Adaptive Position Determination for Keyless Entry Systems
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Solution Overview
Problem
Conventional keyless entry systems inaccurately determine the position of a portable device relative to a vehicle due to changes in door states, leading to incorrect locking and unlocking operations, as radio waves can leak outside when a door is open, causing increased received signal strength and wrongful determination of the device's position.
Innovation Solution
A position determining device and method that adjusts the evaluation criteria for determining the portable device's position based on the open or closed state of vehicle doors, using a door state determining part to calculate and set different conditions for determining the portable device's position, such as varying thresholds for distances or Mahalanobis distances, to accurately reflect the door state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position determination uses fixed thresholds regardless of door state, then the system is simple to operate, but the position determination accuracy deteriorates when doors are open due to radio wave leakage
Solution Approach 1:
The patent applies dynamics by making the determination thresholds adaptive rather than fixed. The system dynamically adjusts the thresholds based on the detected door state (open or closed), allowing the position determination criteria to change according to environmental conditions. This resolves the contradiction by maintaining high accuracy across different states while managing complexity through automated adaptation.
Solution Approach 2:
The patent changes the parameter of determination thresholds based on door state. When doors are closed, one set of thresholds is used; when doors are open, a different set of thresholds is applied to account for radio wave leakage. This parameter adaptation allows accurate position determination in both scenarios without requiring a completely different system for each state.
2Measurement precision
If the system uses multiple determination thresholds for different door states, then the position determination accuracy improves, but the device complexity increases due to additional determination logic
Solution Approach 1:
The patent applies preliminary action by pre-establishing multiple determination thresholds corresponding to different door states before actual position determination occurs. The system prepares both a first determination threshold (for closed doors) and a second determination threshold (for open doors) in advance, selecting the appropriate one based on the current door state. This approach improves accuracy while managing complexity through pre-computed parameters.
Solution Approach 2:
The system uses feedback from door state detection to select the appropriate determination threshold. The door state determining unit provides feedback about whether doors are open or closed, which then feeds into the selection of the corresponding threshold for position determination. This closed-loop feedback mechanism ensures accurate determination while automating the complexity management.
3Reliability
If the system assumes all doors are closed for position determination, then the system is simple to implement, but the reliability deteriorates due to wrongful position determination when doors are open
Solution Approach 1:
The patent applies segmentation by dividing the position determination process into distinct branches based on door state. Instead of using a single unified threshold, the system segments the determination logic into a first determination process (for closed doors) and a second determination process (for open doors). This segmentation improves reliability by ensuring the correct threshold is used for each scenario while organizing complexity into manageable segments.
Solution Approach 2:
The system dynamically adapts its determination criteria based on real-time door state monitoring. Rather than statically assuming doors are closed, the system continuously monitors door state and dynamically switches between appropriate determination thresholds. This dynamic adaptation significantly improves reliability in varying operational conditions.
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
Ensures accurate determination of the portable device's position even when door states change, preventing wrongful locking or unlocking and enhancing convenience by properly setting conditions based on the difference in received signal strength between closed and open door states.
Implementation Method 1
the vehicle-side device transmits radio signals of the low-frequency (LF) band (LF radio signals) from multiple antennas provided on the vehicle. The portable device calculates a distance from each antenna based on the received signal strength of the radio signal received from each antenna
Data Source
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AI summary
A position determining device configured to determine the position of a portable device 3 configured to receive one or more radio signals transmitted from one or more antennas ANT inside a vehicle, respectively, includes a door state determining part 231 configured to determine the open or closed state of a door of the vehicle, an evaluation value calculating part 331 configured to calculate an evaluation value related to the position of the portable device 3 based on the received signal strength of the one or more radio signals at the portable device, and a determination part 233 configured to determine that the portable device 3 is positioned inside the vehicle when the evaluation value satisfies a predetermined condition. At least one of the predetermined condition and a method of calculating the evaluation value is changed in accordance with the open or closed state of the door determined by the door state determining part 231.