Electric Steering Assist Force Reduction for Ignition Failure Detection
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Solution Overview
Problem
Existing electric steering devices fail to notify drivers of erroneous operations or failures in the power supply system, leading to increased steering effort and difficulty during vehicle operation.
Innovation Solution
An electric steering device with an electric actuator, control unit, ignition signal detection, and speed acquisition unit that reduces the steering assist force when the ignition signal is not detected and the vehicle is above a predetermined speed, using a correction coefficient to lower the assist force and alert the driver through a display unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power supply is stopped when the ignition signal is not detected, then energy consumption is reduced and battery exhaustion is prevented, but the driver cannot notice erroneous operation or failure and steering performance deteriorates
Solution Approach 1:
The steering assist force is made dynamically adjustable based on ignition signal detection status. The control unit switches between normal assist force (when ignition signal is detected) and reduced assist force (when ignition signal is not detected), allowing the system to adapt its behavior to different operational states while maintaining reliability awareness.
Solution Approach 2:
The system implements feedback through the ignition signal detection mechanism. When the ignition signal is not detected, the control unit reduces the steering assist force, creating a noticeable change in steering characteristics that provides feedback to the driver about the system state, thereby enabling error detection while managing power consumption.
2Loss of information
If the steering assist force is reduced when ignition signal is not detected, then the driver can easily notice power supply issues, but steering performance deteriorates
Solution Approach 1:
Instead of completely stopping the steering assist force, the system applies a partial assist force when the ignition signal is not detected. This partial action is sufficient to maintain basic steering operability and prevent complete performance deterioration, while still creating a noticeable difference that alerts the driver to the abnormal state.
3Ease of operation
If the power supply is continuously maintained to avoid sudden steering wheel weight changes, then steering performance is maintained, but the driver is hard to notice erroneous operation or failure
Solution Approach 1:
The system introduces an intermediate state between full power supply and complete power cutoff. When the ignition signal is not detected, the power supply is maintained at a reduced level that provides partial steering assist force, serving as an intermediary state that prevents sudden weight changes while still conveying system status information to the driver.
Data Source
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AI summary
An electric steering device includes an electric actuator (208) which generates a steering assist force for a steering mechanism (210) of a vehicle (10), a control unit which controls the steering assist force generated from the electric actuator (208) based on an operation of a steering wheel (202) by a driver, an ignition signal detection unit (2064) which detects presence or absence of an ignition signal of the vehicle (10), and a speed acquisition unit (2066) which acquires a running speed of the vehicle (10). In a case that the ignition signal is not detected and the running speed is a predetermined speed or more, the control unit reduces an upper limit of the steering assist force generated from the electric actuator (208) so as to be smaller than an upper limit in a case that the ignition signal is detected.