Vehicle Control Device Regenerative Braking Force Allocation
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Solution Overview
Problem
Conventional vehicle control systems face instability due to excessive regenerative braking force on low μ roads, leading to early locking of drive wheels and understeer tendencies, especially when there is no significant speed difference between front and rear wheels.
Innovation Solution
A vehicle control apparatus comprising an electric motor for regenerative braking, a friction braking device for trailer wheels, and a behavior estimation unit that reduces regenerative braking force and increases friction braking when understeer is estimated, using sensors for yaw rate, steering angle, and wheel speed to adjust braking force allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking force is generated by the electric motor, then energy recovery efficiency is improved, but drive wheels may lock at an early stage causing vehicle instability
Solution Approach 1:
The control device dynamically changes the regenerative braking force parameter based on vehicle behavior state. When understeer is detected, the regenerative braking force is reduced below the commanded value to prevent drive wheel locking and maintain vehicle stability, while still recovering energy during normal braking conditions
Solution Approach 2:
The system uses feedback from the vehicle behavior estimation unit to continuously monitor for understeer conditions. Based on this feedback, the control device adjusts the regenerative braking force in real-time, reducing it when understeer is detected and maintaining normal levels when vehicle behavior is stable
2Power
If regenerative braking force is excessively allocated to drive wheels, then braking efficiency is improved, but understeer tendency occurs on low μ roads
Solution Approach 1:
The control device modifies the braking force distribution parameter by reducing regenerative braking force when understeer is detected. This parameter change prevents excessive braking force allocation to drive wheels on low μ roads, eliminating the understeer tendency while maintaining overall braking efficiency through coordinated friction braking
3Reliability
If regenerative braking force is reduced to prevent drive wheel locking, then vehicle stability is improved, but braking force allocation becomes less optimal
Solution Approach 1:
The system implements dynamic braking force allocation that adapts to real-time vehicle behavior. The regenerative braking force is reduced only when understeer is detected, while friction braking on trailer wheels is increased dynamically. This dynamic adjustment maintains optimal overall braking performance while preventing drive wheel locking and ensuring vehicle stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution stabilizes vehicle behavior by reducing regenerative braking and increasing friction braking, preventing early locking of drive wheels and understeer, even on low μ roads, by dynamically adjusting braking force based on estimated vehicle behavior.
Implementation Method 1
an electric motor configured to provide a regenerative braking force
Implementation Method 2
a friction braking device configured to provide a friction braking force
Data Source
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AI summary
An object of the present invention is to provide a vehicle control apparatus capable of stabilizing a behavior of a vehicle when a regenerative braking force is generated. To achieve this object, a vehicle control apparatus according to one aspect of the present invention includes an electric motor configured to provide a regenerative braking force to left and right drive wheels that are one of front wheels and rear wheels, a friction braking device configured to provide a friction braking force to left and right trailer wheels that are the other of the front wheels and the rear wheels, and a behavior estimation unit configured to estimate a behavior of a vehicle. The vehicle control apparatus reduces the regenerative braking force and increases the friction braking force provided by the friction braking device, if the behavior estimation unit estimates a preset behavior when the regenerative braking force is generated.