Capacitive Tailgate Obstacle Detection for Pinch Prevention
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Solution Overview
Problem
Existing tactile sensor systems for motor-driven closure elements, such as tailgates and doors, fail to prevent obstacles like body parts from being trapped or injured during closure, as they only recognize obstacles upon contact, and lack effective solutions for preventing injuries during opening operations.
Innovation Solution
A capacitive sensor system that detects changes in capacitance to identify obstacles before contact, allowing for the adjustment of the closure element's speed or stoppage, using a non-contact capacitive sensor integrated into the closure element or vehicle body, which generates an electric field and measures capacitance changes in the signal detection area to prevent pinching and injuries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tactile sensors are used to detect obstacles, then the system can recognize obstacles upon contact, but parts of the body are still trapped and injured before contact occurs
Solution Approach 1:
The capacitive sensor performs preliminary detection of obstacles before the closure element makes contact. By detecting changes in capacitance in the electric field ahead of the closure element, the system identifies obstacles in advance and can stop or slow down the closure element before contact occurs, preventing trapping and injury of body parts
Solution Approach 2:
The patent replaces the mechanical contact-based tactile sensor system with a non-contact capacitive sensor system. Instead of relying on mechanical force detection upon contact, the system uses electrical field-based capacitance measurement to detect obstacles at a distance, eliminating the harmful mechanical contact that causes trapping and injury
2Object-affected harmful factors
If non-contact capacitive sensors are used to detect obstacles before contact, then pinching can be prevented, but the system complexity increases
Solution Approach 1:
The closure element itself serves multiple functions: it acts as both the moving component that closes the opening and as part of the sensor system (either as the sensor element or as the reference electrode). This multi-functionality reduces the need for separate dedicated sensor components, thereby limiting the increase in system complexity while still achieving pinching prevention through non-contact detection
3Object-affected harmful factors
If the sensor detection range is extended to detect obstacles earlier, then safety is improved, but false detection of environmental conditions increases
Solution Approach 1:
The evaluation unit continuously monitors the capacitance measurements and compares them against expected values. When an obstacle is detected, the system can adjust the closure element's speed or stop it entirely. This feedback mechanism allows the system to respond appropriately to true obstacles while using the evaluation unit to distinguish them from environmental conditions, maintaining safety without excessive false detections
Solution Approach 2:
The system changes the parameter being measured from simple presence detection to capacitance value analysis. By evaluating the magnitude and characteristics of capacitance changes rather than just detecting any change, the evaluation unit can distinguish between obstacles (which cause specific capacitance changes) and environmental conditions (which cause different patterns of change), thereby extending detection range without proportionally increasing false detections
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
The capacitive sensor system effectively prevents obstacles from being trapped or injured by detecting them at a distance, reducing the risk of pinching and injury, and can be implemented cost-effectively using existing vehicle components, enhancing safety during both closure and opening operations.
Implementation Method 1
capacitive sensor for detecting a change in capacitance due to an obstacle in a signal detection range of an electric field generated at a sensor element
Implementation Method 2
capacitive sensor for detecting a change in capacitance due to an obstacle in a signal detection range of an electric field generated at a sensor element
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a sensor system and a method for preventing obstacles from becoming trapped or damaged when a motorized locking element, in particular a motorized tailgate, is closing in the opening area of a motor vehicle. The sensor system comprises a capacitive sensor for detecting a change in capacitance due to an obstacle, and an evaluation unit that, based on a measured value from the sensor, can generate a sensor signal and transmit it to a motor control unit, which slows down or stops the speed of movement of the locking element.