Struct EProcessConfig 

pub struct EProcessConfig {
    pub lambda: f64,
    pub alpha: f64,
    pub beta: f64,
    pub sigma_ema_decay: f64,
    pub sigma_floor_ms: f64,
    pub warmup_frames: u32,
}

Anytime-valid e-process for gating degradation decisions.

Mathematical Model

The e-process is a nonnegative supermartingale under H₀ (system is healthy):

E_t = Π_{j=1..t} exp(λ * r_j − λ² * σ² / 2)

where:

• r_j is the standardized residual at frame j: (frame_time − target) / σ
• σ is the estimated standard deviation of frame times
• λ is a tuning parameter controlling sensitivity (default: 0.5)

Decision Rule

• Degrade only when E_t > 1/α (evidence exceeds threshold). Default α = 0.05, so we need E_t > 20.
• Upgrade only when E_t < β (evidence that overload has passed). Default β = 0.5.

Properties

1. Anytime-valid: The test is valid at any stopping time, unlike fixed-sample tests. We can check after every frame without p-hacking.
2. Bounded false positive rate: P(E_t ever exceeds 1/α | H₀) ≤ α (Ville’s inequality).
3. Self-correcting: After a burst passes, E_t decays back toward 1.0, naturally enabling recovery.

Failure Modes

• Sustained overload: E_t grows exponentially → rapid degradation.
• Transient spike: E_t grows briefly → may not cross threshold → PID handles short-term. Only persistent overload triggers e-process gate.
• σ estimation drift: We use an exponential moving average for σ with a warmup period of 10 frames to avoid unstable early estimates.

Fields

lambda: f64

Sensitivity parameter λ. Higher values detect overload faster but increase false positive risk near the boundary.

alpha: f64

Significance level α. Degrade when E_t > 1/α. Default: 0.05 (need E_t > 20 to degrade).

beta: f64

Recovery threshold β. Upgrade allowed when E_t < β. Default: 0.5.

sigma_ema_decay: f64

EMA decay for σ estimation. Closer to 1.0 = slower adaptation. Default: 0.9 (adapts over ~10 frames).

sigma_floor_ms: f64

Minimum σ floor to prevent division by zero. Default: 1.0 ms.

warmup_frames: u32

Warmup frames before e-process activates. During warmup, fall back to PID-only decisions.

Trait Implementations

impl Clone for EProcessConfig

fn clone(&self) -> EProcessConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EProcessConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for EProcessConfig

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for EProcessConfig

fn eq(&self, other: &EProcessConfig) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for EProcessConfig