or tablets, something that's not going to 0:19:41.280 --> 0:19:44.679 withstand high amounts of acceleration, it might be plus reminds 0:19:44.880 --> 0:19:47.840 one point five g's, so one and a half times 0:19:47.880 --> 0:19:51.720 the the gravitational force of that we feel on Earth. 0:19:52.359 --> 0:19:56.920 But if you wanted something more substantial, um, it might 0:19:56.920 --> 0:20:00.159 be plus or remindus to g's. And it's only when 0:20:00.200 --> 0:20:02.479 you're starting to look at something that it's gonna have 0:20:02.520 --> 0:20:04.760 lots of sun stops and starts that you're looking at 0:20:04.760 --> 0:20:07.600 plus or minus five gs or more. Uh Like just 0:20:07.680 --> 0:20:09.639 something like the space shall clearly you're gonna have to 0:20:09.640 --> 0:20:13.359 have plus or minus ten g's. It's not gonna because 0:20:13.400 --> 0:20:16.639 the forces that that experiences are much greater than anything 0:20:16.800 --> 0:20:18.680 that we're going to have on our phones. For most 0:20:18.680 --> 0:20:21.320 of us. Anyway, maybe if you get really mad and 0:20:21.320 --> 0:20:25.320 you throw it really hard, um, in which case you 0:20:25.400 --> 0:20:28.320 might want to pursue a career in the major leagues. 0:20:28.880 --> 0:20:31.720 Uh So the maximum swing uh is one of the 0:20:31.760 --> 0:20:34.280 other things you have to consider. Also, the sensitivity of 0:20:34.320 --> 0:20:38.720 the accelerometer. UM, not like that, but in general you 0:20:38.760 --> 0:20:41.440 wanted to be really a sensitive device because if it's 0:20:41.480 --> 0:20:44.520 not sensitive, it's not gonna pick up uh a slight 0:20:44.600 --> 0:20:47.520 changes in velocity, it's not really doing you any good. UM. 0:20:47.560 --> 0:20:50.359 And then also the bandwidth of the accelerometer. You have 0:20:50.400 --> 0:20:55.560 to figure out how frequently the accelerometer is checking the 0:20:55.680 --> 0:20:59.879 uh the changes in velocity over time, So for example, 0:21:00.080 --> 0:21:03.800 might be fifty hurts, so fifty times a second the 0:21:03.840 --> 0:21:09.480 accelerometer is checking to see about changes in velocity. UM. 0:21:09.520 --> 0:21:12.200 You know it's uh if you're looking at something that's 0:21:13.520 --> 0:21:16.359 checking the acceleration of some of a device that's vibrating 0:21:16.359 --> 0:21:18.639 at a really high frequency, then obviously you're gonna have 0:21:18.720 --> 0:21:21.560 to have a much higher bandwidth. You're gonna have to 0:21:21.640 --> 0:21:25.320 be checking that those changes much more frequently than fifty hurts. 0:21:26.440 --> 0:21:29.560 So one other UH factor that you might want to consider, 0:21:29.920 --> 0:21:33.280 depending on what you're doing with the the device, UM 0:21:33.520 --> 0:21:37.520 is the impedance or buffering. Basically, UH, that's beyond it's 0:21:37.520 --> 0:21:39.200 really we're getting to the point where we're beyond the 0:21:39.240 --> 0:21:43.240 scope of electronics one and one UM. But depending on 0:21:43.240 --> 0:21:45.800 the type of project you you need you might have 0:21:45.880 --> 0:21:50.919 to consider this because uh, analog and digital accelerometers handle 0:21:50.960 --> 0:21:54.800 impedance differently. So, um, you know, if you're really getting 0:21:54.800 --> 0:21:58.400 into the fine points of an electronics project, UH, take 0:21:58.440 --> 0:21:59.920 a look at this before you run out and buy 0:22:00.359 --> 0:22:03.560 a component to add to your to your project, because 0:22:03.760 --> 0:22:05.600 it may be a factor for you, and it may not. 0:22:05.720 --> 0:22:09.359 I mean, if you're doing something uh really simple, then 0:22:09.400 --> 0:22:12.639 it may not necessarily be an issue. I remember, actually 0:22:12.680 --> 0:22:16.360 I think we talked about this a Make project where, um, 0:22:16.400 --> 0:22:20.000 you know, Make magazine from Riley Publishing, they had taken apart. 0:22:20.920 --> 0:22:22.359 They showed a video where they took a part a 0:22:22.400 --> 0:22:25.919 WE remote and basically uh installed it on a in 0:22:25.960 --> 0:22:28.600 a box, um, and put it on a roller coaster 0:22:28.600 --> 0:22:32.520 where they were measuring the acceleration using the basically the 0:22:32.520 --> 0:22:36.439 accelerometer already in the board. UM. So I mean this 0:22:36.520 --> 0:22:39.280 is talking about impedance things that they were already using 0:22:39.320 --> 0:22:42.200 a known device that they just hooked it up to. 0:22:42.560 --> 0:22:45.359 They hacked it apart and uh put it on a 0:22:45.359 --> 0:22:47.760 device where they could measure these things, and it was 0:22:47.920 --> 0:22:49.359 it's kind of cool to be able to do that. 0:22:49.400 --> 0:22:51.560 So I mean, if you're doing something where you're already 0:22:52.000 --> 0:22:56.080 working with like un if you're building it from scratch, 0:22:56.160 --> 0:22:58.920 then this is something you have to look into. Yeah, yeah, definitely, 0:22:59.000 --> 0:23:03.040 so so um something to to investigate more thoroughly. Um 0:23:03.119 --> 0:23:06.120 As we said, there are many, uh, pretty good sources 0:23:06.160 --> 0:23:09.520 of information out there. That Texas Instruments document is one, 0:23:09.560 --> 0:23:13.040 and and there are some others out there, so yeah, 0:23:13.080 --> 0:23:15.679 they Uh, I wanted to also mention that, you know, 0:23:15.800 --> 0:23:18.639 we we've talked a little bit about other We've talked 0:23:18.680 --> 0:23:21.960 extensively about other devices that use accelerometers in a way. 0:23:22.040 --> 0:23:25.200 You can even think of a seismometer as having an accelerometer. 0:23:25.320 --> 0:23:29.919 It's got a a mass that's that's that's kept in 0:23:30.080 --> 0:23:33.600 in separation with the rest of the device, and it 0:23:33.640 --> 0:23:38.560 actually measures the the movement and uh like the it's 0:23:38.600 --> 0:23:42.240 not technically the speed, it's the magnitude and the direction 0:23:42.320 --> 0:23:45.159