EPAS Compliance Compensation for Steering Feel and Stability
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Solution Overview
Problem
Conventional electronic power assisted steering (EPAS) systems face challenges in providing consistent mechanical stiffness due to manufacturing tolerances, leading to tradeoffs between system stability, disturbance rejection, and steering feel, with static compliance that cannot be adjusted post-manufacturing.
Innovation Solution
An EPAS controller dynamically adjusts the steering response by determining compliance compensation torque based on measurements and derivatives, using tunable lookup tables to customize assistance for individual vehicles, overcoming mechanical compliance and improving steering feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional EPAS systems use static compliance settings, then manufacturing is simpler, but steering feel consistency deteriorates due to manufacturing tolerances
Solution Approach 1:
The patent implements dynamic compliance adjustment by allowing the EPAS controller to modify compliance parameters in real-time based on operating conditions and vehicle state, replacing static mechanical compliance settings with adaptive software-controlled parameters that can be tuned individually for each vehicle
Solution Approach 2:
The patent changes physical parameters by using tunable compliance parameters that can be individually adjusted for each vehicle through software configuration, allowing precise control over steering characteristics without requiring physical manufacturing adjustments
2Stability of the object's composition
If conventional EPAS systems increase mechanical stiffness, then system stability improves, but steering feel deteriorates due to excessive rigidity
Solution Approach 1:
The patent applies dynamic adjustment of compliance parameters that allow the system to adapt stiffness characteristics in real-time based on driving conditions, vehicle speed, and steering state, providing stability when needed while maintaining natural steering feel during normal operation
Solution Approach 2:
The patent modifies system parameters by implementing tunable compliance parameters that control the degree of stiffness dynamically, allowing optimization of both stability and steering feel through software-controlled parameter adjustment rather than fixed mechanical design
3Speed
If conventional EPAS systems use high compliance, then steering responsiveness improves, but disturbance rejection deteriorates
Solution Approach 1:
The patent implements dynamic compliance adjustment that adapts the system response based on operating conditions, providing high compliance for responsive steering during normal operation while automatically increasing stiffness to reject disturbances when detected
Solution Approach 2:
The patent changes system parameters by using tunable compliance parameters that control the balance between responsiveness and disturbance rejection, allowing optimal performance across different driving scenarios through software-controlled parameter modification
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture are disclosed to improve electronic power assisted steering in a vehicle. An example apparatus includes memory and a processor to execute instructions to determine a steering column torque associated with a steering column of an electronic power assisted steering (EPAS) system in a vehicle, determine a steering column torque derivative based on a derivative of the steering column torque, determine a compliance compensation torque based on the steering column torque and the steering column torque derivative, and adjust a steering response of the steering column based on the compliance compensation torque.