Vehicle Capacitive Sensor Detection With Adaptive Verification
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Solution Overview
Problem
Capacitive sensors in motor vehicle door handles face high electrical consumption during the search phase for hand presence, which is prolonged compared to verification phases, and there is a need to reduce this consumption while maintaining a predefined range and low false alarm probability.
Innovation Solution
A method involving two distinct sequences of charges/discharges, a first measurement sequence with a shorter duration for the search phase and a second measurement sequence with a longer duration for verification, where the first detection criterion is dynamically updated based on the results of the verification phase to optimize detection and reduce false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of charges/discharges in the sequence is increased to improve sensitivity and detection range, then the sensor becomes more sensitive and detection range increases, but electrical consumption increases significantly
Solution Approach 1:
The patent applies dynamics by making the number of charges/discharges adaptive rather than fixed. The system dynamically adjusts the number of charges/discharges based on the detected capacitance variation magnitude. When a hand is detected with high confidence (large capacitance variation), fewer charges/discharges are performed. When detection is uncertain (small capacitance variation), more charges/discharges are performed to improve measurement precision. This resolves the contradiction by making measurement precision high only when necessary, thereby reducing overall electrical consumption.
Solution Approach 2:
The patent changes the parameter of number of charges/discharges based on detected conditions. The system monitors capacitance variations during the search phase and adjusts the measurement phase parameters accordingly. If the capacitance variation exceeds a threshold, the system performs fewer charges/discharges. If the variation is below the threshold, the system performs more charges/discharges to ensure accurate detection. This parameter adaptation resolves the contradiction between detection sensitivity and electrical consumption.
2Reliability
If the search phase duration is extended to improve hand detection reliability, then detection reliability improves, but electrical consumption increases
Solution Approach 1:
The patent applies partial action by performing only the necessary number of charges/discharges to achieve reliable detection. Instead of always performing a fixed large number of charges/discharges to ensure reliability, the system performs a base number of charges/discharges during the search phase, and only performs additional charges/discharges during the measurement phase if a hand is detected. This partial action approach maintains detection reliability while significantly reducing electrical consumption during the extended search phase.
Solution Approach 2:
The patent segments the detection process into two distinct phases: a search phase with limited charges/discharges for initial detection, and a measurement phase with additional charges/discharges for confirmation. The search phase uses fewer charges/discharges to quickly identify potential hand presence, while the measurement phase uses more charges/discharges only when needed. This segmentation resolves the contradiction by concentrating the energy-intensive measurement activities only when necessary for reliability.
3Reliability
If the number of charges/discharges is increased to reduce false alarm probability, then false alarm probability decreases, but electrical consumption increases
Solution Approach 1:
The patent applies partial action by performing additional charges/discharges only when a hand is detected during the search phase. The system does not continuously perform excessive charges/discharges to prevent false alarms. Instead, it performs a standard number of charges/discharges during the search phase, and only performs additional verification charges/discharges during the measurement phase when a hand is present. This reduces false alarm probability through targeted verification while minimizing unnecessary electrical consumption during periods when no hand is detected.
4Speed
If the capacitive sensor operates continuously with high measurement frequency to improve responsiveness, then responsiveness increases, but electrical consumption increases
Solution Approach 1:
The patent applies periodic action by implementing a structured sequence of search phases and measurement phases. During the search phase, the system performs measurements at a moderate frequency to maintain responsiveness. When a hand is detected, the system transitions to the measurement phase with intensified measurement activity. After the measurement phase, the system returns to the search phase with reduced measurement frequency. This periodic alternation maintains responsiveness during critical detection moments while reducing overall electrical consumption during extended idle periods.
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 electrical consumption and increases responsiveness of the capacitive sensor while ensuring a greater detection range and lower false alarm probability, by adjusting the detection criteria dynamically during the search phase.
Implementation Method 1
searching for a capacitance variation of a capacitive sensor... the presence of a hand in the proximity of the capacitive sensor causes a variation in the capacitance thereof
Data Source
AI summary
Method of searching for a variation in capacitance of a capacitive sensor, includes a phase of searching for variation in capacitance and, when a capacitance variation has been detected, a phase of verifying the variation in capacitance. The search phase includes a recurrent step of searching for variation in capacitance including steps of measuring the duration of a first measurement sequence and determining, according to the measured duration, whether a first predefined detection criterion for variation in capacitance is verified. The verification phase includes steps of measuring the duration of a second measurement sequence and determining, according to the measured duration, whether a second predefined detection criterion for variation in capacitance is verified. The first measurement sequence has a reference duration less than that of the second measurement sequence, and the verification phase includes, when the second detection criterion is not verified, a step of updating the first detection criterion.