Vehicle Behavior Control Apparatus for Steering Stability
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Solution Overview
Problem
Existing vehicle behavior control systems often fail to maintain sufficient steering stability, especially when tires are near the limit of their grip on the road surface, leading to insufficient steering stability during turns.
Innovation Solution
A vehicle behavior control apparatus that estimates the degree of lateral force generation on each wheel, calculates tire load factors, and adjusts the vertical load distribution among wheels to equalize tire load factors during turns, thereby improving steering stability by maximizing the use of tire forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If damping-force characteristics of dampers are controlled to improve roll feeling and suppress roll when tires are in limit region, then roll stability is improved, but steering stability becomes insufficient when vehicle is running at the limit
Solution Approach 1:
The invention changes the control parameters from roll-based metrics (pitch rate, roll rate) to tire load factor-based metrics. By calculating tire load factors for each wheel and using them as control parameters, the system can directly assess and respond to the actual tire grip status, enabling effective steering stability control when tires are operating at the limit
Solution Approach 2:
The invention implements feedback control by continuously monitoring tire load factors and adjusting vertical wheel loads accordingly. The tire load calculation means calculates real-time tire load factors, and the vertical-load control means uses this feedback to dynamically adjust damper forces, creating a closed-loop control system that responds to actual tire conditions rather than relying on predetermined roll suppression strategies
2Reliability
If vertical load is increased on wheels with larger tire load factor to equalize load distribution, then steering stability is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The invention makes the existing damper system multi-functional by enabling it to perform both its original roll suppression function and the new steering stability control function. The same vertical-load control means that adjusts damper forces can simultaneously optimize both roll behavior and steering stability, eliminating the need for separate control systems and reducing overall device complexity
Solution Approach 2:
The invention merges the steering stability control function with the existing roll control function in a unified control system. By combining the tire load calculation means with the existing pitch/roll control means, the system achieves dual functionality through integration rather than addition, managing complexity through consolidation of control objectives
Data Source
AI summary
A tire load calculation section of a controller calculates tire load factors of the respective wheels. A target tire load-factor calculation section calculates a tire load factor average value (ηave) obtained by averaging the tire load factors (ηi) of the respective wheels as a target tire load factor. A target tire vertical-load calculation section calculates target tire vertical loads (Fzrefi) for the respective wheels so that the tire load factors of the respective wheels become equal to the tire load factor average value. A vertical-load control section and a suspension control section control thrusts of electromagnetic dampers for the respective wheels so as to achieve the target tire vertical loads.