Steering Torque Signal Analysis for Driver Hand Detection
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Solution Overview
Problem
Existing vehicle safety systems face challenges in cost-effectively detecting whether a driver is actively holding the steering element, particularly at higher speeds, which is crucial for determining driver engagement and preventing autonomous system interventions that could impair traffic safety.
Innovation Solution
A method using a torque sensor to read torque signals between the steering element and transmission, with threshold values dependent on vehicle speed, to determine if a driver is holding the steering element by evaluating torque differences and durations above or below these thresholds, allowing for precise detection of driver engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive sensor is used on the steering wheel to detect driver hand presence, then the detection precision is improved, but the device complexity and cost increase due to additional hardware
Solution Approach 1:
The torque sensor, originally designed for measuring steering torque in torque overlay steering systems, is made multi-functional by also using it for driver hand presence detection. The same sensor hardware serves dual purposes: controlling steering assistance torque and detecting whether the driver's hands are on the steering wheel, thereby eliminating the need for separate capacitive sensors and reducing overall system complexity
Solution Approach 2:
The patent combines the hand presence detection function with the existing torque sensor and steering assistance control system. By merging these functions into a single integrated system, the patent avoids adding separate detection hardware while maintaining detection capability through intelligent evaluation of torque signals already being processed for steering control
2Device complexity
If a fixed torque threshold is used for hand presence detection, then the detection process is simplified, but the reliability decreases at different vehicle speeds due to varying steering torques
Solution Approach 1:
The patent implements dynamic threshold adjustment where the torque threshold for hand presence detection is not fixed but adapts based on vehicle speed. The system uses speed-dependent threshold values that change according to the vehicle's current speed, allowing reliable detection across different operating conditions while maintaining a relatively simple evaluation process
Solution Approach 2:
The patent changes the parameter of the torque threshold from a fixed value to a speed-dependent variable. By making the threshold parameter dynamic and correlated with vehicle speed, the system maintains high detection reliability across different speed ranges without significantly increasing computational complexity
3Ease of manufacture
If the torque sensor is used for both steering assistance control and hand presence detection, then the cost is reduced by avoiding additional hardware, but the measurement precision for hand presence detection may be compromised
Solution Approach 1:
The patent segments the torque signal evaluation into different components: the steering assistance control uses the overall torque signal for torque overlay, while the hand presence detection function extracts and evaluates specific characteristics of the same signal (such as torque magnitude relative to speed-dependent thresholds and torque signal patterns). This segmentation allows both functions to operate independently with appropriate precision without requiring separate sensors
Data Source
AI summary
A method for detecting a probability of a steering element of a vehicle being held by a hand of a driver is disclosed. The method includes a step of reading in a torque signal representing a torque acting on a torque sensor coupled between the steering element and a steering transmission. The method also includes a step of recognizing a probability of a steering element of a vehicle being held by a hand of a driver if a value of the torque signal and/or an absolute value of the torque signal exceed(s) a threshold value that is dependent on a current vehicle speed in order to detect the probability of the steering element of the vehicle being held by a hand of the driver.