Wireless Key Fob Sensitivity Calibration for Location Accuracy
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Solution Overview
Problem
The accuracy of key fob location in vehicle passive entry systems is limited due to the wide tolerance window required for mass production variations, leading to increased scrap rates and costs.
Innovation Solution
A wireless unit with a receiver, transmitter, RSSI, memory, and control unit that measures and stores sensitivity data, allowing for precise determination of distance between the unit and the vehicle-side transmitter using received signal strength and sensitivity data, thereby narrowing the tolerance window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a wide tolerance window is used for mass production, then manufacturing yield is improved, but location accuracy deteriorates
Solution Approach 1:
The patent changes the parameter approach from using a fixed wide tolerance window for all fobs to using individual sensitivity calibration values for each fob. By measuring and storing the actual sensitivity of each receiver in a data structure during manufacturing, the system can use precise individual parameters rather than broad tolerance ranges, thereby improving location accuracy without sacrificing manufacturing yield.
2Measurement precision
If the tolerance window is narrowed to improve location accuracy, then measurement precision is improved, but the number of discarded fobs increases
Solution Approach 1:
The patent applies preliminary action by measuring and storing the sensitivity of each fob receiver during the manufacturing process itself. This preliminary calibration allows the system to establish precise individual parameters before deployment, eliminating the need to discard fobs due to tolerance variations while maintaining high location accuracy.
3Measurement precision
If individual sensitivity calibration is implemented, then location accuracy is improved, but device complexity increases
Solution Approach 1:
The patent uses a data structure to store and manage individual sensitivity calibration values for each fob. This digital copying approach allows the system to handle individualized parameters efficiently without requiring complex hardware modifications, thereby improving accuracy while minimizing the increase in overall system complexity.
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 solution enhances the accuracy of key fob location determination, reducing scrap rates and costs by allowing each unit to have a unique sensitivity calibration, improving the overall system's precision without increasing discarded units.
Implementation Method 1
a received signal strength indicator (RSSI) for determining a received signal strength of the vehicle-originating signal
Implementation Method 2
a transmitter for transmitting a reply signal... The reply signal includes received signal strength data used for determining a distance between the wireless unit and an associated vehicle-side transmitter
Data Source
AI summary
A wireless unit for a wireless vehicle system includes a receiver for receiving a vehicle-originating signal, a transmitter for transmitting a reply signal, a received signal strength indicator (RSSI) for determining a received signal strength of the vehicle-originating signal, a memory for storing sensitivity data, and a control unit in electrical communication with the receiver, the transmitter, the RSSI and the memory. The receiver has a sensitivity, and the memory is for storing sensitivity data corresponding to the sensitivity of the receiver. The control unit is configured to communicate with the transmitter to direct the transmitter to transmit the reply signal. The reply signal includes received signal strength data used for determining a distance between the wireless unit and an associated vehicle-side transmitter on an associated vehicle. The received signal strength data is based on the received signal strength and the sensitivity data.