Steer Torque Manager for ADAS Handover Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current steer torque managers in advanced driver assistance systems face challenges in simultaneously suppressing steering wheel torque disturbances from drivers resting their hands while ensuring comfortable handover of control to drivers who wish to take control, due to conflicting requirements of torque suppression and comfort, leading to potentially stiff steering wheel feel or unintended handover of control.
Innovation Solution
A steer torque manager that filters the steering wheel torsion bar torque signal to attenuate frequencies up to 2 Hz and modulates the overlay torque request based on the amplitude and frequency content, using a driver activity measure derived from the filtered signal, with more recent values weighted higher, to allow drivers to rest their hands without affecting the torque envelope, while limiting torque when the driver increases steering effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DIL-functionality suppresses large levels of steering wheel torque disturbances to track wheel angle requests, then the lateral position control performance is improved, but the driver experiences uncomfortably stiff or strong steering wheel feel
Solution Approach 1:
The system dynamically adjusts the torque suppression level based on detected driver activity. When driver activity is detected, the system reduces torque suppression to provide natural steering feedback; when no driver activity is detected, the system increases torque suppression to maintain lane position. This dynamic adaptation resolves the contradiction by making the torque suppression level variable rather than fixed.
Solution Approach 2:
The system changes the torque disturbance suppression parameters based on driver activity detection. By monitoring steering wheel torque characteristics and detecting when the driver is actively steering versus when hands are resting, the system adjusts the suppression gain to achieve both good lane keeping performance and comfortable steering feel under different operating conditions.
2Adaptability or versatility
If the DIL-functionality decreases available overlay torque to hand over control to the driver, then the driver can take control of the vehicle, but the driver may experience unintended handover when simply resting hands on the steering wheel
Solution Approach 1:
The system uses feedback from torque disturbance characteristics to detect driver intent. By analyzing the pattern, magnitude, and frequency of steering wheel torque disturbances, the system can distinguish between natural resting torque (which should not trigger handover) and intentional steering input (which should trigger handover). This feedback mechanism prevents false handover activation while maintaining reliable driver takeover detection.
Solution Approach 2:
The handover trigger threshold is dynamically adjusted based on detected driver activity patterns. The system learns and adapts to individual driver behaviors, adjusting the sensitivity of handover detection to avoid triggering on normal resting torque variations while remaining sensitive to genuine driver takeover attempts.
3Ease of operation
If the system allows drivers to rest hands on the steering wheel without activating handover, then driver comfort is improved, but the system may fail to detect when the driver actually wants to take control
Solution Approach 1:
The system continuously monitors steering wheel torque characteristics and compares them against learned driver behavior patterns. By analyzing feedback from torque magnitude, frequency, and temporal patterns, the system can distinguish between relaxed resting (where hands are lightly placed) and active steering (where the driver intends to take control), maintaining both comfort and reliability.
Solution Approach 2:
The system introduces an intermediate detection layer that analyzes torque disturbance characteristics before triggering handover. This intermediary analysis of torque patterns serves as a mediator between the relaxed hand-resting state and the active control state, enabling the system to recognize when the transition from resting to active steering occurs.
Data Source
AI summary
A steer torque manager for an advanced driver assistance system of a road vehicle and a method therefor. A driver-in-the-loop functionality determines when to hand over control to a driver. A wheel angle controller uses an advanced driver assistance system wheel angle request to produce an overlay torque request to be added to a torque request from an electrical power assisted steering. The steer torque manager controls the driver-in-the-loop functionality based on amplitude and frequency content of a torsion bar torque related signal which is filtered to attenuate an amplitude thereof at frequencies up to 2 Hz. The overlay torque request to be provided by the wheel angle controller is modulated based on a measure of driver activity derived from the filtered torsion bar torque related signal, where more recent values are weighted higher than older values, using a time window of 0.5-3 seconds.