Variable Gain Steering System for Wheeled Vehicles
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Solution Overview
Problem
Current steering systems in vehicles require complex "hand over hand" manipulation of the steering wheel, which is not intuitive and takes time to become accustomed to, and existing variable gain systems do not provide a satisfactory alternative.
Innovation Solution
A variable gain "drive-by-wire" steering system that adjusts the ratio of steering wheel movement to vehicle speed, displacement, and time derivatives of control input, allowing continuous control without hand movement from the graspable regions of a rotatable yoke or handle-based operator control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional steering wheel with approximately 900° range of rotation is used, then the vehicle can be steered through the necessary angular range, but the driver must perform complex hand over hand manipulation which is not intuitive and takes time to become accustomed to
Solution Approach 1:
The patent applies dynamics by making the steering system adaptive and variable rather than fixed. The steering ratio is dynamically adjusted based on vehicle speed, providing high gain at low speeds for easy maneuverability and low gain at high speeds for stability. This dynamic adjustment eliminates the need for complex hand-over-hand manipulation while maintaining full steering authority when needed.
Solution Approach 2:
The patent changes the steering ratio parameter dynamically based on vehicle speed. At low speeds, a high steering ratio (e.g., 1:10) amplifies small control inputs for precise maneuvering. At high speeds, a low steering ratio (e.g., 1:2) reduces amplification for stable control. This parameter change resolves the contradiction by adapting the system to different operating conditions.
2Ease of operation
If a constant steering ratio system is used, then the steering mechanism is simple, but the driver cannot achieve comfortable and accurate control across different vehicle speeds
Solution Approach 1:
The steering system transitions from a static constant ratio to a dynamic variable ratio that automatically adjusts with vehicle speed. This dynamic behavior enables comfortable and accurate control at all speeds without requiring complex manual intervention or sophisticated driver skill.
Solution Approach 2:
The system incorporates feedback from vehicle speed sensors to automatically adjust the steering ratio. This feedback mechanism allows the control system to optimize steering characteristics for current operating conditions, achieving accurate control without increasing operational complexity for the driver.
3Ease of operation
If the steering wheel rotation range is limited to reduce hand movement, then continuous control can be maintained, but the steering angle range may be insufficient for certain maneuvers
Solution Approach 1:
The patent changes the steering ratio parameter based on vehicle speed and control position. This allows a limited physical rotation range of the control to produce a full range of steering angles when needed, while maintaining continuous control for normal operation. The system adapts the mechanical advantage to maximize both control continuity and steering authority.
Data Source
AI summary
A wheeled vehicle is steered by a yoke or other operator control the movement of which is limited so that the operator's hands need not change position on the control. The steering is under the control of a microprocessor responsive to an input from the control, the vehicle's speedometer, and to accelerometers responsive to forces acting on the vehicle laterally and perpendicular to the roadway. The relationship between the position of the steerable wheels and the displacement of, or force applied to, the operator control is a function that depends on the magnitude of the displacement or force, speed, and one or more time derivatives of the displacement of, or force on, the operator control. The relationship between the position of the steerable wheels and the displacement of, or force on, the control is overridden when the lateral force is such that the vehicle is in danger of rolling over.