 Good day everyone. This is Ruchad Mistry from the Mechanical Engineering Department, and we'll be continuing the lecture series on robot configurations. This is the third video on this particular series, and today I'll be discussing jointed arm configuration. The learning outcomes of this particular session are at the end of this session, the student will be able to explain jointed arm configurations in industrial robots and identify applications of these configurations based on their features. So last week we saw some other configurations, which are quite outdated, and the jointed arm configuration that we're going to study today is by far the most widely used configuration by almost all industrial robot manufacturers today. I can say that it accounts for nearly more than 90 percent of the configuration that is made today. So if you look at the figure here, this typically shows the jointed arm configuration. It is also called as the articulated configuration by some textbooks and authors, but prefer calling it jointed arm because these typically refer joints of an arm, so that's how the name is. These robots like we discussed in the previous session are defined by the first three axis, and these are all rotary, and it is also called as an RRR configuration, R being rotary, rotary, rotary configuration. This configuration exhibits the highest dexterity amongst all configurations, which you will see in a minute, and it's obvious from the work envelope that this particular configuration has. The rotary joints connect the links to the arms, and the actual industrial robots, if you add the three axis of the wrists are typically six axis industrial robots. Now, if you take a look at this figure, like we were discussing, this is by far the most widely used robotic configuration, and one of the reason it is widely uses, it has one of the largest work envelopes for a given size, and it's quite a very, this envelope is not just big, but it can reach difficult places, which is obvious if you look at it, it can almost reach the floor of its mounting. So it has a very wide reach, very flexible reach, and hence it's the most dexterous configuration that you can find. Nearly more than 90 percent of the robots sold are joint arm configurations. The issue with this obviously in the past, remember, was the robot solution was quite complex. So when it was introduced in the 70s, the software actually came at a premium. Nowadays, this is no longer an issue. Most software and hardware is advanced to such a level that this is by default, the de facto standard which is available in the industry, and hence it accounts for more than 90 percent of all robot shows. This is very typical work envelope of the joint arm configuration. I have recommended that for this particular subject that you refer to the actual manuals by different robot manufacturers because they give more extensive data than any textbook that is available on this particular subject. So I've included a snapshot of a manual from Motoman, which is also one of the top robot manufacturers. So this will give you what is a realistic sense the operating area of this robot along with certain specs. This will give you in a nutshell how this particular configuration is used when it will be deployed in a work cell. So this is typically the work area. Another view actually is also available. Now if you look at the specs, you have the axis against the maximum motion range, you have maximum speed, and the allowable moments. So it tells you what the amount of load each axis can actually bear, and you get an idea what kind of work you can deploy this particular robot for. For example, in this particular case, this robot has six control axes. Let's say three being the first three axes. Well, three obviously are the wrist. Maximum payload is 400 kg. So this is a very heavy payload category robot. Repetibility is spectacular plus or minus 0.5 mm, which is extremely good for the robot of this particular size and payload. Then obviously have the vertical and horizontal reaches, its protection ratings, weight, et cetera. This robot weighs more than two tons total, and it is driven by a three-phase power supply. This indicates that the drive for this particular motor is an AC electric drive, which is also the most common drive that you'll find for most electric robots. Very high speeds are also there in terms of rotation of the joints, though less as compared to a lower payload, which is a bit obvious. Another example, obviously, is a spectator for a robot of a smaller configuration. I recommend that the students look this particular, specifically enough in great detail at a later stage. This is just to give you an idea how the work envelope of jointed-on robots are. This robot, if you notice, is actually a low payload category robot around 10 kgs. So it will be used for smaller pick-and-place tasks and assembly operations. One thing if you notice from the previous robot is joint speeds are definitely higher. Obviously, the lower masses means both greater speeds are possible for a given accuracy. And if you notice the repeatability in this case is plus or minus 0.01 mm. So this is also one of the best robots that you can come after. Even this particular drive is in a single-phase AC and even this robot actually is driven by AC servo motors, which is also the, like I said, the trend. Nowadays, robots are actually driven through AC motors and not DC motors as discussed by most books. The books tend to be quite outdated when it comes to information regarding robot