Feedback Control for Computer Systems. Introducing Control Theory to Enterprise Programmers (ebook)(audiobook)(audiobook)

Spis treści

• Feedback Control for Computer Systems
• Preface
  • What Is Feedback?
  • Why This Book?
  • How to Read This Book
  • Conventions Used in This Book
  • Using Code Examples
  • Safari Books Online
  • How to Contact Us
  • Acknowledgments
• I. Foundations
  • 1. Why Feedback? An Invitation
    • A Hands-On Example
    • Hoping for the Best
    • Establishing Control
    • Adding It Up
    • Summary
    • Code to Play With
  • 2. Feedback Systems
    • Systems and Signals
    • Tracking Error and Corrective Action
    • Stability, Performance, Accuracy
      • The Setpoint
    • Uncertainty and Change
      • Feedback and Feedforward
    • Feedback and Enterprise Systems
    • Code to Play With
  • 3. System Dynamics
    • Lags and Delays
      • Forced Response and Free Response
      • Transient Response and Steady-State Response
    • Dynamics in the Physical World and in the Virtual World
      • Dynamics and Memory
    • The Importance of Lags and Delays for Feedback Loops
      • Avoiding Delays
    • Theory and Practice
    • Code to Play With
  • 4. Controllers
    • Block Diagrams
    • On/Off Control
    • Proportional Control
      • Why Proportional Control Is Not Enough
    • Integral Control
      • Integral Control Changes the Dynamics
      • Integral Control Can Generate a Constant Offset
    • Derivative Control
      • Problems with Derivative Control
    • The Three-Term or PID Controller
    • Code to Play With
  • 5. Identifying Input and Output Signals
    • Control Input and Output
      • Directionality of the Input/Output Relation
    • Examples
      • Thermal Control 1: Heating
        • Situation
        • Input
        • Output
        • Commentary
      • Item Cache
        • Situation
        • Input
        • Output
        • Commentary
      • Server Scaling
        • Situation
        • Input
        • Output
        • Commentary
      • Controlling Supply and Demand by Dynamic Pricing
        • Situation
        • Input
        • Output
        • Commentary
      • Thermal Control 2: Cooling
        • Situation
        • Input
        • Output
        • Commentary
    • Criteria for Selecting Control Signals
      • For Control Inputs
      • For Control Outputs
    • A Note on Multidimensional Systems
  • 6. Review and Outlook
    • The Feedback Idea
    • Iteration
    • Process Knowledge
    • Avoiding Instability
    • The Setpoint
    • Control, Not Optimization
• II. Practice
  • 7. Theory Preview
    • Frequency Representation
    • The Transfer Function
    • Block-Diagram Algebra
    • PID Controllers
    • Poles of the Transfer Function
    • Process Models
  • 8. Measuring the Transfer Function
    • Static Input/Output Relation: The Process Characteristic
      • Practical Considerations
    • Dynamic Response to a Step Input: The Process Reaction Curve
      • Practical Aspects
    • Process Models
      • Self-Regulating Process
      • Accumulating Process
      • Self-Regulating Process with Oscillation
      • Non-Minimum Phase System
    • Other Methods of System Identification
  • 9. PID Tuning
    • Tuning Objectives
    • General Effect of Changes to Controller Parameters
    • ZieglerNichols Tuning
    • Semi-Analytical Tuning Methods
      • Practical Aspects
    • A Closer Look at Controller Tuning Formulas
  • 10. Implementation Issues
    • Actuator Saturation and Integrator Windup
      • Preventing Integrator Windup
      • Setpoint Changes and Integrator Preloading
    • Smoothing the Derivative Term
    • Choosing a Sampling Interval
    • Variants of the PID Controller
      • Incremental Form
      • Error Feedback Versus Output Feedback
      • The General Linear Digital Controller
    • Nonlinear Controllers
      • Error-Square and Gap Controllers
      • Simulating Floating-Point Output
      • Categorical Output
  • 11. Common Feedback Architectures
    • Changing Operating Conditions: Gain Scheduling
      • Gain Scheduling for Mildly Nonlinear Systems
    • Large Disturbances: Feedforward
    • Fast and Slow Dynamics: Nested or Cascade Control
    • Systems Involving Delays: The Smith Predictor
• III. Case Studies
