Electric Power Steering Variable Transition Time
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Solution Overview
Problem
Conventional electric power steering systems face challenges in smoothly switching from automatic steering mode to manual steering mode, leading to safety concerns and driver discomfort due to large torque variations between angle control and torque control command values.
Innovation Solution
The electric power steering apparatus variably sets a gradual-changing time based on the command value difference between angle control and torque control command values when switching from angle control to torque control, using a gradual-changing process to reduce torque variations and enhance safety and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If switching from angle control to torque control is performed without gradual-changing, then switching speed is fast, but driver discomfort and safety are reduced due to large torque variations
Solution Approach 1:
The patent applies dynamics by making the switching process adaptable and variable rather than fixed. The gradual-changing time is dynamically adjusted based on the command value difference between angle control and torque control, allowing the system to optimize both switching speed and driver comfort for each specific situation. This resolves the contradiction by enabling fast switching when the difference is small while providing smooth transitions when the difference is large.
Solution Approach 2:
The patent changes the parameter of switching time from a fixed value to a variable value based on the command value difference. By calculating the difference between angle control command value and torque control command value, and setting the gradual-changing time accordingly, the system achieves optimal balance between switching speed and driver comfort. This parameter change approach directly resolves the technical contradiction.
2Device complexity
If gradual-changing time is fixed, then control is simple, but driver discomfort occurs when command value difference is large
Solution Approach 1:
The patent transforms the fixed gradual-changing time parameter into a variable parameter that changes based on the command value difference. The control unit calculates the difference between angle control and torque control command values, then adjusts the gradual-changing time proportionally. This resolves the contradiction by maintaining simplicity in the control logic while significantly improving driver comfort through adaptive parameter adjustment.
Solution Approach 2:
The patent implements feedback by continuously monitoring the command value difference between angle control and torque control, and using this information to adjust the gradual-changing time. This closed-loop approach ensures that the switching process adapts to real-time conditions, resolving the contradiction between control simplicity and driver comfort by automatically optimizing the transition based on actual system state.
3Ease of operation
If gradual-changing time is extended, then driver comfort is improved, but switching response becomes slow
Solution Approach 1:
The patent changes the gradual-changing time parameter from a constant extended value to a dynamically adjusted value based on command value difference. When the difference is small, the switching time remains short for fast response; when the difference is large, the switching time extends proportionally to maintain driver comfort. This resolves the contradiction by making the switching time adaptive rather than uniformly extended.
Solution Approach 2:
The patent applies dynamics by making the switching process responsive to real-time conditions. The gradual-changing time is not statically extended but dynamically determined based on the command value difference, allowing the system to achieve fast switching when appropriate while providing smooth transitions when needed. This dynamic approach resolves the contradiction between response speed and driver comfort.
Data Source
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AI summary
[Problem] An obj ect of the present invention is to provide an electric power steering apparatus that has safety and a high performance in which an uncomfortable feeling is reduced, by being varied a gradual-changing time based on a command value difference between an angle control command value and a torque control command value when a gradual-changing process, in which a control system is switched from an angle control to a torque control, is performed. [Means for solving the problem] The present invention is the electric power steering apparatus that has a torque sensor which detects a steering torque, and a motor control apparatus to control the motor which applies an assist torque, by which steering is assisted, to a steering system of a vehicle, comprising: a function that switches a control system of the motor between an angle control system to control an angle corresponding to an angle control command value of an automatic steering mode and a torque control system to control a torque corresponding to a torque control command value of a manual steering mode in accordance with a predetermined switching trigger, wherein the electric power steering apparatus variably sets a gradual-changing time corresponding to a command value difference between the angle control command value and the torque control command value when switching from the angle control system to the torque control system by using a gradual-changing.