Feedback Systems¶
Åström, K. J., & Murray, R. M. (2008). Feedback Systems: An Introduction for Scientists and Engineers. Princeton University Press.
Cited by¶
13 citations across 13 artifacts.
Each citation links to the sentence it supports in the citing article.
Primes¶
- Circuit Breaker
This sourceCanonical feedback-control text: develops continuous regulation toward a setpoint (PID) versus discrete switched action, and treats relay feedback with hysteresis as the standard remedy for chattering.
- Controllability
- T2 — Controllability versus stability / unintended consequences
This sourceIntroductory control text covering feedback, stability, time delays, and nonlinear effects across physical/biological/economic systems.
- T2 — Controllability versus stability / unintended consequences
- Discrepancy-Driven Correction
- In engineering control theory the setpoint is compared to the plant output, the gap is the error signal, the controller's gain function maps error to actuation, and the loop is the closed-loop control system.
This sourceSetpoint–error–actuation loop, PID control, gain-and-stability and the integral term for steady-state error.
- In engineering control theory the setpoint is compared to the plant output, the gap is the error signal, the controller's gain function maps error to actuation, and the loop is the closed-loop control system.
- Homeostasis
- homeostasis sits at the intersection of three companion abstractions (#390 observability, #391 controllability, #387 requisite variety); (3) homeostasis delivers a resilience strategy against perturbation — as long as disturbances fit within the mechanism's envelope (correction authority, response speed, variety coverage), the system maintains essential variables within tolerance; outside the envelope, homeostasis fails catastrophically (hypothermia, runaway inflation, cascading cellular stress) —
This sourceCanonical feedback-control text: develops continuous regulation toward a setpoint (PID) versus discrete switched action, and treats relay feedback with hysteresis as the standard remedy for chattering.
- homeostasis sits at the intersection of three companion abstractions (#390 observability, #391 controllability, #387 requisite variety); (3) homeostasis delivers a resilience strategy against perturbation — as long as disturbances fit within the mechanism's envelope (correction authority, response speed, variety coverage), the system maintains essential variables within tolerance; outside the envelope, homeostasis fails catastrophically (hypothermia, runaway inflation, cascading cellular stress) —
- Measurement and Disturbance
- Control systems: Monitoring a system's state through sensors and actuators necessarily couples the system to the controller; the control action itself disturbs the plant, requiring careful design to minimize overshoot and oscillation, as Åström and Murray (2008) develop in their foundational treatment of feedback systems.
This sourceCanonical feedback-control text: develops continuous regulation toward a setpoint (PID) versus discrete switched action, and treats relay feedback with hysteresis as the standard remedy for chattering.
- Control systems: Monitoring a system's state through sensors and actuators necessarily couples the system to the controller; the control action itself disturbs the plant, requiring careful design to minimize overshoot and oscillation, as Åström and Murray (2008) develop in their foundational treatment of feedback systems.
- Monitoring
- The feedback-loop structure builds on monitoring but is not identical to it.
This sourceCanonical feedback-control text: develops continuous regulation toward a setpoint (PID) versus discrete switched action, and treats relay feedback with hysteresis as the standard remedy for chattering.
- The feedback-loop structure builds on monitoring but is not identical to it.
- Non-Stationary Objective
- In control theory, the explicit distinction between regulator problems (constant set-point) and tracking problems (time-varying set-point) turns on the loop time-constant relative to the reference's rate of change.
This sourceStandard control-theory text covering the regulator (constant set-point) versus tracking (time-varying reference) distinction and how loop bandwidth relative to the reference's rate of change governs tracking error.
- In control theory, the explicit distinction between regulator problems (constant set-point) and tracking problems (time-varying set-point) turns on the loop time-constant relative to the reference's rate of change.
- Stability
- Dynamical systems and control engineering (canonical): Lyapunov stability of equilibria; stable versus unstable fixed points; closed-loop stability via gain and phase margins; the PID controller exists to induce stability where it is absent.
This sourceStandard reference on closed-loop stability, gain and phase margins, and the PID controller's stabilizing role.
- Dynamical systems and control engineering (canonical): Lyapunov stability of equilibria; stable versus unstable fixed points; closed-loop stability via gain and phase margins; the PID controller exists to induce stability where it is absent.
- Withdrawal Rebound
- In engineering control it is integrator wind-up: an integral controller wound up against a saturated actuator overshoots sharply when the disturbance is removed.
This sourceDefines the PI controller u(t)=Kp e(t)+Ki∫e dτ, integrator wind-up against a saturated actuator, and the resulting overshoot when the disturbance is removed.
- In engineering control it is integrator wind-up: an integral controller wound up against a saturated actuator overshoots sharply when the disturbance is removed.
Mechanisms¶
- Hysteresis or Deadband Window
- Its strength is that it is the cheapest cure for chatter: a loop that oscillates only because it keeps chasing sub-threshold reversals is stabilised outright, and the two-edged behaviour that makes this work is textbook hysteresis
This sourceShows how hysteresis keeps noisy threshold crossings from causing jitter by making switching depend on prior input.
- Its strength is that it is the cheapest cure for chatter: a loop that oscillates only because it keeps chasing sub-threshold reversals is stabilised outright, and the two-edged behaviour that makes this work is textbook hysteresis
- Motor-Command Echo Routing
- This is the transport-delay problem familiar from control theory, where an unaccounted lag between a command and its observed effect destabilizes the loop.
This sourceExplains transport delay as command-to-response lag whose phase effect can destabilize a feedback loop.
- This is the transport-delay problem familiar from control theory, where an unaccounted lag between a command and its observed effect destabilizes the loop.
- Net-Flow Lever Adjustment
- A policy that reacts only when the level hits a threshold, and then moves a big lever, behaves like bang-bang control — it slams fully on
This sourceShows that thresholded on–off control switches between maximum and minimum action and often oscillates because small errors drive the actuator through its full range.
- A policy that reacts only when the level hits a threshold, and then moves a big lever, behaves like bang-bang control — it slams fully on
- Phase Margin or Dead-Time Test
- The margin is only as good as the characterization: a linear test on a nonlinear loop
This sourceExplains that a stability margin depends on the system characterization and that linearization of a nonlinear system is local to a chosen operating point.
- The margin is only as good as the characterization: a linear test on a nonlinear loop
Verification¶
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Links previously used in the corpus¶
Before the registry existed this work was also linked 5 other ways.
- https://press.princeton.edu/books/hardcover/9780691135762/feedback-systems ×3
- https://authors.library.caltech.edu/records/yzs24-xsx88 ×2
- https://assets.press.princeton.edu/catalogs/math10.pdf ×1
- https://doi.org/10.2307/j.ctvcm4gdk ×1
- https://www.cds.caltech.edu/~murray/books/AM08/pdf/am08-complete_22Feb09.pdf ×1
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