/**
 * Madgwick AHRS (Attitude and Heading Reference System) filter.
 *
 * Fuses 3-axis gyroscope and 3-axis accelerometer data into a stable
 * orientation quaternion using gradient-descent-based correction.
 *
 * Reference: Sebastian Madgwick, "An efficient orientation filter for
 * inertial and inertial/magnetic sensor arrays" (2010).
 *
 * Zero dependencies. The algorithm is ~40 lines of arithmetic.
 */
import { type Quaternion } from "./quaternion";
export declare class MadgwickFilter {
    /** Current orientation estimate. */
    q: Quaternion;
    /**
     * Filter gain. Higher values trust the accelerometer more — less
     * drift but more high-frequency noise. Lower values give smoother
     * tracking but allow more gyro drift.
     *
     * Typical range: 0.01 (very smooth) to 0.5 (aggressive correction).
     * Default 0.1 is a good general-purpose starting point.
     */
    beta: number;
    constructor(beta?: number);
    /** Reset to identity orientation. */
    reset(): void;
    /**
     * Incorporate one IMU sample.
     *
     * @param gx  Gyroscope X (pitch) in **rad/s**
     * @param gy  Gyroscope Y (yaw)   in **rad/s**
     * @param gz  Gyroscope Z (roll)  in **rad/s**
     * @param ax  Accelerometer X (any consistent unit — normalized internally)
     * @param ay  Accelerometer Y
     * @param az  Accelerometer Z
     * @param dt  Time delta in **seconds** since last sample
     */
    update(gx: number, gy: number, gz: number, ax: number, ay: number, az: number, dt: number): void;
}
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