Steering Wheel Capacitive Sensor Segmentation for False Grip Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steering wheel units with capacitive sensors often experience false detection of driver hand grip due to contact with abdominal or femoral parts of obese individuals, and fail to detect hand grip in regions without sensors.
Innovation Solution
A steering wheel unit with a reduced contact sensitivity area adjacent to the driver's seat, where the contact sensitivity is lower than the remaining rim portion, preventing false detection of abdominal or femoral contact while allowing reliable detection of hand grip by setting a threshold for the contact signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a capacitive sensor is disposed over the substantially entire circumference of the rim portion, then the detection coverage is improved, but false detection occurs when abdominal or femoral parts contact the lower rim portion
Solution Approach 1:
The rim portion is segmented into a first region (upper rim) and a second region (lower rim adjacent to seating surface). The capacitive sensor is disposed only in the first region, excluding the second region from sensor coverage. This segmentation resolves the contradiction by providing sufficient detection coverage in hand-grip zones while eliminating false detection sources in the lower region where abdominal or femoral parts may contact.
Solution Approach 2:
Different regions of the rim portion are assigned different functional qualities: the first region (upper rim) has high detection sensitivity for hand grip, while the second region (lower rim) has reduced or no sensor coverage to prevent false detection. This local differentiation allows the system to optimize detection accuracy in critical zones while avoiding harmful false signals from other body parts.
2Reliability
If the capacitive sensor is disposed in a circumferential part except for the lower part of the rim portion, then false detection from abdominal contact is reduced, but hand grip detection in the lower region is lost
Solution Approach 1:
The solution applies local quality by concentrating capacitive sensors in the first region (upper rim portion) where hand grip detection is critical, while deliberately excluding the second region (lower rim portion) from sensor coverage. This creates a non-uniform sensor distribution that optimizes detection accuracy for the primary function (hand grip) while eliminating false detection sources, accepting that the lower region will not detect contact.
3Measurement precision
If the contact sensitivity is increased to ensure reliable hand grip detection, then detection sensitivity is improved, but false detection from abdominal or femoral contact increases
Solution Approach 1:
The rim portion is divided into distinct regions with different sensor configurations. The first region (upper rim) employs capacitive sensors with high contact sensitivity optimized for hand grip detection, while the second region (lower rim) either has no sensor or reduced sensitivity. This segmentation allows high sensitivity in critical zones without propagating false detection risks system-wide.
Solution Approach 2:
Different contact sensitivity levels are assigned to different regions: high sensitivity in the first region for reliable hand grip detection, and low or zero sensitivity in the second region to prevent false detection from abdominal or femoral contact. This local quality differentiation resolves the contradiction by allowing high sensitivity where needed while eliminating false signals where harmful.
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 reduced contact sensitivity area near the driver's seat prevents false detection of abdominal or femoral contact, while ensuring accurate detection of hand grip on the steering wheel, enhancing reliability in self-driving vehicle systems.
Implementation Method 1
a capacitive sensor serving as a contact sensor disposed over the substantially entire circumference in the circumferential direction of a rim portion
Data Source
AI summary
Provided is a steering wheel unit with which misdetections due to contact between a steering wheel and the thigh part of the legs of an overweight person can be avoided, and gripping (contact) by a hand can be accurately detected. In a contact sensor, the contact sensitivity [pF/mm2] of a prescribed area (an area including a blank portion on the side of a rim part of the steering wheel that is near a seat surface of a driver's seat when the vehicle is in a straight traveling state is set to be lower than the contact sensitivity of another area (an area comprising only a conductive part) of the rim part.