Ultratightly Coupled Navigation System Inertial Error Compensation
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Solution Overview
Problem
Navigation systems face challenges in maintaining accuracy in signal challenging environments due to inertial errors and signal interference, particularly in acquiring and tracking GPS signals, which can lead to instability and prolonged signal re-acquisition times.
Innovation Solution
An extended ultratightly coupled navigation system architecture employing an extended Kalman Filter and Pre-Filter algorithm, combined with an inertial compensation unit and stochastic regulator, to mitigate inertial errors and provide stable and accurate geolocation information, even in indoor and urban environments, by using distributed adaptive algorithms for control and estimation of stochastic processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inertial navigation systems are combined with GPS tracking in ultratightly coupled architectures, then tracking accuracy is enhanced, but inertial errors accumulate and degrade navigation accuracy
Solution Approach 1:
The patent implements a feedback mechanism where GPS measurements are used to correct inertial navigation system errors. The system continuously compares inertial predictions with actual GPS measurements and feeds back correction signals to compensate for inertial drift, thereby maintaining navigation accuracy over time despite inertial error accumulation
Solution Approach 2:
The patent introduces an intermediary correction mechanism that processes both inertial and GPS data separately before combining them. This intermediary layer filters and reconciles the two data streams, using GPS to correct inertial errors while preserving the high-rate inertial navigation output, thus resolving the contradiction between enhanced tracking and maintained accuracy
2Measurement precision
If signal processing complexity is increased to maintain accuracy in challenging environments, then position accuracy is improved, but computational intensity and system size increase
Solution Approach 1:
The patent performs preliminary processing of inertial and GPS data separately before their combination. By pre-processing and organizing the data streams in advance, the system reduces the computational burden during the critical fusion stage, maintaining high position accuracy while lowering overall computational intensity and system complexity
3Reliability
If GPS signal tracking is maintained in interference environments, then navigational information is obtained, but signal acquisition time increases after signal loss
Solution Approach 1:
The patent prepares the system in advance for signal loss by maintaining inertial navigation capability that can operate independently. When GPS signals are lost or degraded, the pre-prepared inertial system provides immediate continuity of navigational information, cushioning against the time delay that would otherwise occur during signal re-acquisition
Data Source
AI summary
A present invention embodiment includes a navigation system with a front-end GPS receiver, auxiliary sensors and a digital signal processor providing filtering and other processing. The navigation system enhances a UTC type architecture by employing an inertial compensation unit and a stochastic regulator. The inertial compensation unit compensates for inertial errors within the sensors, while the stochastic regulator applies an optimal stochastic control law to control system operation. The inertial compensation unit and stochastic regulator mitigate instability within the navigation system and provide: the functionality to attain high position accuracy in the sub-meter range that is stable and reliable; an optimal solution evident in the process of signal recovery time after loss and reacquisition, thereby resulting in signal-loss recovery with an order of magnitude improvement; and the ability to mitigate inertial errors that originate in the sensors. The navigation system provides navigation information for indoor and urban environmental conditions.