Steering Rack Force Calculation for Vehicle Comfort
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern steering systems provide strong feedback on force conditions, which can be disturbing and affect driving comfort, especially when not required.
Innovation Solution
A method to determine a steering rack force by combining a first force/torque-based force with a second force derived from vehicle variables like speed and steering angle, allowing for adjustable feedback levels through a control variable, enabling a comfortable driving experience by decoupling steering torque from roadway properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the target steering torque is calculated exclusively as a function of the first steering rack force (based on motor torque), then the driver receives strong feedback on the real force conditions in the steering gear, but this strong feedback is perceived as disturbing and affects driving comfort
Solution Approach 1:
The patent segments the steering rack force calculation into two independent components: a first steering rack force (RFD) based on motor torque for dynamic feedback, and a second steering rack force (RFC) based on vehicle variables for comfort. These segmented components are then combined through a functional block to produce the resulting steering rack force, allowing independent optimization of each component's contribution.
Solution Approach 2:
The patent changes the parameters used to calculate steering rack force by introducing a dual-calculation approach: one parameter set (motor torque) for dynamic feedback and another parameter set (vehicle variables like speed and steering angle) for comfort. A control variable dynamically adjusts the weighting between these parameter sets, enabling parameter transformation based on driving conditions.
2Ease of operation
If the steering torque is decoupled from roadway properties to improve comfort, then driving comfort is enhanced, but dynamic feedback on roadway properties is lost
Solution Approach 1:
The patent implements a dynamic control variable that automatically adjusts the balance between feedback and comfort based on driving conditions. The control variable responds to changes in vehicle state (speed, acceleration, steering angle) and dynamically modifies the weighting between the first and second steering rack forces, enabling the system to adapt between feedback-oriented and comfort-oriented modes in real-time.
Solution Approach 2:
The patent introduces a feedback mechanism where the control variable monitors driving conditions and adjusts the steering rack force calculation accordingly. The system uses feedback from vehicle sensors (speed, acceleration, steering angle) to determine when dynamic feedback is needed versus when comfort should be prioritized, creating a closed-loop control system that balances both requirements.
3Adaptability or versatility
If a control variable is introduced to adjust the influence of first and second steering rack forces, then the degree of feedback can be adapted to requirements, but the device complexity increases
Solution Approach 1:
The control variable serves multiple functions: it adjusts the feedback level, adapts to different driving conditions, and can interface with existing vehicle sensor systems. The functional block that combines the two steering rack forces using the control variable is designed to be universally applicable across different vehicle platforms and steering system configurations, reducing the need for additional specialized components.
Data Source
AI summary
A method for determining a steering rack force (FR) for a steering system of a vehicle, in which a first steering rack force (RFD) is ascertained as a function of at least one force that occurs in the steering system or at least one torque (tor_RA) that occurs in the steering system. So as to provide less strong feedback on the force conditions in the steering system for reasons of driving comfort, in particular when this is currently not required, it is proposed to ascertain a second steering rack force (RFC) as a function of at least one vehicle variable (v, ang_RA), which characterizes the state of movement of the vehicle, and to generate a resulting steering rack force (FR) based on the first steering rack force (RFD) and the second steering rack force (RFC).