Steering Device Clutch Angle Ratio Control
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Solution Overview
Problem
The existing steer by wire vehicle steering devices cause uncomfortable driving experiences due to self-steering or steering lock issues when the clutch mechanism is erroneously connected, often due to foreign substances, leading to deviations in turning angle ratios and unintended motor operation.
Innovation Solution
A vehicle steering device with a clutch mechanism that controls the angle ratio between the steering unit and turning mechanism to be equal to or smaller than the mechanical angle ratio at startup, and includes a mode switching mechanism to EPS mode when excessive steering torque is detected, ensuring safe operation and notification of abnormal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clutch mechanism is erroneously connected due to foreign substance, then the steering device operates with mechanical angle ratio, but the deviation between quick ratio and mechanical angle ratio increases causing self-steer and driver discomfort
Solution Approach 1:
The control device detects clutch connection status before normal steering operation begins, and issues a warning to the driver in advance. This preliminary detection and warning allows the driver to address the erroneous connection before it causes self-steer or discomfort during steering operations.
Solution Approach 2:
The control device continuously monitors clutch connection status and provides feedback to the driver through warning signals. This feedback mechanism enables the driver to understand the clutch status and take appropriate actions to maintain safe steering operation.
2Reliability
If the clutch mechanism is erroneously connected with slow ratio, then the actual turning angle exceeds target turning angle, but the steering wheel becomes locked causing driver discomfort
Solution Approach 1:
The control device detects erroneous clutch connection before steering operations that would cause locking occur, and warns the driver in advance. This prevents the steering wheel from becoming locked during normal steering operations.
Solution Approach 2:
The control device provides continuous feedback about clutch connection status to the driver, enabling the driver to understand when the clutch is erroneously connected and adjust steering operations accordingly to avoid locking.
3Extent of automation
If the motor operates to compensate deviation between quick ratio and mechanical angle ratio, then feedback control is executed, but the deviation is not compensated and self-steer occurs
Solution Approach 1:
The control device monitors clutch connection status and steering angle deviations, and provides feedback to the driver about the erroneous connection condition. This allows the driver to understand why the feedback control cannot compensate for the deviation and take appropriate actions.
Solution Approach 2:
The control device acts as an intermediary between the clutch mechanism and the driver, detecting the erroneous connection status and communicating it to the driver through warnings. This intermediary function prevents the driver from experiencing unexpected self-steer without blaming the automated control system.
Data Source
AI summary
A mode setting unit of ECU controls a turning angle so as to be a turning angle in accordance with a steering angle detected by a steering angle sensor. When a vehicle is started, the mode setting unit controls an angle ratio so as to be an angle ratio that is equal to or smaller than a ratio of the turning angle to the steering angle (mechanical angle ratio) when a steering wheel and a turning mechanism are connected by a clutch mechanism.