Passive Entry System Duty Cycle Control
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Solution Overview
Problem
Passive entry/passive start systems face challenges in energy consumption and user experience due to continuous interrogation signal transmission, which can cause battery drain or delayed detection of the user's approach, leading to potential warranty issues.
Innovation Solution
A dynamic adjustment of the interrogation signal duty cycle based on the portable device's range and rate of approach, using time-of-flight and RSSI techniques to conserve energy and ensure timely detection, with increased power consumption only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system transmits interrogation signals at a high rate (small intermission period), then the detection of the portable device is timely and accurate, but battery drain occurs due to excessive energy consumption
Solution Approach 1:
The patent applies dynamics by making the interrogation signal transmission rate adjustable rather than fixed. The system dynamically changes the transmission duty cycle based on the detected range of the portable device: using high transmission rates when the device is close to ensure accurate detection, and low transmission rates when the device is far to conserve battery power. This resolves the contradiction by adapting the measurement precision to the actual operational needs at different ranges.
Solution Approach 2:
The patent changes the parameter of transmission duty cycle based on the detected range of the portable device. When the device is within a first range (closer), the system uses a first duty cycle (higher transmission rate); when the device is in a second range (farther), the system uses a second duty cycle (lower transmission rate). This parameter adjustment resolves the contradiction between detection accuracy and energy consumption by matching the transmission intensity to the actual detection requirements.
2Use of energy by moving object
If the system transmits interrogation signals at a low rate (long intermission period), then battery consumption is reduced, but the user's action of attempting to open the door may not be detected if the user approaches in between the transmitted interrogation signals
Solution Approach 1:
The system dynamically adjusts the transmission duty cycle based on the detected range of the portable device. When the device is detected in a closer range, the system increases the transmission rate to ensure reliable detection of user actions. When the device is in a farther range, the system reduces the transmission rate to conserve battery power, as the probability of detection is naturally lower at greater distances. This dynamic adjustment resolves the contradiction between energy consumption and detection reliability.
Solution Approach 2:
The patent changes the transmission duty cycle parameter based on the detected range: using a first (higher) duty cycle when the portable device is in a first (closer) range to ensure reliable detection, and a second (lower) duty cycle when the device is in a second (farther) range to reduce battery consumption. This parameter adaptation resolves the contradiction by matching the transmission intensity to the actual operational requirements at different distances.
3Measurement precision
If the system continuously transmits interrogation signals to monitor the portable device, then the location of the portable device is constantly checked, but excessive energy consumption occurs
Solution Approach 1:
The patent applies periodic action by transmitting interrogation signals at different duty cycles based on the detected range of the portable device. Instead of continuous transmission, the system uses periodic transmissions with varying frequencies: higher frequency (shorter period) when the device is close to maintain accurate location monitoring, and lower frequency (longer period) when the device is far to reduce energy loss. This periodic action with adaptive periods resolves the contradiction between monitoring accuracy and energy consumption.
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 reduces energy consumption while ensuring timely detection of the portable device, minimizing battery drain and improving user experience by adjusting the interrogation signal duty cycle dynamically with the device's proximity and movement.
Implementation Method 1
A controller determines at least a range of the portable device as a function of the time-of-flight of the interrogation and response signals
Data Source
AI summary
A passive entry-passive start portable device detection system. A portable device includes a transceiver. At least one vehicle-based transceiver broadcasts an interrogation signal. The transceiver of the portable device transmits a response signal in response to the interrogation signal. A controller determining at least a range of the portable device as a function of the time-of-flight of the interrogation and response signals. The controller controls a measurement duty cycle of the interrogation signal as a function of the determined range.