Virtual Steering Model for Motor-Driven Power Steering Tuning
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Solution Overview
Problem
Existing motor-driven power steering systems face challenges in predicting control logic performance during initial feedback controller mapping, leading to inefficient development and tuning processes.
Innovation Solution
A virtual steering model is established, using a reaction force apparatus between the steering wheel and rack gear, with a state equation induced to determine target steering torque through numerical integration, allowing feedback control to align the steering torque with the target, and system parameters like torsion bar rigidity and rack gear weight are adjusted to enhance steering feel and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If open-loop control is used for motor-driven power steering, then hardware distribution can be adjusted, but repeated tunings are required to obtain desired steering performance
Solution Approach 1:
The patent applies preliminary action by establishing a virtual steering model that predicts steering performance before actual hardware implementation. The model includes a reaction force apparatus and state equations that allow developers to pre-determine control logic performance and steering characteristics, eliminating the need for repeated physical tunings and reducing development time
2Reliability
If feedback control is used to improve control robustness, then tuning efficiency is improved, but it is difficult to predict control logic performance in the initial stage
Solution Approach 1:
The patent applies copying by creating a virtual steering model that replicates the actual steering system's behavior. This virtual model includes a reaction force apparatus and state equations that mirror the physical system, allowing developers to predict control logic performance and test feedback control strategies in a virtual environment before implementing them in the actual system
Solution Approach 2:
The virtual steering model enables preliminary prediction of control logic performance by solving state equations and calculating steering torques before actual implementation. This allows developers to optimize feedback control parameters and predict system behavior in advance, eliminating the uncertainty present in traditional feedback control development
3Productivity
If a virtual steering model is used to predict steering performance, then development efficiency is improved, but system complexity increases due to state equations and numerical integration
Solution Approach 1:
The patent applies mechanics substitution by replacing complex physical testing and tuning processes with a computational virtual steering model. The model uses state equations and numerical integration to simulate steering behavior, substituting physical experimentation with mathematical computation, thereby improving development efficiency while managing complexity through software-based solutions
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
This approach improves development efficiency and tuning efficiency by predicting steering performance and generating various types of steering feel, effectively addressing the limitations of open-loop and feedback control methods, especially in steer-by-wire systems without mechanical connections.
Implementation Method 1
rigidity of a torsion bar used as the reaction force apparatus
Implementation Method 2
a torsion bar damper
Data Source
AI summary
A steering control method and apparatus of a motor-driven power steering system, ma include setting, by a controller, a virtual steering model including a reaction force apparatus provided between a steering wheel and a rack gear; inducing, by the controller, a state equation for the virtual steering model, the state equation representing momentum of the steering wheel, the reaction force apparatus, and the rack gear as state variables of the state equation; determining, by the controller, target steering torque acting in the reaction force apparatus through numerical integration of the state equation; and feedback-controlling, by the controller, a steering motor control amount to the motor-driven power steering system to bring a steering torque of the motor-driven power steering system into agreement with the target steering torque.