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| Preface | |
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| Foundations | |
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| Why Feedback? An Invitation | |
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| A Hands-On Example | |
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| Hoping for the Best | |
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| Establishing Control | |
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| Adding It Up | |
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| Summary | |
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| Code to Play With | |
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| Feedback Systems | |
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| Systems and Signals | |
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| Tracking Error and Corrective Action | |
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| Stability, Performance, Accuracy | |
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| The Setpoint | |
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| Uncertainty and Change | |
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| Feedback and Feedforward | |
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| Feedback and Enterprise Systems | |
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| Code to Play With | |
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| System Dynamics | |
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| Lags and Delays | |
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| Forced Response and Free Response | |
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| Transient Response and Steady-State Response | |
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| Dynamics in the Physical World and in the Virtual World | |
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| Dynamics and Memory | |
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| The Importance of Lags and Delays for Feedback Loops | |
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| Avoiding Delays | |
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| Theory and Practice | |
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| Code to Play With | |
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| Controllers | |
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| Block Diagrams | |
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| On/Off Control | |
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| Proportional Control | |
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| Why Proportional Control Is Not Enough | |
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| Integral Control | |
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| Integral Control Changes the Dynamics | |
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| Integral Control Can Generate a Constant Offset | |
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| Derivative Control | |
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| Problems with Derivative Control | |
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| The Three-Term or PID Controller | |
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| Code to Play With | |
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| Identifying Input and Output Signals | |
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| Control Input and Output | |
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| Directionality of the Input/Output Relation | |
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| Examples | |
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| Thermal Control 1: Heating | |
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| Item Cache | |
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| Server Scaling | |
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| Controlling Supply and Demand by Dynamic Pricing | |
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| Thermal Control 2: Cooling | |
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| Criteria for Selecting Control Signals | |
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| For Control Inputs | |
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| For Control Outputs | |
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| A Note on Multidimensional Systems | |
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| Review and Outlook | |
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| The Feedback Idea | |
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| Iteration | |
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| Process Knowledge | |
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| Avoiding Instability | |
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| The Setpoint | |
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| Control, Not Optimization | |
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| Practice | |
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| Theory Preview | |
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| Frequency Representation | |
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| The Transfer Function | |
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| Block-Diagram Algebra | |
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| PID Controllers | |
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| Poles of the Transfer Function | |
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| Process Models | |
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| Measuring the Transfer Function | |
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| Static Input/Output Relation: The Process Characteristic | |
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| Practical Considerations | |
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| Dynamic Response to a Step Input: The Process Reaction Curve | |
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| Practical Aspects | |
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| Process Models | |
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| Self-Regulating Process | |
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| Accumulating Process | |
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| Self-Regulating Process with Oscillation | |
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| Non-Minimum Phase System | |
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| Other Methods of System Identification | |
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| PID Tuning | |
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| Tuning Objectives | |
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| General Effect of Changes to Controller Parameters | |
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| Ziegler-Nichols Tuning | |
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| Semi-Analytical liming Methods | |
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| Practical Aspects | |
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| A Closer Look at Controller Tuning Formulas | |
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| Implementation Issues | |
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| Actuator Saturation and Integrator Windup | |
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| Preventing Integrator Windup | |
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| Serpoint Changes and Integrator Preloading | |
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| Smoothing the Derivative Term | |
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| Choosing a Sampling Interval | |
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| Variants of the PID Controller | |
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| Incremental Form | |
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| Error Feedback Versus Output Feedback | |
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| The General linear Digital Controller | |
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| Nonlinear Controllers | |
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| Error-Square and Gap Controllers | |
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| Simulating Floating-Point Output | |
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| Categorical Output | |
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| Common Feedback Architectures | |
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| Changing Operating Conditions: Gain Scheduling | |
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| Gain Scheduling for Mildly Nonlinear Systems | |
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| Large Disturbances: Feedforward | |
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| Fast and Slow Dynamics: Nested or "Cascade" Control | |
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| Systems Involving Delays: The Smith Predictor | |
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| Case Studies | |
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| Exploring Control Systems Through Simulation | |
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| The Case Studies | |
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| Modeling Time | |
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| Control Time | |
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| Simulation Time | |
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| The Simulation Framework | |
