Vehicle Turning Control With Steering Hold Torque Simplification
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Solution Overview
Problem
The existing travel control devices for vehicles face increased calculation loads when deriving torques for automatic turning support control, as they need to account for both vehicle body slip angle and front wheel steered angle, leading to complexity in maintaining the steering angle at a neutral point.
Innovation Solution
A travel control device configuration that separates the front wheel steered angle adjustment and turning control, allowing the steering device to apply a holding torque only when steering is not performed, thereby eliminating the need to derive torque components related to the front wheel steered angle, reducing the calculation load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the holding torque is derived by considering both vehicle body slip angle and front wheel steered angle, then the steering angle can be accurately maintained at the neutral point, but the calculation load of the travel control device increases
Solution Approach 1:
The patent extracts and removes the front wheel steered angle component from the holding torque calculation when steering is not being performed. By determining that only the vehicle body slip angle component is needed in this specific condition, the system eliminates unnecessary calculation elements while maintaining the accuracy of steering angle maintenance at the neutral point.
Solution Approach 2:
The patent dynamically adjusts the calculation approach based on the steering state. When steering is not being performed, the system uses a simplified calculation considering only vehicle body slip angle. When steering is being performed, the system transitions to a more comprehensive calculation that includes both vehicle body slip angle and front wheel steered angle. This dynamic adaptation optimizes calculation load while maintaining accuracy when needed.
2Reliability
If the front wheel steered angle adjustment device is driven during turning support control, then the turning state can be precisely controlled, but the device complexity and control difficulty increase
Solution Approach 1:
The patent segments the turning support control into two distinct modes based on steering state. In the first mode (steering not being performed), only the turning control device is driven to adjust the steered angle. In the second mode (steering being performed), both the turning control device and front wheel steered angle adjustment device are driven. This segmentation simplifies control in the predominant case while maintaining precision when needed.
Solution Approach 2:
The patent applies partial action by driving only the turning control device when steering is not being performed, which is sufficient for maintaining the neutral point. The front wheel steered angle adjustment device is activated only when necessary (when steering is being performed), avoiding excessive control complexity for the common case while ensuring precision when required.
Data Source
AI summary
A travel control device includes a turning control unit configured to execute turning support control causing a turning state quantity to follow a target turning state quantity by causing at least one of a front wheel steered angle adjustment device, a rear wheel steered angle adjustment device, and a braking device to be driven, and a steering instruction unit configured to, when steering is not being performed during the execution of turning support control, derive a holding torque and instruct a steering device to apply the holding torque to a steering wheel. The turning control unit causes the rear wheel steered angle adjustment device and/or the braking device to be driven but causes the front wheel steered angle adjustment device not to be driven when steering is not being performed. The turning control unit causes the front wheel steered angle adjustment device to be driven when steering is being performed.