Closed-loop vs. Open-loop Kalman Filter Architectures in Airborne Aided Inertial Navigation
2026-07-03 • Robotics
Robotics
AI summaryⓘ
The authors compare two ways of improving navigation systems that use inertial sensors: closed-loop (feedback) and open-loop (feedforward) designs. Closed-loop systems constantly correct their errors using feedback, which helps keep them stable over time. Open-loop systems keep sensors separate to allow for safety and fault detection but may have less smooth performance. Their simulations show how each approach works differently depending on the quality of the sensors used, highlighting trade-offs between smoothness and long-term stability. This helps understand how design choices affect navigation accuracy and reliability.
Kalman filterinertial navigation system (INS)closed-loop systemopen-loop systemerror-state estimationsensor fusionaided inertial navigationgeodetic coordinatesinertial sensorsfault isolation
Authors
Antonia Hager, Torleiv H. Bryne
Abstract
Closed-loop (or feedback) error-state Kalman filters with their relatives and offspring are the state-of-the-art in modern aided inertial navigation research. Estimated inertial navigation system (INS) errors are continually fed back to the INS to correct the nominal system state before subsequent predictions. Conversely, in safety-critical aeronautical applications, open-loop (or feedforward) systems are an undisputed standard, where the inertial mechanization is strictly decoupled to allow for operational independence and fault isolation of computing units. We assess the performance impacts of this architectural choice beyond qualitative system-safety justifications using a standard inertial mechanization in geodetic coordinates and direct position aiding. Simulations using a variety of inertial sensor error characteristics, ranging from consumer to navigation grade systems, showcase the trade-off between smooth information fusion for high-end IMUs using an open-loop filter and the inherent long-term stability of the closed-loop architecture.