Dual Doppler Radar Door Opening for False Trigger Rejection
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Solution Overview
Problem
Existing hands-free door opening systems for vehicles, particularly those using Doppler radar, face challenges in reliability and robustness due to false detections caused by perturbations such as rain, snow, or movements not intended to open the door.
Innovation Solution
The method employs two Doppler radars positioned to emit waves oriented towards the rear and ground of a vehicle, measuring in-phase and phase-offset components of reflected waves, and comparing these components to predetermined shapes and thresholds to reliably detect a predetermined movement, such as a forth-and-back leg movement, and trigger door opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single Doppler radar is used to detect foot movements for hands-free door opening, then the ease of operation is improved, but the reliability deteriorates due to false detections from environmental perturbations
Solution Approach 1:
The detection system is divided into two independent Doppler radars positioned at different locations and orientations. Each radar independently monitors for foot movements, and only when both radars detect the characteristic movement pattern simultaneously does the system trigger door opening. This segmentation allows the system to maintain ease of operation while significantly improving reliability by cross-validating detections across multiple sensors.
2Device complexity
If capacitive sensors are used for foot detection, then the device complexity is reduced, but the reliability deteriorates due to sensitivity to exterior perturbations like rain and snow
Solution Approach 1:
The patent replaces capacitive sensors with Doppler radar technology. Capacitive sensors rely on electrical field changes that are easily disturbed by environmental factors like rain and snow. Doppler radar, in contrast, uses electromagnetic wave reflection and Doppler frequency shift detection, which are much more resistant to weather conditions. This substitution maintains relatively simple device architecture while dramatically improving detection stability in adverse environments.
3Reliability
If hand detection is used for door opening confirmation, then the reliability is improved compared to no confirmation, but the ease of operation deteriorates as it requires manual contact
Solution Approach 1:
The patent replaces mechanical hand contact detection with contactless Doppler radar-based foot movement detection. The radar system detects the characteristic back-and-forth motion of a user's foot or lower leg, providing security confirmation without requiring physical contact. This substitution maintains high reliability for authorized access while dramatically improving ease of operation by eliminating the need for manual handle contact.
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 significantly enhances the reliability and robustness of door opening detection by synchronizing signals from both radars and filtering out non-intended movements, thereby reducing false activations and ensuring secure hands-free access.
Implementation Method 1
The invention relates to a method for opening/closing a door via detection of movement of a user's lower limb, using a Doppler radar
Implementation Method 2
each radar comprising an antenna, means for transmitting and receiving radar waves
Data Source
AI summary
Disclosed is a method for opening a door of a motor vehicle equipped with a device with two Doppler radars for detecting a predetermined movement of a part of the body of a user, the method including: for each radar, comparing the characteristic parameter with a predetermined shape including a predetermined number of peaks a characteristic value of which is higher than a predetermined persistence threshold; if the characteristic parameter has, for the first and second radars, the predetermined shape in a given interval of interest, and if, in the interval of interest, the first radar also sees a predetermined number of changes of phase between the in-phase component and the phase-offset component, then, the predetermined movement is detected and the door is opened, the door otherwise not being opened.