Electric Power Steering Lateral Acceleration Reactive Force Control
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Solution Overview
Problem
Conventional electric power steering systems fail to provide a steering feel that corresponds to lateral acceleration, leading to an insufficient sense of unity between the driver and the vehicle, especially under varying driving conditions.
Innovation Solution
An electric power steering system with a controller that computes a correction control component to increase steering reactive force based on lateral acceleration, while adjusting the target rotation angle and assist elasticity component to maintain a harmonious balance between the driver's sense of lateral acceleration and steering response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedback control is executed based on the target steered angle defined by the second normative model, then a rigid steering feel is reliably obtained, but the driver's sense of unity with the vehicle becomes insufficient when lateral acceleration increases
Solution Approach 1:
The patent dynamically adjusts the target steered angle based on detected lateral acceleration. When lateral acceleration exceeds a threshold, the target steered angle is modified to increase the steering reactive force, allowing the system to adapt between rigid steering feel and driver unity sense depending on driving conditions
Solution Approach 2:
The patent changes the parameter of target steered angle based on lateral acceleration magnitude. By modifying this parameter in response to detected lateral acceleration, the system achieves different steering characteristics appropriate for different driving conditions, resolving the contradiction between rigid feel and driver unity
2Adaptability or versatility
If the steering reactive force is increased to match lateral acceleration, then the driver's sense of unity with the vehicle improves, but the steering responsiveness may become excessive
Solution Approach 1:
The patent carefully adjusts the target steered angle parameter based on lateral acceleration to increase steering reactive force while maintaining appropriate steering responsiveness. The controlled modification of this parameter ensures both driver unity and responsive steering
3Force
If the magnitude of steering torque used to compute target rotation angle is increased, then the steering reactive force increases, but the balance between lateral acceleration and steering response becomes失衡
Solution Approach 1:
The patent modifies the target rotation angle parameter based on lateral acceleration rather than simply increasing steering torque magnitude. This parameter change approach increases steering reactive force while preserving the harmonious balance between lateral acceleration and steering response
Data Source
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AI summary
In an electric power steering system, a vehicle reactive force model (82) computes a correction spring reactive torque (T sp3* ) in such a manner that an elasticity component included in a steering reactive force is increased with an increase in a lateral acceleration (LA). As the lateral acceleration (LA) increases, an increase in a basic drive torque is suppressed by a larger amount. By an amount by which the magnitude of the basic drive torque is suppressed, a target pinion angle computed by a target pinion angle computing unit decreases and a correction component for a basic assist component is decreased. A steering assist force is decreased, and a steering reactive force is increased with a decrease in the steering assist force. Thus, it is possible to obtain an appropriate steering reactive force based on the magnitude of the lateral acceleration (LA).