OpenGNC is a professional-grade, high-fidelity Guidance, Navigation, and Control (GNC) library for spacecraft simulation, orbital mechanics, and mission analysis. Built with SI units and aerospace standards, it provides a comprehensive suite of tools for satellite engineers and researchers.
Explore the Documentation | View Examples | Contributing
- SI Unit Compliance: All calculations strictly use SI units (meters, kilograms, seconds, radians) unless otherwise explicitly suffixed.
- High-Fidelity Environment: Integrated models for NRLMSISE-00 density, IGRF-13 magnetic fields, and EGM2008 gravity harmonics.
- Validated Algorithms: Implementations of industry-standard filters (MEKF, UKF) and deterministic methods (QUEST, TRIAD).
- Optimization Ready: Built-in support for Optimal Control (LQR) and Model Predictive Control (MPC) using CasADi.
- Modular Architecture: Easily swap integrators, disturbance models, or sensors for customized simulations.
- Atmospheric Models: NRLMSISE-00 (high-fidelity), Harris-Priester (diurnal bulge), and Exponential density.
- Geomagnetic Models: IGRF-13 (International Geomagnetic Reference Field) and Tilted Dipole models.
- Solar & Ephemeris: Analytical solar position, shadow models (Umbra/Penumbra), and Planetary ephemeris.
- Gravity Field: Recursive EGM2008 Spherical Harmonics (up to N-degree), J2, and Two-body attraction.
- Propagators: Cowell’s Method, Keplerian elements, and SGP4 for TLE propagation.
- Numerical Integrators: High-order fixed and adaptive steps: RK4, RK45 (Runge-Kutta-Fehlberg), and DOP853.
- Orbital Maneuvers: Hohmann transfer, Bi-elliptic, Phasing, Plane changes, and Lambert Targeting.
- Initial Orbit Determination (IOD): Robust Gauss, Laplace, and universal variable methods.
- Kinematics: Quaternion, Euler Angle, and DCM (Direction Cosine Matrix) transformations.
- Dynamics: Euler's equations for rigid body rotation, including variable inertia and disturbances.
- Determination: Deterministic TRIAD and QUEST algortihms for attitude from vector observations.
- State Estimation:
- MEKF: Multiplicative Extended Kalman Filter for attitude.
- UKF: Unscented Kalman Filter for non-linear state estimation.
- EKF/KF: Standard and Extended Kalman Filters for orbital state mapping.
- Control Law Design:
- Classic: PID controllers and B-Dot detumbling logic.
- Optimal: LQR (Linear Quadratic Regulator) and LQE (Kalman Filter design).
- Advanced: Nonlinear MPC (Model Predictive Control) and Sliding Mode Control.
- Sensors: Realistic Star Tracker, Sun Sensor, Magnetometer, and Gyroscope models with bias/noise.
- Actuators: Model Reaction Wheels (saturation/jitter) and Thrusters (Chemical/Electric).
- FDIR (Fault Detection): Parity Space methods, Residual Generation, and Safe Mode logic.
- SSA (Space Situational Awareness): Conjunction Assessment (CAT), Maneuver Detection, and TLE interface.
-
Mission Design:
$\Delta v$ Budgeting, Communication Link Budgets, and Ground Station Coverage tools. - EDL (Entry, Descent, Landing): Ballistic & Lifting entry dynamics, heating models, and Aerocapture guidance.
- Ground Segment: CCSDS packet formatting, decommutation, and telemetry data-link layers.
- 3D Trajectories: Interactive Plotly-based orbital trajectory and attitude visualization.
- Telemetry Dashboards: Web-based GNC dashboards using Dash for real-time like simulation monitoring.
- Coordinate Frames: Visualizers for ECI, ECEF, Hill (RSW), and Body frame transformations.
- Static Allocation: Core Kalman Filters (MEKF, UKF) are implemented in header-only C++17/20 with strict static memory allocation (no
malloc/newin hot paths). - SIMD Acceleration: Full Eigen integration for vectorized matrix operations on ARM and x86 architectures.
- Lock-Free Communication: High-speed, wait-free SPSC (Single-Producer Single-Consumer) Queue for telemetry and command dispatching.
- Monte Carlo Harness: Scale simulations to 10,000+ runs with parallel processor execution.
- Statistical Analyzer: Built-in tools for 3-Sigma margin proofs, convergence rates, and stability limits.
- Consistency Verification: Automated NIS (Normalized Innovation Squared) and NEES tests to validate filter optimality against stochastic truth.
pip install opengncpip install "opengnc[mpc]"git clone https://github.com/BatuhanAkkova/opengnc.git
cd opengnc
pip install -e ".[dev]"import numpy as np
from opengnc.environment.mag_field import igrf_field
from opengnc.kalman_filters.mekf import MEKF
from opengnc.utils.quat_utils import quat_rot
# Get Earth's magnetic field at a specific ECI position
B_vec = igrf_field(pos_eci=np.array([7000e3, 0, 0]), time="2024-01-01")
# Initialize a Multiplicative Extended Kalman Filter
mekf = MEKF(q_init=np.array([0, 0, 0, 1]), covariance=1e-3 * np.eye(6))| Application | Description | Visualization | Script |
|---|---|---|---|
| CubeSat Detumbling | B-Dot magnetic control using noisy magnetometer data. |  |
01_cubesat_detumbling.py |
| MPC Rendezvous | Optimal multi-burn approach in GEO using NMPC. |  |
04_autonomous_rendezvous.py |
| MEKF Estimation | High-fidelity orientation tracking fusing star tracker & gyro. |  |
05_attitude_estimation_mekf.py |
| VLEO Maintenance | Altitude keeping in high-drag orbits using electric propulsion. |  |
02_vleo_orbit_maintenance.py |
| Gauss IOD | Initial Orbit Determination from 3-LoS vectors. |  |
10_gauss_iod_determination.py |
| Viz & Plots | Comprehensive orbital and attitude visualization demo. |  |
11_visualization_demo.py |
| Mission Sim | Core demonstration of the simulation and logging framework. | - | example_simulation.py |
Distributed under the MIT License. See LICENSE for more information.
Contributions are welcome! Please see CONTRIBUTING.md for guidelines. For support or feedback, please contact Batuhan Akkova.