Control System Modelling Case Studies

Purpose

The case study is a Research Paper and is to be used as a tool to assist you in developing new skills in research, analysis and technical communication. The case study report is intended to encourage the development of your ability to critically review a chosen topic relevant to the unit of Control Systems and your ability to prepare a formal research report on an assigned topic. These skills will be very valuable for your professional development and will greatly assist you in taking on the responsibilities of a professional engineer.

You are provided with an opportunity to practice and develop your skills in critical thinking, develop a better understanding of the subject content in the unit being studied, and to develop ways of improving your study methods. You are expected to write a technical report which expresses these ideas in a formal way. As a result you will also be able to develop and practice your technical writing skills.

Describe with diagrams an example process control system of your choice from the suggestions below.

Suggestions: oil refining, paper manufacturing, chemicals, power plants, or, automation in food processing. 

Automation In Bottle filling Process Control

Process control system is an aspect in engineering designing order that deals with structures, architectures, systems and calculations for keeping up the yield of a particular procedure inside a coveted range (Wightman, 2013). The functions involved with it are predictable, consistent and stable for operating up to the targeted level of the desired performance. This system involves lots of different system, circuits, logic controllers and others. The present report covers an important system known as Programmable logic Controller (PLC) with the help of automated bottle filling process.

The report throws light upon the working and role of PLC in the above mentioned process. The automation of the process with PLC eradicates any chances of negligence and increases the efficiency and accuracy of the mechanism with least human interference.

The report has been detailed in parts to give a clear picture and understanding of the mechanism. The several parts comprises of the details of the process, description of PLC along with its block diagram and the transfer function block diagram.

The Automation process in the filling of the bottle deals with PLC control process. Automation assumes an inexorably essential part in the world wealth. One of the vital utilizations of automation and process control is in the soda pop and other drink enterprises, where a specific fluid must be filled ceaselessly (Baldea & Harjunkoski, 2014). For these sorts of utilizations, the pattern is moving far from the individual gadget or machine toward ceaseless automation arrangements. Completely Integrated automation develops this progression into reliable practice. Completely Integrated Automation encloses the entire generation line, from receipt of merchandise, the creation process, filling and bundling, to shipment of merchandise. The filling procedures takes place in accordance with desires input volume required to be filled. A deduction mechanism is used for filling and capping of the bottles with help of sensors. All the various process discussed are controlled and maintained by the PLC and SCADA (Supervisory Control and Data Acquisition) (Chawathe, 2016). This not only monitors the filling of the bottle rather it controls every operation from controlling of movement of the bottles on the conveyer belt to the capping system and the filling of the fluid through solenoid valve.

Bottles are positioned in a container on a conveyer belt; they are detected to identify their accurate presence. IR sensors are utilized for detecting the bottles. Contingent upon the yield of the sensor, all the relating pumps gets switched on and operation of filling the bottles starts. On the off chance that the specific container is absent at that point the pump in that particular position is turned off, in this way keeping away from wastage of the fluid (Hasan & Moinuddin, 2013). The filling operation is detailed with a client characterized volume choice menu which empowers the client to pick the volume of fluid to be filled. The filling procedure is done in light of timing. Contingent upon the preset estimation of the clock the pump is exchanged on for that specific timeframe and the filling is finished.

Input module

 The input module incorporates the IR sensors. Two sets of IR sensors are used whose yield is passed on to the PLC. The 1^st IR combine sensors are kept close to the input side, the place where the containers are pushed onto the conveyer, are known as detection sensors and the next one is utilized for ceasing the movement of filling and topping operation section known as the stop sensor (Chakraborty, 2015). In this manner, these are the data sources which are to be provided to the input section.

 The sensor’s yield cannot be offered specifically to the PLC since the info voltage going into the PLC ought to be 24V. Subsequently, they are provided through flag molding a circuit which regulates the info signals and thusly give it as a contribution to the PLC (Ramirez, Rincon & Parada, 2014). These inputs are provided through relay circuits having three terminals which are NO, common and NC. The common terminal makes the 24V available into the PLC as an input. Thus depending upon the vital signals the opening or closing of the circuit takes place.

