Steering Reaction Force Control via Lateral Acceleration
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Solution Overview
Problem
Conventional steer-by-wire systems do not effectively match the physical sensation of the operator through the steering wheel with the actual vehicle behavior during turning, particularly due to neglecting lateral acceleration, leading to discomfort and a mismatch between intended operation and vehicle response.
Innovation Solution
A control system that includes a steering angle detector, speed detector, and reaction-force generator, with a controller that calculates lateral acceleration and adjusts the reaction force ratio to the steering angle, using a rigidity characteristic map to ensure the reaction force increases with lateral acceleration, thereby aligning the operator's sensation with vehicle behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the reaction force is set based on human system dynamic characteristic to reduce operator burden, then the operator's burden is reduced, but the operating sensation does not match with actual vehicle behavior
Solution Approach 1:
The patent dynamically changes the reaction force parameter based on lateral acceleration. When lateral acceleration increases, the reaction force ratio increases to provide stronger feedback. This parameter adaptation resolves the contradiction by making the reaction force match actual vehicle behavior during turning while maintaining comfort during straight-line driving.
Solution Approach 2:
The system transitions from a static reaction force setting to a dynamic one that adapts to driving conditions. By continuously adjusting the reaction force ratio according to detected lateral acceleration, the system maintains both operator comfort and accurate feedback about vehicle behavior across different operating states.
2Loss of information
If the reaction force to steering angle ratio increases with lateral acceleration, then the operating sensation matches vehicle behavior, but the system complexity increases
Solution Approach 1:
The patent replaces complex mechanical coupling between steering and vehicle dynamics with an electrical control system. Sensors detect steering angle and vehicle state, the controller processes this information, and actuators generate appropriate reaction forces. This substitution achieves accurate feedback matching while keeping the system architecture manageable through electronic control rather than mechanical linkages.
Solution Approach 2:
The system implements a feedback loop where lateral acceleration is detected, processed by the controller, and used to adjust the reaction force. This closed-loop feedback mechanism enables the reaction force to automatically match vehicle behavior without requiring complex manual tuning or additional hardware.
Data Source
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AI summary
A vehicle control system is provided, which includes a steering angle detector configured to detect a steering angle of a steering wheel by the operator, the steering wheel is mounted on the vehicle, a speed detector configured to detect a traveling speed of the vehicle, a reaction-force generator configured to generate a reaction force of the steering wheel, and a controller. The controller includes a processor configured to execute a lateral acceleration calculating module to calculate a lateral acceleration based on the traveling speed and the steering angle, a rigidity characteristic setting module to set the reaction force so that a rigidity value that is a ratio of the reaction force to the steering angle increases as the lateral acceleration increases, and a reaction-force control module to control the reaction-force generator so that the reaction force becomes the reaction-force value set by the rigidity characteristic setting module.