 So, let's start the next lecture on Integrated Philosophy of Mechanical and Electrical Nomen Thinking. This is like a mechatronics thinking. So far we have been discussing some part of it already, but let us kind of discuss it a little more in the, with more examples and some kind of a formal thinking, okay. So, we will begin this lecture with what is the idea basically. So, as we have been talking about, if you recall, we have said that like in this philosophy you think in one domain to kind of ease out the things in other domain. In other words, you need to think integrated in both the domains of a mechatronic system like mechanical domain and electronics domain. So, typically the plant of the system would exist in the mechanical domain and mechanical plant will have some complexities that are coming because of the natural phenomenon, okay. So, for example, there is a friction phenomena which is natural to have for any of the motion systems. Then, if you talk backlash phenomena that will be there for transmission systems, then like that some kind of a nonlinearities in the heat transport kind of a system, mass transport system, we have been so far looking at only like motion kind of a systems mechanical, but you may have like the systems which have other phenomena in the fluid domain. For example, you will have flow phenomena happening in the nonlinear kind of a domain. So, considering all these effects of different phenomena that are happening in the mechanical domain, how do we think that, okay, we have to kind of ease out, you know, control of these phenomena in such a way that like, you know, your electronics domain also has some, you know, easy kind of a way to control. So, you change something in the mechanical domain design to affect like, you know, something in the electronics domain, that is a central idea, okay. Likewise, you can have in the electronics domain, we do a control, okay. So, to ease out something in the electronics domain, we have seen like, you know, we can do some modifications in the mechanical domain, likewise, to ease out something in the mechanical domain, you do some kind of things in the electronics domain. For example, if you talk of this electronic fuel injection system, okay, so the previous systems, if you know of car engines, you know, we are working with formula racing team, they might appreciate this a little bit better. The injection of the fuel into the system or engine was based on some kind of a mechanical elements which are moving in some kind of a fashion, okay, and that was some kind of a complex cam based mechanism to kind of open the, you know, the fuel, whatever, fuel port to kind of inject the fuel into the system at some particular time in the cycle of the engine operation of a automobile. Now, this complexity of this all these mechanical chains of like driving the cam and like you know, affecting the fuel injection can be taken care of by using the electronics fuel injection system where like, you know, by the digital command of some electronic interface, the fuel will be injected in the system. Now this kind of a way of doing things will have a more flexibility of planning the fuel injection into the engine based on many different kind of aspects of the, you know, working of the engine and like to make the engine more efficient to work, okay, so this is one of the kind of ways in which you can do something in electronics domain to ease out like, you know, the complexity of mechanism that are to be used in the mechanical domain. Okay, so like that you will find like, you know, many kind of systems are getting developed nowadays, you know, with the electronics kind of commands more than like mechanical elements put together. So many machines can be operated instead of having like, you know, these complex mechanical drives, you can have electronic kind of drives. Now one other example, okay, you might have heard about these typewriters in the olden era where they used to make like, you know, they are very interesting like mechanism used to be there for typing keys, okay, so you press on the key on a keyboard and like, you know, the mechanism would kind of impact some letter on the paper, okay. So that kind of way of typing now can be eased out by as you can see like, you know, the nowadays what people are typing is based on all electronics kind of keys, okay. So these are some of the kind of, you know, examples of other direction, okay, which so far we have not looked at. And this has a value, okay, so this has a great value in developing efficient systems which will work, you know, very nicely in conjunction with each other and deliver like, you know, the whatever is demanded or desired application. Then this arm has been designed to optimize for the weight of it, if you see carefully, okay. So weight, now one can kind of get a little bit more detail into what are the forces really coming on the arm, okay, what are the forces that are coming on the arm and arm is actuated by actuator and imagine that, you know, you have this arm here, okay. So we will see that arm in a while, but like, you know, you can just see, I'll just recall here like, you know, there are these examples from the discussion on the CD-ROM drive and the scanner that we had already done in the class that in CD-ROM, you have a backlash-free motion or friction-free motion that is obtained by compliant mechanism in the mechanical domain so that you can ease out control in the electronics domain, okay. So that there are control challenges which are nonlinear control with friction, absolutely difficult to handle for like, you know, especially for this nano positioning and reversal of direction with the nano positioning system. In focusing servo or in the tracking servo also, you may need to reverse in direction depending upon where the data is there on the surface of CD. And in scanner, you can see that, you know, there are multiple reflectors were used to reduce the image size and reduce the cost of the photo detector sensor, otherwise you