Steering Control Device with Dual Limiting Circuits
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Solution Overview
Problem
Existing steering control devices face challenges in effectively limiting the steering angle and steered angle to prevent them from exceeding their respective upper limit values, leading to potential overheating and reliability issues with the spiral cable, especially when the steering angle ratio is high or low.
Innovation Solution
A steering control device with a steering angle obtaining circuit and a steered angle obtaining circuit, along with first and second limiting circuits that apply reaction forces to prevent further operation when the steering or steered angle approaches its threshold, using a reaction force actuator and steering actuator to manage the steering angle ratio and prevent excessive operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steering limiting process is performed based on steering angle threshold, then steering angle is protected from exceeding upper limit, but steered angle may exceed its upper limit when steering angle ratio is low
Solution Approach 1:
The steering control device divides the limiting control function into two independent circuits: a first limiting circuit that monitors steering angle against a steering angle threshold, and a second limiting circuit that monitors steered angle against a steered angle threshold. This segmentation ensures that each circuit independently protects its respective parameter, preventing both steering angle and steered angle from exceeding their upper limits regardless of the steering angle ratio.
Solution Approach 2:
The system dynamically adjusts which limiting circuit becomes active based on real-time operating conditions. When the steering angle ratio changes, the control device dynamically switches between steering-angle-based limiting and steered-angle-based limiting, ensuring appropriate protection is always applied. This dynamic adaptation resolves the contradiction by making the limiting strategy flexible rather than fixed.
2Reliability
If steering limiting process is performed based on steered angle threshold, then steered angle is protected from exceeding upper limit, but steering angle may exceed its upper limit when steering angle ratio is high
Solution Approach 1:
The steering control device divides the limiting control function into two independent circuits: a first limiting circuit that monitors steering angle against a steering angle threshold, and a second limiting circuit that monitors steered angle against a steered angle threshold. This segmentation ensures that each circuit independently protects its respective parameter, preventing both steering angle and steered angle from exceeding their upper limits regardless of the steering angle ratio.
Solution Approach 2:
The system dynamically adjusts which limiting circuit becomes active based on real-time operating conditions. When the steering angle ratio changes, the control device dynamically switches between steering-angle-based limiting and steered-angle-based limiting, ensuring appropriate protection is always applied. This dynamic adaptation resolves the contradiction by making the limiting strategy flexible rather than fixed.
3Reliability
If spiral cable length is set for minimum steering angle ratio, then steering angle is protected at minimum ratio, but protection is insufficient at other steering angle ratios
Solution Approach 1:
The steering control device divides the limiting control function into two independent circuits: a first limiting circuit that monitors steering angle against a steering angle threshold, and a second limiting circuit that monitors steered angle against a steered angle threshold. This segmentation ensures that each circuit independently protects its respective parameter, preventing both steering angle and steered angle from exceeding their upper limits regardless of the steering angle ratio.
Solution Approach 2:
The dual-limiting circuit system serves multiple functions: it protects the spiral cable from overheating, adapts to varying steering angle ratios, and provides comprehensive protection across the entire operating range. By making the limiting control system universal rather than ratio-specific, it resolves the contradiction between reliability and adaptability.
Data Source
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AI summary
A steering control device can restrain a steering from being operated to cause a steered angle and a steering angle to exceed their upper limit values. A first limiting reaction force setting circuit (M6) increases a first reaction force (Fiel) rapidly if the steering angle (θh) becomes no smaller than a steering angle threshold (θhth). A second limiting reaction force setting circuit (M8) increases a second reaction force (Fie2) rapidly if the steered angle (θp) becomes no smaller than a steered angle threshold (θpth). A target steering angle setting circuit (M22) sets a target steering angle (θh*) based on steering torque (Trq) applied to the steering minus the first reaction force (Fiel), the second reaction force (Fie2), etc. A steering angle control circuit (M24) sets reaction torque (Trqa*) as a manipulated variable for feedback controlling the steering angle (θh) to the target steering angle (θh*). An operation signal generation circuit (M26) outputs an operation signal (MSs) to a reaction force motor so as to achieve reaction torque (Trqa*).