Gravity Compensation Techniques in Inertial Navigation Systems

Gravity compensation in inertial navigation systems (INS) addresses the errors introduced by local variations in the Earth’s gravitational field and by sensor biases, both of which degrade positioning accuracy over time. Modern INS employ strapdown architectures in which accelerometers and gyroscopes measure linear and angular motion directly in the vehicle frame. Uncompensated gravity disturbance vectors, arising from deflections of the vertical and topographic anomalies, induce Schuler oscillations and horizontal drift in long-duration navigation. Compensation techniques fall broadly into model-based methods—using high-degree spherical harmonics or empirical regional polynomials—and data-driven schemes that estimate local gravity disturbance from onboard measurements. Hybrid approaches integrate global gravity models such as the Earth Gravitational Model 2008 (EGM2008) with real-time sensor outputs, filtering and machine-learning algorithms to update gravity corrections along the trajectory. Vehicle-borne and airborne gravimetry experiments further refine compensation by directly measuring local gravity vectors, enabling sub-mGal accuracy in applications ranging from marine navigation to airborne geodesy. Advances in micro-electromechanical systems (MEMS) and laser Doppler velocimetry (LDV) have improved the precision of onboard gravity sensing, while algorithms to estimate accelerometer bias from gravity vector residuals ensure long-term stability. Together, these innovations underpin the global deployment of high-precision INS in autonomous vehicles, UAVs and marine vessels, delivering reliable navigation in GPS-denied environments.

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Research from all publishers

One study has demonstrated a vehicle-borne gravity vector measurement method by integrating strapdown INS with GNSS and laser Doppler velocimetry, achieving internal coincidence accuracy within 3.3 mGal at 1.7 km without post-error compensation and improving vertical gravity vector accuracy by up to 38 %. A separate investigation using a compact MEMS-based INS/GNSS unit on static platforms and unmanned aerial vehicles has shown that, after thermal bias correction and extensive filtering, the system can recover periodic Earth tide signals and isolate local gravity variations linked to topography. A foundational work has applied the EGM2008 spherical harmonic model to compute real-time gravity vectors for high-precision long-term INS, optimising the calculation to sub-second execution and demonstrating attenuation of Schuler oscillation and reduction of horizontal position error by nearly 50 % in rugged terrain.

Gravity Compensation Techniques in Inertial Navigation Systems publication trend

The graph below shows the total number of articles in gravity compensation techniques in inertial navigation systems across all publications each year (not limited to Nature Index journals).

Technical terms

Inertial navigation system (INS): A self-contained system using accelerometers and gyroscopes to determine position and orientation without external references.

Strapdown INS (SINS): An INS configuration in which sensors are rigidly fixed to the vehicle frame, requiring mathematical transformation to the navigation frame.

Gravity disturbance vector: The local deviation of the true gravity field from the normal gravity, causing horizontal components that affect inertial measurements.

Deflection of the vertical (DOV): The angular deviation between the true plumb line and the ellipsoidal normal, contributing to horizontal gravity disturbances.

Earth Gravitational Model 2008 (EGM2008): A high-degree spherical harmonic representation of the Earth’s gravity field used for gravity vector computation.

Accelerometer bias: A systematic error in accelerometer output that, if uncorrected, accumulates into navigation drift over time.

References

1. Vehicle-Borne Gravity Vector Measurement Method Based on SINS/GNSS/LDV Integrated Navigation. IEEE Access (2024).
2. Using a SPATIAL INS/GNSS MEMS Unit to Detect Local Gravity Variations in Static and Mobile Experiments: First Results. Sensors (2023).
3. Gravity Compensation Using EGM2008 for High-Precision Long-Term Inertial Navigation Systems. Sensors (2016).