Drive Force Control Device for Vehicle Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drive force control devices for vehicles struggle to stabilize behavior when the steering angle exceeds the vehicle's stable turning radius, particularly at high speeds, leading to potential oversteer and loss of control.
Innovation Solution
A drive force control device that computes a steering angle-based turning radius and a limit turning radius based on vehicle speed, adjusts the target turning radius, and distributes drive force to right and left wheels to achieve target rotational speeds, thereby stabilizing vehicle behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the steering angle is increased to achieve a tighter turning radius, then the vehicle's turning capability is improved, but the vehicle stability deteriorates when the steering angle exceeds the stable turning radius
Solution Approach 1:
The control device applies preliminary anti-action by detecting when the steering angle exceeds the stable turning radius and automatically adjusting the drive force distribution to counteract the emerging instability. Specifically, when oversteer is detected, the system reduces drive force to the rear wheels or increases drive force to the front wheels, creating a counteracting moment before the instability fully develops, thereby preventing loss of vehicle control
Solution Approach 2:
The system implements dynamics by continuously varying the drive force distribution ratio between front and rear wheels based on real-time steering angle and vehicle speed conditions. The control device dynamically adjusts the torque split ratio according to the calculated stable turning radius, enabling the vehicle to maintain optimal stability across different operating conditions while preserving tight turning capability when needed
2Speed
If the drive force is increased to improve acceleration performance, then the vehicle's speed capability is improved, but the vehicle stability deteriorates during high-speed turning
Solution Approach 1:
The control device dynamically adjusts the drive force distribution based on vehicle speed and steering angle. At high speeds during turning, the system automatically modifies the torque split ratio to maintain stability, while allowing high acceleration performance during straight-line or low-speed turning conditions. This dynamic adaptation resolves the contradiction between speed capability and high-speed turning stability
Solution Approach 2:
The system changes the drive force distribution parameter (torque split ratio) based on operating conditions. When vehicle speed exceeds a threshold and steering angle indicates turning, the control device adjusts the distribution ratio to favor front-wheel drive or reduce rear-wheel drive force, thereby maintaining stability at high speeds while preserving acceleration capability when conditions permit
Data Source
AI summary
A drive force control device, which controls a drive force distribution device that distributes a drive force to right and left rear wheels at variable distribution ratios, computes a steering angle-based turning radius determined in accordance with a steering angle, computes a limit turning radius, which is a minimum value of the turning radius with which the vehicle is turnable while keeping a stable travel state, in accordance with a vehicle speed, sets the larger one of the steering angle-based turning radius and the limit turning radius as a target turning radius, computes target rotational speeds for the right and left rear wheels on the basis of the target turning radius and the vehicle speed, and adjusts the ratios of distribution of the drive force to the right and left rear wheels such that actual rotational speeds of the right and left rear wheels approximate the target rotational speeds.