Vehicle Steering Torque Reduction via Centralized Limitation
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Solution Overview
Problem
Existing vehicle steering systems face challenges in controlling and limiting steering torque effectively, leading to potential loss of quality in additional steering functions due to the complexity of calculating and combining driver's torque and assist motor torque, which can result in safety violations and inaccuracies.
Innovation Solution
A method that uses a sensor to detect driver-applied torque and applies a reduction factor to imposed torques through a central reduction unit, allowing for continuous reduction of torques if safety criteria are violated, simplifying the control of steering systems by eliminating the need for individual torque calculations in the steering control loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual torque calculations are performed in the steering control loop for each additional function, then torque limitation can be achieved, but the complexity of the control loop increases and quality of functions degrades
Solution Approach 1:
The patent extracts the torque calculation and limitation logic from the complex steering control loop into a separate, dedicated torque limitation unit. This unit independently calculates the driver's torque and applies limitation based on safety criteria, without requiring integration into the existing complex control loop. This resolves the contradiction by maintaining torque safety while eliminating the complexity that would otherwise degrade function quality.
Solution Approach 2:
The patent introduces an intermediary torque limitation unit that acts as a mediator between the driver's torque input and the steering assistance system. This intermediary component processes the torque signal independently, applying safety-based limitation without requiring the complex control loop to calculate individual torques for each function. The intermediary handles the complexity isolation, allowing the main control loop to remain simple while torque safety is ensured.
2Productivity
If multiple torque imposing functions operate simultaneously without centralized limitation, then steering assistance performance is maximized, but safety violations may occur due to excessive total torque
Solution Approach 1:
The patent merges all torque imposing functions into a unified torque limitation framework. Instead of allowing multiple functions to operate independently with potential torque conflicts, the system combines all torque demands and applies a single, centralized limitation based on the driver's torque and safety criteria. This ensures that the total torque remains within safe boundaries while still allowing multiple assistance functions to operate effectively.
Solution Approach 2:
The patent implements a feedback mechanism where the torque limitation unit continuously monitors the driver's torque and the total imposed torque, comparing them against safety criteria. When the total torque approaches unsafe levels, the system automatically reduces the assistance torque to maintain safety. This feedback loop ensures safety compliance while allowing maximum steering assistance performance within safe boundaries.
3Ease of operation
If torque limitation is applied at the driver's torque interface, then controllability is ensured, but the quality of additional steering functions is reduced due to rough torque calculation
Solution Approach 1:
The patent creates a simplified copy or model of the driver's torque signal specifically for limitation purposes, rather than requiring precise calculation of the actual driver's torque. This copy is sufficient for safety limitation but does not require the complex, high-precision calculations that would degrade function quality. The copy approach maintains controllability while avoiding the precision-loss trade-off.
Data Source
AI summary
A method for reducing the steering torque in a steering system of a vehicle. A method including the steps of monitoring a driver's torque as applied by a driver of the vehicle; providing a plurality of torques that can be imposed on the steering system; and reducing the torques that can be imposed on the steering system by a central reduction factor if monitoring of the steering system reveals a violation of a safety criterion.