4WD Control Logic for ABS Signal Differentiation
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Solution Overview
Problem
The 4WD control logic in electronic 4WD systems generates side effects that cause undesirable conversion to 2WD mode when an ABS signal is activated, particularly on low-friction roads, leading to deteriorated performance and potential shutdown of the 4WD system, especially in ABS solo vehicles without cooperative control logic.
Innovation Solution
An electronic 4WD system with reinforced ABS cooperative control performance is implemented by recognizing ABS ACT and 4WD_OPEN signals, determining the driver's intention through brake and accelerator pedal signals, and maintaining or stopping the 4WD mode accordingly, using a sub-logic to prevent side effects, thereby enhancing stability and performance on low-friction roads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the 4WD control logic automatically stops 4WD mode when an ABS signal is generated without brake pedal input, then the braking stability is prioritized, but the 4WD mode is unnecessarily converted to 2WD mode on low-friction roads
Solution Approach 1:
The patent applies local quality by differentiating the control response based on the specific condition causing the ABS signal. When the brake pedal is pressed, 4WD mode is stopped to prioritize braking stability. However, when the ABS signal is generated without brake pedal input (indicating wheel speed difference on low-friction roads), the 4WD mode is maintained to preserve 4WD performance. This localized differentiation of control logic resolves the contradiction between braking stability and 4WD performance.
2Device complexity
If the electronic 4WD system uses conventional 4WD control logic without additional ABS logic, then the system complexity is reduced, but the side effects cause undesirable conversion to 2WD mode and potential system shutdown
Solution Approach 1:
The patent merges the ABS signal processing logic with the existing 4WD control logic in the 4WD ECU. Instead of adding a separate ABS logic module, the system integrates the brake pedal signal detection and 4WD mode control into the existing 4WD control unit. This merging approach maintains system simplicity while effectively preventing unwanted 4WD mode conversion and system shutdown.
Solution Approach 2:
The 4WD ECU performs self-service by independently processing the ABS signal and making control decisions without requiring additional logic from the ABS ECU. The system uses its own resources (brake pedal signal detection capability) to resolve the contradiction between braking stability and 4WD performance, eliminating the need for complex inter-ECU coordination.
Data Source
AI summary
The present invention relates to an electronic 4WD system having reinforced ABS cooperative control performance, in which an ABS ACT signal by an ABS (Anti-Lock Brake System) controller and a 4WD_OPEN signal by the ESC (Electronic Stability Control) controller are used. When the ABS ACT signal and the 4WD_OPEN signal are recognized, it is determined that it is an ESC vehicle and a 4WD mode is stopped. When only the ABS ACT signal is recognized, it is determined that it is an ABS vehicle and the intention of a user is determined on the basis of whether a brake pedal has been pressed down or an accelerator pedal has been released, and then a 4WD mode is stopped.