 So, now we will continue our discussion on these elements of mechatronic systems. Last time we had seen some sensor elements, right. Remember this like you can have a look at this, ok. So, let us flash through these slides and like go through, ok. So, last time we had seen these different elements of mechatronic systems and then like focused on our sensors and seen some of the classifications of the sensors based on the analog and digital output and based on the principle of operation of the sensors, ok. So, in today's class we will continue little bit of a discussion pending which is on the MEMS sensors. So, which are which are kind of these days more popular for many applications because of their cost advantages. So, the MEMS refers to microelectromechanical systems where they are fabricated by IC technology, ok. You might have seen like know this foundry is where I know these people wear this kind of a test free clothes and then like know enter the foundry and then fabricated chips. So, in that chips usually like computer chips will have only electronic components. Now, if you can imagine if your computer chip will have some kind of a mechanical kind of components then like know it refers to this MEMS technology of bulk fabrication of many many sensors at a time on the surface of a wafer, ok. So, because like know you can fabricate maybe thousands of sensors in one kind of a process its manufacturing is very easy, manufacturing cost is very low, ok. Manufacturing may not be so easy because it undergoes like you know BLSI processes which are kind of based on the equipments which are costly equipments. So, so the advantages here are like you can have integrated fabrication of sensors with both mechanical and electronic components on the same sensor then low cost of fabrication. Let me see if I can get a pointer properly laser pointer you can see low cost due to mass fabrication and the techniques and processes can be designed to create really really small systems, ok. So, this is very interesting kind of area of application or area of research also there are many interesting systems that can be developed based on this MEMS technology, ok. And one should be aware about this, ok. Some of the maybe we can reserve some separate lecture on this actually at some point in the future classes. So, where like know we can demonstrate some interesting sensors and like actuators also in the MEMS based technologies, ok. For now like know we will kind of like go forward with other kind of topics that we would like to see here, ok. So, this sensor selection again will come to this topic later on also, but we need to have some kind of a common sense understanding for sensor selections. For example, if you want to kind of get a sensor selected for a given mechatonic system see this is like a evolving design processes iterative and evolving, ok. So, you cannot immediately come up with the specifications of the sensor, but we will have some kind of idea then like know you change the like know start developing first kind of a design then with the analysis you find ok we need to fine tune some specifications like that this like a design is like evolving process for mechatonic systems. So, we have to go through this kind of a evolving process we may not have all the details at a one go, but as we start thinking about applications like know we will get to know more and more details and then we can incorporate them into the requirements and like know development selection of the sensors and things like that. So, from the systems requirement perspective you need to kind of get to the sensor requirements, ok. So, that process is maybe somewhat like know based on prior experience or maybe based on some mathematical analysis there are many different ways we can do that, ok. And again iterative way it will go, ok. So, we will go through this kind of a process sometime later, but these are some kind of a issues that one needs to be looking at for selection of sensors, ok. Then second one is a noise consideration, so if you are doing the analog sensing versus digital sensing you need to worry about a noise in that way. So, you may need to filter or you need to take care of the noise in analog domain or in the digital domain, ok. So, for example, if the wire or the sensor is already giving some kind of a noise before even getting into digital domain you may pass a sensor output through some analog filter, ok. Some simple RC kind of a circuit will take care of that. Then you of course, you will have a cost implications with this, then mathematical modeling is going to be important for simulations to kind of come up with precise specifications for your sensor. And then you typically go through manufacturer catalog and match the requirements whatever you have generated the sensor requirements, you need to be matching with manufacturers catalog and getting like selecting a proper sensor, ok. So, that is the kind of a process that goes on for the sensor selection, ok. So, we will do this process sometime later, but like you should be aware about these parts here. Then we have a next element which is actuator in the system. Now, for actuator we have lots of different kind of choices. So, from the mechatonic's perspective now I am not kind of really talking about only like many kinds of different kinds of actuators that are found in the literature, ok. We can have actuators which are like I would say servo controllable, ok that is what is important here. So, there are many many actuators that can be servo controllable possibility, but these are like some of the most popular kind of actuators. So, solenoids is one of the important class, they are used in mainly like push like they are not servo usually, so solenoids are not a servo actuators, but they are like now digital on or off kind of actuator, ok. So, they are used in many kind of you know mechatonic systems especially the process industries and things like that where you want to suddenly open a valve or close a valves which is which is not it is like a digital opening and closing or you need to remove the articles or parts from the conveyor belt which are not really suiting the you need to reject the parts from the conveyor belt, ok that kind of a