Portland Community College | Portland, Oregon

MT224 is part 1 of 3 of our series on semiconductor manufacturing equipment. In MT224 we study the common components used in equipment. In MT227 and 228, we learn about the equipment as a whole system and how to maintain it.   In MT224, we will cover controllers, controlling software, signal conditioning, sensors, switches, DC and stepper motors and pneumatics. We will examine how equipment can use these components together to achieve automatic control.

At the end of the course, the student should be able to:

1)     Identify the basic components of a modern control system

2)     explain how these components work (i.e. describe how a stepper motor takes discrete steps or how pneumatic valves open and shut)

3)     perform simple calculations on the functionalities of these components (i.e. tell what resolution a 12 bit A/D converter gives; tell the temperature of a thermocouple reading from its voltage vs. temperature characteristics.)

4)    build, in a laboratory setting, simple systems in which these components can perform their basic functions (i.e. use a computer to instruct a stepper motor to go 10 steps clock wise and 2 steps counter clock wise.)

5)    build a simple system where the various components can work together to achieve automatic control (i.e. build a close loop control system with sensors, controllers and actuators to perform desired control tasks.)

2. Transferable skill-set intended outcomes: The student will have the opportunity to utilize and enhance the following set of skills in this class:

Hands-on problem solving—labs

Team work—group projects

Communication--laboratory reports

Discipline—class attendance, class participation

The course will include instructor delivered lectures and demonstrations stressing key topics in the course. In preparation for the lecture portion of the course, students will be expected to complete all reading and homework assignments. Students will also reinforce and practice concepts learned in a laboratory setting.

Assessment of student performance in this course will be in the form of homework, quizzes, exams, in-class lab performance and lab reports.

REQUIRED STUDENT COMPETENCIES:

Chapter 1              Control System

Section 1         Control system

1                 Know that a control system is made of 3 major components: controller, sensors and actuators. Know the basic functions of these components and how together they can perform a control task.

2                 Be able to give examples of control system in daily life and in the fabrication.  Also be able to tell in such an example which part is the controller, sensor, or actuator.

Section 2         Controller

1                 Know commonly used controller types

2                 Know the advantage of micro-processor based controllers

3                 Know the major components of a micro-processor based controller: CPU, memory, I/O, and peripheral power supply.

4                 Know the types of micro-processor based controllers and their characteristics in terms of where the major components of the controllers are built into (CPU/Memory/IO on a chip vs. CPU/Memory/IO on a board, etc.)

5                 Be able to select the most suitable controller type based on the application.

6                 Tell types of controllers used in fab equipment.

Section 3         PC based controller

1                 Know major components of a PC and their basic functions: CPU, Memory, Bus, I/O and how signal travels among them

2                 Know commonly used bus and IO port types.

3                 Know necessary functions performed by the interface between PC and sensors/actuators.

4                 Know what components of the interface perform which functions above.

5                 Know the structure of the interface and how signals travel between controller and sensor/actuator.

6                 Be able to work out the above interface for a given control task.

7                 Know how the Daq card interface and GPIB interface relate to the above generic interface structure.

8                 In laboratory setting, assemble a basic Daq card interface to read and write multiple channel digital signals from/to a PC.

9                 In laboratory setting, assemble a basic GPIB interface to read single channel analog voltage signal as measured by a multi-meter into a PC.

Section 4         Control software

1                 Learn the basic elements of control software.

2                 Learn to write very basic control software programs in LabView.

Chapter 2              Signal Conditioning

Section 1         Explain types of signal conditioning needed for sensors: signal amplification, filtering, impedance isolation

Section 2         Op-amp

1                 Know circuit connection, amplification factor, equivalent input and output impedance of four types of op-amp circuits: Voltage follower, inverting op-amp, non-inverting op-amp, and differential op-amp.

2                 Explain how op-amps can be used to achieve signal amplification and the transformation from high impedance to low impedance signals. Know that op-amps are typically not used for power amplification of actuators.

3                 Be able to design a suitable op-amp circuit based on the amplification, impedance isolation, and polarity need of the application.

