Steering Control Device Attenuation Torque Adjustment
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Solution Overview
Problem
Conventional steering control devices fail to smoothly transition from turning to turning-back operations, leading to an uncomfortable 'catching feeling' for drivers due to delayed detection and reduction of assist torque during turning-back operations from maximum steering angles.
Innovation Solution
A steering control device with an assist controller and active-passive determination processor that computes a steering mode determination value based on steering angle speed and torque, increasing attenuation torque for turning operations and reducing it when the steering mode shifts to passive, thereby alleviating impact loads and discomfort during turning-back operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the attenuation torque is increased when the steering angle approaches the maximum steering angle to suppress impact load, then the impact load at the time of end abutting is reduced, but the driver feels a sense of uncomfortableness (catching feeling) at the instant the turning-back operation is started
Solution Approach 1:
The control device determines the steering mode (active or passive) in advance based on the steering angle speed and torque products before the turning-back operation is fully detected. When passive steering mode is determined, the attenuation torque is reduced proactively, so that when the turning-back operation is detected, the driver does not feel the catching feeling. This preliminary determination and adjustment of attenuation torque resolves the contradiction between suppressing impact load and maintaining driver comfort.
Solution Approach 2:
The control device dynamically adjusts the attenuation torque based on the real-time steering mode determination. The attenuation torque is increased when active steering mode is detected (to suppress impact load) and reduced when passive steering mode is detected (to improve driver comfort). This dynamic adjustment allows the system to adapt to changing steering conditions and resolve the contradiction between impact load suppression and driver comfort.
2Object-affected harmful factors
If the assist torque is reduced from the time of a steering angle before the maximum steering angle to reduce the impact load, then the impact load at the time of end abutting is suppressed, but the turning-back operation cannot be detected until the steering angle reaches a second predetermined angle
Solution Approach 1:
The control device continuously monitors the steering angle speed and torque products to determine the steering mode in real-time. This feedback mechanism allows the system to detect the transition from active to passive steering mode and adjust the attenuation torque accordingly. The feedback control enables early detection of turning-back operations and proactive reduction of attenuation torque, eliminating the detection delay while maintaining impact load suppression.
3Speed
If the attenuation torque is increased to suppress steering angle speed, then the steering angle speed is reduced, but the assist torque cannot be generated for turning-back operation until the steering mode is detected
Solution Approach 1:
The control device performs preliminary determination of the steering mode based on steering angle speed and torque products before the turning-back operation is fully executed. When passive steering mode is determined, the attenuation torque is reduced in advance, enabling the assist torque to be generated promptly for turning-back operation. This preliminary action eliminates the delay in assist torque generation and improves turning-back operation responsiveness while maintaining steering angle speed suppression.
Data Source
AI summary
A steering control device includes: an assist controller configured to carry out, by an assist torque, an assist control of alleviating an operation force of a steering wheel; an assist torque computer configured to compute a target assist torque in which an attenuation torque for suppressing a steering angle speed of the steering wheel is superimposed on a reference torque; and an active-passive determination processor configured to compute a steering mode determination value representing a steering mode by a driver with respect to the steering wheel in accordance with a product of the steering angle speed and a steering torque at a time of a steering operation of the steering wheel by the driver as well as a product of the steering angle and a time differential value of the steering torque at the time of the steering operation.