Steering Wheel Manual Guidance Detection Using Torque Filtering
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Solution Overview
Problem
Existing methods for detecting manual guidance of a steering wheel, such as capacitive sensors and torque sensor analysis, are either costly for mass production or prone to noise from road irregularities and autonomous driving functions.
Innovation Solution
A device and method utilizing a torque sensor, angular speed sensor, and calculation unit to calculate and filter driver torque, determining a steering angle component compared to a threshold to reliably detect manual guidance, with low-pass filters and a comparator to set a flag indicating manual control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensors are mounted on the steering wheel to detect manual guidance, then detection capability is improved, but manufacturing complexity and cost increase making it unsuitable for mass production
Solution Approach 1:
The steering wheel's existing torque sensor serves dual purposes: its primary function for steering control and a secondary function for detecting manual guidance. The control unit analyzes the torque sensor's existing output signal to determine driver hand presence, eliminating the need for separate capacitive sensors and reducing manufacturing complexity while maintaining detection capability.
2Device complexity
If torque sensor signal analysis is used to detect manual guidance, then device complexity is reduced, but measurement precision deteriorates due to significant signal oscillation from road irregularities and autonomous driving functions
Solution Approach 1:
The control unit extracts only the steering angle component from the torque sensor signal that is relevant to manual guidance detection. By isolating this specific component and comparing it against threshold values, the system achieves precise detection of driver hand presence while filtering out irrelevant signal oscillations caused by road irregularities and autonomous driving functions.
3Speed
If torque sensor signal is used without filtering, then response speed is improved, but reliability deteriorates due to false positives from road noise and autonomous interventions
Solution Approach 1:
The control unit applies partial filtering by extracting only the necessary steering angle component from the torque sensor signal rather than applying comprehensive filtering. This selective approach maintains adequate response speed while sufficiently reducing false positives from road noise and autonomous interventions, achieving an optimal balance between response speed and detection accuracy.
Data Source
AI summary
A device (1) and a method for detecting manual guidance of a steering wheel by a driver, have a torque sensor (3) for measuring a steering wheel torque (Ts) of the steering wheel; an angular speed sensor (4) for measuring an angular speed (ωc) of a steering wheel column connected to the steering wheel; and a calculation unit (5) for calculating a driver torque (Td) exerted by the driver on the steering wheel as a function of the measured steering wheel torque (Ts) and the measured angular speed (ωc) of the steering wheel column, and for filtering the calculated driver torque (Td) to determine a steering angle component (θcT) which is compared with a threshold (θtol) to recognize manual guidance of the steering wheel by the driver.