Power Steering Actuator Initial Diagnosis via Zero Torque Energization
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Solution Overview
Problem
Power steering apparatuses with multiple actuators face challenges in performing initial diagnostics on actuators that are not typically powered during normal operation, leading to undetectable abnormalities and potential unintentional steering wheel rotation.
Innovation Solution
Incorporating a controller-connected vehicle communication bus that energizes the first actuator to apply zero torque for initial diagnosis, using multi-phase rotating electric machines and hydraulic actuators to facilitate abnormality detection without causing discomfort to the driver, and enabling appropriate handling processes for improved system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first actuator is not energized during normal operation, then the system operates normally without unnecessary torque, but the initial diagnosis of the first actuator cannot be performed
Solution Approach 1:
The controller performs preliminary energization of the first actuator during vehicle startup before normal operation begins. This preliminary action enables initial diagnosis of the actuator's abnormality without affecting subsequent normal operation, as the energization is confined to the startup phase only.
2Reliability
If the first actuator is energized for initial diagnosis, then abnormality can be detected, but the steering wheel may rotate unintentionally against the driver's intention
Solution Approach 1:
The controller applies preliminary anti-action by energizing the first actuator in a controlled manner during startup that generates torque insufficient to overcome static friction and move the steering wheel. This prevents unintentional steering wheel rotation while still enabling electrical diagnostics of the actuator components.
Solution Approach 2:
The controller changes the energization parameters during startup to maintain current levels below the threshold that would cause mechanical movement. By adjusting voltage and current parameters to sub-threshold values, the actuator can be electrically tested without producing harmful mechanical effects on the steering wheel position.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective initial diagnosis of normally non-driven actuators without causing unintentional steering wheel movement, allowing for prompt abnormality handling and enhanced system reliability by canceling torques generated during diagnosis and ensuring safe operation.
Implementation Method 1
The first actuator is constituted by a multi-phase rotating electric machine, and is disposed on the steering column side with respect to the intermediate shaft, and is operable to output the steering assist torque
Data Source
AI summary
A power steering apparatus has a first actuator provided as a multi-phase rotating electric machine and disposed on a steering column side of an intermediate shaft and a second actuator disposed on a rack gear side thereof. A first ECU controls a drive of the first actuator and detects an abnormality of the first actuator. The first ECU changes an output of the first actuator based on a notification from a communication bus. The first ECU performs an initial diagnosis of the first actuator at a vehicle startup time for detecting abnormality, by supplying an electric power to the first actuator for not providing a torque to a steering wheel.