Steering Control Torque Segmentation for Consistent On-Center Feel
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Solution Overview
Problem
Existing electric power steering devices struggle to adjust on-center feeling without disrupting the already set steering feeling due to adjustments in viscosity or friction components.
Innovation Solution
A steering control device that includes a target steering torque setting unit, a calculation unit to calculate steering assist torque, and a current drive unit to control motor current, utilizing a first torque calculation based on steering angle gain and a second torque for hysteresis, allowing for on-center feeling adjustment while minimizing impact on the existing steering feeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the viscosity component or friction component is adjusted to improve on-center feeling, then the on-center feeling is improved, but the steering feeling that has already been set is disrupted
Solution Approach 1:
The patent segments the steering torque into multiple independent components: base torque, viscosity torque, friction torque, and on-center torque. By separating the on-center feeling adjustment into its own independent torque component, the system can modify on-center feeling without affecting other steering characteristics. Each torque component is calculated and applied independently, allowing selective adjustment of on-center feeling while preserving the originally set steering feeling.
Solution Approach 2:
The patent introduces an intermediary on-center torque component that acts as a mediator between the driver's steering input and the final steering force. This intermediary component specifically addresses on-center feeling by applying an additional torque that counteracts the natural return-to-center tendency, allowing independent optimization of on-center feeling without altering the base steering characteristics defined by other torque components.
2Adaptability or versatility
If the viscosity component is increased to enhance on-center feeling, then the on-center feeling is improved, but the steering assist torque required for following the target steering torque increases
Solution Approach 1:
The patent divides the steering assist torque into multiple independent components, allowing the on-center torque to be calculated and applied separately from the viscosity torque. This segmentation enables the system to optimize on-center feeling through the on-center torque component without requiring excessive increases in the viscosity component, thereby reducing the overall steering assist torque burden while maintaining effective on-center control.
Data Source
AI summary
A steering control device includes: a target steering torque setting circuitry; a calculation circuitry; and a current drive circuitry. The target steering torque setting circuitry includes a first torque calculation circuitry configured to calculate a first shift amount by multiplying a rotation angular velocity of the motor by a steering angle gain, and to obtain a first torque based on a post-shift steering angle obtained by adding the first shift amount to the steering angle and a base map showing a characteristic of gradually increasing a base torque with the post-shift steering angle, a second torque calculation circuitry configured to obtain a second torque for imparting hysteresis to the target steering torque by using the rotation angular velocity of the motor, and a target steering torque calculation circuitry configured to add the first torque and the second torque to be output as the target steering torque.