EPS Motor Grip Detection via Steering Wheel Oscillation
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Solution Overview
Problem
Autonomous vehicles face challenges in determining whether a driver is gripping the steering wheel accurately, particularly during transitions from autonomous to manual control, as existing methods may lead to unsafe assumptions about driver engagement.
Innovation Solution
The method involves sending an excitation instruction to an electrically assisted power steering system (EPS) motor to oscillate the steering wheel, with a torque sensor monitoring the movement and generating pattern data, and a processor determining the driver's grip based on this data and system position data, using calibration to increase accuracy and differentiate grip degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is added to the steering wheel to detect driver grip, then the detection capability is improved, but the device complexity increases
Solution Approach 1:
The EPS motor is made multi-functional by enabling it to both assist steering and detect driver grip through impedance sensing. The same motor structure serves dual purposes: providing power assistance during steering operations and acting as a sensor for detecting driver hand presence and grip strength through electrical impedance measurements during oscillation cycles.
Solution Approach 2:
The EPS motor performs self-diagnosis and driver detection functions using its own operational characteristics without requiring external sensing components. The motor's electrical impedance and current consumption during oscillation provide inherent information about driver grip, allowing the system to monitor driver status using resources already present in the steering system.
2Productivity
If the autonomous system assumes driver control based on alert notification, then the transition speed is improved, but the reliability deteriorates
Solution Approach 1:
The system implements continuous feedback monitoring of driver grip status through EPS motor impedance sensing during and after handoff transitions. The motor's electrical characteristics provide real-time feedback about whether the driver has actually grasped the steering wheel, allowing the autonomous system to verify driver engagement before and during mode transitions rather than relying on assumptions.
Solution Approach 2:
The system performs preliminary driver grip verification before completing the autonomous-to-manual transition by monitoring EPS motor impedance during the handoff alert period. This preliminary detection ensures the driver is actually prepared to take control before the autonomous system disengages, preventing unsafe transitions while maintaining efficient handoff timing.
3Measurement precision
If calibration is performed based on driver characteristics, then the measurement precision is improved, but the loss of time increases
Solution Approach 1:
Driver-specific calibration parameters are determined in advance during initial system setup or previous driving sessions, storing impedance characteristics and grip patterns for later use. This preliminary calibration allows the system to quickly reference pre-established driver profiles during actual operation, achieving high measurement precision without requiring time-consuming calibration procedures during each driving session or handoff event.
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
This approach effectively determines whether and to what degree a driver is gripping the steering wheel, preventing unsafe transitions and ensuring driver preparedness for manual control, thereby enhancing safety in autonomous vehicles.
Implementation Method 1
sending an excitation instruction to move a steering wheel of a vehicle to an electrically assisted power steering system (EPS) motor; in response to receiving the excitation instruction, moving, by the EPS motor, the steering wheel
Implementation Method 2
monitoring the movement of the steering wheel by the torque sensor; generating, by the torque sensor, pattern data based on the monitoring
Data Source
AI summary
Aspects of the disclosure relate generally to determining by what degree a driver is gripping a steering wheel. In one example, a computer may send an electrically assisted power steering system (EPS) motor an excitation command to move. The EPS motor may respond by moving a flexible coupling between the steering wheel and the EPS motor. This may cause a corresponding movement at the steering wheel. A torque sensor may generate pattern data by monitoring the flexible coupling during the movement. The EPS motor may generate system position data for the entire steering system, for example, from the tires to the steering wheel. The pattern data and the system position data may be compared by the computer to determine the degree of grip. In this regard, the computer may determine the degree of a driver's grip without the need for additional sensors.