Measurement Framework

Simulation Fidelity Must Be Measured

If simulation cannot be measured structurally, it cannot be trusted as a training system.

Simulation Fidelity Rating (SFR) is a structured method for evaluating whether a system delivers physically and neurologically valid training. It is not a style score, a comfort score, or an immersion score. It is a training-validity framework.

Definition Architecture Measurement Classification Consequences Impact Evaluation Determination

What SFR Measures


SFR evaluates whether a simulation system preserves the structure, timing, and integration required for correct human learning. The goal is not visual believability alone. The goal is correct training.

SFR = DOF + Vestibular Load + Sync + Unified Feel
DOF

Degrees of Freedom

Whether the system provides the required degrees of freedom in a physically meaningful way, including independence of axes and relevance to vehicle dynamics.

Vestibular Load

Vestibular Load

Whether the system delivers usable rotational and translational cues that the vestibular system can interpret correctly.

Vestibular Load reflects the system's ability to deliver correct rotational perception timing. Full treatment is provided on the yaw in simulation page.
Sync

Synchronization

Whether motion, visuals, force feedback, and software outputs remain temporally aligned.

Unified Feel

Unified Feel

Whether the system behaves as a coherent whole rather than a collection of disconnected effects.

What SFR Does Not Measure


A simulator can feel intense and still train incorrectly.

Three Layers of Measurement


1
Physics Truth Layer
Measures whether the system reflects real vehicle dynamics.
  • Center-of-mass alignment
  • Rotational accuracy
  • Translational accuracy
  • Independent degrees of freedom
  • Absence of cross-axis contamination
2
System Coherence Layer
Measures whether the system functions as a unified real-time environment.
  • Motion to visual latency
  • Motion to control alignment
  • Hardware and software synchronization
  • Signal phase consistency
  • Stability under load
3
Human Transfer Layer
Measures whether the system preserves correct timing and perception in the user.
  • Vestibular validity
  • Sensory integration stability
  • Reaction time preservation
  • Absence of delay-based adaptation
  • Neurological relevance

Vestibular validity and neurological relevance in this layer are grounded in correct rotational perception and motion timing. Full treatment is on the yaw in simulation page.

Failure in any single layer compromises training validity.

Why Measurement Matters


Simulation is not neutral. If the architecture is wrong, the motion is wrong. If the motion is wrong, the learning is wrong. SFR exists to separate valid training systems from systems that only appear realistic.

Step 1Wrong structure
Step 2Wrong motion
Step 3Wrong timing
Step 4Wrong learning
Step 5Wrong performance

How SFR Is Interpreted


High SFR

Structurally Valid Training System

  • Likely in-the-loop
  • Supports correct timing and transfer
  • All three measurement layers satisfied
Moderate SFR

Partial Fidelity

  • Some valid components
  • Incomplete system integrity
  • Limited transfer potential
Low SFR

Significant Structural Limitations

  • Structural deficiencies across multiple layers
  • May reinforce incorrect timing
  • False cue relationships likely

Extended Validation Layer


Where laboratory or instrumented validation exists, SFR can be extended through additional measured performance variables.

Total Fidelity = SFR × G × (1 + NA)
Optional extended formula for instrumented validation only
G: Measured Force Output

Measured force output, only when instrumented data exists.

NA: Neurological Accuracy

Neurological Accuracy or Equivalency, only when independently measured. Scientific basis on the yaw in simulation page.

These variables are optional and should only be used when validated by instrumented testing. Systems should not be penalized for absent lab data, but validated systems may be distinguished by it.

Typical System Profiles


System Type Expected SFR Profile Measurement Observations
True CoM Independent DOF System High All three measurement layers satisfy criteria independently
Stewart Platform / Hexapod Moderate to Limited Axis coupling reduces DOF score; yaw continuity limited by platform geometry
Seat Mover Limited Motion not CoM-referenced; reduced synchronization and vestibular layer scores
Four-Post / D-BOX Type System Limited Primarily vertical displacement; rotational layer scores incomplete
Static Simulator Low No motion layer present; vestibular and synchronization scores not applicable
System classification is determined on the classification page using these measurement outcomes.

How Measurement Maps to Classification


SFR produces a measurement outcome. Classification interprets that outcome within the framework's category structure. High SFR scores are generally associated with in-the-loop systems. Lower scores indicate increasing structural limitations. Formal category definitions are owned by the classification page.

For structural category definitions, system-type mapping, and the in-the-loop standard, see the classification page.

View Classification Standard →

Determination


A simulation system is only valid if it preserves the structure, timing, and integration required for correct human learning.

If the timing is wrong, the training is wrong.

Common Misunderstandings


Does more movement mean higher fidelity?

No. Correctness matters more than magnitude.

Does actuator count determine fidelity?

No. Independence, origin, and timing matter more than quantity.

Can a visually impressive simulator still score poorly?

Yes. Spectacle does not guarantee structural validity.

Why is vestibular load included?

Because the brain depends on motion timing, not visuals alone, to build correct reactions.

Continue Through the Framework


Applied Framework

See How Systems Compare

Framework-based interpretations highlight how different system architectures align with or diverge from training-valid standards.

View Interpretations →
Application Layer

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Apply the framework to a real system, environment, or use case through a structured review pathway.

For teams, facilities, researchers, and organizations seeking structured classification or review.

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