Chapter 3              Sensors

Section 1         Position sensors

1                 Know how a potentiometer can be used to measure position.

2                 Know how to design an interface circuit between a potentiometer and a controller.

3                 Know the advantages and issues of using a potentiometer as a position sensor.

4                 Know how an absolute optical encoder can be used to measure position

5                 Know what determines its resolution

6                 Know how to design an interface circuit between an absolute encoder and a controller.

7                 Know the advantages and issues of using an absolute encoder as a position sensor.

8                 Know how an incremental optical encoder can be used to measure position

9                 Know what determines its resolution

10              Know how to design an interface circuit between an incremental encoder and a controller to extract both step and direction information.

11              Know the advantages and issues of using an incremental encoder as a position sensor.

Section 2         Optical sensors

1                 Know how light can create a change in resistance of voltage in photo-resistor, photo-diode, photo-transistor, and photovoltaic cell.

2                 Know how to design an interface circuit to transform resistance changes in a photo-sensor into a voltage signal.

Section 3         Temperature sensor

1                 Know common types of temperature sensors

2                 Know how a thermal couple sensor can be used to measure temperature

3                 Know its advantages and limitations

4                 Know how to correlate between voltage output and temperature measured using tables or graphs.

Section 4         Sensor lab

1                 Be able to assemble the above sensors, their interface circuits and a PC as a controller together to measure the intended physical parameter in a laboratory setting.

Chapter 4              Relays and Switches

Section 1         Relays

1                 Know how electromechanical relays can be used to turn on-off current.

2                 Know how a week control signal can be used to control the on-off of a strong current via a relay

Section 2         Power transistors

1                 Know that power transistors can be used to amplify current enough to drive actuators, modify their power, or turn them on and off.

2                 Know that transistors are used to amplify current. Be able to determine base current from base voltage, Ice from Ib.

3                 Know how to bias the base voltage using a voltage divider circuit.

4                 Know A,B,C classes of operation of power transistors and their advantages and disadvantages.

5                 Know that power transistors need proper heat dissipation.

6                 Be able to choose a suitable power transistor for the specific application from a table based on Ic, Vce, amplification factor and power rating.

Chapter 5              DC motors

Section 1         Theory of operation

1                 Explain how DC motors can turn and keep on turning

2                 Understand the quantitative relation between speed, CEMF, armature current and torque.

Section 2         Series-wound DC motors:

1                 Understand what a series-wound DC motor is

2                 Understand characteristics of its speed vs. torque relation and thus its advantages and disadvantages.

Section 3         Shut-wound DC motors:

1                 Understand what a shut-wound DC motor is

2                 Understand characteristics of its speed vs. torque relation and thus its advantages and disadvantages.

Section 4         Permanent-magnet motors

1                 Understand what a PM DC motor is

2                 Understand qualitatively and quantitatively characteristics of its speed vs. torque relation and thus its advantages and disadvantages.

3                 Be able to predict its performance based on the speed vs. torque relation.

Section 5         DC motor control circuits

1                 Understand how to control motor direction and stoppage using circuits.

2                 Understand how to use analog drive to achieve motor speed control. Be able to do so in a laboratory setting.

3                 Understand how to use pulse-width-modulation to achieve motor speed control. Be able to do so in a laboratory setting.

Chapter 6              Stepper Motors

Section 1         Theory of operation

1                 Explain how stepper motors can take discrete steps

2                 Explain its advantages and disadvantages

3                 Understand the different characteristics and features of the speed vs. torque curve.

4                 Distinguish between slewing and single-stepping modes

Section 2         Excitation modes

1                 Understand excitation sequence of a two-phase vs. four-phase motor.

Section 3         How to achieve finer step size:

1                 Understand how finer step size can be achieved by multi-pole rotors, by multi-stack rotors, by variable-reluctance stepper motors, and by hybrid stepper motors.

Section 4         Stepper motor driver circuit

1                 Understand how 4-phase stepper motor control circuit works

2                 Understand how 2-phase stepper motor control circuit works

3                 Be able to control a stepper motor with a stepper motor control circuit connected to a PC in a laboratory setting.