Vehicle Steering System Failure Torque Feedback
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Solution Overview
Problem
In vehicles with front-axle and rear-axle steering assemblies, a failure of the front-axle steering assembly leads to delayed or unresponsive steering due to the rear-axle's limited adjustment speed and steering angle, causing unintended steering angles and potential vehicle swaying, necessitating a method for safe and intuitive driving behavior.
Innovation Solution
A method involving detection of front-axle steering assembly failure, exclusive use of rear-axle steering, comparison of steering commands with limit values, and application of torque by an electric motor on the steering wheel to counteract excessive commands, ensuring real-time response and predictable driving behavior, with continuous execution until the failure is resolved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rear-axle steering assembly is used exclusively to steer the vehicle after front-axle steering failure, then the vehicle maintains maneuverability, but the steering response is delayed and the driving behavior becomes unpredictable
Solution Approach 1:
The system applies a counteracting torque via the electric motor based on feedback from comparing the steering command with limit values. This feedback mechanism provides the driver with tactile information about the system's state and compensates for the limited adjustment speed, making the delayed response more predictable and controllable.
Solution Approach 2:
The system changes the physical parameter of torque applied to the steering wheel by the electric motor. By dynamically adjusting this torque parameter based on the detected steering command and limit values, the system compensates for the rear-axle steering assembly's limited adjustment speed and angle, improving steering predictability.
2Stability of the object's composition
If the rear-axle steering assembly adjusts wheels at limited speed and angle, then the system remains stable, but the steering command cannot be executed quickly or fully
Solution Approach 1:
The system applies a preliminary counteracting torque before the steering command can cause excessive wheel rotation. By comparing the steering command with limit values and applying opposing torque in advance, the system prevents the steering angle from exceeding safe limits while maintaining system stability.
Solution Approach 2:
The electric motor dynamically changes the torque parameter applied to the steering wheel, increasing it when limit values are approached and decreasing it when operating within safe parameters. This dynamic parameter adjustment allows the system to maintain stability while maximizing the allowable steering adjustment speed.
3Adaptability or versatility
If the driver issues a steering command exceeding the rear-axle steering assembly's capabilities, then the driver's intent is expressed, but the vehicle responds with delay or not at all
Solution Approach 1:
The system provides continuous feedback to the driver through the electric motor's counteracting torque. When the steering command approaches or exceeds the rear-axle steering assembly's capabilities, the feedback torque informs the driver of the system's limits, allowing the driver to adjust their input and avoid excessive delay.
Solution Approach 2:
The system allows partial execution of steering commands that exceed the rear-axle steering assembly's capabilities. By applying a counteracting torque rather than completely blocking the steering wheel, the system enables some steering motion while preventing excessive angles, thus reducing response delay while maintaining safety.
4Device complexity
If the rear-axle steering assembly has limited steering angle compared to front-axle steering, then the system remains simple, but the maximum steering angle cannot be achieved
Solution Approach 1:
The system replaces mechanical steering angle limitations with an electrical control mechanism. The electric motor applies torque to the steering wheel to simulate mechanical stops at the rear-axle steering assembly's maximum angles, effectively extending the usable steering angle range through electrical rather than mechanical means.
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
This method ensures the vehicle responds to steering commands in real time, maintains predictable behavior, and allows safe maneuvering by aligning all wheels' center planes parallel, facilitating straight driving and easier control.
Implementation Method 1
an electric motor coupled to the steering wheel... applying a torque acting on the steering wheel via the electric motor coupled to the steering wheel
Data Source
AI summary
The disclosure relates to a method for operating a steering system of a vehicle having a front-axle steering assembly, a rear-axle steering assembly and a steering wheel. The method involves detecting a failure of the front-axle steering assembly, steering the vehicle exclusively via the rear-axle steering assembly based on a steering command issued by a driver via the steering wheel, comparing at least one detected physical value of the steering command with a limit value associated with the rear-axle steering assembly and, provided the at least one associated limit value is reached or exceeded by the at least one detected physical value of the steering command, applying a torque acting on the steering wheel via the electric motor coupled to the steering wheel, which torque counteracts the steering command.