Redundant Power Steering Control for Steering Angle Error Reduction
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Solution Overview
Problem
There is a need to reduce errors between command steering angles and actual controlled steering angles in motor-driven power steering systems for autonomous vehicles, as these errors can impact steering safety and stability.
Innovation Solution
A power steering control system with a redundant structure is implemented, which includes multiple position and speed controllers, and current controllers that average command steering angles and current control signals to reduce errors and ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a motor-driven power steering system is used to assist driver steering, then steering performance and steering feel are improved, but errors between command steering angle and actual controlled steering angle may occur
Solution Approach 1:
The patent implements different control strategies for different operational modes. In normal driving mode, a single controller operates to maintain simplicity. In redundant control mode, multiple controllers are activated with weighted voting to enhance reliability. This local differentiation of control quality based on operational context resolves the contradiction between precision and reliability.
Solution Approach 2:
The system dynamically changes the control parameter configuration by switching between single-controller and multi-controller modes. The controller weight parameters are adjusted based on system health status, with healthy controllers receiving higher weights. This parameter change enables the system to adapt between precision-oriented normal operation and reliability-oriented redundant operation.
2Reliability
If a redundant structure is implemented in the power steering control system, then steering safety and stability are enhanced, but device complexity increases
Solution Approach 1:
The redundant control structure is implemented dynamically rather than statically. Controllers are activated or deactivated based on real-time health monitoring and voting results. This dynamic approach allows the system to utilize redundancy only when needed, reducing average complexity while maintaining high reliability during critical operations.
Solution Approach 2:
The patent extracts the essential redundancy function from the control system by implementing a voting mechanism that selectively activates additional controllers only when required. Rather than permanently maintaining complex redundant structures, the system extracts and activates redundancy only during fault conditions, thereby reducing overall system complexity while preserving reliability benefits.
3Stability of the object's composition
If multiple controllers are used to reduce control signal errors, then steering stability is improved, but response time and control efficiency decrease
Solution Approach 1:
The system implements periodic health monitoring and voting cycles rather than continuous multi-controller operation. Controllers are evaluated at specific intervals, and redundancy is activated periodically when faults are detected. This periodic approach maintains stability through regular monitoring while minimizing the time loss associated with continuous complex control processing.
Solution Approach 2:
The patent applies partial redundancy by using weighted voting where not all controllers have equal influence. Healthy controllers contribute more to the control decision than faulty ones, allowing the system to achieve stability with partial utilization of available controllers rather than requiring full engagement of all redundant components, thus reducing response time overhead.
Data Source
AI summary
Disclosed herein are a power steering control system with redundant structure and a control method thereof. The power steering control system is configured with a redundant structure for driving control of an autonomous vehicle, the first steering device and second steering device of the redundant power steering control system transmit signals to each other to average command values, and in particular, the speed controllers thereof transmit signals to each other to average them and perform speed control. Accordingly, it is possible to perform accurate position control and stably control driving by ensuring that the redundant power steering control system reduces an error in control signals. In addition, it is possible to improve driving stability by controlling driving normally even if one of the steering devices fails.