Steer-By-Wire Turning Control Using Estimated Suspension Stroke
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Solution Overview
Problem
Existing vehicle turning systems struggle to accurately control turning angles during travel, especially when the vehicle is under acceleration or deceleration, as they rely on differences between actual and standard suspension strokes, which become less effective at higher speeds.
Innovation Solution
A turning system that estimates suspension stroke based on the vehicle's moving state, including lateral and longitudinal accelerations, to calculate toe angle changes and adjust the turning angle control accordingly, using a steer-by-wire system with a turning ECU that integrates sensors for real-time data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the turning angle is controlled based on the difference between actual stroke and standard stroke, then the control is simple to implement, but the control accuracy deteriorates during vehicle travel and under acceleration/deceleration
Solution Approach 1:
The patent introduces an estimated stroke as an intermediary value that represents the suspension stroke under standard load conditions during vehicle travel. This estimated stroke acts as a mediator between the actual measured stroke and the standard stroke, allowing the system to calculate toe angle changes accurately by comparing actual stroke against this corrected reference value, thereby resolving the inaccuracy caused by dynamic load changes during acceleration and deceleration
Solution Approach 2:
The patent dynamically adjusts the reference stroke parameter from a fixed standard stroke to a variable estimated stroke that changes based on vehicle acceleration and deceleration states. By modifying this key parameter to reflect real-time driving conditions, the system maintains accurate toe angle control despite variations in vehicle load and motion state
2Device complexity
If the turning angle control uses standard stroke only, then the system complexity remains low, but the reliability of control deteriorates under varying vehicle loads and acceleration conditions
Solution Approach 1:
The patent performs preliminary calculation of the estimated stroke based on vehicle acceleration and deceleration before using it for toe angle control. This advance preparation of the corrected reference value ensures that the control system has accurate data ready when needed, improving reliability without significantly increasing system complexity
Solution Approach 2:
The patent replaces the purely mechanical stroke comparison method with a hybrid approach that incorporates electronic sensing of acceleration/deceleration and computational estimation of the standard stroke. This substitution of mechanical measurement with electronic sensing and calculation enhances control reliability while maintaining manageable system complexity
Data Source
AI summary
In a turning system for a vehicle, a toe angle change is acquired based on an estimated stroke which is a stroke of a suspension which is estimated based on a moving state of a vehicle and an actual stroke which is an actual stroke of the suspension detected by a stroke sensor, and control of a turning angle of a vehicle wheel is performed based on the acquired toe angle change. Accordingly, it is possible to appropriately perform control of a turning angle even in travel.