Dead Reckoning Positioning with Periodic Attitude Correction
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Solution Overview
Problem
Dead reckoning navigation systems with fewer sensors, such as those using a monoaxial accelerometer and a monoaxial gyroscope, suffer from lower accuracy in determining vehicle position and attitude due to increased noise and error accumulation over time, which affects their reliability for long-term navigation.
Innovation Solution
A position detecting apparatus and method that includes a sensor unit with a vehicle speed sensor, acceleration sensor, and angular velocity sensor, utilizing a dead reckoning calculating unit to calculate state quantities like vehicle position, speed, and attitude, and a state quantity correcting unit to improve accuracy through periodic corrections based on vehicle attitude changes and speed components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a dead reckoning navigation system uses fewer sensors (such as monoaxial accelerometer and monoaxial gyroscope) to reduce cost, then the device complexity and cost are reduced, but the measurement precision and reliability of vehicle position and attitude determination deteriorate due to increased noise and error accumulation over time
Solution Approach 1:
The patent changes the computational parameters by introducing periodic correction cycles where the calculation frequency is dynamically adjusted. During correction periods, the system uses lower frequency calculations with external reference data, while between corrections it uses higher frequency dead reckoning calculations. This parameter change allows the system to maintain high measurement precision over long periods despite using fewer sensors, as the periodic corrections reset the error accumulation without requiring continuous high-frequency sensor input
Solution Approach 2:
The patent implements periodic correction action where the navigation system alternates between dead reckoning calculation phases and correction phases. In correction phases, external reference information (such as GPS or map matching data) is used to correct accumulated errors. This periodic action structure allows the system to maintain long-term accuracy by regularly resetting error accumulation, effectively resolving the contradiction between using fewer sensors and maintaining measurement precision over time
2Speed
If dead reckoning navigation calculates state quantities at high frequency to improve responsiveness, then the speed of position updates is improved, but the loss of time for error correction increases, affecting long-term navigation accuracy
Solution Approach 1:
The patent applies dynamics by making the calculation frequency adaptive rather than fixed. The system dynamically adjusts the calculation frequency based on the correction cycle phase: during dead reckoning phases, it operates at high frequency for rapid position updates, while during correction phases, it operates at lower frequency to allow external reference data to reset errors. This dynamic frequency adjustment resolves the contradiction by allowing high speed updates when needed while periodically sacrificing some speed to correct accumulated errors, optimizing the balance between responsiveness and long-term accuracy
Data Source
AI summary
A position detecting apparatus and method used in a navigation system, which can improve positional accuracy and bearing accuracy even in a system equipped with few sensors, are provided. A position detecting apparatus used in a navigation system for detecting a vehicle position includes: a sensor unit including a vehicle speed sensor, an acceleration sensor, and an angular velocity sensor; and a dead reckoning calculating unit for calculating state quantity inclusive of a current vehicle position, a vehicle speed, and a vehicle attitude angle based on a signal output from each of the sensors at a predetermined periodic interval. The dead reckoning calculating unit includes: a movement calculating unit for calculating a movement during a period from a previous state quantity calculation time up to a current state quantity calculation time; a change amount detecting unit for calculating an amount of change in vehicle attitude; a movement resolving unit for resolving the movement into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; and a state quantity calculating unit for determining, by calculation, a vehicle position at the current state quantity calculation time using each of the components.