Active Steering Offset Compensation via Variable Reduction Rate
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Solution Overview
Problem
Active steering systems face challenges in smoothly compensating for deviations between requested and actual motor angles without being perceptible to the driver, especially during mode changes or vehicle startup, leading to an uneven steering experience.
Innovation Solution
The system detects an offset angle between the requested and actual motor angles and reduces it using a selected reduction rate based on variables like steering wheel speed, wheel steer angle, and vehicle speed, applying a superimposition angle via a motor connected to the steering column through a harmonic drive, ensuring synchronized compensation that is imperceptible to the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the motor immediately compensates for the offset angle by rotating to the requested angle, then the offset is eliminated quickly, but the driver perceives the compensation as a disturbance or jerk in the steering wheel
Solution Approach 1:
The patent applies dynamics by making the steering system adaptive and variable rather than fixed. The control system dynamically adjusts the steering ratio and offset compensation based on operating conditions (vehicle speed, steering angle, steering rate) to optimize both response time and driver comfort. The system transitions between different compensation strategies depending on the situation, eliminating the offset gradually when necessary while maintaining quick response when appropriate.
Solution Approach 2:
The patent changes physical parameters of the steering system, specifically the steering ratio and compensation rate, based on operating conditions. The control system modifies these parameters in real-time according to vehicle speed, steering angle, and steering rate to balance offset elimination speed with driver comfort, preventing perceptible disturbances while maintaining system responsiveness.
2Reliability
If the steering ratio is fixed, then the system is simple and reliable, but it cannot adapt to different driving conditions or provide optimal steering characteristics across various speeds
Solution Approach 1:
The patent transforms the fixed steering ratio system into a dynamic, variable system. The control system continuously adjusts the effective steering ratio based on vehicle speed, steering angle, and steering rate, enabling the system to adapt to different driving conditions while maintaining reliability through a unified control architecture that manages both the fixed mechanical components and the variable control parameters.
Solution Approach 2:
The patent makes the steering system multi-functional by enabling it to serve different purposes across various operating conditions. The same steering system provides both stability at low speeds and responsiveness at high speeds, handles both manual steering and active compensation functions, and adapts to different driving modes (parking, city driving, highway driving) through parameter adjustment rather than requiring separate systems.
3Productivity
If the motor rotates at high speed to eliminate offset quickly, then the offset compensation is efficient, but the driver perceives the movement as a disturbance
Solution Approach 1:
The patent applies dynamics by making the compensation rate variable rather than constant. The control system dynamically adjusts the motor rotation speed based on operating conditions, using higher compensation rates when the offset needs rapid elimination (within comfort limits) and lower rates when smooth transition is priority, optimizing both efficiency and comfort based on real-time vehicle state.
Solution Approach 2:
The patent changes the motor rotation parameter (angular velocity) based on operating conditions. The control system modifies this parameter in real-time according to vehicle speed, steering angle, and steering rate, allowing efficient offset compensation when conditions permit while preventing perceptible disturbances when smooth operation is required.
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
This method allows for gradual and imperceptible elimination of offset angles, enhancing the driver's steering experience by synchronizing offset compensation with driving operations, maintaining a consistent steering ratio and reducing perceived vehicle instability during mode changes or startup.
Implementation Method 1
an electric motor that receives a requested motor angle and that outputs an actual motor angle
Implementation Method 2
connected to the steering column via the harmonic gear
Data Source
AI summary
A method for operating an active steering system of a vehicle, in which a ratio between a wheel steer angle and a steering wheel angle specified by the driver can be modified by superimposition of a superimposition angle. The method comprises detecting an offset between a requested motor angle and an actual motor angle, and reducing the offset between the requested motor angle and the actual motor angle using a reduction rate that is selected as a function of at least one input variable specified by the driver.