Vehicle Braking Force Distribution for Suspension Conversion Rates
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Solution Overview
Problem
Existing vehicle braking/driving force control systems face challenges in maintaining balanced control ranges for all wheels, leading to premature exceeding of control limits, especially due to differences in suspension link mechanism conversion rates between front and rear wheels.
Innovation Solution
A vehicle braking/driving force control apparatus with actuators for independent wheel control, suspension link mechanisms with varying conversion rates, and distribution setting means to allocate braking/driving forces based on conversion rates, ensuring larger forces are applied to wheels with higher conversion rates during motion control to prevent limit exceedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If braking/driving force is controlled to control vehicle motion, then vehicle motion control is achieved, but the braking/driving force becomes biased to front or rear wheel side causing certain wheel to reach output limit earlier than other wheels
Solution Approach 1:
The control apparatus applies different force distribution strategies to different wheels based on their local characteristics. Specifically, it identifies which wheel (front or rear) has a smaller suspension link mechanism conversion rate and allocates more braking/driving force to that wheel, while allocating less force to wheels with larger conversion rates. This localized adaptation prevents any single wheel from reaching its output limit prematurely.
Solution Approach 2:
The system dynamically changes the force distribution parameters based on the suspension link mechanism conversion rates. By adjusting the proportion of braking/driving force allocated to each wheel according to their respective conversion rates, the system optimizes the utilization of available force range across all wheels, preventing premature limit exceedance.
2Adaptability or versatility
If suspension link mechanism conversion rates differ between front and rear wheels, then vehicle design flexibility is improved, but force distribution balance deteriorates causing premature limit exceedance
Solution Approach 1:
The control apparatus recognizes and adapts to the local differences in suspension link mechanism conversion rates between front and rear wheels. It specifically targets the wheel with the smaller conversion rate and allocates more force to it, compensating for the inherent design asymmetry and maintaining overall force distribution balance.
Solution Approach 2:
The system intentionally introduces asymmetry in force distribution to counterbalance the asymmetry in suspension conversion rates. By allocating force unevenly (more to wheels with smaller conversion rates, less to wheels with larger conversion rates), it achieves symmetric utilization of the control range across all wheels.
Data Source
AI summary
When an ECU carries out vehicle yaw motion control on such a vehicle that a conversion rate of converting the braking/driving force into a vertical force is larger on rear wheels than on front wheels, a driver-requested braking/driving force is distributed to the four wheels so that a distribution ratio is larger for the rear wheels than for the front wheels. Thus, when roll control necessary as a result of the vehicle yaw motion control is carried out, a target braking/driving force of a turning outer wheel for which the largest control driving force is required becomes hard to reach a driving limit. From the foregoing, when vehicle motion control is carried out with use of a braking/driving force of each wheel, each wheel is prevented from reaching a driving force limit as much as possible.