actuation one can do by solenoid. So, many many different places they have applications, ok. Then AC or DC motors these are like a very important class because they are most popular actuators in mechatonic systems then you can have a stepper motors also a big class and then for the systems which are very heavy you will have or which have very high power requirements you will have hydraulic actuators and nowadays like you know very precise applications piezoelectric motors for example, autofocus cameras or DSLR cameras will have these piezoelectric motors for moving for the motion of the lens. So, you can see that very interesting sound that comes when you when the lens is focusing in your SLR camera, ok that is because of these piezoelectric motors then you may have pneumatic actuators also possibility, ok. So, we will go briefly through each of them and like not so many details, but as we go along we will get into more and more details. So, this is a motor which is DC motor along with the encoder here. So, this is what we will probably use for our programming or like you know learning the practical parts of the system, ok. So, with the Tiva board we will use this kind of a motor with the encoder attached to it for like understanding some of the fundamentals of control that this course has to offer. Now, coming to the DC motors like you know so this is you know the principle there are two primary classes which is brush type and brushless type. So, brushless types are where you use it for the applications where you need a high speed and then wide variety of these motors are available in the market, ok. The very high precision manufacturing or very high quality motors will find from the companies like Maxon or Valheber, ok. Those kind of companies will produce these motors which are very very good quality motors, but otherwise also like you know there are many many companies in the market where like you know these motors can be available and speed torque range, size, voltage ranges you will have like a lot of variety you will find with the DC motors, ok. Then stripper motors are another kind of a popular actuators for mechanical microtronic systems. They are used in the places where you do not need a sensor, ok. So, you can rely on the steps saying making sure that you know the steps are not missed in the in the drive based on the capacity. So, you choose a motor of a capacity that ok the steps would not be missed and you are kind of you know simply give so many number of steps and the application will be running smoothly. If there are like you know external loads which will prevent the steps to be slipped then like you know these actuators are not really really good, ok. So, you need to make sure that you know the torque that is required for the application is not not higher than like you know what your choice of the motor. So, motor should be given delivering like no higher torque than what application needs then they should be fine. And it the stripper motors also have this kind of a holding torque which eliminates the need for brakes if at all some application requires that again there are several constructions and configurations possible. So, we will get into some of some more details, but like we will give some kind of idea about how they work for example here. So, this operation principle is is very simple here you you excite one coil and then like now you excite the next coil the the rotor will move to the next position, ok. And then you will have a sequence of excitation of different different coils there are typically four coils in the stripper motor 1 a 1 bit way to be there are a standard kind of a terminology that is used there and these operate in a in a very different many different logics that can be possible. So, for example, in this case like maybe I will show you the the animation of the logic, ok. So, you you have only one single kind of excitation happening at a time now, ok. So, this is one kind of a mode of operation, ok. It is called full step kind of operation. Then if you see if you want like only like half of this step to be happening. So, what we can do can you think about, ok. For example, one of the ways to kind of get to like you know this microstepping modes, ok. There are different this microstepping modes can be possible. One of the ways to get to that is like you know you control the voltage itself on on each of the coils, ok. So, I will tell you how we can control the voltage and do that when we see this like half step mode you may understand things better, ok. So, half step mode you will see this is the kind of thing that will happen when this is going to happen, can you see that. So, you excite one coil and like you know other coil next to it both together, ok. So, we will make the position of the rotor into some kind of a middle position here, ok. Now, if I want to change this middle position to either side of this coil or side of that coil I can excite these two windings differentially, are you with me. So, we you should think about, ok. How can we have like you know some multiple steps possibility between the two half steps, ok. So, this is one half step up here and other half step, ok or within one full step, ok. How can I have more steps than half step possibility, ok. So, think about that it is very interesting way you can see that you know we can operate stepper motors to kind of give you really, really high resolution, although the steps are designed or like you know the motor is designed to kind of give only this single step or half step or something. We can possibly by changing the control or by changing the amount of energization of one coil versus other coil, one can kind of have like many, many different possibilities, ok. So, we will look at those possibilities again in the future when we deal with like more details about actuators, ok. There are these different applications of stepper motor, dot matrix printers nowadays these are extinct now, you might not have even heard of this name of dot matrix printers, ok. Floppy drives also are kind of extinct, it used to be in the past you have like a magnetic disk and you can drive things by, I mean store the data on the disk which is now it is all replaced by your pen drives, then