drives. That's also the reason I urge students actually to look at the brochures of actual robot manufacturers so they get real data and most updated data. Some robot manufacturers will identify and advertise all their product lineup in terms of either the payload or the reach. And what KUKA has done over here is they have given a nice table regarding their different configurations which are available. For example, they have a 300 kg robot which is available with a range of approximately 2.7 meters. And they have 120 kg robot available with 2.7 meters. Then one of the largest robots, the robots with a maximum reaches around 3.9 meters. So just under four meters of reach. So one more thing is it is better to have a detailed study of different configurations by different manufacturers. So you get an idea. What is the typical range of these particular robots that the manufacturers are packaging and selling? So in my observation, most top manufacturers have robots from payloads as low as 2 kg to has a higher something in the order of 400 kg. There may be custom built robots which have payloads in excess of 800 kgs as well. Okay. So let's look at some of the images of jointed arm configurations. I have taken these two from Vicky. At the left, you will see a jointed arm configuration typically for palletizing, which is a very common application that you can find. And the one at the right involves most likely some sort of a cutting or welding operation. Another sample images. Now you can see this is a modern version of the Yasaka or Motomon robot. And this is a slightly older version. And from the shape you can realize this typically is a longer reach and higher payload. Robot configuration. This one is actually from Fanook. Again, you'll find them quite similar, but there are some distinctive features. And these are advertised features which you can find on the manufacturer's website. But there's also one more reason I included these pictures. And I'll tell you why that was the case. Now, did you notice any, you can say typical colors that you come across and is there a pattern? I believe that so. Some manufacturers tend to prefer one particular color when they tend to make their robots. See if you can find out and then we'll discuss which manufacturer tends to prefer a certain color. So it's almost become a benchmark, though that's not always the case. Now continuing again, typical advantage of jointed arm configuration. So it has the maximum reach within, reach position within the envelope. So within a given envelope, there are a lot of singularities, but jointed arm configuration has, you can say the advantage that it can reach most spaces within the envelope. And these are available today with very high repeatability, capable of fast operation. One more thing is access from all sides. So it allows you to, you can say design the work space in a more, a lot less rigid way compared to the other configurations. As I said before, this is one of the most widely used configuration and it has effectively replaced all other configurations by the year 2000. So this is the one which is being made right now. One more thing is from an academic perspective, control is more expensive and difficult than other configurations. That's why we tend to associate that control is a kind of a limitation, though like I said before, with the advent of better hardware and software, this is no longer the case. It's advantages far outweigh its disadvantages. Since all joints are rotary, construction cannot be rugged enough compared to let's say a cylindrical answer or a cartesian configuration. Even other, having said so, let me tell you that even today, these configurations are available with 1000 kg payload. So in spite of this limitation, you can see how versatile this configuration is and that is the reason you will find this configuration all the way from a 2 kg payload to nearly 1000 kg payload. What applications are, except for high speed assembly applications, let's say for example, electronics industry where SCARA robots are preferred and are advantages outright and certain applications where you need approach from top where delta configuration is more appropriate. You'll see them pretty much for each and every application in industry. So there's no point pointing out only one or two applications. This is by far most widely used application in industry altogether. So right from welding to assembly line to sealing to plasma spring, you'll find this particular configuration. Now what is new about this? The jointed arm configuration is now exclusive with almost all industrial applications. So that's the case. And these have now evolved into what is called as collaborative robot configuration. So you basically have a trunk like construction with two robot arms on each side. So this is a new development which we'll see in a later chapter. And this is how you can say the development of the jointed arm configuration is today. You can look up the sample videos on YouTube. They are quite informative and you'll get a general idea of what the jointed arm configuration is. References, there are plenty of references, like I said. The best references are the websites of the manufacturers themselves. Those are the best when it comes to it. But for general data, I recommend International Federation of Robotics. Robot Park, which is also very informative and some of the other websites along with the standard textbooks which are for this particular case. Thank you and we'll continue the discussion with robotics in the next series.