Hybrid Steering System Hydraulic Failure Detection
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Solution Overview
Problem
Existing hybrid steering systems in vehicles face challenges in detecting hydraulic failures, especially during automated operation, as failures in the hydraulic power steering system can be difficult to detect and may lead to safety risks.
Innovation Solution
A method involving a control device that determines a target steering angle change and temporarily provides a steering torque greater than the determined change when the target change is below a threshold, allowing for the detection of hydraulic failures by measuring steering angle velocity and acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a flow detector is used to detect hydraulic flow, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical/hydraulic flow detector with an electrical control system that uses the electric power steering system to create test conditions. The control device sends test signals through the electric motor to generate measurable electrical signals that indirectly indicate hydraulic system status, eliminating the need for separate hydraulic sensing hardware.
Solution Approach 2:
The electric power steering system is used to detect hydraulic failures by having it perform a diagnostic function. The control device utilizes the existing motor and control circuitry to send test signals and measure electrical responses that reveal hydraulic system conditions, making the system self-diagnostic without external specialized equipment.
2Measurement precision
If the electric power steering system provides steering torque corresponding to the determined target steering angle change, then steering accuracy is improved, but hydraulic failure detection capability deteriorates
Solution Approach 1:
The control device performs preliminary diagnostic actions by sending test signals through the electric motor before actual steering operations occur. These test signals create measurable electrical responses that can detect hydraulic failures in advance, allowing the system to identify problems before they affect normal steering function.
Solution Approach 2:
The control device periodically sends test signals through the electric motor to continuously monitor hydraulic system health. These periodic diagnostic signals are distinct from normal steering commands and allow ongoing detection of hydraulic failures without interfering with regular steering operations.
Data Source
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AI summary
The present invention relates to a method for determining hydraulic failure of a hybrid steering system (10) during automated operation of a vehicle (1), said hybrid steering system (10) comprising: a steering column (SC) connected to a wheel axle (X) with steerable wheels (W); an electric power steering system (EPS) connected to the steering column (CS); and a hydraulic power steering system (HRS) connected to the electric power steering system (EPS), the method comprising: determining (s101 ) a target steering angle change (Δδ target) based on a requested steering angle and a current steering angle; controlling (s102) the electric power steering system (EPS) to temporarily provide a steering torque corresponding to a first target steering angle change larger than the determined target steering angle change (Δδ target), when the determined target steering angle change (Δδ target) is lower than a predetermined threshold value; determining (s103) a steering angle velocity and/or steering angle acceleration resulting from the provided steering torque; and determining (s104) whether a hydraulic failure has occurred based on the determined steering angle velocity and/or steering angle acceleration.