Electric Power Steering Assist Control for Canted Roads
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electric power steering devices struggle to provide adequate assist force when driving on inclined roads, leading to increased driver burden due to high computation loads and complex structures in detecting road cant, resulting in insufficient assist force during extended straight-line travel.
Innovation Solution
An electric power steering device with a control system that determines whether the vehicle is traveling in a straight line and computes a compensation component for increasing assist force based on integrated steering torque, superimposing it on the basic assist force only when necessary, thereby reducing driver burden and maintaining favorable steering feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a dead zone is established in basic assist control to increase steering rigid feel, then steering rigid feel is improved, but assist force becomes insufficient when traveling on canted roads
Solution Approach 1:
The assist control is segmented into two independent components: basic assist control (with dead zone for rigid feel) and integration assist control (without dead zone for continuous assist). This allows each component to fulfill its specific function without compromising the other, resolving the contradiction between rigid feel and sufficient assist force on canted roads.
Solution Approach 2:
The system dynamically switches between different assist control modes based on driving conditions. The integration assist control is activated when steering torque remains within the dead zone for an extended period, providing adaptive assist force that responds to the actual driving situation while preserving the dead zone structure for normal steering operations.
2Measurement precision
If neural network computation is used to determine road cant state, then accuracy in detecting canted roads is improved, but computation load and device complexity increase
Solution Approach 1:
The patent extracts the essential function of road cant detection from complex neural network computation and implements it through a simpler integration-based method. By monitoring the cumulative steering torque over time, the system can detect canted road conditions without requiring sophisticated computation, thus achieving the desired measurement precision with significantly reduced device complexity.
Solution Approach 2:
Instead of using expensive and complex neural network computation resources, the patent employs a computationally inexpensive integration method that accumulates steering torque data over time. This approach provides sufficient detection accuracy for road cant conditions while being far more economical in terms of computational resources and device complexity.
3Force
If integration assist control is applied continuously, then assist force is improved during straight-line travel, but steering rigid feel deteriorates during non-straight-line travel
Solution Approach 1:
The system dynamically adjusts the assist control strategy based on real-time driving conditions. When the vehicle travels in a straight line on a canted road, the integration assist control is activated to provide sufficient assist force. When the vehicle performs steering maneuvers, the system switches to basic assist control to maintain appropriate steering rigid feel, thus adaptively resolving the contradiction between assist force and steering feel.
Solution Approach 2:
The system continuously monitors steering torque and vehicle state to determine when integration assist control should be activated or deactivated. This feedback mechanism ensures that assist force is provided only when necessary (during straight-line travel on canted roads) while maintaining proper steering rigid feel during normal steering operations, effectively resolving the contradiction between the two requirements.
Data Source
AI summary
A current command value computing section includes an integration control computing section. Based on an integration of the steering torque τ, the integration control computing section computes a steering torque integration control amount Iint*, which is a compensation component for increasing the assist force. The integration control computing section functions as a determining device that determines whether the vehicle is traveling forward in a straight line. When the determining device determines that the vehicle is traveling forward in a straight line, the integration control computing section outputs the steering torque integration control amount Iint* to an adder. The current command value computing section superimposes the steering torque integration control amount Iint* on a basic assist control amount Ias* computed by a basic assist control section, and outputs the obtained value, as a current command value Iq* corresponding to a target assist force, to an output section.