PLC can be stated as a typical solid state device. Its function is to control the logic, timing, counting capabilities, sequencing and arithmetic data manipulation. It can be seen as a mechanical PC that comprises of a central processor unit, I/O interface, memory unit and also programming device (Wang, 2013). The insight of the controller is provided through the central processing unit. It acknowledges information; status data from different detecting gadgets like proximity switches, limit switches executes the stored control program fed by the user in the memory thus gives suitable output orders to the devices like switches, solenoid valves, and so on. The hardware unit of a PLC consists of components such as memory; I/O, Processor unit (CPU), Programming device, power supply unit and other devices. The architecture of the PLC can be shown below with the three basic sections: CPU, Memory Control Unit (EPROM, RAM), Input/Output section for communicating with Peripherals (DAC, ADC):

Fig 1: Architecture of Programmable Logic Controller

Source: Created by Author

All the control operations required such as filling and the capping are done utilizing the PLC. The whole packaging procedure is automated by encouraging the important terms into the PLC utilizing ladder logic. The Ladder logic is an important strategy for programming of a PLC (Ramanathan, 2014). Subsequently, contingent upon the logic built up the different operations occur and both the filling of bottle and capping of containers are finished.

The PLC’s input/output unit goes about as an interface for the real-time world. Contributions from genuine input are provided to the working input unit which can be controlled in light of the programming fed, and the outcomes are offered back to the machines from the PLC’s output unit. All control operations and logics, information exchange and information control operations are finished with the help of Central Processing Unit. The statuses and results are placed in the PLC’s memory (Sánchez-Pacheco, 2014). PLC's are utilized for an extensive variety of uses particularly in the enormous field of automation and control. They are all around adjusted to a scope of computerization errands.

Signal conditioning

The working voltage of the yield devices is lower when contrasted with that of a PLC. The PLC yield is 24V while output devices, for example, equip engines and pump requiring 12V for their operations. Henceforth, the Output waves from the PLC mostly are supported with help of Relay-drive unit that drives the yield devices by providing the ideal voltage necessary for their operation (Lai, 2015). The requirement for the 12V operation is accessible at the relay unit of its basic terminal. The operated solenoid valve starts working when gets signal from the PLC for filling the bottle. The input side detection sensors decide the continuation of the process.

The different Output devices utilized as a part of the packaging procedure are rigging engines, pumps, LED's and actuators. These are associated with the output module. The gear motor and the apparatus engine are utilized to make the conveyer run in the forward direction. There are absolutely five pumps utilized for the filling procedure (Obermeier, Braun & Vogel-Heuser, 2015). Three pumps are associated with the procedure tanks while the two other pumps are associated with the tank 1 and water tank 2 separately. Actuators are utilized for capping the containers. The actuator applies a compelling force on the tops which firmly closes the bottle.

Bottle detection with sensors

Containers are positioned in the separate holders which are settled on the conveyer towards the input side. IR sensors are utilized to identify the nearness of the containers in the holder. Contingent upon the sensor’s output the operation of filling and capping happens. To set the status of the containers or the bottles a time delay is set keeping in mind the end goal. Bottle 1 is available making the relating status bit in PLC set to 1 else it is changed to 0 (Sheoran & Tailor, 2014). The results of these sensors from here are passed onwards to the PLC along with relying upon this yield the filling and topping procedure for the containers happens (Rao & Dey, 2016). In this manner, if each of n containers is available on the side of the input then the sensor suggests the comparing yield to the PLC. Thus switches ON the relating pumps for the filling operation to happen. In the event that a specific bottle is absent the comparing pumps stay OFF.

Once bottles detection is seen on the input side the motor connected switches ON. Next, the conveyer moves forward with the bottle.  The bottle then reaches the wanted position for the filling of the bottle and then the conveyor stops (Baldea, & Harjunkoski, 2014). The filling of the bottles occurs with the desired preset value provided into the selection menu. This input is fed into the PLC then the filling takes place accordingly.

  The bottles after getting filled moves with the help of the conveyer towards the capping arrangements. IR sensors help in placing the bottles accurately at the right place. The moment the bottle reaches the correct position the motor stops and the conveyer stops moving. After this the actuator arrangement works for the capping process (Dixit, 2015). The force applied by the actuator arrangement firmly closes the cap and the motor starts with the movement of the conveyer.

