Lecture 4 SE201

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Lecture 4 SE201

• Design Process
• Automation/Control

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Outlines

• Systems specification
• The four different characteristics to meet in
  design
• General Approach
• Control system design process
• Design examples

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Four Important characteristics

• Complexity of the design
• Tools, issues and knowledge to be used in the
  process
• Trade-off
• Judgment about compromises between desirable
  conflicting criteria.

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• Risk
• due to the fact that the final product generally
  does not appear the same as it had been
  originally visualized.
• The result is that designing a system is a
  risk-taking activity.
• Design Gaps
• Process is iterative and can be improved
  incrementally

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Approach

• The main approach to the most effective
  engineering design is parameter analysis and
  optimization.
• Parameter analysis is based on
• (1) identification of the key parameters,
• (2) generation of the system configuration,
• (3) evaluation of how well the configuration
  meets the needs.
• These three steps form an iterative loop. The
  objective is to optimize the parameters.

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Design of Turntable speed Control

• Problem Formulation
• Many modern devices use a turntable to rotate
  a disk at a constant speed.
• For example, a CD player, a computer disk drive,
  and a phonograph record player all require a
  constant speed of rotation in spite of motor wear
  and variation and other component changes.
• Our goal is to design a system for turntable
  speed control that will ensure that the actual
  speed of rotation is within a specified
  percentage of the desired speed.
• We will consider a system without feedback and
  a system with feedback.

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The Design System design Process
1. Establish control goals
2. Identify variables to control

• Example Control the velocity of a motor
• Example the velocity of the motor
• Example 2 of error Selection of
  sensors to measure the controlled variable
• Example Negative feedback system block
  Configuration Actuator Voltage generator, dc
  motor Motor pump and valve.
• Example Physical model, differential equation.
  modeling
• Example Summing amplifier

3. Write the specifications for the variables
4.0 Establish the system Configuration and
identify the actuator
5.0 Obtain a model of the process, the actuator
and the sensor
6.0 Describe a controller and select the key
parameters to be adjusted
7.0 Optimize the parameters and Analyze the
performance.
If the performance does not meet the
specification then iterate the Configuration and
the actuator

If the meet the specification then finalize the
design
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Example 2 Pencil sorter

• We have a company producing pencils. The pencils
  go through different quality tests. The company
  is has a huge production volume and all the
  checks are done manually this may generate sales
  loss due to production delays. If the company is
  reduces the quality tests, it may reach the
  market early but unhappy customers could run
  away.
• We would like to find a feasible and practical
  solution that will allow a high volume
  production with good quality standards.

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Example 3 Ball bearing sorter

• We have a production line of ball bearing that
  can be coming in four or more different sizes.
• We would like to design a system that will be
  able to sort the ball bearings according to their
  size and put them in different locations or
  containers.

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Performance Specification for control

• Describe how the closed-loop should perform. It
  includes
• Good regulation against disturbance
• Desirable response to command
• Realistic actuator signals
• Low sensitivity
• Robustness

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Component Selection

• Component
• DC Motor (Actuator)
• Amplifier
• Battery
• Sensors

• Justification
• Liner relation speed vs voltage
• Battery does not have enough power to drive the
  DC motor
• Need for a source
• For closed loop

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Design Example I Turntable Speed Control
Open Loop
Closed loop
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Insulin Delivery Control System
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approach to dynamic system problems can be listed
as follows

• Define the system and its components.
• Formulate the mathematical model and list the
  necessary assumptions.
• Write the differential equations describing the
  model.
• Solve the equations for the desired output
  variables.
• Examine the solutions and the assumptions.
• If necessary, reanalyze or redesign the system.

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Vehicle Dynamics
Movement around Center of Gravity
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Suspension Components
Suspension
Tire
Acts as a Spring-Mass-Damper
Springs and Dampers Most Common Suspension Type
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Quarter Car Suspension

• Quarter Car models one-fourth of a automobile
  suspension.
• Only Captures Vertical Movement.

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Half Car Suspension

• Incorporates Two Quarter Car models connected
  with a Beam.
• Allows modeling of pitch as well as body position.

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Full Car Suspension

• Advantages
• Captures all of the motions of a real vehicle
• Pitch and Roll can be evaluated simultaneously
  with vertical compliance
• Disadvantages
• Existing Full-Car Models are expensive
• New Models are difficult to develop

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Negative feedback system blockConfiguration
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Modeling
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Use of the different Models
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Modeling Techniques
Differential equations Physically Based Models
State space Formulation
Transfer Functions
Representation
Block Diagrams
Give a very good understanding of the different
functionality of the system