EPAS Filter Unit for Realistic Steering Feedback
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Solution Overview
Problem
Current dynamically controlled Electric Power-Assisted Steering (EPAS) systems provide poor feedback about the primary driving state of a vehicle, leading to a synthetic steering sensation due to misinterpretation of chassis information as noise.
Innovation Solution
Incorporating a filter unit to selectively filter out specific information components from actual value information, preventing them from being included in setpoint value information, thereby preventing compensation by the control unit and allowing desired feedback to be perceived by the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an active, dynamic control unit is used to regulate the power steering force, then the steering assistance can be dynamically adjusted based on driving conditions, but the feedback about the primary driving state to the driver is degraded because chassis information is misinterpreted as noise and compensated
Solution Approach 1:
The patent extracts and removes the harmful information components (chassis feedback information) from the actual value information before it reaches the control unit. By using the filter unit to take out these specific frequency components, the system prevents the loss of desired feedback information while maintaining the benefits of dynamic control.
Solution Approach 2:
The filter unit acts as an intermediary between the steering device and the control unit. It mediates the information flow by selectively removing harmful components while preserving useful feedback, allowing the control unit to operate dynamically without misinterpreting chassis feedback as noise.
2Object-affected harmful factors
If the control unit compensates for all information components in the actual value information, then noise and adverse effects from the road are dampened, but desired feedback about the primary driving state is also removed resulting in a synthetic steering sensation
Solution Approach 1:
The filter unit extracts only the harmful information components corresponding to chassis feedback while leaving other information intact. This selective extraction allows the control unit to compensate for road noise without removing the desired feedback about primary driving state, maintaining realistic steering sensation.
Solution Approach 2:
The patent applies different treatment to different information components within the actual value information. The filter unit applies a specific filtering characteristic to certain frequency ranges (where chassis feedback resides) while leaving other frequency ranges unaffected, allowing selective compensation of harmful factors while preserving useful feedback.
3Device complexity
If a static boosting curve is used to determine power steering force, then the control system is simple and easy to adjust, but the system cannot act dynamically and does not account for dynamic behavior of the steering device
Solution Approach 1:
The patent transitions from a static boosting curve to a dynamic control system with an active control unit that continuously adjusts power steering force based on real-time driving conditions. The filter unit enables this dynamic system to maintain simplicity by pre-defining filtering characteristics, combining dynamic adaptability with ease of adjustment.
Solution Approach 2:
The patent implements a feedback-based dynamic control system where the control unit receives actual value information from the steering device, processes it through the filter unit, and adjusts power steering force accordingly. This closed-loop feedback mechanism enables dynamic adaptation while the filter unit maintains system simplicity by automatically removing harmful components.
Data Source
AI summary
A method and apparatus for controlling an electrically power-assisted steering device for vehicles including a control unit providing control information to a steering device. The method and apparatus includes a setpoint signal value transmitter providing setpoint value information and obtaining actual value information from the steering device. The actual value information is fed to the setpoint signal value transmitter and a difference value information is obtained from the setpoint value information and actual value information with the difference value information fed to the control unit. A filter unit filters information components from one of the actual value information provided, the actual value information fed to the setpoint signal value transmitter, the setpoint value information or the difference value information.