Navigation Equipment Heading Detection Multipath Error Reduction
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Solution Overview
Problem
Navigation equipment in urban areas faces reduced availability and large positioning errors due to multipath propagation and reduced satellite visibility, leading to incorrect vehicle positioning and route guidance.
Innovation Solution
The navigation equipment includes a radio wave receiving unit, signal processing unit, GPS satellite behavior estimating unit, pseudo range error estimating unit, user position observing unit, user velocity and heading observing unit, and user heading searching unit to identify pseudo range errors and detect vehicle heading even with one or two GPS satellites, reducing multipath propagation influence without reducing availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS positioning is used in urban areas with buildings, then vehicle position can be measured, but multipath propagation causes large positioning errors
Solution Approach 1:
The patent introduces dead reckoning sensor data as an intermediary to bridge GPS positioning errors caused by multipath propagation. The system combines GPS position measurements with dead reckoning velocity and heading information to compute corrected position estimates, effectively using the dead reckoning system as a mediator to counteract multipath errors.
Solution Approach 2:
The patent implements feedback by continuously comparing GPS-derived position with dead reckoning-derived position and using the difference to correct ongoing positioning estimates. The system feeds back the corrected position information to improve subsequent positioning accuracy, creating a closed-loop error correction mechanism.
2Reliability
If GPS positioning is used in urban areas with buildings, then vehicle position can be measured, but reduced satellite visibility reduces availability
Solution Approach 1:
The patent applies beforehand cushioning by maintaining dead reckoning positioning capability as a backup system that can operate independently of GPS satellite visibility. This pre-established alternative positioning method cushions against availability losses when satellite blockage occurs, ensuring continuous navigation functionality.
Solution Approach 2:
The patent merges GPS positioning with dead reckoning positioning into a unified navigation system. By combining these two positioning methods, the system achieves improved reliability where the strengths of dead reckoning (independence from satellite visibility) complement the strengths of GPS (absolute position accuracy), ensuring continuous operation regardless of satellite blockage.
3Measurement precision
If dead reckoning sensor correction is applied to eliminate GPS problems, then positioning accuracy improves, but system complexity increases
Solution Approach 1:
The patent segments the positioning system into distinct functional modules: GPS signal reception, dead reckoning sensing, position computation, and error correction. This segmentation allows each component to be optimized independently and simplifies the integration logic, managing system complexity through modular architecture while achieving improved positioning accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution improves positioning accuracy by detecting vehicle heading and reducing multipath errors, even when only one or two GPS satellites are available, ensuring reliable route guidance and vehicle positioning in urban environments.
Implementation Method 1
a radio wave receiving unit for receiving radio waves emitted from a plurality of GPS satellites
Implementation Method 2
a signal processing unit for identifying the GPS satellites which are emission sources of the radio waves received by the radio wave receiving unit to measure a pseudo range and a range rate
Implementation Method 3
When a building or the like exists around the road along which the vehicle is traveling, the radio wave from a GPS satellite is reflected by the building or the like and propagates through a plurality of paths (a multipath)
Data Source
AI summary
A navigation equipment includes a user position observing unit 15 for calculating the position of the navigation equipment by using the pseudo range and position of each GPS satellite, and a pseudo range error, a user velocity and heading observing unit 16 for calculating the velocity of the navigation equipment from a measured range rate, the position of each GPS satellite, and the position of the navigation equipment, and a user heading searching unit 17 for, when a multipath error is smaller than a specified value, searching for, as the heading of the navigation equipment, a heading whose range rate, which is calculated from a relative movement between the navigation equipment when the navigation equipment changes its heading within a predetermined angle range and a GPS satellite, matches the measured range rate.