Electric Power Steering Torque Plausibility Check
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power steering systems, particularly those with electric power steering (EPS), face challenges in managing torque combinations during advanced driver assistance functions, leading to potential safety issues due to unaccounted changes in manual and motor torque, which can result in over-assistance or uncontrollable steering.
Innovation Solution
A method and system that computes and checks motor torque by considering measured manual torque and added torques from special functions, allowing for correction of manual torque to maintain safe and approved parameters, ensuring the motor torque remains within limits and preventing functional limitations, using a 3-level design and plausibility checks to manage torque superposition effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If advanced driver assistance functions are implemented with increased torque superposition, then driver assistance capability is improved, but safety control becomes more difficult due to unaccounted changes in manual and motor torque combinations
Solution Approach 1:
The patent applies preliminary action by pre-defining a motor torque limit curve that accounts for various combinations of manual torque and added torque from special functions. Before safety issues arise, the system establishes these limits and uses them to constrain motor torque output, ensuring that even when multiple torque sources are combined, the total remains within safe operating parameters.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual manual torque and added torque from special functions, comparing their combination against the pre-defined motor torque limit curve. The system uses this feedback to dynamically adjust and limit the motor torque output, ensuring that the combined torque remains within safe boundaries while still providing necessary driver assistance.
2Ease of operation
If motor torque is increased to provide greater assistance, then steering ease is improved, but the risk of over-assistance and uncontrollable steering increases
Solution Approach 1:
The patent applies preliminary anti-action by establishing a motor torque limit curve that preemptively counteracts the risk of over-assistance. The limit curve is designed to prevent motor torque from exceeding safe levels that could cause uncontrollable steering, while still allowing sufficient torque to provide effective driver assistance. This preliminary constraint structure prevents harmful effects before they can occur.
3Reliability
If plausibility checks are performed on motor torque combinations, then safety is improved, but system complexity increases due to additional monitoring requirements
Solution Approach 1:
The patent applies partial action by implementing plausibility checks that focus specifically on the critical combination of manual torque and added torque from special functions. Rather than monitoring all possible torque parameters comprehensively, the system performs targeted checks on the most safety-critical torque combinations, achieving adequate safety validation without requiring exhaustive monitoring of every torque parameter.
Data Source
AI summary
Provided is a method for operating a power steering system and to such a power steering system. A motor torque is computed by an electronic processor and is established by suitable motor actuation, wherein a plausibility check of the computed motor torque is carried out, taking a measured manual torque into consideration. A value of the additional torques of at least one special function is further considered in the plausibility check.