kalman_dr 0.1.0

4D Extended Kalman Filter for dead reckoning during GPS loss. Covariance-driven accuracy with EKF and linear extrapolation modes. Pure Dart, no native dependencies.

kalman_dr

Kalman filter dead reckoning for Dart location services.

A 4D Extended Kalman Filter that predicts position through GPS loss using covariance-driven accuracy reporting. Pure Dart, no native dependencies.

Features

• 4D state vector: latitude, longitude, speed, heading
• Covariance-driven accuracy: honestly degrades over time during GPS loss
• Safety cap: stops at 500m accuracy — no false confidence
• Two modes: EKF (full) and linear extrapolation (lightweight)
• Decorator pattern: wraps any LocationProvider transparently

Usage

import 'package:kalman_dr/kalman_dr.dart';

// Create a Kalman filter
final kf = KalmanFilter();

// Predict position forward by 1 second
final predicted = kf.predict(const Duration(seconds: 1));

// Update with a GPS measurement
final updated = kf.update(
  latitude: 35.1709,
  longitude: 136.8815,
  accuracy: 5.0,
  speed: 12.5,
  heading: 90.0,
);

Wrap a location provider

final provider = DeadReckoningProvider(
  inner: SimulatedLocationProvider(),
  mode: DeadReckoningMode.kalman,
);

provider.positions.listen((position) {
  // Receives GPS when available, Kalman predictions when GPS is lost
  print('${position.latitude}, ${position.longitude} '
      '(accuracy: ${position.accuracyMetres}m)');
});

Safety Classification

ASIL-QM (display only). The filter provides position estimates for display purposes. It does not control vehicle systems. When accuracy exceeds the 500m safety cap, the provider stops emitting positions rather than showing unreliable data.

License

BSD-3-Clause — see LICENSE.