Steering Wheel Hand-Off Detection Using Touch and Torque Sensing
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Solution Overview
Problem
Existing methods for determining a driver's hand state on a steering wheel are prone to errors when a heavy object or an object generating an electric field is placed on the wheel, leading to incorrect detection of the driver's hand presence.
Innovation Solution
A driver state determination method using a combination of touch sensing and steering torque sensors to differentiate between hand-off, normal grip, abnormal grip, and hand-off determination pending states, with predetermined value and variance criteria to accurately assess the driver's hand position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a contact sensor (electrostatic sensor or pressure-sensitive sensor) is used to determine hand-on state, then the detection sensitivity is improved, but false positive occurs when heavy objects or objects generating electric field contact the sensor
Solution Approach 1:
The patent combines multiple sensors (contact sensors and torque sensors) to determine hand-on state. The control unit integrates signals from both sensor types, requiring consistent indications from multiple sensors to confirm hand-on state, thereby reducing false positives caused by heavy objects or electric field interference on contact sensors alone.
Solution Approach 2:
The torque sensor acts as an intermediary verification mechanism. Instead of relying solely on contact sensor output, the system uses torque sensing as an intermediate step to verify whether the detected contact corresponds to actual driver hand presence, filtering out false signals from objects placed on the steering wheel.
2Reliability
If multiple sensors are combined to improve detection accuracy, then the reliability of hand-on state determination is improved, but the device complexity increases
Solution Approach 1:
The steering wheel assembly serves multiple functions: it is both the interface for driver control and the mounting structure for multiple sensors. The control unit performs multiple functions including processing contact sensor signals, torque sensor signals, and integrating these inputs to determine hand-on state, reducing the need for separate dedicated components.
Solution Approach 2:
The patent merges the functionality of contact detection and torque measurement into a unified hand-on state determination system. By combining these sensor types and processing their outputs together in a single control unit, the system achieves reliable detection without requiring completely separate independent subsystems.
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 method effectively prevents incorrect hand presence detection, ensuring accurate determination of the driver's hand state and enabling precise control transfer during autonomous driving.
Implementation Method 1
a touch sensor that detects a touch input by a driver of a vehicle and generates a touch sensing value corresponding to the touch input
Implementation Method 2
a steering torque sensor that detects a steering torque input from the driver and generates a steering torque sensing value corresponding to the steering torque input
Data Source
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AI summary
A driver state determining method may include: obtaining a touch sensing value corresponding to a touch input by a driver of a vehicle, and a steering torque sensing value corresponding to a steering torque input from the driver; determining a state of the driver as one of a hand-off state, a normal grip state, an abnormal grip state, or a hand-off determination pending state based on at least one of the touch sensing value or the steering torque sensing value, and outputting a guide message according to the determination result.