Electric Power Steering Smooth Mode Transition
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Solution Overview
Problem
Existing electric power steering systems experience uncomfortable feelings and steering difficulties when switching between automatic and manual steering modes, due to abrupt changes in command values and inadequate handling of road surface reactions and driver inputs.
Innovation Solution
An electric power steering apparatus that includes a steering angle control section and a switch judging and gradual-change gain generating section, which judges the steering state based on manual input and adjusts control gains to smoothly transition between automatic and manual steering modes, using threshold-based manual input judgment and smoothing filters to reduce uncomfortable feelings and improve steering responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If steering angle control is performed during automatic steering, then automatic steering accuracy is improved, but steering intervention by driver becomes difficult and unsafe
Solution Approach 1:
The control system dynamically switches between steering angle control and assist control modes based on driver input detection. When manual steering input exceeds a threshold, the system transitions from rigid steering angle control to assist control, allowing driver intervention while maintaining automatic steering functionality during normal operation
Solution Approach 2:
The system changes control parameters by switching between different control modes (steering angle control vs. assist control) based on the detected steering state. This parameter change enables the system to adapt between prioritizing automatic steering accuracy and prioritizing driver intervention capability
2Speed
If steering state switching is performed abruptly, then response to driver input is improved, but uncomfortable feeling and vibrations increase
Solution Approach 1:
The system performs preliminary detection of driver steering input and prepares for mode switching before the actual transition occurs. By detecting steering torque or angular velocity in advance, the system can smoothly transition between control modes, preventing abrupt changes that cause vibrations and uncomfortable feelings
Solution Approach 2:
The control system acts as an intermediary between the automatic steering control and the driver's manual input. It detects driver intent through steering torque sensors and angular velocity sensors, then mediates the transition between control modes to eliminate abrupt changes and reduce steering wheel vibrations
Data Source
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AI summary
[Problem] An object of the present invention is to provide an electric power steering apparatus that achieves manual steering even if steering intervention is performed by a driver during automatic steering, ensures more safety when the driver steers urgently, and enables both assist control and steering angle control. [Means for solving the problem] An electric power steering apparatus comprises a steering angle control section that calculates a steering angle control current command value for steering angle control based on at least a steering angle command value and an actual steering angle, and a switch judging and gradual-change gain generating section that judges a steering state based on manual input judgment and performs switching of the steering state; the switch judging and gradual-change gain generating section comprises a manual input judging section that performs the manual input judgment by using a threshold to a steering torque; and the electric power steering apparatus calculates a current command value by using at least the steering angle control current command value.