need such a large kind of a stripper photo detector sensor which is very expensive to produce in the first place, okay. So that can be reduced in the cost can be reduced by using this, you know, multiple photo detector reflectors. So these are the examples where you do something in the mechanical domain to ease out something in the electronics domain, okay. And many places you find like, you know, that use of electronics itself will ease out like, you know, a lot of designs parts in the mechanical domain for a lot of different examples. As we saw in the engine case or like, you know, say, for example, ATM machine, they're also like, we'll find ease out the tertiary of counting the nodes by a person, okay, there are some mechanisms and like, you know, some electronic systems that are used to count the nodes, okay. So those are, those are kind of, you know, examples, we can think of. And like, again, I'm coming back to the heart is striped, you have this arm, okay, for a heart is striped back shooter, and that is been designed to like, no optimize for weight. Okay. So let's get into a little bit more of the thinking of why what so what is the shape of this arm and why it's basically to kind of like reduce the weight wherever the stresses are having like, no higher values, they're only you need a material, okay, where the stress values are very low or there is no stress, those parts of material can be removed. And if you imagine, like, no, when this arm moves very fast on the surface of the disk, what kind of forces are going to come on the arm? Think about that. Okay. If you think carefully, like, no, this is a circular motion for the arm, and it is very fast motion. So one probably may not be able to like, no, ignore the centrifugal acceleration forces. Okay. So the forces coming on the, on the, like, no root of the arm because this is a mass which is getting thrown, I mean, or it has a tendency to throw out in the, by the acceleration of omega square r. So any mass up here will have like omega square into the r kind of a force coming up there. And that force is, is basically in the outward direction, which is getting acted, which is getting added up to the forces that are acting and the root here or at any section, if I kind of cut the arm, I'll see that, okay, the mass, which is beyond that cut will have a tendency to get thrown away because of the high speed, like say, speed is omega for the arm. Then, like, no, you, you can imagine that you'll have that force at, if you cut at different, different sections here, as you cut the, like, no, lower and lower sections here at the root towards the center of the rotation of the arm, the forces or amount of material that is there beyond that cut will, will make sure, will make it that the force coming on the, on this, like, no cross sections are more and more towards the root, okay. That is only, we are talking about the centri-fugal acceleration force. And then, because of this tangential acceleration of the mass, which is moving, you'll have some kind of a torque that is created here, okay. So, those kind of forces are, are going to come on the arm and one can think about and make sure that the arm is steady, you know, arm should not kind of give away to these forces and, first of all, fail in the, in the stress. But other more important aspect many times is this, this arm should not deflect more than what is required or more than some kind of a tolerance that can be allowed. So, because the arm deflection is what is going to cause a lot of errors in the, in the, in the system, okay. So, this deformation of arm should not happen so, so much. So, many times, like, no, we, we think that, okay, stress is what is, we have to design all the systems for. I mean, if you see, like, you know, your mechanical elements design course, many times we talk about stress more than anything else in the design of mechanical elements, okay. So, they should not fail, basically. But, but more than that, like, you know, many systems who would have this requirement that instead of failing, they should not deform more to disturb the operation, okay. That is more, like, no, more rigor or more, more, more stronger constraint that is put, which is more, like, no, which typically gives you a design, which has much lesser stress than, like, no, what is, like, what is, what will cause the system to fail, okay. So, keep in mind that, you know, when we design the mechanical systems, they are designed more for the stress, more for the deformation than for the stress, okay. So, we move forward and, like, no, see this arm open up and see more details about it. Now, this is, like, no, more, like, an observation here. So, you can observe that there is a coil up here and when the coil current is passed, the arm will get executed. Now, one can imagine that very easily that, okay, look, when the current is passed through this coil, okay, by the virtue of the placement of this coil or, like, you know, the way the coil is designed, you see that this arm has a current in this direction when the other arm has current in the opposite direction. So, if I, like, you know, look at this magnet, what should be the profile of the magnet in terms of its poles, okay, so that, see, these are already, like, you know, these are opposite directions for the current. So, if you imagine if this magnet has the top, entire top has a north pole, then the magnetic field is going to be in only one direction for both the sides and if that is the case, then the forces that are getting applied on these coils are going to be equal and opposite direction, okay, considering that the field has a uniformity and then, like, you know, your arm is not going to move at all, okay, so the fact that the arm is, like, you know, designed to move means that, like, you know, on this magnet, there are, there should be, like, you know, on one side, there should be north pole and on the other side, there should be the south pole and that is possible, okay, so another thing to observe is that, like, we