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Module code and Title
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IOT201TC Control Technology of IoT
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School Title
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School of Internet of Things
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Assignment Title
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Assignment
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Submission Deadline
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23:59 China time (UTC+8 Beijing) on Sunday 8 December 2024
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Final Word Count
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N/A
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ASSIGNMENT TASK (INDIVIDUAL WORK)
You are required to work individually to complete the assignment. There are 5 questions and you have to answer all of them. In order to complete the assessment, you need to apply the skills that you developed in the lecture where you learned how to analyse and design a control system.
It is strongly encouraged that you do some additional research to identify, collect, and compare further relevant information that can be incorporated into your report. When using different sources, you must ensure that they are correctly referenced, and you need to synthesize your own ideas and present them in your own words.
SUBMISSION FORMAT INSTRUCTIONS
The assignment must be typed and submitted via Learning Mall Online to the correct dropbox. Only electronic submissions are accepted - no hard copies. You can include and submit the scanned hand- written file for your calculation in the report. The report should be submitted in a single PDF file and the format should follow the below structure:
· Cover page filled in with your student ID
· Your answer to each question
· List of references
All students must download their file and check that it is viewable after submission. Document uploads may become corrupted during the uploading process (e.g., due to slow internet connections). Therefore, students themselves are responsible for submitting a functional and correct file that needs to be tested after submitting it.
Deadline reminder: 23:59 China time (UTC+8 Beijing) on Sunday 8 December 2024
LEARNING OUTCOMES
This assignment tests your ability to:
A. Show familiarity with typical field bus control systems, e.g., Ethernet/IP, ControlNet, LonWorks, and Controller Area Network (CAN).
B. Demonstrate understanding of the control theories and methods, e.g., mathematical modelling for control systems, PID controller, time-domain interpretation, and frequency-domain interpretation.
C. Design the PID controllers for linear continuous time systems and linear discrete time systems.
D. Demonstrate understanding of concepts on network control and its analysis, design and simulation.
ASSIGNMENT QUESTIONS
Question 1a (10 marks)
Industrial control systems have transitioned from early analog communication methods, such as the 4-20 mA current loop which facilitated single-point connections, to sophisticated digital communication networks like Fieldbus. Nowadays, industries employ a diverse array of Fieldbus technologies tailored to their specific operational needs, including Foundation Fieldbus, PROFIBUS, DeviceNet, ControlNet, InterBus, HART, MODBUS, CAN Bus, Ethernet, and LonWorks.
For this question, analyze and compare the traditional 4-20 mA communication systems with modern Fieldbus systems by addressing the following aspects:
1. Transmission System: Compare how the transmission methods differ between 4-20 mA systems and Fieldbus systems. (1 mark)
2. Communication System: Discuss the differences in communication protocols and methods between the two systems. (1 mark)
3. Transmission Line for Process Control: Evaluate the differences in the transmission lines used in process control applications for both systems. (1 mark)
4. Network Expansion: Assess the capacity and ease of expanding networks in both 4-20 mA and Fieldbus systems. (1 mark)
5. Control Network and I/O Devices: Analyze the control network architecture and the handling of I/O devices in the field for each system. (1 mark)
6. Comparison Table: Create a table that highlights the key differences between the 4-20 mA system and Fieldbus system. (2 marks)
7. Conclusion: Summarize the major motivations and advantages that lead industries to prefer Fieldbus systems over traditional 4-20 mA systems. (2 marks)
Question 1b (10 marks)
In recent years, the industrial sector has increasingly moved towards adopting Industrial Ethernet technologies, driven by the rise of the Industrial Internet of Things (IIoT). For instance, technologies such as EtherCAT and POWERLINK have gained popularity, whereas traditional fieldbus systems like PROFIBUS and CANopen are witnessing a decline in usage. This shift is evident in industry reports that highlight the growing dominance of Industrial Ethernet over fieldbus solutions.
Examine the reasons behind the industry's transition from fieldbus technologies to Industrial Ethernet. Your analysis should address the following key factors:
1. Communication Speed: Evaluate how the communication speed of Industrial Ethernet compares to that of traditional fieldbus systems and its impact on industrial applications. (2 marks)
2. Safety and Security: Discuss the advancements in safety and security features offered by Industrial Ethernet technologies compared to fieldbus technologies. (2 marks)
3. Interoperability: Analyze how Industrial Ethernet enhances interoperability among different devices and systems compared to fieldbus technologies. (2 marks)
4. Scalability: Compare the scalability of Industrial Ethernet solutions with fieldbus systems and how this affects their deployment in industrial environments. (2 marks)
5. Cost: Assess the cost implications of adopting Industrial Ethernet over fieldbus technologies, including both initial investment and long-term operational costs. (2 marks)
In your answer, provide a comprehensive evaluation of these factors to explain why industries are increasingly favoring Industrial Ethernet technologies over traditional fieldbus systems.
Question 2 (20 marks)
In a modern industrial setting, a conveyor belt system is used to transport packages through various stages of processing. This system is equipped with IoT sensors that monitor package weight and belt speed. The sensor data is transmitted to a central control unit via the IoT network. The control system adjusts the motor's torque to maintain the desired belt speed and accommodate the varying weights of packages. As shown in Figure 2, when the motor applies a torque T, a friction force is developed that is proportional to the belt’s angular velocity. In this system, the friction constant b is 0.07 N s/rad, and the moment of inertia J is 0.1 kg m². The output variable is the angular velocity ω(t), and the initial angular velocity at t=0 is 0.6 rad/s.
