Navigation Terminal Tunnel Branch Road Determination
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Solution Overview
Problem
Navigation devices struggle to determine the road traveled after passing a branch in blocking areas where GPS satellite signals are not receivable, such as tunnels, especially when there are multiple exits, and this issue is exacerbated in standalone terminal devices like smartphones that lack vehicle speed and direction sensors.
Innovation Solution
A terminal device equipped with map data, GPS reception, blocking area identification, physical amount estimation, and guidance functionality that suspends guidance at a branch point and determines the road based on estimated movement distance and GPS signal reception, resuming guidance when GPS signals are re-established.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dead reckoning system using vehicle speed sensor and directional sensor is used to acquire current position in tunnels, then current position can be acquired in blocking areas, but device complexity increases and directional sensor is required
Solution Approach 1:
The patent extracts and removes the directional sensor from the dead reckoning system, keeping only the vehicle speed sensor. The system achieves position determination in tunnels by integrating vehicle speed data with map data and tunnel structure information, eliminating the need for directional sensors while maintaining reliability in blocking areas.
Solution Approach 2:
The patent introduces map data and tunnel structure data as intermediary elements between the vehicle speed sensor and the position determination system. By using these intermediaries, the system can determine position without direct directional measurement, resolving the contradiction between reliability and device complexity.
2Measurement precision
If navigation device determines road after branch in tunnel using dead reckoning, then position can be tracked, but calculation complexity increases and requires directional information
Solution Approach 1:
The patent performs preliminary actions by pre-storing tunnel structure data including branch positions and road configurations in map data before the vehicle enters the tunnel. This allows the system to determine which road the vehicle is traveling on after a branch by comparing estimated position with pre-stored structural information, reducing real-time calculation complexity while maintaining accuracy.
3Device complexity
If standalone terminal device like smartphone is used without vehicle speed and direction sensors, then device complexity is reduced, but current position cannot be determined in tunnels
Solution Approach 1:
The patent makes the terminal device universal by enabling it to function as a navigation device in tunnels without requiring vehicle-specific sensors. The system achieves this by using the terminal's existing capabilities (GPS receiver, processor) combined with map data and tunnel structure data to determine position, allowing smartphones to reliably navigate in blocking areas without additional hardware.
Solution Approach 2:
The patent replaces the mechanical sensor-based measurement system with an information processing system. Instead of using physical sensors to measure speed and direction, the system uses GPS radio wave reception combined with map data matching and tunnel structure information to determine position, eliminating the need for mechanical sensors while maintaining reliability.
4Measurement precision
If vehicle speed is acquired from vehicle to terminal device, then movement distance can be estimated in tunnels, but road determination after branch still cannot be made
Solution Approach 1:
The patent implements feedback by continuously comparing the estimated position (based on vehicle speed and time) with the pre-stored tunnel structure data and map data. When the estimated position reaches a branch point, the system uses feedback from the tunnel structure information to determine which road the vehicle is traveling on, preventing loss of road identification information while maintaining precise movement distance estimation.
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
Enables determination of the road traveled after a branch without directional information, reducing calculation load and allowing immediate resumption of guidance upon GPS signal recovery, effectively navigating through tunnels with multiple exits.
Implementation Method 1
including a GPS receiver that receives radio waves from GPS satellites (hereinafter, referred to as GPS radio waves) and acquiring the current position on the basis of the received GPS radio waves
Data Source
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AI summary
An object is to make it possible to determine a road being traveled after a branch in a blocking area such as a tunnel in which radio waves from GPS satellites are not receivable even in a case in which the road has a branch. A navigation device is provided with a GPS receiver and map data including tunnel data. In addition, the navigation device periodically acquires a vehicle speed from a vehicle with wires or without wires. The navigation device provides guidance on the current position N that is acquired at the GPS receiver, and when GPS radio waves become unreceivable after the vehicle passes a tunnel entrance I, calculates a travel distance L on the basis of a vehicle speed acquired from the vehicle and a time T up to a branch P, and continues providing the guidance on the current position N up to the branch P. After passing the branch P, the navigation device suspends the guidance, calculates a distance La between the branch P and a tunnel exit, which is shorter, and in a case in which GPS radio waves are not received even after a movement distance from the branch P exceeds the La, after passing the branch, determines a road B whose distance is longer as the road being traveled, and provides guidance on the current position.