Vehicle Positioning Accuracy via GPS Reliability Index
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Solution Overview
Problem
Existing position sensing systems for vehicles face accuracy issues due to cumulative errors in dead reckoning without GPS data, especially in environments where GPS signals are unreliable, such as multilevel parking structures and inner-city areas, leading to decreased positioning accuracy.
Innovation Solution
A method and device that determine the reliability of GPS output data components and calculate error indices to adjust the contribution of each component to correction processing, allowing for accurate positioning even without error indexes from the GPS receiver, by dividing components into groups and setting unreliable components to zero contribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receiver output data is used for Kalman filter correction processing, then positioning accuracy is improved, but the system cannot operate in environments where GPS signals are unavailable or unreliable
Solution Approach 1:
The system dynamically adjusts the correction processing based on GPS signal quality indicators. When GPS signals are available and reliable, correction processing is applied to improve positioning accuracy. When GPS signals are unavailable or unreliable (indicated by poor quality metrics), the system automatically suspends correction processing to maintain system operability. This dynamic switching resolves the contradiction between achieving high positioning accuracy through GPS correction and maintaining reliability in GPS-denied environments.
2Device complexity
If simple calculation is used to determine error indexes for GPS output data, then device complexity is reduced, but positioning accuracy deteriorates due to incorrect error indexes
Solution Approach 1:
The system uses inexpensive, widely-available GPS receivers that do not output error indexes, accepting that these devices lack the sophisticated error measurement capabilities of expensive specialized receivers. By implementing software-based Kalman filter correction processing that can work with or without error indexes, the system compensates for the limitations of cheap GPS hardware, achieving accurate positioning without requiring costly specialized equipment.
3Measurement precision
If GPS output data with multipath interference is used for correction processing, then positioning accuracy deteriorates due to incorrect error indexes, but filtering out such data reduces the amount of available correction information
Solution Approach 1:
The system implements feedback mechanisms to monitor GPS signal quality and detect multipath interference conditions. By continuously assessing the quality of GPS output data and comparing it against expected patterns, the system can identify and filter out corrupted data while retaining valid correction information. This feedback-based quality control ensures that only reliable GPS data is used for Kalman filter correction, maintaining positioning accuracy while minimizing loss of useful correction information.
Data Source
AI summary
A position sensing device and method are provided for executing correction processing based on a reliability and error index of each component of GPS output data to increase positioning accuracy. Correction processing is performed to correct a position determination result obtained through dead reckoning, and a vehicle speed, a pitch angle, and a sensor mounting angle used in position determination executed through dead reckoning in a measurement period of GPS in accordance with direction-specific positional components and speed components of a vehicle, which are measured with GPS to determine a reliability of each of the direction-specific positional components and speed components of the vehicle and calculate an error index of a component determined to be a reliable component, to set the degree of contribution of a measurement component determined to be unreliable to correction processing to zero or almost zero, and to reduce the degree of contribution of a measurement component determined to be reliable to correction processing in accordance with a value of the error index.