Autonomous Vehicle Steering Control Using Target Yaw Rate
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Solution Overview
Problem
Conventional vehicle stabilization control systems are designed for driver-operated steering and are not suitable for autonomous driving, as they rely on steering wheel angle inputs which do not accurately reflect the target yaw rate during autonomous operations.
Innovation Solution
A vehicle travel control device that includes an electric power steering (EPS) system and a control unit capable of calculating a target steering angle by combining autonomous driving steering and counter steering angles, without relying on the steering wheel angle, to ensure accurate vehicle stabilization during autonomous driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional vehicle stabilization control is used during autonomous driving, then the system structure remains simple, but the control accuracy deteriorates because steering wheel angle does not reflect target yaw rate
Solution Approach 1:
The patent changes the input parameter from steering wheel angle to target state quantity (target yaw rate) for calculating counter steering angle during autonomous driving. This parameter change ensures that the calculation basis accurately reflects the actual driving intent, resolving the contradiction between maintaining simple system structure and achieving high control accuracy.
2Reliability
If steering wheel angle is used for counter steering angle calculation during autonomous driving, then the calculation method remains simple, but the vehicle stabilization performance deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of the calculation method based on driving mode. During autonomous driving, the system dynamically switches from using steering wheel angle to using target state quantity for counter steering angle calculation. This dynamic adaptation ensures reliable vehicle stabilization performance while managing control method complexity through context-aware processing.
Solution Approach 2:
The patent introduces target state quantity as an intermediary parameter that mediates between the autonomous driving control and vehicle stabilization control. This intermediary accurately conveys the driving intent during autonomous operation, enabling reliable stabilization without directly relying on steering wheel angle, thus resolving the contradiction between stabilization reliability and control complexity.
3Extent of automation
If the driving entity changes from driver to autonomous driving system, then the automation level increases, but the applicability of conventional stabilization control decreases
Solution Approach 1:
The patent makes the stabilization control system dynamic by adjusting its input parameter selection based on the driving entity. When the autonomous driving system is the active entity, the system dynamically switches to using target state quantity instead of steering wheel angle. This dynamic adaptability maintains high automation level while ensuring the control system remains versatile and applicable across different driving modes.
Solution Approach 2:
The patent enhances the universality of the control system by making it functional for both driver-operated and autonomous driving modes. Through conditional parameter selection (steering wheel angle for driver mode, target state quantity for autonomous mode), the system achieves multi-functionality that adapts to different driving entities, resolving the contradiction between automation level and system adaptability.
Data Source
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AI summary
A vehicle travel control device (10) includes: an EPS device (50) turning a wheel (5) of a vehicle (1); and a control device (100) performing autonomous driving control that controls autonomous driving of the vehicle (1). The autonomous driving control includes: calculating a target steering angle (δa) of the wheel (5); and actuating the EPS device (50) to turn the wheel (5) such that a steering angle of the wheel (5) becomes the target steering angle (δa). The calculating the target steering angle (δa) includes: calculating an autonomous driving steering angle (δb) and a target state quantity (ST) required for automatic steering in the autonomous driving; calculating a counter steering angle (δc) required for vehicle stabilization control, based on the target state quantity (ST) without using a steering wheel angle (cps); and calculating a sum of the autonomous driving steering angle (δb) and the counter steering angle (δc) as the target steering angle (δa).