Steering Force Control Using Dual Matrices for Linear Feel
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Solution Overview
Problem
Existing steering force controllers face challenges in providing a linear steering feel due to delayed intervention timing and excessive assistance at high steering velocities, requiring precise and costly control systems, and struggle to balance stiffness and sensitivity.
Innovation Solution
A steering force controller that detects steering angular velocity, steering angle, and vehicle speed, using a main control matrix for steering angular velocity and vehicle speed, and a subsidiary control matrix for steering angle and vehicle speed to generate a control quantity for steering assist force, ensuring a more linear steering feel without significant cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If steering angle is used to control steering assist force, then fuel efficiency is improved by setting electrical current to 0 at neutral position, but intervention timing is delayed and startup steering becomes heavy
Solution Approach 1:
The control device performs preliminary action by detecting steering angular velocity to anticipate the driver's steering operation before the steering angle becomes significant. When steering angular velocity exceeds the threshold, the control device activates steering assist force in advance, preventing the delay that would occur if waiting for steering angle to reach a detectable level. This preliminary detection and activation resolves the contradiction by maintaining fuel efficiency at neutral position while ensuring timely intervention when steering begins.
2Loss of time
If steering angular velocity is used to control steering assist force, then intervention timing is shortened, but lateral acceleration becomes large and steering assistance becomes excessive at high steering velocities
Solution Approach 1:
The control device applies local quality by implementing different control strategies for different operating conditions. When steering angular velocity is below the threshold, no steering assist force is applied (fuel efficiency mode). When steering angular velocity exceeds the threshold, steering assist force is applied proportionally to the steering angular velocity (assistance mode). This conditional, location-specific control resolves the contradiction by providing timely intervention only when needed, avoiding excessive assistance during normal straight-line driving while ensuring appropriate support during actual steering operations.
3Loss of time
If highly precise control is implemented by dividing steering angle resolution into detailed units, then intervention timing is improved, but device cost and development cycle increase
Solution Approach 1:
The control device uses copying by substituting the complex, high-resolution steering angle measurement with a simpler steering angular velocity measurement. Instead of implementing expensive high-resolution angle sensors and complex control algorithms, the system copies the essential information needed for timely intervention through angular velocity detection. This approach achieves the timing improvement goal while avoiding the increased device complexity and cost associated with highly precise angle resolution systems.
Data Source
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AI summary
A main control matrix (M1), a subsidiary control matrix (M2), a vehicle speed sensor (41) configured to detect a vehicle speed (V), a steering angular velocity sensor (42) configured to detect a steering angular velocity (ω), and a steering angle sensor (43) configured to detect a steering angle (θ) are provided. The main control matrix (M1) is a control map where the steering angular velocity (ω) and the vehicle speed (V) are set as displacements, whereas the subsidiary control matrix (M2) is a control map where the steering angle (θ) and the vehicle speed (V) are set as displacements. A final instruction value is obtained by correcting a value obtained from the main control matrix (M1) with a value obtained from the subsidiary control matrix (M2) .