Lecture 4 SE 201 Design Process AutomationControl Previous

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Lecture 4 SE 201 Design Process: Automation/Control

Lecture 4 SE 201 Design Process: Automation/Control

Previous Lecture: Design System’s specification The four different characteristics to meet in design General

Previous Lecture: Design System’s specification The four different characteristics to meet in design General Approach Control system design process Design examples

Four Important characteristics Complexity of the design: – Tools, issues and knowledge to be

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.

Risk: – due to the fact that the final product generally does not appear

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

Approach The main approach to the most effective engineering design is parameter analysis and

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.

Design of Turntable speed Control Problem Formulation : Many modern devices use a turntable

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.

The Design System design Process 1. Establish control goals Example: Control the velocity of

The Design System design Process 1. Establish control goals Example: Control the velocity of a motor 2. Identify variables to control Example: the velocity of the motor 3. Write the specifications for the variables 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 + - 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 K Example: Summing amplifier 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

Performance Specification Describe how the closed-loop should perform. It includes: – Good regulation against

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

Component Selection Component – DC Motor (Actuator) – Amplifier – Battery – For closed

Component Selection Component – DC Motor (Actuator) – Amplifier – Battery – For closed loop Justification – Liner relation speed vs voltage – Battery does not have enough power to drive the DC motor – Need for a source – Sensors

Design Example I: Turntable Speed Control Open Loop Closed loop

Design Example I: Turntable Speed Control Open Loop Closed loop

Insulin Delivery Control System

Insulin Delivery Control System

approach to dynamic system problems can be listed as follows: 1. Define the system

approach to dynamic system problems can be listed as follows: 1. Define the system and its components. 2. Formulate the mathematical model and list the necessary assumptions. 3. Write the differential equations describing the model. 4. Solve the equations for the desired output variables. 5. Examine the solutions and the assumptions. 6. If necessary, reanalyze or redesign the system.

Vehicle Dynamics Movement around Center of Gravity

Vehicle Dynamics Movement around Center of Gravity

Suspension Components Suspension Tire Acts as a Spring-Mass-Damper Springs and Dampers Most Common Suspension

Suspension Components Suspension Tire Acts as a Spring-Mass-Damper Springs and Dampers Most Common Suspension Type

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

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

Half Car Suspension Incorporates Two Quarter Car models connected with a Beam. Allows modeling

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

Full Car Suspension Advantages – Captures all of the motions of a real vehicle

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

Negative feedback system block Configuration Desired – Measured Output Desired Output Comparison Actuator Measurement

Negative feedback system block Configuration Desired – Measured Output Desired Output Comparison Actuator Measurement Positive feedback -> Error is increasing Slide 10 Process Output

Modeling Detailed Non-Linear Model Real System Detailed Linear Model

Modeling Detailed Non-Linear Model Real System Detailed Linear Model

Use of the different Models Design Detailed Non-Linear Model Real System Parameter Calculation Parameter

Use of the different Models Design Detailed Non-Linear Model Real System Parameter Calculation Parameter Identification Detailed Linear Model Analysis Validation and Verification

Modeling Techniques Differential equations: Physically Based Models State space Formulation Transfer Functions Representation Block

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 back to slide 5