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| Components | |
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| Plants and Systems | |
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| Controllers | |
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| Actuators and Filters | |
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| Convenience Functions for Standard Loops | |
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| Generating Graphical Output | |
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| Case Study: Cache Hit Rate | |
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| Defining Components | |
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| Cache Misses as Manufacturing Defects | |
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| Measuring System Characteristics | |
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| Controller Tuning | |
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| Simulation Code | |
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| Case Study: Ad Delivery | |
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| The Situation | |
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| Measuring System Characteristics | |
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| Establishing Control | |
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| Improving Performance | |
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| Variations | |
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| Cumulative Goal | |
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| Gain Scheduling | |
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| Integrator Preloading | |
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| Weekend Effects | |
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| Simulation Code | |
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| Case Study: Scaling Server Instances | |
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| The Situation | |
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| Measuring and Tuning | |
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| Reaching 100 Percent With a Nonstandard Controller | |
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| Dealing with Latency | |
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| Simulation Code | |
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| Case Study: Waiting-Queue Control | |
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| On the Nature of Queues and Buffers | |
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| The Architecture | |
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| Setup and Tuning | |
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| Derivative Control to the Rescue | |
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| Controller Alternatives | |
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| Simulation Code | |
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| Case Study: Cooling Fan Speed | |
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| The Situation | |
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| The Model | |
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| Tuning and Commissioning | |
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| Closed-Loop Performance | |
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| Simulation Code | |
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| Case Study: Controlling Memory Consumption In a Game Engine | |
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| The Situation | |
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| Problem Analysis | |
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| Architecture Alternatives | |
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| A Nontraditional Loop Arrangement | |
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| A Traditional Loop with Logarithms | |
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| Results | |
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| Simulation Code | |
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| Case Study Wrap-Up | |
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| Simple Controllers, Simple Loops | |
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| Measuring and Tuning | |
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| Staying in Control | |
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| Dealing with Noise | |
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| Theory | |
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| The Transfer Function | |
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| Differential Equations | |
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| Laplace Transforms | |
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| Properties of the Laplace Transform | |
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| Using the Laplace Transform to Solve Differential Equations | |
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| A Worked Example | |
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| The Transfer Function | |
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| Worked Example: Step Response | |
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| Worked Example: Ramp Input | |
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| The Harmonic Oscillator | |
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| What If the Differential Equation Is Not Known? | |
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| Block-Diagram Algebra and the Feedback Equation | |
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| Composite Systems | |
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| The Feedback Equation | |
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| An Alternative Derivation of the Feedback Equation | |
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| Block-Diagram Algebra | |
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| Limitations and Importance of Transfer Function Methods | |
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| PIO Controllers | |
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| The Transfer Function of the PID Controller | |
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| The Canonical Form of the PID Controller | |
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| The General Controller | |
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| Proportional Droop Revisited | |
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| A Worked Example | |
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| Poles and Zeros | |
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| Structure of a Transfer Function | |
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| Effect of Poles and Zeros | |
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| Special Cases and Additional Details | |
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| Pole Positions and Response Patterns | |
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| Dominant Poles | |
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| Pole Placement | |
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| What to Do About Delays | |
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| Root Locus Techniques | |
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| Construction of Root Locus Diagrams | |
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| Root Locus or "Evans" Rules | |
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| Angle and Magnitude Criteria | |
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| Practical Issues | |
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| Examples | |
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| Simple Lag with a P Controller | |
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| Simple Lag with a PI Controller 253 | |
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| Frequency Response and the Bode Plot | |
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| Frequency Response | |
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| Frequency Response in the Physical World | |
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| Frequency Response for Transfer Functions | |
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| A Worked Example | |
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| The Bode Plot | |
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| A Criterion for Marginal Stability | |
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| Other Graphical Techniques | |
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| Topics Beyond This Book | |
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| Discrete-Tune Modeling and the z-Transform | |
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| State-Space Methods | |
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| Robust Control | |
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| Optimal Control | |
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| Mathematical Control Theory | |
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| Appendices | |
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| Glossary | |
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| Creating Graphs with Gnuplot | |
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| Complex Numbers | |
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| Further Reading | |
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| Index | |