Magnetic Torque Overlay Steering Vibration Rejection
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Solution Overview
Problem
Hydraulic-power steering systems face challenges in minimizing undesirable vibrations in the handwheel due to road-wheel imbalance, as existing methods either fail to effectively reduce the source of disturbance or result in trade-offs with other design considerations.
Innovation Solution
A magnetic torque overlay (MTO) system with a control module that generates a base torque command, modifies it using a disturbance-rejection module, and applies the final torque command to a magnetic actuator to minimize handwheel vibrations, utilizing differential pressure and vehicle signals to estimate and counteract the disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical methods are used to minimize transmissibility in hydraulic-power steering systems, then handwheel vibrations are reduced, but other performance aspects of the system are compromised
Solution Approach 1:
The patent replaces mechanical disturbance-rejection methods with a magnetic actuator system. The magnetic actuator generates compensating torque based on detected road-wheel imbalance, eliminating the need for mechanical modifications to the steering gear while maintaining overall system performance and adaptability.
Solution Approach 2:
The patent introduces a magnetic actuator as an intermediary element between the disturbance detection and the steering system. This magnetic actuator generates a counter-torque to offset the vibrations caused by road-wheel imbalance, providing a non-invasive solution that doesn't compromise other steering functions.
2Object-affected harmful factors
If targeted algorithms are used in electric-power steering systems to reject road-wheel imbalance disturbance, then transmissibility is minimized with minimal impact on other performance aspects, but this approach cannot be directly applied to hydraulic-power steering systems
Solution Approach 1:
The patent creates a universal disturbance-rejection solution that works with hydraulic-power steering systems by adding a magnetic actuator. This allows the same control algorithm approach used in electric-power steering to be applied to hydraulic systems, achieving multi-functionality across different steering system types.
Solution Approach 2:
The magnetic actuator serves as an intermediary that enables algorithmic disturbance rejection in hydraulic systems without requiring conversion to electric-power steering. It bridges the gap between control algorithms and hydraulic actuation mechanisms.
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
Effectively reduces or eliminates undesirable vibrations in the handwheel by actively counteracting road-wheel imbalance, improving the driving experience while maintaining system performance.
Implementation Method 1
A magnetic actuator in a steering gear of the MTO steering system receives the final torque command and converts the final torque command into a force to be applied to a piston
Implementation Method 2
A measurement of differential pressure across a piston in the MTO steering system
Data Source
AI summary
A control system and method for a hydraulic-power steering system of a vehicle including magnetic torque overlay (MTO) is provided. The control system and method minimize undesirable vibration in a handwheel of the vehicle as a result of disturbance in its front road wheels (e.g., road-wheel imbalance). In the control system and method, a base torque command is determined or generated. At least the base torque command is passed to a disturbance-rejection module. The disturbance-rejection module modifies the base torque command to minimize the vibration.