Steering Control Apparatus Cable Attachment Diagnosis
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Solution Overview
Problem
The existing steering systems with variable steering ratios face challenges in reliably diagnosing cable attachment, particularly when the vehicle is stationary, as the conventional lock-to-lock steering method may incorrectly assess the spiral cable's attachment due to differences in steering wheel angles between active and inactive states, and the power supply cables are not easily ruptured, leading to potential movement restrictions.
Innovation Solution
A steering control apparatus with a cable-attachment diagnostic controller that regulates the steering ratio to ensure the steering input unit moves within an allowable region defined by a steering limiter, allowing for accurate detection of correct cable attachment by controlling the steering ratio to be lower than 1 and moving the steering input unit over a defined range when correctly attached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cable-attachment diagnostic operation based on lock-to-lock steering is performed when the vehicle is at rest with the variable steering ratio steering system being shut down, then the diagnostic operation can be performed, but the steering wheel angle defined by the rack stopper is not identical to that with the variable steering ratio steering system being active, leading to incorrect assessment of cable attachment
Solution Approach 1:
The patent applies the Dynamics principle by making the steering ratio variable rather than fixed. The variable steering ratio control mechanism adjusts the steering ratio based on operating conditions, allowing the system to adapt between different states (vehicle at rest vs. active). This resolves the contradiction by enabling the diagnostic operation to be performed with accurate angle assessment through dynamic adjustment of the steering ratio, ensuring the steering wheel angle definition remains consistent regardless of system state.
2Strength
If the power supply cable is made thick enough to supply adequate electric current for operating the electric motor, then the cable is not easily ruptured, but if the check of cable attachment is unsatisfactory, movement of the steering wheel is restricted by the spiral cable before the rack shaft reaches the rack stopper
Solution Approach 1:
The patent applies the Segmentation principle by separating the functions of the cable system into distinct components: a thick power supply cable for adequate current transmission and a separate spiral cable for steering wheel rotation. This segmentation allows each cable to be optimized for its specific function - the power cable for strength and current capacity, and the spiral cable for flexible rotation - thereby resolving the contradiction between cable strength and steering wheel movement freedom.
Data Source
AI summary
A steering control apparatus for a vehicle including a steering input unit movable to set a steering input, and a steering output unit arranged to output a steering output, the steering input unit being connected via a cable to a body of the vehicle, includes a steering ratio control unit, a steering limiter, and a cable-attachment diagnostic controller. The steering ratio control unit regulates a variable steering ratio as a rate of change in the steering output with respect to a change in the steering input. The steering limiter restricts movement of the steering input unit to limit the steering input. The cable-attachment diagnostic controller is activated in a cable-attachment diagnostic mode, to control the steering ratio in such a manner that the steering input unit is movable over an allowable region defined by the steering limiter when the cable is correctly attached.