Hybrid Steering System with Virtual and Mechanical Stops
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Solution Overview
Problem
Conventional electronic steering systems face issues with undesirable sound and tactile feedback due to metal-to-metal contact at mechanical stops, and the use of compliant members limits angular rotation, which is undesirable in systems with limited rotational ranges.
Innovation Solution
A steering method and system that utilize a processor to receive position signals from a steering column, determine position-related characteristics, and apply a resistive force using an electric motor to dynamically set a virtual stop, in conjunction with a progressive mechanical stop, to limit rotation and provide tactile feedback without excessive rotational limitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical stop is used to limit steering column rotation, then rotation is mechanically limited to a first range of rotation, but metal-to-metal contact occurs causing undesirable sound and tactile feedback
Solution Approach 1:
The patent introduces a compliant member as an intermediary between the mechanical stop and the steering column. This compliant member acts as a mediator that absorbs the impact and prevents direct metal-to-metal contact, thereby eliminating the undesirable sound and tactile feedback while maintaining the rotation limitation function.
Solution Approach 2:
The patent replaces the purely mechanical stop system with an electro-mechanical system. A sensor detects the steering column position and signals the controller, which then activates an actuator to apply a counterforce before the mechanical stop is reached. This substitution of mechanical contact with electronic control and active counterforce application eliminates the harmful metal-to-metal contact effects.
2Object-affected harmful factors
If a compliant member is provided for the mechanical stop, then sound and tactile feedback are reduced, but an excess amount of angular rotation is consumed
Solution Approach 1:
The patent applies partial action by using the compliant member only in the critical region near the mechanical stop, rather than throughout the entire rotation range. The compliant member is positioned to engage only when the steering column approaches the stop position, providing cushioning exactly where needed without consuming excess angular rotation during normal steering operations.
Solution Approach 2:
The compliant member serves as a localized intermediary that provides cushioning only in the specific region where the mechanical stop engages. This targeted approach allows the compliant member to reduce sound and tactile feedback without requiring a large angular rotation range, as it only activates when necessary near the stop position.
3Object-affected harmful factors
If a virtual stop is implemented using an actuator, then metal-to-metal contact is minimized, but device complexity increases
Solution Approach 1:
The patent makes the actuator multi-functional by using it for both steering assistance and virtual stop implementation. The same actuator that provides electro-hydraulic steering control also applies counterforce to create the virtual stop effect. This eliminates the need for a separate mechanical stop mechanism, reducing overall system complexity while maintaining the benefit of minimized metal-to-metal contact.
Solution Approach 2:
The patent merges the virtual stop function with the existing electro-hydraulic steering system. The actuator that normally provides steering force is also used to apply counterforce when approaching the virtual stop position. By combining these functions into a single integrated system, the patent avoids adding separate components and maintains relatively simple device architecture.
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
The solution minimizes metal-to-metal contact, reduces undesirable feedback, and optimizes angular rotation by using a hybrid system of progressive mechanical stops and electric motor-based torque feedback, enhancing operator experience and system efficiency.
Implementation Method 1
electric motor-based torque feedback
Data Source
AI summary
A steering system and method can determine one or more position-related characteristics of a steering column of a machine, determine that the one or more position-related characteristics indicate that a resistive force is to be applied to the steering column, and control operation of an electric motor to apply the resistive force to the steering column, wherein a mechanical stop (e.g., a progressive mechanical stop) can be provided to restrict rotation of the steering column. One or more virtual stops may be set to limit rotation of the steering column by way of controlling the operation of the electric motor to apply the resistive force.