Module 4-5 AR Midterm

Actuator

Actuator

A device within a machine that generates force, torque, or displacement in response to an electrical, pneumatic, or hydraulic input in a controlled manner, serving as the "muscles" of machines.

How are actuators classified based on the type of energy they use?

Actuators are categorized by the energy type they utilize: Electrical, Elecromechanical, Elecromagnetic, Hydraulic, Pneumatic

Electrical Energy

Powered by electric currents.

Electromechanical Energy

Converts electrical energy into mechanical movement.

Electromagnetic Energy

Uses magnetic forces for motion.

Hydraulic Energy

Operates with pressurized liquids.

Pneumatic Energy

Driven by compressed air.

Three Types of DC Motors

Permanent Magnet, Brushed, and Brushless

Permanent Magnet DC Motor (PMDC)

A type of DC motor with a permanent magnet stator and a wound armature, commonly used in applications like toys, tools, and appliances.

Brushed DC Motor

A type of DC motor where the rotor has windings connected to the commutator, requiring brushes for commutation, commonly used in applications like electric vehicles and industrial machinery.

Brushless DC Motor (BLDC)

A type of DC motor with a permanent magnet rotor and a stator with electronically controlled windings, offering higher efficiency and reliability, commonly used in applications like drones, HVAC systems, and electric vehicles.

AC Motors

Motors that operate on alternating current (AC) and are classified into types like Synchronous Motors, Induction Motors, Single-phase Motors, and Three-phase motors, each with specific characteristics and applications.

Three-phase Motors

Operate on a three-phase power supply, offering a more balanced and efficient power transfer. Applications: These motors are predominantly used in industrial environments for heavy-duty applications such as compressors, pumps, and lifting gear.

Synchronous Motors

AC motors where the rotor rotates at the same speed as the rotating magnetic field, ideal for applications requiring constant speed like synchronous clocks.

Induction Motors (Asynchronous Motors)

AC motors where the rotor rotates at a speed less than the rotating magnetic field, commonly used in applications like pumps, fans, and compressors.

Single-phase Motors

AC motors that do not require a separate starting mechanism, suitable for applications like household appliances, fans, and office machinery.

Stepper Motor

A type of electric motor that moves in discrete steps, each step representing a fixed angle of rotation, operating on the principle of electromagnetism, commonly used in applications requiring precise positioning and speed control.

primary characteristics and applications for stepper motor

Flashcard: Primary Characteristics: Step angle, holding torque, rotor inertia. Applications: Robotics, 3D printers, CNC machines.

Unipolar Stepper Motor

A type of stepper motor that is easier to operate due to its design allowing current to flow in one direction.

Bipolar Stepper Motor

A type of stepper motor that requires a more complex control system because the current flows in both directions.

Servo Motor

A closed-loop actuator offering precise control of angular or linear position, velocity, and acceleration, commonly used in mechatronics applications such as aerospace, medical devices, feedback control, and industrial automation.

Pulse Width Modulation (PWM)

Coded signals used to control the movement of a servo motor's output shaft by varying the width of electrical pulses.

Characteristics for servo motor

• Feedback control

• Position Accuracy

• Control Signal

Applications for Servo Motor

• Robotics

• Medical Devices

• Aerospace

• Consumer Electronics

• Industrial Automation

Motor Nameplate

Provides specifications such as model, power ratings, electrical characteristics, and operational parameters of the motor, including details like model number, frame number, poles, enclosure type, electrical code, design letter, insulation class, voltage ratings, full load RPM, full load amps, service factor, and duty cycle.

Variable Frequency Drive (VFD)

A motor controller that varies the frequency and voltage of the power supply to control the speed of an electric motor.

How does a Variable Frequency Drive work?

Controlling the speed of an electric motor by varying the frequency and voltage of the power supplied to the motor, utilizing Pulse Width Modulation (PWM).

Applications for Variable Frequency Drive

• HVAC Systems

• Pump Operations

• Industrial Machinery

• Cranes and Hoists

• Fan System

• Compressors

Hydraulic System

Technology that uses an incompressible fluid, such oil or water, to transfer force from one location to another

Pascal's Law

The principle stating that an increase in pressure at any point in a confined fluid is transmitted equally to all other points in the fluid.

Mechanical Advantage (MA)

The ratio of output force to input force in a system, with Ideal Mechanical Advantage (IMA) calculated as the ratio of load piston area to effort piston area in a hydraulic system.

IMA (Ideal Mechanical Advantage)

in a hydraulic system is given by: 𝐼𝑀𝐴 = 𝐴2/A1 = 𝐷1/ 𝐷2

What are the main components of a hydraulic system?

• Pump

• Reservoir

• Non-return Valve

• Accumulator

• Pressure Relief Valve

• Actuators

• Directional Control Valves

Open-Center Hydraulic System

A system where fluid flows but there is no pressure when the actuating mechanisms are idle.

Fluid Flow

Fluid circulates through the system even when idle.

No Idle Pressure

No significant pressure in the system unless actuated.

Valve Configuration

selector Valves are usually arranged in series

Closed-Center Hydraulic System

A system where the fluid is under pressure whenever the power pump is operating.

Continuous Pressure

Fluid remains under pressure as long as the pump operates.

Actuator Arrangement

Actuators are set up in parallel

Pressure Control

Pressure is managed by a regulator; a relief valve provides backup safety.

Pneumatic System

A system that uses compressed air to perform work by capturing, transporting, and utilizing air to power various tasks.

Components of a Pneumatic System

Includes a silencer, pressure-relief valve, filter, motor, compressor, cooler, filter and water trap, and air receiver.

Directional Control Valve

A component in hydraulic and pneumatic systems that directs the flow of fluid (liquid or gas) to different paths.

