Vehicle Steering Device Speed-Adaptive Transfer Function Control
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Solution Overview
Problem
Existing vehicle steering devices face challenges in maintaining directional stability and responsiveness due to changes in frequency responsiveness properties, particularly at varying vehicle speeds, leading to driver discomfort and instability.
Innovation Solution
A steering device with operation input detection, target turning amount calculation, transfer function setting, correction turning amount calculation, and final target turning amount calculation to adjust wheel turning based on detected inputs and vehicle conditions, ensuring appropriate directional stability and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple first-order lag is used for the response to motion condition amount, then the device complexity is reduced, but the directional stability and responsiveness of the vehicle deteriorate at varying vehicle speeds
Solution Approach 1:
The patent applies dynamics by making the transfer function adjustable based on vehicle speed. The control system switches between different transfer functions (first transfer function for low speed, second transfer function for high speed) depending on the detected vehicle speed, allowing the system to adapt its dynamic characteristics to maintain optimal directional stability across different operating conditions.
Solution Approach 2:
The patent changes the parameter of the transfer function according to vehicle speed. By detecting vehicle speed and selecting appropriate transfer functions with different characteristics (first transfer function with certain damping for low speed, second transfer function with different damping for high speed), the system optimizes the frequency responsiveness property of motion condition amounts at different speeds.
2Speed
If the differential term is decreased on steering wheel returning, then the responsiveness is improved, but the directional stability is reduced
Solution Approach 1:
The patent applies dynamics by making the transfer function adjustable based on vehicle speed. The control system switches between different transfer functions (first transfer function for low speed, second transfer function for high speed) depending on the detected vehicle speed, allowing the system to adapt its dynamic characteristics to maintain optimal directional stability across different operating conditions.
Solution Approach 2:
The patent changes the parameter of the transfer function according to vehicle speed. By detecting vehicle speed and selecting appropriate transfer functions with different characteristics (first transfer function with certain damping for low speed, second transfer function with different damping for high speed), the system optimizes the frequency responsiveness property of motion condition amounts at different speeds.
3Device complexity
If the frequency responsiveness property is not corrected, then the device complexity is reduced, but the driver feels strangeness and discomfort at varying vehicle speeds
Solution Approach 1:
The patent applies dynamics by making the transfer function adjustable based on vehicle speed. The control system switches between different transfer functions (first transfer function for low speed, second transfer function for high speed) depending on the detected vehicle speed, allowing the system to adapt its dynamic characteristics to maintain optimal directional stability across different operating conditions.
Solution Approach 2:
The patent changes the parameter of the transfer function according to vehicle speed. By detecting vehicle speed and selecting appropriate transfer functions with different characteristics (first transfer function with certain damping for low speed, second transfer function with different damping for high speed), the system optimizes the frequency responsiveness property of motion condition amounts at different speeds.
Data Source
AI summary
A target turning angle calculation part 51 calculates a target turning angle δ on the basis of a steering angle θ and a vehicle speed V. A correction turning angle calculation part 52 calculates a transfer function K(s) which is a second transfer function, depending on the vehicle speed V, by using a difference between a transfer function G(s) which is a first transfer function determined on the basis of the specification of the vehicle and a stationary component G(0) of the transfer function G(s), the first transfer function having as an input a turning angle δ and as an output a yaw rate γ of the vehicle, the second transfer function having as an input a target turning rate δ*′ obtained by temporally differentiating the target turning angle δ* and as an output a correction turning angle δc. The correction turning angle calculation part 52 calculates a correction turning angle δc by multiplying the transfer function K(s) by the target turning rate δ*′. A final target turning angle calculation part 53 inputs thereto the target turning angle δ* from the target turning angle calculation part 51 and the correction turning angle δc from the correction turning angle calculation part 52 and calculates a final target turning angle δd by adding the correction turning angle δc to the target turning angle δ*.