will see this more in detail, like, you know, how one can observe the, see, by looking at the magnet shape here, okay, you can see only part of the shape, the rest part is below this arm, so if you see carefully the shape of the magnet, based on the shape, one cannot kind of make out at, okay, where its poles are, okay, so how do you observe the poles, okay, that is the next question, so we will see how to do that and other thing that there is a direct drive to this arm, okay, so this mechanical arm is not connected to some kind of a gear system here or sector of the gear here and like, it is driven by motor or pinion which is attached to motor, that kind of design is not there for the, at this drive, you know, we don't want to introduce any friction and any, I would say, any more friction, so there may be some friction at this joint, okay, this is a revolute joint but it will have a bearing and the bearing will cause only like, you know, some kind of a rolling friction rather than any, you know, sliding friction, so we avoid this sliding friction by not attaching gear and motor kind of a system and motor system also will be bulky here and then one can imagine, okay, why not attach motor itself here on this joint, like, you know, it will be, again, like, you know, the direct drive for the motor, you need a bulky motor, okay, typically if you see the motor specifications, the kind of torques that are needed versus speed, so here the torque needed for getting this arm to move fast on the surface of the disk is relatively high and because of that, you will need a high torque kind of a motor which is going to be bulky. Typically, motors are designed for small motors, you know, will be having higher speeds and lesser torque and that's where, like, many times motor will always be used in conjunction with some kind of a gear transmission system, so in the CD-ROM drive, we also saw the same thing, okay, it was happening there, okay, yeah, this is another kind of a thing that we talked about just now, so where are the proper poles on the magnet and why they are at those places, so the reason for the poles, so one south pole will be here and one north pole will be here because, like, you know, we want this coil to always see a feed which is opposite to the feed that this coil is missing, so that the total force on the coil which is produced by Lorentz force will be in one direction, will not be opposing each other, okay, all right, then, yeah, so next maybe when we discuss this more, like, no, I may have some, you know, gadget to show you how do you kind of see the poles of magnets, okay, we'll try on some kind of magnets, I don't know whether we'll have this hard disk drive magnet itself available, but if at all that is available, I'll show you that only, so now you can see here, like, no little more kind of a details, okay, so observe this carefully and, like, no, see, think what observations you can make and then, like, no, if you have any questions that you can ask about, okay, so think about some questions that you can ask, okay, and then, like, no, I'll propose these questions anyway, but you pause here for a while and think what kind of questions come to your mind when you see this kind of a design, okay, so what you observe here is, like, no, this very thin kind of a arm up here, up here, and up here, there are three levels in which, like, no, three layers in which you'll have this arm put, okay, and actually the reading is only in this part, okay, this is some kind of a read head here, the top side of the reader and the bottom side of the read head, okay, so actually if you see this carefully, like, no, this is some kind of a, you know, tweezers like thing which has to be opened up here and the disc will be inserted there and then, like, no, the head will be going on both the sides, there will be one head on the top side and one head on the bottom side, so why this is kind of a design is there, okay, and this arm, you see, there is no head here at all, okay, why that is so, so these kind of questions, you know, you need to see and, like, no, see answers to these kind of questions and then, like, no, this is a actuator, this actuator's head, okay, that arm's head here, okay, and this head is actually the reading, like, no, there is some kind of a magnetic sensors which are used to read the data on the surface of the disc, this is like a magnified form of it, so this one mm, you can see that small kind of a very small tiny kind of a mechanism is there and there is this kind of a fracture mechanism, like, no, a compliant mechanism which is pressing the disc on the surface, this, pressing the sensor, not the disc, the sensor on the surface of the disc, actually, if you see, then, like, no, the obvious question comes in the mind that, okay, since in this PSP, you see that, okay, this is kind of, once I remove the disc from within, like, no, they pinch each other on, like, no, they are in pre-stressed kind of a condition, that means, like, when I put it on the disc surface, this head is going to kind of, like, no, press on the surface of the disc and then that press, wouldn't it create any, any kind of a friction on the surface, why we want to kind of, like, press this on the surface of the disc? Can you think about that? It may create a pressure, a friction there, where we are creating this kind of additional friction. Isn't it counter-intuitive that, okay, we want to kind of, like, you know, have a magnetic reading happen with a, absolutely no contact so that we don't have friction disturbing the positioning of the head on the surface of the disc, okay? So, this arm will have this unnecessary friction that may be coming up. Think about this and then, like, no, it has something to do with the interesting way in which this system actually works. We move on now to the next kind of, you know, generalized, generalization of this concept of these different designs, such that they can be used now, these ideas or different kind of concepts that so far we have been