Driving Force Control Apparatus for Wheel Slipping Resolution
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Solution Overview
Problem
Existing four-wheel drive vehicles face challenges in promptly resolving rear wheel slipping due to idling, leading to increased time required to regain driving force and resume forward travel, as they either set insufficient motor output torque or gradually reduce motor driving force to estimate road friction coefficients.
Innovation Solution
A driving force control apparatus that uses a processor to set the control amount of driving force based on vehicle acceleration, incorporating feedforward and feedback control to adjust the driving force transmitted to the wheels, with the processor calculating a vehicle acceleration-associated feedforward control amount and performing feedback control based on a target slipping rate to enhance traction and reduce slipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor output torque is set to resolve wheel slipping, then wheel slipping is reduced, but the time required to regain driving force increases
Solution Approach 1:
The patent dynamically adjusts motor output torque based on wheel slipping detection. When slipping is detected, the control unit increases motor output torque above the normal level to quickly regain traction, then gradually reduces it as grip is restored. This parameter change approach allows the system to transition from a static torque value to a dynamic adjustment strategy, resolving the contradiction between ensuring wheel grip and minimizing time loss.
Solution Approach 2:
The patent implements a feedback control mechanism where the control unit continuously monitors wheel rotation speed and slipping rate. Based on this feedback, the control unit adjusts motor output torque in real-time: increasing torque when slipping is detected and reducing torque when grip is regained. This closed-loop feedback system enables the vehicle to automatically adapt to changing road conditions, resolving the technical contradiction by making torque adjustment responsive to actual wheel grip status.
2Measurement precision
If motor driving force is gradually reduced to estimate road friction coefficient, then road friction coefficient estimation is achieved, but the time required to resolve slipping increases
Solution Approach 1:
The patent performs preliminary action by first resolving the slipping state through increased motor output torque before proceeding with road friction coefficient estimation. The control unit prioritizes regaining wheel grip as the primary objective, using gradual torque reduction only after slipping is resolved. This sequential approach ensures that safety and vehicle controllability are maintained while still achieving the measurement objective, resolving the contradiction between estimation accuracy and time efficiency.
Solution Approach 2:
The patent skips the traditional gradual torque reduction method during active slipping and directly applies increased motor output torque to quickly resolve the slipping state. The road friction coefficient estimation is performed afterward when the vehicle is in a stable state, rather than during the slipping event itself. This skipping approach eliminates the time delay associated with gradual torque reduction while maintaining the ability to estimate road friction coefficients, resolving the technical contradiction.
Data Source
AI summary
A driving force control apparatus for controlling a driving force to be transmitted to a wheel includes a processor. The processor is configured to set, when the wheel is idled, a control amount of the driving force to be transmitted to the wheel based on a vehicle acceleration.