Programmable Logic Controller

The block diagram of the process can be drawn out such:

     

Fig 2: Block diagram of the Automated Bottle Filling Process

Source: Created by Author

Block Diagram and Transfer Function combined together can be a very powerful method to present a Process control. Here the Symbols denote:

R(S) = reference output

U(S) = Input (actuating signal)

Y(S) = Output

G(S) = Forward path transfer function

H(s) = Feedback transfer function

F(S) = Feedback signal

E(S) = Error Signal

Block diagram for the transfer function can be shown below:

 

Fig 3: Block diagram of the Transfer Function

Source: Created by Author

Conclusion

  The main aim of understanding the Process control through any automation process has been very much fulfilled. The PLC plays an important role in this process. It controls the overall processes going on in the filling of the bottle. The predefined volume specification can be counted as an additional feature. The PLC collects the input from all over the input devices and then passes it onto the output devices. The SCADA works on for the monitoring of the whole event at different stages. The user-defined filling necessities can be more accurately programmed in accordance to shape, bottle weight, and size. It can further be improvised by using predefined piston arrangement.

References

Baldea, M., & Harjunkoski, I. (2014). Integrated production scheduling and process control: A systematic review. Computers & Chemical Engineering, 71, 377-390.

Chakraborty, K., Roy, I., De, P., & Das, S. (2015). Controlling the Filling and Capping Operation of a Bottling Plant using PLC and SCADA. Indonesian Journal of Electrical Engineering and Informatics (IJEEI), 3(1), 39-44.

Chawathe, A., Dabhade, V., Kamath, V., & Patil, G. (2016). AUTOMATED BOTTLE FILLING SYSTEM.

Dixit, A., Mendiratta, R., Choudhary, T., & Kumari, N. (2015). ‘Review Paper on PLC & Its Application In Automation Plants.

Hasan, M. M., & Moinuddin, S. M. (2013). PLC Controlled Automatic Bottle Filling System (Doctoral dissertation, East West University).

Lai, W. Y., Onn, N., Tang, C. H. H., & Hussein, M. (2015). Position Control of Hydraulic Actuators Using Fuzzy Pulse Width Modulation (PWM). In Applied Mechanics and Materials (Vol. 735, pp. 294-298). Trans Tech Publications.

Obermeier, M., Braun, S., & Vogel-Heuser, B. (2015). A Model-Driven Approach on Object-Oriented PLC Programming for Manufacturing Systems with Regard to Usability. IEEE Transactions on Industrial Informatics, 11(3), 790-800.

Ramanathan, R. (2014, August). The IEC 61131-3 programming languages features for industrial control systems. In World Automation Congress (WAC), 2014 (pp. 598-603). IEEE.

Ramirez, M. M. G., Rincon, J. C. V., & Parada, J. F. L. (2014, February). Liquid level control of Coca-Cola bottles using an automated system. In Electronics, Communications and Computers (CONIELECOMP), 2014 International Conference on (pp. 148-154). IEEE.

Rao, P., & Dey, A. K. (2016, April). Hybridization and real-time optimization based automated intelligent liquid dispensing system. In Energy Efficient Technologies for Sustainability (ICEETS), 2016 International Conference on (pp. 734-738). IEEE.

Sánchez-Pacheco, F. J., Sotorrío-Ruiz, P. J., Heredia-Larrubia, J. R., Pérez-Hidalgo, F., & de Cardona, M. S. (2014). PLC-based PV plants smart monitoring system: field measurements and uncertainty estimation. IEEE Transactions on Instrumentation and Measurement, 63(9), 2215-2222. Trivedi, M., Sheoran, V., & Tailor, D. (2014). An analysis and control of a closed loop conveyor system using PLC and sensors. Int. J. Innov. Emerg. Res. Eng., 1(1), 1-6.

Wang, R., Guan, Y., Liming, L., Li, X., & Zhang, J. (2013). Component-based formal modeling of PLC systems. Journal of Applied Mathematics, 2013.

Wightman, E. J. (2013). Instrumentation in process control. Butterworth-Heinemann.