Inertial Navigation Error Correction Using Vehicle Immobility
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Solution Overview
Problem
Inertial navigation units in vehicles suffer from precision errors and drifts due to low-cost sensors, and reliance on satellite signals is unreliable in areas with obstructed reception, necessitating a method to improve navigation accuracy without increasing sensor costs.
Innovation Solution
A method that detects periods of vehicle immobility to determine and correct errors in inertial unit signals using data fusion algorithms and Kalman filters, incorporating Allan variance calculations to differentiate between sensor errors and actual vehicle movements, thereby enhancing navigation reliability with low-performance sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-cost inertial sensors are used, then the navigation system cost is reduced, but the measurement precision and reliability deteriorate due to errors and drifts
Solution Approach 1:
The system uses the vehicle's own immobility periods to automatically detect and correct IMU errors without external assistance. The processing unit analyzes IMU signals during stationary periods to determine position and heading errors, then applies corrections independently, enabling low-cost sensors to achieve high precision through self-calibration
Solution Approach 2:
The system implements a feedback mechanism where IMU error is continuously detected during immobility periods and fed back to correct subsequent navigation calculations. The processing unit monitors IMU signals, determines errors when the vehicle is stationary, and applies corrections to maintain accurate position and heading despite using low-cost sensors
2Measurement precision
If satellite signals are used for recalibration, then the measurement precision is improved, but the reliability deteriorates when signals are unavailable due to obstruction or jamming
Solution Approach 1:
The system prepares for satellite signal unavailability by continuously monitoring for immobility periods and building up correction data during stationary phases. This beforehand preparation ensures that when satellite signals are blocked or jammed, the system already has accumulated correction information to maintain navigation reliability without external signals
3Measurement precision
If magnetometer signals are used for recalibration, then the measurement precision is improved, but the reliability deteriorates due to interference from metallic masses
Solution Approach 1:
The system extracts and eliminates the harmful influence of metallic masses by excluding magnetometer-based recalibration from the navigation system. Instead of using magnetometer signals that are corrupted by vehicle metal structures, the system relies solely on IMU self-calibration during immobility periods, removing the source of interference entirely
4Measurement precision
If vehicle immobility periods are used for error determination, then the measurement precision is improved, but the reliability deteriorates when occupants move the vehicle during stationary periods
Solution Approach 1:
The system dynamically adapts its error detection process by continuously monitoring for actual vehicle movement during supposed immobility periods. When occupant movement is detected, the system adjusts its calibration approach, using only the portions of stationary periods where true immobility is confirmed, thereby maintaining reliability while preserving precision corrections
Data Source
AI summary
A method for navigating a vehicle equipped with an inertial navigation system, comprising the step of calculating successive vehicle positions and headings from signals from the inertial navigation system. It includes the steps of: - detecting at least one period of vehicle immobility in heading and position; - processing the signals provided by the inertial navigation system during each period of immobility, which indicate vehicle movement, to determine an error in the inertial navigation system; - taking into account the error determined in the calculation of the vehicle's position and heading from the inertial navigation system signals.