Electric Power Steering Torque Integral Mode Switching
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Solution Overview
Problem
Conventional electric power steering systems face challenges in smoothly switching from automatic to manual steering modes due to noise in torque sensors and inertial torques, leading to uncomfortable driver experiences and potential failure in immediate mode switching.
Innovation Solution
An electric power steering apparatus that integrates steering torque to determine when to switch modes, using a torque integral judging section to compare the integrated torque value with predetermined thresholds, eliminating the need for multiple thresholds and reducing calculation load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-based thresholds with multiple predetermined values are used for mode switching judgment, then the reliability of mode switching can be improved, but the device complexity and calculation load increase
Solution Approach 1:
The patent changes the parameter basis for mode switching from time-based thresholds to torque integral-based thresholds. By integrating steering torque over time and comparing the accumulated value against a single predetermined threshold, the system achieves reliable mode switching without requiring multiple time-based thresholds, thus reducing computational complexity while maintaining switching reliability.
2Measurement precision
If multiple predetermined torque thresholds are set for accurate mode switching, then the measurement precision can be improved, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent extracts the essential feature of torque magnitude by integrating the steering torque signal over time, removing the need to detect and compare against multiple discrete torque thresholds. This extraction of the integral value simplifies the detection process while preserving the ability to accurately determine when driver intervention occurs.
3Reliability
If torque sensor noise and inertial torques are considered in mode switching, then the reliability can be improved, but the loss of time for switching increases
Solution Approach 1:
The patent applies beforehand cushioning by integrating the steering torque signal before making the mode switching decision. This integration process acts as a cushion that filters out transient noise and inertial torque effects, allowing the system to maintain high reliability while responding quickly to genuine driver intervention without requiring excessive delay for multiple threshold checks.
Data Source
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AI summary
[Problem] An object of the present invention is to provide an electric power steering apparatus that does not give uncomfortable feeling to a driver by detecting that the driver steers a steering wheel in an automatic steering mode by means of a steering torque from a torque sensor and switching to a manual steering mode by a capacity (an integrated value) corresponding to the occurring torque magnitude. [Means for solving the problem] The present invention comprises a steering angle control section that calculates a motor current command value 2, a torque integral judging section that outputs a steering torque judging signal by integrating a steering torque, which is compared with a threshold, and a switching section that inputs the motor current command value 1 and the motor current command value 2, and is switched in accordance with a switching signal or the steering torque judging signal; the torque integral judging section comprises a torque value comparing section, an integral calculating section and a switch judging section; and the switching section is switched depending on a switching command of an automatic steering mode and a manual steering mode or the steering torque judging signal.