Capacitive Sensor Non-Contact Detection for Power Door Safety
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Solution Overview
Problem
Power closures like Power Sliding Doors and Power Lift Gates face challenges in meeting federal safety standards due to their significant mass and inertia, often causing injuries during unattended closures, and current technologies rely heavily on Hall Effect speed control algorithms that require extensive characterization for environmental and operational variations.
Innovation Solution
The Flextronics Capacitive Sensor system integrates with a motion controller to detect objects using a non-contact method, generating an electrical field that senses intrusions and adjusts the closure system's speed and direction to prevent contact, allowing for configurable obstacle detection and reaction without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Hall Effect speed control algorithm is used for contact based obstacle detection, then obstacle detection capability is achieved, but huge characterization effort is required during development to optimize detection for environmental changes, voltage variation, and vehicle slope
Solution Approach 1:
The patent replaces the mechanical/Hall Effect based speed control algorithm with a capacitive sensor system that uses electrical field detection. The capacitive sensor generates an electrical field that detects objects through capacitance changes, eliminating the need for complex environmental characterization required by Hall Effect algorithms while maintaining reliable obstacle detection capability.
Solution Approach 2:
The patent introduces a capacitive sensor as an intermediary detection mechanism between the closure system and obstacles. Instead of relying on contact-based Hall Effect sensing, the capacitive sensor acts as a mediator that detects objects through electrical field interaction, providing reliable detection without requiring extensive system characterization for various environmental conditions.
2Reliability
If contact based obstacle detection is used with significant mass closure systems, then obstacle detection is achieved, but pinch force imparted on objects can cause injury due to momentum and energy
Solution Approach 1:
The patent implements preliminary action by using capacitive sensing to detect objects before the closure system makes contact. The electrical field detection occurs in advance of physical contact, allowing the system to identify obstacles and adjust speed or reverse direction before pinch force can be applied, thereby preventing injury while maintaining reliable detection.
Solution Approach 2:
The patent replaces contact-based mechanical detection with non-contact capacitive sensing. By substituting the mechanical contact approach with electrical field detection, the system achieves reliable obstacle detection without imparting harmful pinch forces on detected objects.
3Object-affected harmful factors
If non-contact capacitive sensing is used for obstacle detection, then zero contact force is achieved, but the system must continuously monitor capacitive sensor output to determine object presence
Solution Approach 1:
The patent applies self-service by designing the capacitive sensor system to automatically and continuously monitor its own output signal. The control micro continuously reads the capacitive sensor analog/digital output to determine object presence, with the system self-regulating based on capacitance changes without requiring external intervention or complex additional monitoring mechanisms.
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 effectively prevents injuries by enabling early detection and adaptive response to various objects, from human bodies to inanimate objects, across different environments and operational conditions, ensuring compliance with safety standards while reducing characterization efforts.
Implementation Method 1
The Capacitive Sensor generates an electrical field. Intrusions into this field are detected allowing the control system to react without contact.
Implementation Method 2
The capacitive electronics in turn senses that change in field and generates an analog/digital voltage proportional to change in field.
Data Source
AI summary
A non-contact object detection system includes a capacitor sensor and a control system, the control system providing a AES (Adaptive Excitation Signal) to the capacitor sensor, the AES (Adaptive Excitation Signal) configured according to an environment in which the capacitor sensor is deployed, the AES (Adaptive Excitation Signal) configured to produce a threshold voltage from the capacitor sensor to the control system in the environment when an object is not in a detection area of the capacitor sensor.