Steering Assist Control with Torque-Angle Feedback Decoupling
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Solution Overview
Problem
Existing steering control devices face challenges in optimizing steering characteristics and dynamic behavior due to the need for complex adjustments between assist components, which are not efficiently addressed by current systems.
Innovation Solution
A steering control device that utilizes a controller to calculate a basic assist component through torque feedback control, adjusting the steering torque input by the driver, and incorporates an angle command value calculator using a model expression to optimize steering characteristics and dynamic behavior, while compensating for disturbances and vehicle states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the first assist component and second assist component are adjusted to optimize steering characteristics, then the steering characteristics are improved, but the adjustment process becomes complex and difficult to facilitate
Solution Approach 1:
The patent segments the assist force calculation into distinct components: a basic assist component (first assist component) and a feedback assist component (second assist component). This segmentation allows independent adjustment of each component without affecting the other, simplifying the optimization process. The basic assist component calculator computes the first assist component based on steering torque, while the angle feedback controller computes the second assist component based on angle deviation, enabling separate tuning for static and dynamic steering characteristics.
Solution Approach 2:
The patent introduces an intermediary variable (angle command value) that mediates between the basic assist component and the feedback control. The angle command value is calculated based on the basic assist component and serves as a reference for the angle feedback controller. This intermediary structure decouples the adjustment of the basic assist component from the feedback control parameters, allowing independent optimization without complex mutual adjustments.
2Measurement precision
If the assist compensation component is calculated using torque feedback control, then the steering torque accuracy is improved, but the calculation complexity and adjustment difficulty increase
Solution Approach 1:
The patent separates the torque feedback control into a dedicated basic assist component calculator that operates independently from the angle feedback control system. This segmentation allows the torque feedback control to be adjusted without affecting the angle feedback control parameters, simplifying the adjustment process while maintaining steering torque accuracy through the torque-based calculation of the basic assist component.
3Speed
If the steerable angle command value is calculated using basic drive torque, then the steering response is improved, but the system becomes sensitive to disturbances and vehicle state changes
Solution Approach 1:
The patent implements a two-layer feedback structure: the angle feedback controller continuously monitors the actual steerable angle and adjusts the assist force to maintain the angle command value, providing feedback that compensates for disturbances and vehicle state changes. This feedback mechanism ensures that while the system responds quickly to steering inputs, it also maintains stability and accuracy under varying conditions by continuously correcting deviations from the commanded angle.
Data Source
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AI summary
This steering control device (50) is provided with a microcomputer (51) that controls driving of a motor (40). The microcomputer (51) comprises: a basic assist component calculation unit (70) for calculating a basic assist component (Tb*); an angle command value calculation unit (71) for calculating an angle command value (θp*); an angle feedback control unit (72) that calculates an assist command value (Ta*) via angle feedback control in which a pinion angle (θp) is made to follow the angle command value (θp*); and a control signal generation unit (55) that generates a motor control signal (S_m) on the basis of the assist command value (Ta*). The basic assist component calculation unit (70) comprises: a torque command value calculation unit (74) for calculating a torque command value (Th*) that is a target value for steering torque (Trq) to be input by a driver; and a torque feedback control unit (75) that calculates the basic assist component (Tb*) via torque feedback control in which the steering torque (Trq) is made to follow the torque command value (Th*).