Steering Control Stabilizing Wheel Return Speed via Angular Acceleration Feedback
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Solution Overview
Problem
Conventional steering control systems face challenges in stabilizing the returning speed of the steering wheel, particularly during low-vehicle speed ranges, leading to inhibition of steering when the driver performs turn steering due to torque issues.
Innovation Solution
A steering control apparatus that calculates a returning speed stabilization torque based on the second-order time differential value of steering wheel position-related information, adjusting the torque output to stabilize the returning speed and prevent inhibition during turn steering by differentiating between turning and returning states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a correction torque is added to assist steering wheel return, then the steering wheel returns to neutral position, but the returning speed becomes unstable due to torsion bar twisting
Solution Approach 1:
The control unit calculates a stabilization torque based on the angular acceleration of the motor, which serves as feedback from the system's actual behavior. This feedback mechanism allows the system to detect and correct speed fluctuations caused by torsion bar twisting, thereby stabilizing the returning speed while maintaining the steering wheel's return to neutral position.
Solution Approach 2:
The system dynamically adjusts the correction torque by incorporating angular acceleration as an additional parameter. By changing the torque calculation to include this parameter, the system adapts to the dynamic conditions during steering wheel return, compensating for torsion bar effects and stabilizing the returning speed.
2Stability of the object's composition
If counter-return command value is calculated based on angular acceleration during turning, then returning speed is stabilized, but torque in direction that inhibits steering is outputted during turn steering
Solution Approach 1:
The system dynamically determines whether the steering wheel is in a turning state or returning state by evaluating the sign of the angular velocity. Based on this dynamic state assessment, the control unit selectively applies the stabilization torque only during the returning phase, not during turning. This dynamic approach allows the system to stabilize returning speed while preventing inhibition of steering during turn steering operations.
Data Source
AI summary
In a steering control apparatus, a basic assistance torque calculating unit calculates a basic assistance torque. A correction torque calculating unit calculates a correction torque to be added to the basic assistance torque. In the correction torque calculating unit, a returning state determining unit determines whether a steering wheel is turning or returning. A returning speed stabilization control unit calculates a returning speed stabilization torque to stabilize a returning speed of the steering wheel, as the correction torque. The returning speed stabilization control calculates the returning speed stabilization torque such as to bring a second-order time differential value of steering wheel position-related information correlated with a steering wheel position closer to zero, and such that an absolute value of the returning speed stabilization torque when the steering wheel is returning is relatively greater than that when the steering wheel is turning.