Electric Power Steering Control for Stable Vehicle Entry and Exit
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Solution Overview
Problem
The usability of a steering wheel is compromised when a driver uses it for getting on or off a vehicle, as easy rotation hinders its utility for support during these actions, leading to poor usability.
Innovation Solution
A vehicle control system that includes an electric power steering device with a controller programmed to suppress steering wheel rotation during getting-on or getting-off actions by switching to a temporal mode, which reduces assist torque and increases damping, making the wheel harder to rotate and thus easier to use as a support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the steering wheel allows free rotation for steering purposes, then the ease of operation is improved, but the stability of the vehicle direction is worsened when the occupant uses the steering wheel as a support
Solution Approach 1:
The system dynamically adjusts the rotational characteristics of the steering wheel based on the detected operational state. During normal steering, free rotation is permitted for ease of operation. When getting-on or getting-off actions are detected, the system transitions to temporal mode where rotation is suppressed, thereby maintaining vehicle direction stability during these transitions.
Solution Approach 2:
The control device preemptively suppresses steering wheel rotation when getting-on or getting-off actions are detected, preventing potential instability before it occurs. This preliminary anti-action ensures that the steering wheel remains stable and provides reliable support during occupant transitions, avoiding unwanted vehicle direction changes.
2Productivity
If the electric power steering device provides continuous assist torque, then the productivity of steering operations is improved, but the loss of time for system response to different operational modes increases
Solution Approach 1:
The control device continuously monitors occupant actions through the state sensor and provides feedback to determine when to switch between normal mode and temporal mode. This feedback mechanism enables rapid detection of getting-on or getting-off actions and immediate switching of the assist torque characteristic, minimizing response time and ensuring appropriate steering behavior without unnecessary delays.
Data Source
AI summary
A vehicle control system includes: an electric power steering device that generates an assist torque that assists turning of a wheel caused by a steering wheel rotation; a controller that controls the electric power steering device to generate the assist torque according to the steering wheel rotation in a normal mode; and a state sensor that detects a vehicle travel state and a state of an occupant at a driver's seat. When the occupant at the driver's seat performs a getting-on action or a getting-off action when the vehicle is in an ignition-ON state, the controller controls the electric power steering device in a temporal mode. In the temporal mode, the controller changes a method of controlling the electric power steering device such that the steering wheel rotation is suppressed as compared with a case of the normal mode.