Radar Handle Sensing for Reliable Hand Presence Detection
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Solution Overview
Problem
Existing hand presence detection systems on operating devices, such as joysticks, suffer from false-positive and false-negative detections due to electromagnetic interference, temperature and humidity sensitivity, and issues with gloves, particularly with capacitive measurements.
Innovation Solution
Employing a radar sensor within the handle of the operating device to detect hand presence, which avoids the need for metal plates and reduces electromagnetic interference, and uses radar wave attenuation to distinguish between a user's hand gripping the handle and other objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive measurement with metallic elements is used to detect hand presence, then detection can be implemented, but false-positive detections occur due to metallic objects acting as antennas and electromagnetic interference
Solution Approach 1:
The patent replaces capacitive measurement (electrical field-based) with radar measurement (electromagnetic wave-based). The radar sensor emits electromagnetic waves that penetrate the handle casing and are absorbed by the hand, providing reliable detection without the false positives associated with capacitive sensors and metallic elements.
Solution Approach 2:
The patent removes metallic elements from the handle casing that were previously used for capacitive detection. By extracting these problematic metallic components, the system eliminates the source of electromagnetic interference and false-positive detections while maintaining hand presence detection capability through radar.
2Measurement precision
If capacitive measurement is used for hand detection, then presence can be detected, but detection accuracy deteriorates when user wears gloves or when temperature and humidity vary
Solution Approach 1:
The patent substitutes capacitive sensors with radar sensors that measure electromagnetic wave absorption. Since radar waves penetrate materials differently based on their dielectric properties, the system can distinguish between bare hands and gloved hands by analyzing the absorption characteristics, maintaining accuracy across varying environmental conditions.
3Length of stationary object
If radar sensor is placed close to detect hand presence, then detection range is sufficient, but DC peak effect obscures objects in close range
Solution Approach 1:
The patent applies local quality by having different parts of the radar signal serve different purposes: the DC peak region provides information about very close objects (the handle itself), while other frequency regions provide information about the hand at intermediate distances. The evaluation unit selectively processes different signal components to achieve accurate detection at various ranges.
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
Improves detection reliability by preventing false positives from metallic objects and gloves, maintaining accuracy regardless of environmental conditions, and ensuring accurate hand presence detection without requiring openings in the handle casing.
Implementation Method 1
the radar waves may penetrate a casing of the handle... The presence detector is configured to estimate the presence of the hand using the radar sensor signal
Data Source
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AI summary
An operating device for a machine is provided, for example for an agricultural or constructional vehicle. The operating device (10) comprises a handle (11) configured to be gripped by a hand (100) of a user. The operating device (10) comprises a presence detector (15) configured to detect a presence of the hand (100) on the handle (11). The presence detector (15) comprises a radar sensor (20) providing a radar sensor signal, wherein the presence detector (15) is configured to estimate the presence of the hand (100) using the radar sensor signal.