Vehicle Drive State Control for Stability
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Solution Overview
Problem
Existing vehicle control systems fail to effectively manage drive state transitions between front wheel drive, rear wheel drive, and all wheel drive, particularly when lateral acceleration exceeds a certain threshold, leading to unintended sudden changes in turning characteristics.
Innovation Solution
A vehicle control method that includes a drive state control device to switch between front wheel independent drive, combined drive, rear wheel independent drive, and combined drive states, prohibiting state changes when lateral acceleration exceeds a threshold value set based on divergence reference values, ensuring stable drive states and preventing sudden changes in turning characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If drive state switching is allowed during high lateral acceleration, then drive adaptability is improved, but turning characteristic stability deteriorates due to sudden changes
Solution Approach 1:
The control device prohibits switching between drive states when lateral acceleration exceeds a predetermined threshold, preventing sudden changes in turning characteristics before they can occur. This preliminary restriction avoids the harmful effect of instability during high lateral acceleration conditions.
Solution Approach 2:
The switching prohibition threshold is made variable based on vehicle speed, increasing with higher speeds to maintain appropriate stability margins. This dynamic adjustment allows the system to adapt the stability constraint according to operating conditions.
2Stability of the object's composition
If drive state switching is restricted during high lateral acceleration, then turning characteristic stability is improved, but drive state adaptability deteriorates
Solution Approach 1:
By establishing a speed-dependent threshold for switching prohibition, the system preemptively prevents instability issues while allowing adaptability within safe operating ranges. The threshold increases with vehicle speed, permitting more switching freedom at low speeds while maintaining stability at high speeds.
3Device complexity
If a fixed lateral acceleration threshold is used for switching prohibition, then control simplicity is improved, but accuracy in preventing turning characteristic divergence deteriorates
Solution Approach 1:
The switching prohibition threshold is made variable based on vehicle speed, increasing with higher speeds. This dynamic adjustment provides more precise control across different operating conditions while maintaining relatively simple control logic, avoiding the need for complex multi-dimensional thresholds.
Data Source
AI summary
A vehicle in which a drive state can be favorably selected in a configuration that separately and independently drives front and rear wheels and a method for controlling the vehicle. In the vehicle and control method thereof, a drive state control device prohibits operation of a first switch between front wheel drive (FWD) and all wheel drive (AWD) and a second switch between rear wheel drive (RWD) and AWD when a lateral acceleration related value of the vehicle exceeds a first threshold value G1. The first threshold value G1 is set with a divergence reference value Gref as a reference. The Gref value is determined considering factors such as lateral acceleration, turning characteristics and the drive state of the vehicle.