Steering Controller Kinetic Friction Estimation
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Solution Overview
Problem
Conventional electric power assisted steering (EPAS) systems lack the ability to accurately estimate kinetic friction in electromechanical steering actuators online during operation, leading to inconsistent steering responses due to varying friction levels over the lifetime of components and manufacturing inconsistencies.
Innovation Solution
The implementation of a steering controller that applies an input torque to the steering system, determines angular acceleration, and calculates friction torque by subtracting response torque from input torque, allowing for real-time friction estimation and compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EPAS systems operate without real-time friction estimation, then the system structure remains simple, but steering response consistency deteriorates due to varying friction levels
Solution Approach 1:
The system uses its own operational data (input torque, angular acceleration) to self-diagnose and estimate friction levels without requiring external sensors or additional measurement equipment. The controller performs friction estimation using readily available signals from the steering system operation.
Solution Approach 2:
The system continuously monitors the relationship between input torque and angular acceleration, using this feedback to estimate friction levels in real-time. This feedback mechanism allows the system to adapt to changing friction conditions and maintain consistent steering response.
2Measurement precision
If real-time friction estimation is implemented, then steering response consistency improves, but computational requirements and control complexity increase
Solution Approach 1:
The patent replaces physical friction measurement devices or complex mechanical test procedures with a computational model that estimates friction using torque and acceleration data. This substitution achieves accurate friction estimation through software-based calculation rather than hardware-based measurement.
Solution Approach 2:
The system changes the operational parameters used for control by incorporating friction estimation into the control algorithm. The controller adjusts assist torque based on estimated friction levels, transforming the control strategy from fixed-parameter to adaptive-parameter control.
3Use of energy by moving object
If friction compensation is not applied, then the control system remains simple, but energy efficiency deteriorates due to inconsistent steering assist
Solution Approach 1:
The system transitions from static friction assumptions to dynamic friction estimation that adapts to changing operating conditions. The friction estimate is continuously updated based on real-time torque and acceleration measurements, allowing the control system to optimize energy efficiency across varying steering conditions.
Data Source
AI summary
Methods and apparatus for determining kinetic friction in electromechanical steering actuators are disclosed herein. In some examples, the apparatus comprises a steering controller. In some examples, the steering controller is to apply an input torque to a steering system via a motor. In some examples, the steering controller is to determine an angular acceleration of the steering system in response to the input torque. In some examples, the steering controller is to determine a response torque based on the angular acceleration. In some examples, the steering controller is to determine a friction torque of the steering system based on the input torque and the response torque.