Fault detection and isolation

A control-engineering discipline that detects departures from expected system behavior and determines the likely fault type, location or component before recovery action.

Version

v1 · 2026-09-08 · History

Domain-specific #

4517

Origin domain

control engineering

Subdomain

specialized structures

Core Idea

FDI separates recognizing that something is wrong from identifying which fault best explains the evidence. Observed and predicted behavior generate residuals whose structured patterns or classifiers distinguish normal uncertainty from candidate failure modes. The abstraction is therefore identified by a declared carrier, a transformation or constraint over that carrier, and an invariant that tells an analyst whether the named structure is genuinely present.

The load-bearing residual is not the broad topic of control engineering. It is A control-engineering discipline that detects departures from expected system behavior and determines the likely fault type, location or component before recovery action.

Scope of Application

Fault detection and isolation belongs to control engineering and is useful where the analyst can specify a monitored plant, sensors, model or learned baseline, residual signals, thresholds, fault hypotheses, isolation logic and recovery interface, then evaluate detection meets the declared false-alarm and delay criteria and isolation uniquely or probabilistically attributes the fault within the modeled hypothesis set. The scope is broad within that domain but bounded by the need for detection meets the declared false-alarm and delay criteria and isolation uniquely or probabilistically attributes the fault within the modeled hypothesis set. Conceptual diagnostic-control identity only; safety-critical recovery requires validated system-specific engineering.

Clarity

The abstraction clarifies a crowded vocabulary by making detection meets the declared false-alarm and delay criteria and isolation uniquely or probabilistically attributes the fault within the modeled hypothesis set the center of the account. A claim should name the carrier, the governing operation or relation, the applicable assumptions, and the recognition test. A bare label is insufficient because the name Fault detection and isolation can be used for a formal identity, an implementation, or a neighboring result unless carrier and convention are stated.

Manages Complexity

Without the abstraction, an analyst must reason directly over many local details: the carrier roles, admissibility assumptions, competing conventions, derived invariants, boundary cases, and proof or validation obligations specific to Fault detection and isolation. Fault detection and isolation compresses them into the roles in the structural signature. That compression permits comparison across instances without erasing the variables that determine validity. It also exposes which details may be varied safely and which are constitutive.

Abstract Reasoning

1. Identify the carrier. State what the elements, states, objects, or observations are: a monitored plant, sensors, model or learned baseline, residual signals, thresholds, fault hypotheses, isolation logic and recovery interface. Reject examples whose alleged carrier belongs to a different problem. 2. Lock the constitutive rule. Express detection meets the declared false-alarm and delay criteria and isolation uniquely or probabilistically attributes the fault within the modeled hypothesis set independently of one notation or implementation.

Knowledge Transfer

Knowledge transfers strongly among subfields of control engineering because they reuse a monitored plant, sensors, model or learned baseline, residual signals, thresholds, fault hypotheses, isolation logic and recovery interface, Observed and predicted behavior generate residuals whose structured patterns or classifiers distinguish normal uncertainty from candidate failure modes., and type the carrier, state every parameter and convention in the definition, test that detection meets the declared false-alarm and delay criteria and isolation uniquely or probabilistically attributes the fault within the modeled hypothesis set, compare the nearest accepted identity, and report counterexamples, uncertainty, and limiting cases.

Relationships to Other Abstractions

Current abstraction Fault detection and isolation Domain-specific

Parents (1) — more general patterns this builds on

• Fault detection and isolation is a kind of Fault Tolerance Prime

  The proposed strict upward parent is prime:fault_tolerance.

Hierarchy paths (3) — routes to 3 parentless roots

• Fault detection and isolation → Fault Tolerance → Robustness

Show alternative paths (2)

Neighborhood in Abstraction Space

Fault detection and isolation sits in a moderately populated region (44^th percentile for distinctiveness): it has near-neighbors but no dense thicket of look-alikes.

Family — Unclustered & Miscellaneous (1565 abstractions)

Nearest neighbors

• System identification — 0.90
• Distribution-free control chart — 0.89
• Failure detector — 0.89
• Separation principle — 0.89
• Failure cause — 0.89

Computed from structural-signature embeddings · 2026-09-08