Dual Doppler Radar Trunk Opening With False Trigger Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Doppler radar systems for hands-free vehicle trunk opening are unreliable and prone to false detections due to external disturbances and inability to distinguish intended foot movements from other movements, especially when the foot slips or passes by the vehicle without the intention to open the trunk.
Innovation Solution
The method employs two Doppler radars, one oriented towards the rear and one towards the ground, measuring in-phase and phase-shift components of reflected radar waves, comparing these to predetermined patterns and thresholds to reliably detect the intended movement and synchronize the signals to ensure accurate trunk opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single Doppler radar is used to detect foot movement, then the system can detect movement and trigger trunk opening, but the detection reliability is poor and false detections occur frequently
Solution Approach 1:
The detection system is divided into two independent Doppler radars: a first radar oriented toward the rear of the vehicle and a second radar oriented toward the ground. Each radar independently monitors for foot movement, and both must detect the predetermined movement pattern simultaneously to trigger trunk opening. This segmentation eliminates false detections from single-radar errors while maintaining manageable system complexity through modular architecture.
2Reliability
If capacitive sensors are used for foot detection, then the system can detect foot presence, but the sensors are highly sensitive to external disturbances such as rain and snow
Solution Approach 1:
The patent replaces capacitive sensors with Doppler radar technology. Radar detects movement through electromagnetic wave reflection and Doppler frequency shift analysis, which is inherently insensitive to environmental conditions like rain, snow, or humidity that affect capacitive sensing. The radar measures velocity and movement patterns of the foot without being influenced by atmospheric phenomena.
3Ease of operation
If the Doppler radar detects any movement towards the bumper, then the trunk opens, but it cannot distinguish between intended foot movements and incidental movements such as passing by or foot sliding
Solution Approach 1:
The system analyzes the dynamic characteristics of detected movements, including velocity, acceleration, and movement pattern over time. The predetermined movement requires specific dynamic parameters that match intentional foot kicking motions. Incidental movements like passing by or foot sliding produce different dynamic signatures and are filtered out, maintaining convenience while eliminating false activations.
4Reliability
If two Doppler radars are used with signal synchronization and pattern matching, then false detections are minimized and detection reliability is improved, but the device complexity increases
Solution Approach 1:
The control unit receives feedback from both radars and implements a logical AND operation: trunk opening is triggered only when both the first radar (oriented toward rear) and second radar (oriented toward ground) simultaneously detect the predetermined movement pattern. This feedback-based cross-validation mechanism significantly reduces false detections while the processing remains systematic and manageable through defined logical operations.
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 provides a robust and reliable detection system that minimizes false openings by synchronizing the signals from both radars, ensuring that only intended movements trigger the trunk opening, thus enhancing the reliability and precision of foot movement detection.
Implementation Method 1
detection of a predetermined movement of a lower limb of a user's body by emitting radar waves directed towards the rear of the vehicle and by analyzing the waves reflected by the presence of the user
Implementation Method 2
The detection of a predetermined movement triggers the opening of the trunk. Such a detection system is for example disclosed in patent application DE102012014482 A1
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention proposes a method for opening a door of a motor vehicle (V), the vehicle (V) being equipped with a device (D) for detecting a predetermined movement of a part of the body of a user, the method being characterised in that it comprises the following steps: • previously equipping the device with two Doppler radars, a first radar (R1) being adapted to emit waves oriented towards the rear of the vehicle (V), a second radar (R2) being adapted to emit waves oriented towards the ground (V), each comprising an antenna (A1) with means for emitting and receiving radar waves (10), and means (20) for processing reflected radar waves adapted to detect the predetermined movement, measuring, at a fixed frequency and for each radar (R1, R2), a phase component (I1, I2) and a phase shift component (Q1, Q2) of the reflected waves, · determining a characteristic parameter (A1, A2, F1, F2) of at least one of the two components for each radar; • comparing, for each radar, the characteristic parameter to a predetermined form, comprising a predetermined number of peaks, for which a characteristic value (Per) is greater than a predetermined persistence threshold, · if the characteristic parameter has, for the first and second radar, the predetermined form in the same interval of interest (Δt), • and if, in said interval of interest, the first radar also has a predetermined number of phase changes between the phase component and the phase shift component, · then the predetermined movement is detected and the door is opened, otherwise, the door is not opened.