looking at these existing mechatronics systems, how they can be a little bit generalized for any kind of motion control systems. So, typical, so far mechatronics in the engineer, like, you know, the motion control is a base thing to understand. I mean, we'll take this as a base example case of, you know, development of some of these ideas and concepts, but they can be extended and applied in the other domain of mechanical field. I mean, like, you know, say, thermal domain or manufacturing or many other domains of mechanical phenomena that might be happening for which, like, you know, you may have electronic control to be exercised. So, we talk of motion control because, like, you know, this is one of the wider kind of use in the mechatronics domain, okay. Many system mechatronics systems, you'll find that they'll have this motion, some motion kind of a thing getting controlled. So, let's say, if you are asked to get a design of a single kind of a linear axis motion, motion control system or mechatronics system that works at high speed and has a 100 nanometer kind of resolution, okay. So, now, we have a field for what is 100 nanometer. You remember, again, we have talked about, like, you know, this in, while discussing the CD-ROM, we have 1.6 micron kind of a spacing between the tracks of the CD. And we need, like, you know, roughly this kind of positioning accuracy, okay. So, suppose you are asked to design this, now, obviously, based on CD-ROM drive, you can say that, okay, look, for this kind of a thing, I may go for a compliant mechanism. But are there any other kind of, you know, ways of doing the same thing? So, say, if you are given that, okay, I want it all very short range. So, if you see, your CD-ROM typically maybe roughly like a short range kind of a mechanism when we talk of compliant mechanism, maybe 1 mm, 2 mm kind of a motion, not even 2 mm, it may be almost like a 1 mm motion that may be happening in the CD-ROM kind of a head case for the compliant mechanism, okay. So, only that much motion I want, like, no, I will go for a compliant mechanism. If I want much smaller kind of a range, okay, still I can go for a compliant mechanism. But there can be an option here of PISOS, okay. So, PISOS will have a very short range and they may get you, like, you know, the resolution better than 100 nanometer. Many times, like, you know, PISOS resolutions are much better than, like, no, they can be in the range of about 10 nanometer also possibility, okay. So, when you want very, very high resolution, but only over very short range about 50 micron, 100 micron range, then PISOS are preferred as a actuator mechanism. And now we are talking in general of, like, no, bigger size system. So, in some CD-ROM drive systems also people might have in the past ride out, I mean, I have never seen in PISOS used in CD-ROM drive. There is a reason for that, but, like, no, people might have tried that in the beginning to kind of, like, no, see the motion possibilities with PISOS to kind of give you that much accuracy. And one of the bigger disadvantage of PISOS is that, like, see, one good advantage is that they can be positioned better than 100 nanometer. And why that is happening if you see carefully, PISOS typically require very high voltage when they are to be actuated, okay. So, the voltages are easily in the range of 50, 100 volts kind of range. And that much voltage given, and it deforms very, very small even at that voltage, okay, based on their, like, you know, the different kind of coefficient like D33 and those kind of, you know, these are coefficients. So, if that small kind of deformation is there with very high voltage, one can see that if I apply millivolts, I'm going to get, like, you know, the deformation to be much, much lesser in, say, some few nanometers kind of accuracy. So, from that perspective, the PISOS can be given very robustly, like, you know, very small kind of emotions very easily. So, it's just a little bit of a common sense thinking one can do and say, okay, oh, look, the resolution of the voltage that I can apply is maybe a 1 volt, 2 volt kind of resolution I can apply or, like, you know, even millivolts is fair to kind of apply. You know, the noises are, like, you know, maybe in the same millivolts kind of a range, but I can go beyond 10, 20 millivolts, I will not find, like, you know, the noise will be bothering you so much. So, PISOS would be very good kind of actuators for very, very small kind of a resolution and of course, you need to pay more for the cost of the driving PISOS. Like, you know, you need to have a driver which is giving you this high voltages for the PISOS to drive and they should not have, you know, very large range demand, okay. So, if the actuator demands, like, okay, I want to move larger distances, then PISOS may not be a good choice. Nowadays also, like, you know, you'll find there are something called inch-form motors. So, let me see if I can give you some kind of a flavor of that in this inch-form motors. Maybe we'll give when we talk about actuators. Maybe we can talk a little more about. But basically, these are, like, you know, multiple PISO actuators together working in tandem in the sense that they'll push something, like, in the form of a wave. So, maybe the closest example I can give here is something like a centipede. Have you observed how centipede moves? That motion of the centipede with, like, you know, so many legs moving in tandem creates some kind of a small wave. As you see that centipede moving, you see some waves are going because of the leg motions. And those waves are actually, like, you know, if you imagine those are PISOS. So, the way that PISOS are, like, moved, like the motion takes place in that kind of a fashion. And then one can kind of enhance the range of PISO actuators. And there are actuators, people have designed like that, you know, by using this kind of inch-form motors. That's what they call it, based on the warm kind of a motion. The similar principle is used by me making of the