Vehicle Distance Calculation Offset Error Compensation
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Solution Overview
Problem
Current navigation systems using acceleration sensors for distance calculation during GPS failures suffer from significant offset errors, leading to inaccurate distance determination due to changing offset values and inclines, which result in incorrect speed and distance measurements.
Innovation Solution
A method that corrects the offset error by extrapolating speed from a 'last' measured value before GPS failure, determining the deviation when GPS is available again, and using this to calculate a better offset value, which is then used for accurate speed profiling and distance calculation, reducing errors through algebraic correction formulas and a second-order polynomial offset estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If acceleration sensors are used for distance calculation during GPS failure, then vehicle-independent measurement is achieved, but offset errors cause significant measurement inaccuracies
Solution Approach 1:
The system uses feedback from GPS measurements before and after the failure period to estimate and compensate for offset errors in the acceleration sensor data during the GPS failure period, thereby maintaining measurement precision while keeping the system vehicle-independent
Solution Approach 2:
The system performs preliminary estimation of offset values using acceleration sensor data before GPS failure occurs, and continues to update these estimates using data from after the failure period, allowing accurate distance calculation throughout the entire failure duration
2Device complexity
If constant offset value is used for acceleration sensor compensation, then calculation simplicity is maintained, but changing offset values cause continued measurement drift
Solution Approach 1:
The system transitions from using a constant offset value to a time-dependent offset estimation that dynamically adapts to changing conditions during GPS failure, improving measurement precision while maintaining reasonable calculation complexity through continuous estimation updates
Solution Approach 2:
The system changes the offset parameter from a static constant to a dynamic time-dependent value that is continuously estimated and updated during the GPS failure period, allowing the compensation to adapt to changing offset conditions and eliminate measurement drift
3Device complexity
If linear distance between GPS positions is used during failure, then calculation is simple, but the measured distance is always less than or equal to actual distance covered
Solution Approach 1:
The system replaces the simple linear distance calculation between GPS positions with a more sophisticated method using acceleration sensor data integration, allowing accurate measurement of the actual path distance covered during GPS failure while maintaining calculation feasibility
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 approach significantly reduces offset-related errors, ensuring accurate distance and speed estimation during GPS outages, even in complex terrain, and prevents implausible speed estimates, thereby improving the accuracy of route length calculation.
Implementation Method 1
the quantities to be determined, acceleration a, speed v and distance s of the application under consideration, are not immediately available, i.e. already during the GPS downtime must be determined
Data Source
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AI summary
The method involves determining an estimated speed characteristic by temporal integration of length acceleration value when position and/or speed data of a vehicle is unavailable. Estimated speed values and speed data are compared for derivation of an offset compensation, and a length of a distance traveled by the vehicle is calculated as the sum of the integration of the characteristics and compensation, when the data are reavailable. Independent claims are also included for the following: (1) a computer program with program code unit in order to execute a method of vehicle-side calculation of the length of a distance traveled (2) a device for vehicle-side calculation of the length of a distance traveled.