What do pneumatic and hydraulics systems use?

Directional control valves to regulate the flow of fluid or air through the system. These valves can act as ON/OFF switches, allowing them to be either completely open or closed.

Valve Actuation Symbols

Symbols representing different methods of actuating valves, such as push-button, lever, solenoid, etc.

Some Valve Actuation Symbols

• Push Button

• Plunger

• Lever

• Roller

• Pedal

• Pneumatic Pressure

• Spring

• Solenoid

Understanding Valve Symbols

• Each square in the valve symbol represents a possible position of the valve.

• Arrows within the squares tell us the flow paths available in each position.

• Ports are indicated by lines or points on the square and they are usually labeled, e.g., P for pressure inlet, A and B for work lines (output ports), and T for tank or return port.

Flow Paths

Routes that fluid can take through a valve, indicated by arrows within each position symbol.

Number of Ports

The total entry and exit points for fluid on a valve, represented by lines or points on the valve symbol.

Hydraulic and Pneumatic Actuators

Devices that convert fluid power into mechanical force and motion, utilizing single-acting and double-acting cylinders.

Single-Acting Cylinders

Cylinders that operate with control pressure on one side of the piston, producing motion in one direction and using a spring to return to the starting position.

Double-Acting Cylinders

Cylinders that apply fluid pressure on both sides of the piston, allowing controlled motion in both extend and retract directions without a spring.

Process Control Valves

Valves used to control fluid flow rate in fluid dynamics, often paired with diaphragm actuators to convert pressure into mechanical motion.

Discrete Signals

Digital signals that take on a limited number of values, mostly binary digits 1 or 0.

Binary Representation

These binary signals represent distinct states such as on/off, open/closed, or start/stop.

Physical Translation

Actuators and sensors in a mechatronics system usually operate with discrete signals, translating the binary inputs and outputs into physical actions.

Continous Change

Signals continuously change and adapt, unlike discrete signals which are binary

Regulatory Objective

The main goal of discrete control signals is to maintain a consistent output at a predetermined level.

Closed-Loop Analogy

Operates similarly to closed-loop systems, providing feedback and control.

Model in Automation Systems

A detailed yet simplified representation of a system's behavior used for analyzing and predicting its actions for effective control.

Programmable Logic Controller (PLC)

A type of microprocessor-based controller designed for industrial automation, utilizing programmable memory to store and execute control instructions.

PLC uses

• Programmable Memory

• Logic Operation

• Sequencing

• Timing and Counting

• Arithmetic Functions

• User-Friendly Interface

Control in Automation Systems

Involves decision-making processes for effective management and regulation of industrial processes.

Ladder Programming

A programming method developed for PLCs to simplify user accessibility by using symbolic elements to depict complex control logic and ensure consistency in programming.

Ladder Programming simplifies

• User Accessibility

• Programming Process

• Learning Curve

• Industry Adoption

Ladder Logic Diagram

Provide a method to symbolically show how relay control schemes are implemented in PLCs.

PLC (Programmable Logic Controller)

An industrial digital computer used to automate processes by controlling machinery and factory assembly lines.

Relay

An electromechanical device that opens or closes a circuit in response to a voltage change by activating a switch.

When a Voltage is applied

 Current flows through a coil.

 The coil becomes magnetized.

 Magnetic force pulls contacts closed, completing the circuit

When a voltage is removed

• Magnetization ceases.

• Contacts are released, opening the circuit

Rung

A horizontal instruction line in a ladder diagram that connects two vertical rails, representing a logic operation in a PLC program.

Ladder Diagram

A schematic representation of a control logic sequence in PLC programming, consisting of rails, rungs, inputs, and output devices.

Rails

Vertical lines at the edges of the ladder diagram representing active and zero-volt connections of the power supply.

Rungs

Horizontal lines connecting the rails, equivalent to wires in a relay logic circuit, and numbered in ascending sequential order for reference.

Inputs

External control actions like buttons or switches hardwired to the PLC and depicted as NO (Normally Open) or NC (Normally Closed) contacts.

Outputs

Devices controlled by the PLC, e.g., motors or valves. Hardwired to PLC and shown as relay coil symbols

Logic Expressions

Combine inputs and outputs to create control operations.

Determine the behavior of the outputs based on input conditions

Section on Signals to recognize

• Rung

• Branch

• Contact NO

• Contact NC

• Coils

• Instruction Block

Output Devices

Devices controlled by the ladder logic such as relays, motors, or lights.

TON instruction

a timing function that delays the activation of an output for a specified duration after its input becomes true.

Preset Time

The duration of the delay

Accumulated time (ACC)

The current elapsed time.

Time base (T#)

The time unit used for PT and ACC.

IN bit

The input that triggers the timer.

Q bit (output)

The output that is activated after the delay.

CTU (Count Up)

counts input pulses and activates an output when the count reaches a preset limit. It counts integers from a given value upwards, incrementing by 1 with each pulse.

Counter value (CV)

The current count.

Preset value (PV)

The count at which the output will be activated.

Count Input (CU)

The input that increments the counter

Reset Input (R)

Input that resets the counter to zero

Q bit (output)

The output that indicates the count has reached the preset value

EQUAL

compares the first input to the second input and produces an output when both values match

Source A

The first source in the EQUAL instruction.

Source B

The second source in the EQUAL instruction.

Output bit (Q)

The output that is set when Source A equals Source B

MOV (Move)

transfers or copies an input value from a source to a specified destination (output) address in the PLC memory.

Source Value

The data that needs to be moved

Destination address

The location where the data will be stored

Timer done bit (DN bit)

Indicates when the timer has completed timing.