Spanda

State Estimation

State estimation declares sensor fusion inputs and estimate types for mission assurance.

Syntax

state_estimator RoverState {
    inputs [gps.fix, imu.data, wheel_odometry];
    output StateEstimate;
}

Core types

Type	Role
`StateEstimate`	Named estimate with confidence and source attribution
`BeliefState`	Aggregated estimates from all estimators
`SensorFusionState`	Per-estimator fusion snapshot

Analysis

spanda state estimate <file.sd> runs static analysis:

Extracts estimator inputs and weighted fusion previews (by sensor type)
Builds an aggregate belief state
Validates non-empty inputs

Results are also included in spanda assure JSON under state.

Runtime

At robot setup, each state_estimator registers a SensorFusion binding. A single estimator aliases fusion (same as observe { }). fusion.read() / {Name}.read() perform weighted fusion by sensor type (GPS, Lidar, IMU, …), include sources and estimator fields, and populate state_estimate.confidence.

Optional spanda-fusion package (import assurance.fusion;) exposes the same weight table via weight_for_sensor and confidence_for_types for custom tooling.

Example

See examples/assurance/rover_assurance.sd.

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