lot of robots may have many, many different applications, ok. So, we will see some of them CD-ROM drives may there are some interesting way stepper motors have been used, ok. Now, we look at little bit of hydraulic actuators. So, in hydraulics you can have two possibilities, one is like a linear actuators or you can have hydraulic motors also possible, ok. So, we will see like how hydraulic motors can be made to work actually, so we will see that. Hydraulic motors actuators would be useful in the places where you need very high force and you need very high torque in very small kind of a compact environment, ok. However, they are like as you as a name suggest like no you need some kind of fluid that can be giving this pressurized fluid which can be giving this actuation. So, you need this entire system of like you know oil tank and like oil pressurization and things like that, ok. So, that entire system needs to be there together then you will have like very high forces and tors in a small place that can be possibility. Because of the high tors naturally like they will be very fast they will having relatively low inertia and very fast response, ok. There are many different hydraulic motors possible with the principles like you know the Bain motors is one of the ways that you can have hydraulic motors created or you have axial piston motor or slush plate motor, ok. So, you like you know just google about this and you will see how these motors these hydraulics are working. The applications will be to you say mainly in the conveyor belts or earth moving machinery here like big machinery where you want to kind of dig out some things and those very high forces are needed there that is where you use these hydraulic actuators, ok. So, this is one of the you know open up picture of hydraulic actual piston motor. So, you can see that pistons are up here and they are like operating this swash plate here. This swash plate is like a rotary plate with the pistons which are coming at an angle. So, you can imagine when this piston is pushed here the torque which will be created will push the shaft it will rotate the shaft in this direction, ok. And once that piston is in its end position then like you know the hydraulic force will be removed here and then the next piston will be operated, ok. And then the next piston in this position will be again pushing this to the end position and again this operation continues with multiple pistons that are there and the way this motor is rotated, ok. So, very high force can be applied here with the high pressure of the oil that is there in the piston, ok. And then that can be controlled in by using some hydraulic servo valves, ok. So, that is another kind of element that will be needed in the system to that is our electromechanical interface to these actuators, ok. Alright, some applications here, ok. The last element, ok, is controller, ok. So, we will talk briefly about controller again. I am just giving you some more brief overview of things where we have to talk a lot more details as we go along in the course, ok. So, but this is some kind of a like you know brief idea you should have in your mind to kind of slowly start understanding like more and more details about, ok. So, argument there is a questions based on this to think about and then like we will take up these questions as we as we go along that will be a good way to kind of understand things better. So, controller is also very important element of the electronic system. So, why is controller design, ok, can lead to substantial savings in the cost, ok. So, I will see some examples and understand this part. This is very, very important point that we need to be aware about that, you know the way you design control, ok, would have a lot of cost implications, ok. See controllers for example, used in hydraulic, used in hard disk drives, ok, they have been designed to kind of perform really, really well in a with a so, which will not demand a lot of investment into the sophisticated nature of the arm that is there for the hard disk drive to. See this arm positioning on the surface of hard disk drive is extremely high precision kind of application is required there. But the way the controllers and in general mechanical system is developed like you can have that at a very low cost that can be possible. And maybe we will have some chance of looking at a hard disk drive little more in detail as we go along. Then there are different kinds of algorithms that can be possible, ok. So, some of the algorithms are listed here, but they are not a complete list. You have, you will have lot of lot of possibilities in this domain, ok, tons of papers, tons of literature is published on the control algorithms for many different applications. Then you can have a types of algorithm based on the implementation class, ok. So, you can have analog domain implementation or digital domain implementation like that you can have controller developed in different domains, mostly like know when we talk about mechanical system will chiefly consider this digital domain implementation by using microcontroller or microprocessor. And analog domain also is possibility, but we will see like know whenever like we have some simple kind of controllers implemented then like know analog domain can be ok, some kind of a PDPID kind of controllers we can implement by using these opams basically opam circuitry. But then we cannot change the gains on the fly, there are some disadvantages to the system, but as long as we know that ok this is what we want finally and this fix is not going to change ever then like know analog domains controllers are not a problem. But digital domain nowadays like know are available at very low cost of people I don't think are going to the analog domain kind of circuits these days. Very advantage analog domain will give is is like know the continuous domain implementation or application, which is not possible in digital domain we need to have some kind of a sampling done for getting the digital domain implementation in place, ok. So, there are some design analysis issues for controllers which we have to again deal with anyway in the in the in the great details later, ok. So, I think maybe we will stop here.