similar principle is used. So, those are used for enhancing the range with PISOS. For moderate range, like, you know, one mm, you can go for compliant mechanism designs. Large range, you can have, you know, or rack and pinion or screw drive kind of designs. And extremely large range motion, you can go for the belt drive systems. Okay. So, like that, there are, like, no possibilities for different, different kind of motion control systems. And so, you know, one can say, okay, look, I go for, like, no, large range. If I go for large range belt drive or the system, some kind of a system, and do I, do we like it 100 nanometer resolution? Oh, no, no, that is not possible to get, right? So, you cannot just do this. Okay. So, large range, we have seen also possibility of large range in the, in the CD-ROM drive. Okay. So, CD surface, you have to move larger distances, 100 nanometer resolution, only, like, you know, the short range of up to 1000 micron or one mm was taken care of by the compliant mechanism. But rest of the motion was coming actually by the rack and pinion kind of a drive. So, you use some combination of, you know, rack and pinion belt drive or screw drive, along with compliant mechanism. Okay. So, there will be two actuators here in this kind of a case. If you want to go really 200 mm, like a large motion, and with the resolution of these 100 nanometers, then you need to have a double actuator system. So, two actuators are there, but only one sensor will be there. One sensor will be looking at very high precision locomotion that is happening, and then it will give a feedback to both of these systems in an interesting kind of a way, how to design control for that is, itself is an interesting, you know, control algorithm design problem or development problem. So, that problem will be solved in the mathematical domain to implement control algorithm, which can take care of moving the both actuators in some kind of a coordination with each other, such that you get this motion over the larger range also and larger resolution also. So, together that can be achieved. So, each of these things one can again kind of categorize as, okay, what is a plant here? What are the sensors and actuators for different, different cases and things and why they are used? This is another kind of a thought process one can get into and be able to kind of appreciate, okay, what people have like, you know, done in the design in this case. So, based on that kind of a thinking one can come up with this, you know, filling up this chart of the, you know, range versus resolution chart. And what are the actuator systems that you can see or what are the control systems or actuator sensor together, which can put in these bubbles here, okay. So, typically if you see like, you know, range, which is higher and resolution, which is lower, okay, this domain is little difficult to obtain by a single actuator, okay. So, here we need two actuator kind of a design, okay. But many other places like, you know, if you go linearly along this direction on this diagram, then you find that, okay, all these are like, you know, it can be done with a single actuator, single sensor kind of designs, okay. So, also like, you know, typically people may not be interested in this, this range is very low, which is coming almost like a resolution itself. That kind of a thing, I mean, may not have a requirement to wear, like, you know, the range is so low that it comes almost close to the resolution requirements, which is impossible for, so this is like, you know, unfeasible or empty area, you'll find no bubbles would be required up here. Mainly like, you know, the systems will be centered around this, most of the systems will be centered around this, and some special systems will require, like, you know, very high resolution and high range. Typically, combination of high resolution and high range will be very, very small number of applications, okay. So, in the nature also, if you see like something which is happening at a larger range, there'll be hardly like, you know, the resolution of those things will be low, okay. If you see the systems, you developed also like, you know, mechanical systems developed, for example, the crane system, okay, the transports material from one place to other place for the building construction or some other kind of application. There also, you see that the positioning resolution or like, you know, resolution of the placement of the object will be much lesser, much like, you know, coarser than for a smaller system like, say, some CDROM drive system or like, that is extremely small, but you can kind of like, you know, see through that, wherever there is a high resolution requirement, like, you know, typically the ranges are going to be small, and wherever there is a larger ranges, like, you know, the resolution also will be a little coarse there. The requirement also will be a little coarse. So, we will typically, we'll move along like, you know, there's some kind of a one axis up here, central axis here, okay. And there are some special systems only, they'll be having this kind of a requirement of both together. And this is an interesting area, I mean, like, nowadays with the advances in the nanotechnology and micro technology, this area is getting now more and more kind of explored for interesting research applications there. Okay, so we move on to the next slide. So you pause here and like, you know, think how we can fill in each bubble and like, you know, you have your own kind of a, you know, filling done here on the paper. Okay, this will be this kind of a thought process will be like, you know, very interesting to open up some of the concepts in your mind. Okay, even if you go to wrong, don't worry about it. Okay, like, you know, let it be whatever you think, whatever comes to your mind that can raise, like, you know, raise some kind of a questions later and when they are kind of clarified, you'll have some, some form conceptual understanding that will be happening here. Okay.