Electric Power Steering Soft Stop via Torque Position Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current vehicle steering systems experience harsh, abrupt feelings when steering into corners due to metal-on-metal clunk in the steering rack end-of-travel hardware, leading to both audible and tactile annoyances, and existing solutions are often cost-prohibitive or time-consuming to address.
Innovation Solution
A control system that estimates a command adjust value based on hand wheel position and torque to generate a motor assist command, reducing end-of-travel harshness by applying a gain and/or damping to the steering system, primarily through an electric power steering system with sensors and a control module that processes signals to condition and filter inputs for determining optimal assist commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rack and pinion travel stops are modified to reduce end-of-travel harshness, then steering smoothness is improved, but manufacturing cost and development time increase
Solution Approach 1:
The patent replaces mechanical modifications to the rack and pinion travel stops with an electronic control system. The EOT control module monitors handwheel position and torque, then dynamically adjusts motor assist commands to provide a soft stop effect, eliminating the need for costly mechanical redesign while achieving the same steering smoothness improvement
Solution Approach 2:
The patent introduces an intermediary control system between the driver's handwheel input and the steering rack. The EOT control module acts as a mediator that processes handwheel position and torque signals, then generates adjusted motor assist commands to smooth out end-of-travel harshness without directly modifying the mechanical travel stops
2Ease of operation
If rack and pinion travel stops are modified to reduce end-of-travel harshness, then steering smoothness is improved, but development time increases
Solution Approach 1:
The patent replaces time-consuming mechanical modifications to the rack and pinion travel stops with a software-based electronic control solution. The EOT control module uses sensor inputs and control algorithms to achieve steering smoothness, significantly reducing development time compared to iterative mechanical design and testing
Solution Approach 2:
The patent implements preliminary action by pre-programming the EOT control logic in the control module. The system is pre-configured with the control algorithm that monitors handwheel position and torque, and automatically applies the appropriate motor assist adjustments when approaching end-of-travel conditions, eliminating the need for time-consuming field adjustments or mechanical rework
3Ease of operation
If motor assist command is adjusted based on handwheel position and torque, then end-of-travel harshness is reduced, but control system complexity increases
Solution Approach 1:
The patent applies universality by using the existing motor assist system to perform multiple functions: normal steering assistance and end-of-travel soft stop. The same motor and control module that provide routine power steering assistance are also used to generate the EOT soft stop effect, eliminating the need for separate mechanical components and reducing overall system complexity
Solution Approach 2:
The patent implements feedback by continuously monitoring handwheel position and torque inputs, then using this information to dynamically adjust the motor assist command. The EOT control module compares the current handwheel state against predefined thresholds and automatically modulates the motor output to provide smooth deceleration near end-of-travel, creating a closed-loop control system that manages complexity through intelligent algorithms
Data Source
AI summary
A control system for controlling a steering system near an end of travel region is provided. The control system includes a first module that selectively estimates a command adjust value based on a hand wheel position and a hand wheel torque. A second module generates a motor assist command based on the command adjust value to control the steering system.