Steer-By-Wire Steering Ratio Control for Driver-Expected Response
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Solution Overview
Problem
Steer-by-wire systems in vehicles do not adequately tailor steering behavior to the driver's expectations, leading to potential surprises and reduced safety and comfort.
Innovation Solution
A method for determining a variable steering ratio based on angular steering means speed, vehicle speed, and steering means angle, using mathematical functions or look-up tables, to ensure the steering behavior aligns with the driver's expectations, preventing overshooting or undershooting of road wheel angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed steering ratio is used in steer-by-wire systems, then the system structure is simple, but the steering behavior does not match driver expectations at different speeds and maneuvering scenarios
Solution Approach 1:
The patent applies dynamics by making the steering ratio variable rather than fixed. The steering ratio is dynamically adjusted based on steering means angular speed and vehicle speed through mathematical functions or look-up tables, allowing the system to adapt to different driving conditions and match driver expectations without requiring complex mechanical structures
Solution Approach 2:
The patent changes the parameter of steering ratio from a constant value to a variable parameter that depends on steering means angular speed and vehicle speed. This parameter change enables the system to provide different steering characteristics for different maneuvering scenarios while using simple computational methods to determine the appropriate ratio
2Reliability
If the steering ratio is not adjusted according to angular steering means speed, then the control system is simple, but overshooting or undershooting of road wheel angles occurs
Solution Approach 1:
The patent implements feedback by using the actual steering means angular speed (measured from the steering means angle sensor) to dynamically adjust the steering ratio. This feedback mechanism ensures that the road wheel angle accurately follows the driver's intended trajectory by compensating for the rate at which the steering means is being turned, preventing overshooting or undershooting
Solution Approach 2:
The patent applies preliminary action by calculating the appropriate steering ratio in advance based on the current steering means angular speed and vehicle speed, before the driver's steering input is fully executed. This pre-calculation using mathematical functions or look-up tables ensures that the steering system is ready to respond accurately to the driver's intentions
Data Source
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AI summary
The disclosure relates to a method for providing a steering ratio for a steer-by-wire system (20) of a vehicle (10). The steering ratio is a ratio between a steering means angle (β) and a road wheel angle (α). The steering means angle (β) is associated with a steering means (18) configured to be operated by a driver, and the road wheel angle is associated with a road wheel (12). The road wheel (12) is controllable using the steering means (18). The method comprises obtaining first data (38) indicative of an angular steering means speed, and providing the steering ratio based on the first data (38). Also, a method for operating a steer-by-wire system (20) of a vehicle (10) is presented. The method comprises obtaining third data (42) indicative of a steering means angle, providing a steering ratio using the method for providing a steering ratio, and providing a reference road wheel angle based on the third data (42) and the steering ratio. Moreover, a use of the first data (38) for determining a steering ratio for a steer-by-wire system (20) of a vehicle (10) is presented. Furthermore, a data processing apparatus (24), a computer program (32), and a computer-readable storage medium (30) are presented. Finally, a steer-by-wire system (20) for a vehicle (10) and a vehicle (10) comprising the steer-by-wire system (20) are presented.