Electric Power Steering Linear Force Control
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Solution Overview
Problem
Existing power steering apparatuses fail to provide a suitable auxiliary steering force that adapts to varying vehicle speeds, resulting in a heavy feeling at high speeds and a light feeling at low speeds, which is not satisfactory for drivers.
Innovation Solution
An electric power steering apparatus that includes a steering torque sensor, speed sensor, auxiliary steering force setting unit, map setter, current signal supply, and motor driving unit, allowing for a linear adjustment of auxiliary steering force based on vehicle speed, with a feedback mechanism to ensure the force remains within performance limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed auxiliary steering force is provided, then the steering apparatus is simple to control, but the steering force feels heavy at high speeds and light at low speeds, reducing driver satisfaction
Solution Approach 1:
The patent implements dynamic adjustment of auxiliary steering force based on vehicle speed through a speed sensor that detects vehicle speed and a control unit that varies the motor's auxiliary steering force according to the detected speed, enabling the system to adapt from heavy force at high speeds to light force at low speeds
Solution Approach 2:
The patent changes the parameter of auxiliary steering force based on vehicle speed parameter detection, using a speed sensor to detect vehicle speed and a control unit to adjust the motor current and output force accordingly, creating a linear relationship between speed and auxiliary steering force
2Ease of operation
If the auxiliary steering force is increased to improve steering ease, then steering becomes easier, but the steering wheel feels too heavy at high speeds, reducing steering precision
Solution Approach 1:
The system dynamically adjusts the auxiliary steering force based on real-time vehicle speed detection, automatically reducing the force at high speeds to maintain steering precision while providing enhanced force at low speeds for easier manipulation
Solution Approach 2:
The patent uses a speed sensor to detect vehicle speed and feeds this information back to the control unit, which then adjusts the motor's auxiliary steering force accordingly, creating a closed-loop control system that optimizes steering ease across different speed conditions
3Measurement precision
If the auxiliary steering force is decreased to improve steering precision at high speeds, then steering precision improves, but steering becomes difficult at low speeds, reducing ease of operation
Solution Approach 1:
The control unit dynamically varies the auxiliary steering force based on detected vehicle speed, providing high force at low speeds for ease of operation and low force at high speeds for steering precision, optimizing both parameters across the speed range
4Adaptability or versatility
If a linear adjustment of auxiliary steering force is implemented, then driver satisfaction improves, but the control system becomes more complex
Solution Approach 1:
The patent establishes a linear relationship between vehicle speed and auxiliary steering force by adjusting motor current proportionally to speed, achieving smooth and predictable force variation that enhances driver satisfaction while maintaining a relatively simple control algorithm
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables a stable and adaptable auxiliary steering force that varies linearly with vehicle speed, enhancing driver satisfaction by providing the appropriate force needed at different speeds, ensuring operation within the apparatus's performance boundaries.
Implementation Method 1
a motor (108) for generating an auxiliary steering force
Data Source
AI summary
An electric power steering apparatus including a motor includes: a steering torque sensor; a speed sensor; an auxiliary steering force setting unit configured to output a signal representing a linear change of a gradual increase or decrease; a map setter configured to receive a signal output from the auxiliary steering force setting unit and to set an auxiliary steering force map where a maximum steering torque, a maximum target motor current, or a ratio of a target motor current to a steering torque at a specific speed gradually increases or decreases; a current signal supply configured to output the steering torque signal and a target motor current signal corresponding to the speed signal according to the auxiliary steering force map; and a motor driving unit configured to supply a current corresponding to the target motor current signal to the motor.