  • 12. Exploring Control Systems Through Simulation
    • The Case Studies
    • Modeling Time
      • Control Time
      • Simulation Time
    • The Simulation Framework
      • Components
      • Plants and Systems
      • Controllers
      • Actuators and Filters
      • Convenience Functions for Standard Loops
      • Generating Graphical Output
  • 13. Case Study: Cache Hit Rate
    • Defining Components
      • Cache Misses as Manufacturing Defects
    • Measuring System Characteristics
    • Controller Tuning
    • Simulation Code
  • 14. Case Study: Ad Delivery
    • The Situation
    • Measuring System Characteristics
    • Establishing Control
    • Improving Performance
    • Variations
      • Cumulative Goal
      • Gain Scheduling
      • Integrator Preloading
      • Weekend Effects
    • Simulation Code
  • 15. Case Study: Scaling Server Instances
    • The Situation
    • Measuring and Tuning
    • Reaching 100 Percent With a Nonstandard Controller
    • Dealing with Latency
    • Simulation Code
  • 16. Case Study: Waiting-Queue Control
    • On the Nature of Queues and Buffers
    • The Architecture
    • Setup and Tuning
    • Derivative Control to the Rescue
    • Controller Alternatives
    • Simulation Code
  • 17. Case Study: Cooling Fan Speed
    • The Situation
    • The Model
    • Tuning and Commissioning
    • Closed-Loop Performance
    • Simulation Code
  • 18. Case Study: Controlling Memory Consumption in a Game Engine
    • The Situation
    • Problem Analysis
    • Architecture Alternatives
      • A Nontraditional Loop Arrangement
      • A Traditional Loop with Logarithms
    • Results
    • Simulation Code
  • 19. Case Study Wrap-Up
    • Simple Controllers, Simple Loops
    • Measuring and Tuning
    • Staying in Control
    • Dealing with Noise
• IV. Theory
  • 20. The Transfer Function
    • Differential Equations
    • Laplace Transforms
      • Properties of the Laplace Transform
    • Using the Laplace Transform to Solve Differential Equations
      • A Worked Example
    • The Transfer Function
      • Worked Example: Step Response
      • Worked Example: Ramp Input
      • The Harmonic Oscillator
    • What If the Differential Equation Is Not Known?
  • 21. Block-Diagram Algebra and the Feedback Equation
    • Composite Systems
    • The Feedback Equation
      • An Alternative Derivation of the Feedback Equation
    • Block-Diagram Algebra
    • Limitations and Importance of Transfer Function Methods
  • 22. PID Controllers
    • The Transfer Function of the PID Controller
    • The Canonical Form of the PID Controller
    • The General Controller
    • Proportional Droop Revisited
      • A Worked Example
  • 23. Poles and Zeros
    • Structure of a Transfer Function
    • Effect of Poles and Zeros
      • Special Cases and Additional Details
        • Complex conjugate poles
        • Multiple poles
        • Poles on the imaginary axis
        • Pole/zero cancellations
    • Pole Positions and Response Patterns
      • Dominant Poles
      • Pole Placement
    • What to Do About Delays
  • 24. Root Locus Techniques
    • Construction of Root Locus Diagrams
    • Root Locus or Evans Rules
    • Angle and Magnitude Criteria
    • Practical Issues
    • Examples
      • Simple Lag with a P Controller
      • Simple Lag with a PI Controller
  • 25. Frequency Response and the Bode Plot
    • Frequency Response
      • Frequency Response in the Physical World
      • Frequency Response for Transfer Functions
      • A Worked Example
    • The Bode Plot
    • A Criterion for Marginal Stability
    • Other Graphical Techniques
  • 26. Topics Beyond This Book
    • Discrete-Time Modeling and the z-Transform
    • State-Space Methods
    • Robust Control
    • Optimal Control
    • Mathematical Control Theory
• V. Appendices
  • A. Glossary
  • B. Creating Graphs with Gnuplot
    • Basic Plotting
    • Plot Ranges
    • Inline Transformations
    • Plotting Simulation Results
    • Summary
  • C. Complex Numbers
    • Basic Operations
    • Polar Coordinates
    • The Complex Exponential
  • D. Further Reading
    • Recommended Reading
    • Additional References
    • Mathematical Prerequisites
• Index
• Colophon
• Copyright

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