Adaptive Derivative Gain for Power Steering Torque Feel
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power steering controllers become increasingly complex, leading to difficulties in configuration and potentially providing an artificial driving experience, which can be unpleasant and counter-intuitive for drivers.
Innovation Solution
A power steering device with a controller using a closed-loop control law and a three-dimensional mapping to adjust the derivative gain based on actual steering wheel torque and vehicle longitudinal speed, ensuring optimal stability, comfort, and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the controller incorporates increasingly numerous and complex electronic and software functions to improve steering wheel torque consistency with vehicle dynamics, then the steering torque regulation accuracy is improved, but the device complexity increases and configuration becomes more difficult
Solution Approach 1:
The patent adjusts the derivative gain parameter dynamically based on steering wheel torque magnitude and vehicle speed conditions. By changing this key control parameter adaptively, the system achieves accurate torque regulation across different driving situations without requiring complex control algorithms, thus resolving the contradiction between accuracy and complexity.
2Measurement precision
If the controller uses complex electronic and software functions to provide consistent steering wheel torque, then the steering accuracy is improved, but the driving feel becomes artificial and counter-intuitive
Solution Approach 1:
The patent implements dynamic adjustment of the derivative gain based on real-time operating conditions (steering torque magnitude and vehicle speed). This dynamic adaptation allows the control system to maintain accuracy while adapting to natural driving variations, preserving intuitive driving feel rather than providing a fixed artificial response.
Solution Approach 2:
By changing the derivative gain parameter according to operating conditions, the system maintains torque consistency while adapting to different driving scenarios. This parameter adaptation ensures the steering feel remains natural and intuitive across various situations rather than appearing artificial.
3Device complexity
If a fixed derivative gain is used in the derivative feedback branch, then the controller simplicity is maintained, but the responsiveness and stability vary suboptimally across different vehicle situations
Solution Approach 1:
The patent transitions from a fixed derivative gain to a dynamic gain that adapts to operating conditions. This dynamic approach improves stability and responsiveness across different situations while adding only minimal complexity through a straightforward gain adjustment mechanism based on torque and speed thresholds.
Data Source
AI summary
A power-steering device includes a steering wheel and an assistance motor controlled by a controller which uses at least one closed-loop control law ensuring an adjustment of the steering wheel torque, the controller including at least one feedback arm which calculates a drift component by measuring or assessing an actual force parameter corresponding to the actual steering wheel torque, by next calculating a time drift value of the actual force parameter, and then multiplying the time drift value by a drift gain, wherein the controller uses three-dimensional cartography to adjust the drift gain according to a portion of the actual force parameter and the longitudinal velocity of the vehicle, according to a first domain, referred to as “parking domain”, which extends from a longitudinal vehicle velocity of zero to a predetermined longitudinal velocity threshold, and a second domain, referred to as “driving domain”, which extends beyond the longitudinal velocity threshold.