/**
 * Configuration options for the Multi-Sensor EKF.
 */
export interface MultiSensorEKFOptions {
    /**
     * Half-life for uncertainty growth in milliseconds.
     * The state uncertainty doubles every halfLifeMs when no measurements arrive.
     * Lower values = faster decay of old estimates.
     * @default 10000 (10 seconds)
     */
    halfLifeMs: number;
}
/**
 * Default options for MultiSensorEKF.
 */
export declare const DEFAULT_EKF_OPTIONS: MultiSensorEKFOptions;
/**
 * Multi-sensor Extended Kalman Filter for position fusion.
 *
 * Combines position measurements from multiple sources (GPS, VPS, anchors) and
 * displacement measurements from PDR using a constant-velocity motion model.
 *
 * Key features:
 * - All methods take explicit timestamps (no Date.now() inside)
 * - Confidence-weighted fusion via measurement noise parameter
 * - Half-life decay of old estimates via process noise scaling
 * - Supports both absolute position and relative displacement updates
 *
 * State vector: [latitude, longitude, velocity_lat, velocity_lon]
 *
 * @example
 * ```ts
 * const ekf = new MultiSensorEKF({ halfLifeMs: 10000 });
 *
 * // Initialize with first position
 * ekf.updatePosition(43.123, -79.456, 0.0001, 0);
 *
 * // Predict forward
 * ekf.predict(1000);
 *
 * // Update with new GPS measurement (low confidence = high noise)
 * ekf.updatePosition(43.124, -79.455, 0.001, 1000);
 *
 * // Get fused position
 * const pos = ekf.getPosition(); // { latitude: ~43.1235, longitude: ~-79.4555 }
 * ```
 */
export declare class MultiSensorEKF {
    #private;
    constructor(options?: Partial<MultiSensorEKFOptions>);
    /**
     * Predict step: project state forward to the given timestamp.
     * Increases uncertainty based on elapsed time and half-life configuration.
     *
     * @param timestampMs - Current timestamp in milliseconds
     */
    predict(timestampMs: number): void;
    /**
     * Update state with a position measurement (GPS, VPS, anchor).
     *
     * @param latitude - Measured latitude in degrees
     * @param longitude - Measured longitude in degrees
     * @param measurementNoise - Measurement noise variance (higher = less trust)
     * @param timestampMs - Measurement timestamp in milliseconds
     */
    updatePosition(latitude: number, longitude: number, measurementNoise: number, timestampMs: number): void;
    /**
     * Update state with an odometry measurement (PDR displacement).
     *
     * Unlike position updates, odometry provides relative displacement rather than
     * absolute position. The displacement is added directly to the state.
     *
     * @param dx - Displacement east in meters (positive = east)
     * @param dy - Displacement north in meters (positive = north)
     * @param measurementNoise - Measurement noise variance (higher = less trust)
     * @param timestampMs - Measurement timestamp in milliseconds
     */
    updateOdometry(dx: number, dy: number, measurementNoise: number, timestampMs: number): void;
    /**
     * Get the current position estimate.
     * @returns Position or null if filter not initialized
     */
    getPosition(): {
        latitude: number;
        longitude: number;
    } | null;
    /**
     * Get the current velocity estimate.
     * @returns Velocity in degrees per second, or null if filter not initialized
     */
    getVelocity(): {
        vLat: number;
        vLon: number;
    } | null;
    /**
     * Get the current position uncertainty (trace of position covariance).
     * Higher values indicate less certainty in the position estimate.
     * @returns Uncertainty value, or Infinity if filter not initialized
     */
    getUncertainty(): number;
    /**
     * Get the last update timestamp.
     * @returns Timestamp in ms, or null if filter not initialized
     */
    getLastTimestamp(): number | null;
    /**
     * Check if the filter has been initialized with at least one measurement.
     */
    isInitialized(): boolean;
    /**
     * Reset the filter state.
     * Call on floor changes, large position jumps, or time gaps.
     */
    reset(): void;
}