Steer-By-Wire Reaction Force Control for Variable Gear Ratios
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In steer-by-wire type steering devices, the setting of steering reaction force applied to the steering operation input member can become too small or too large depending on the steering gear ratio and operation angular velocity, increasing the operational burden on the driver.
Innovation Solution
A steer-by-wire type steering device with a control device that adjusts the steering gear ratio based on vehicle speed and controls the reaction force actuator output amount based on the operation angular velocity, using a reaction force actuator to apply an appropriate steering reaction force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the steering gear ratio is set to be variable and the steering reaction force is set to be variable in accordance with operation angular velocity, then the steering performance can be optimized for different vehicle speeds, but the steering reaction force may become too small or too large depending on the steering gear ratio, increasing the operational burden on the driver
Solution Approach 1:
The patent applies dynamics by making the reaction force actuator's output characteristics variable rather than fixed. The control device dynamically adjusts the output amount of the reaction force actuator based on the current steering gear ratio, ensuring that the steering reaction force remains within an appropriate range even as the steering gear ratio changes with vehicle speed. This dynamic adjustment resolves the contradiction by allowing the system to adapt to different operating conditions while maintaining comfortable and safe steering characteristics.
Solution Approach 2:
The patent implements feedback control where the control device continuously monitors the steering gear ratio and uses this information to adjust the output amount of the reaction force actuator. The control device calculates the appropriate reaction force based on the current steering gear ratio and operation angular velocity, creating a closed-loop control system. This feedback mechanism ensures that the steering reaction force is appropriately adjusted in response to changes in steering gear ratio, preventing the force from becoming too small or too large and thereby reducing the operational burden on the driver.
2Speed
If the steering gear ratio is changed in accordance with vehicle speed, then the steering responsiveness can be improved, but the steering reaction force setting becomes complex and may become inappropriate under different conditions
Solution Approach 1:
The control device performs multiple functions: it determines the steering gear ratio based on vehicle speed, calculates the operation angular velocity, and adjusts the output amount of the reaction force actuator all in one integrated system. This multi-functional approach simplifies the overall control architecture while achieving both steering responsiveness improvement and appropriate reaction force setting. The single control device handles all adjustments, avoiding the need for separate complex control systems for each function.
Solution Approach 2:
The patent changes parameters (steering gear ratio and reaction force actuator output amount) based on operating conditions (vehicle speed and operation angular velocity). The control device adjusts these parameters dynamically to maintain optimal steering characteristics across different vehicle speeds and steering conditions. This parameter-based control approach allows the system to achieve improved responsiveness while keeping the control logic relatively simple through mathematical relationships between parameters.
3Stability of the object's composition
If the steering reaction force is increased to prevent excessive steering input member rotation, then the steering stability can be improved, but the operational burden on the driver increases
Solution Approach 1:
The patent applies dynamics by making the reaction force actuator's output characteristics variable rather than fixed. The control device dynamically adjusts the output amount of the reaction force actuator based on the current steering gear ratio, ensuring that the steering reaction force remains within an appropriate range even as the steering gear ratio changes with vehicle speed. This dynamic adjustment resolves the contradiction by allowing the system to adapt to different operating conditions while maintaining comfortable and safe steering characteristics.
Solution Approach 2:
The patent changes parameters (steering gear ratio and reaction force actuator output amount) based on operating conditions (vehicle speed and operation angular velocity). The control device adjusts these parameters dynamically to maintain optimal steering characteristics across different vehicle speeds and steering conditions. This parameter-based control approach allows the system to achieve improved responsiveness while keeping the control logic relatively simple through mathematical relationships between parameters.
Data Source
AI summary
A steering device according to the present invention includes: a steering input device including a reaction force actuator that applies a steering reaction force to a steering operation input member; and a control device including a steering gear ratio change unit that changes a steering gear ratio in accordance with a vehicle speed, a reaction force actuator control unit that controls an output amount of the reaction force actuator in accordance with an operation angular velocity of the steering operation input member, and a reaction force actuator output amount change unit that changes, based on the steering gear ratio, the output amount of the reaction force actuator. This makes it possible to set an appropriate steering reaction force applied to the steering operation input member, thereby stably reducing the operational burden on a driver.