Figure 2. IoT-enabled motor feedback control system.
(a) Construct a block diagram that shows the input and output parameters of the conveyor belt system. (2 marks)
(b) Derive the conveyor belt’s equation of motion from the mathematical model of SDOF torsional system. (4 marks)
(c) Transform. the conveyor belt’s equation of motion to the laplace domain and construct its transfer function. (6 marks)
(d) Compute the conveyor belt’s response for a unit step input and plot the results until the steady-state condition is achieved. (8 marks)
Question 3 (20 marks)
In this task, you will investigate the effects of proportional and integral control actions on the system performance. You may use MATLAB in answering this question. Let’s consider a typical feedback system as shown in Figure 3. The item to be controlled is a servo with torque signal . The error signal is defined as the differences between system’s output signal and input signal .
Figure 3. A typical feedback control system.
The physical parameters of servo are given in the table below:
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Physical Parameter
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Symbol
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Value
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Unit
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Moment of inertia
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15 ´ 10-2
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kg m2
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Friction constant
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3 ´ 10-2
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N s/rad
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Initial angular velocity
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0
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rad/s
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The controller transfer function are given as follow:
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Control Type
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Symbol
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Transfer Function
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Proportional
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P
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Proportional-Integral
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PI
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(a) For the proportional (P) control, derive the mathematical model of the servo, transfer function , and transfer function . In addition, construct a block diagram for each transfer function. (4 marks)
(b) For the proportional (P) control, derive the expression of steady-state error for a unit step input. Furthermore, calculate the proportional constant so that the . Show the results in a step response graph. (4 marks)
(c) For the proportional-integral (PI) control, derive the transfer function and construct its block diagram.
(4 marks)
(d) For the proportional-integral (PI) control, calculate the steady-state error for a unit step input and compare the results to the proportional (P) control. Provide your comparative analysis by highlighting the effect of integrator to the system’s steady-state error. (4 marks)
(e) Design a proportional-integral control (PI) for the following specification:
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Design criteria
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Symbol
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Requirement
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Damping ratio
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0.707
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Percent overshoot
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P.O.
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< 17 %
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Proportional constant
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0.27
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and plot the system’s response as well as root locus diagram for a unit step input. Shows that the system's response in these two plots satisfies the design requirements. (4 marks)
Question 4 (20 marks)
Proportional-Integral-Derivative (PID) controllers are used in most automatic process control applications in industry today to regulate flow, temperature, pressure, level, and many other industrial process variables. Most PID controllers require tuning to time the speed of the output action properly, so in this task you will design a PID controller for a typical process control, as shown in Figure 4.
Figure 4. A typical process control system.
The transfer function of controller and process are given in the following table:
(a) Design a PID controller by tuning the proportional , integral , and derivative gain using the closed-loop Ziegler–Nichols tuning method. Assume the disturbance effect to the system is negligible i.e. . Your solution should include the process for calculating the ultimate gain and the ultimate period . (8 marks)
(b) Compute the system’s response to a unit step input using the tuned parameters and . Plot the response and present the step-response characteristics such as rise time, transient time, settling time, overshoot, peak, and peak time. (6 marks)
(c) Compute the system’s response to a unit step input and an impulse disturbance with magnitude equal to . Analyse and compare the system’s response with and without diturbance effect. (6 marks)
Question 5 (20 marks)
The recent expansion of IoT technology has been remarkable, with a notable increase in the use of Wireless Network Control Systems (WNCS). Traditional control theory typically examines dynamical systems where each element is interconnected through "ideal channels." However, the integration of communication networks into control systems introduces a paradigm where control is mediated through "non-ideal channels," marking a significant divergence from traditional setups. Figure 5 illustrates a streamlined representation of a WNCS configuration. It demonstrates the control of two devices—a servo and an LED—over a WiFi network, facilitated by the MQTT protocol. To clarify the operational mechanics of a WNCS, you are challenged to design, simulate, and evaluate a simplified model of this system.
Figure 5. Simplified wireless network control system
(a) Design a schematic diagram of the simplified WCNS shown in Figure 5 using fritzing software for the following apparatus:
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Item
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Quantity
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Remarks
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Controller (ESP8266)
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1 unit
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NodeMCU Devkit
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Servo
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1 unit
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Basic servo
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LED
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1 unit
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R/G/B colours
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Resistor
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1 unit
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220 Ohm
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Breadboard
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1 unit
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Full or half size
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(2 marks)
(b) Construct the circuit using the schematic diagram designed in task a) and include pictures of the completed circuit in your report. (2 marks)
(c) Create a program to connect the ESP8266 to a WiFi network. Create two topics that will allow clients to subscribe and control the LED and servo through Node-RED and deliver the following output scenario:
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Item
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Control
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Remarks
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LED
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ON/OFF
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Client control the LED to turn ON or OFF using Node-RED
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Servo
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FULL/HALF
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Client control the servo to rotate full or half using Node-RED.
Full à rotate 180 deg from initial position and return to intial position.
Half à rotate 90 deg from initial position and return to intial position.
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(4 marks)
(d) Create Node-RED flows in client PC/laptop to subscribe on the selected topic and control the LED and servo according to the output scenario in task c). (4 marks)
(e) Upload the code in task c) to ESP8266 and create a video to demonstrate the working system. Furthermore, upload the video to the online platform. and include the link in your report for evaluation. (4 marks)
(f) Analyze the feasibility of implementing such system in the industry. Your analysis may include, but is not limited to, challenges/issues, examples, and benefits of WNCS.
(4 marks)