Vehicle Brake Force Control for Mixed Off-Road Surface Conditions
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Solution Overview
Problem
In-vehicle systems face a significant decrease in startability and runnability when road-surface conditions are inaccurately recognized, leading to inappropriate control modes being activated, particularly when multiple conditions such as rocky, muddy, and sandy areas are encountered.
Innovation Solution
The system employs a Multi Terrain Select (MTS) off mode, which determines an intermediate brake force control between rock, mud, and sand modes, based on a combination of wheel speed, acceleration, and G-sensor data to accurately assess the road-surface condition, thereby preventing a remarkable decrease in startability and runnability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the system selects a control mode based on a single road-surface condition from multiple acquired conditions, then the control decision is simplified and executed quickly, but the startability of the vehicle may decrease remarkably when the actual condition is close to a different acquired condition
Solution Approach 1:
The patent introduces an intermediate control mode that acts as a mediator between conflicting road-surface condition controls. When multiple road-surface conditions are acquired (e.g., rocky and muddy), the system determines an intermediate control between the respective controls for each condition, rather than selecting one control directly. This intermediate control serves as a compromise solution that prevents remarkable decrease in startability while maintaining reasonable control decision speed.
2Measurement precision
If the system performs complex probability calculations to determine the most likely road-surface condition, then the measurement precision of road-surface condition is improved, but the device complexity and calculation time increase
Solution Approach 1:
The patent extracts the essential control parameters from complex probability calculations and directly uses the acquired road-surface conditions to determine intermediate controls. Instead of performing complex probability computations to determine a single most likely condition, the system takes out the key information from multiple condition acquisitions and directly synthesizes an intermediate control, thereby reducing device complexity while maintaining sufficient measurement precision.
3Stability of the object's composition
If the system applies strong brake force control based on rocky area detection, then the vehicle stability on rocky surfaces is improved, but the startability decreases when the actual condition is closer to muddy or sandy areas
Solution Approach 1:
The patent changes the brake force parameter dynamically based on the determined control mode. When an intermediate control is determined (indicating multiple road-surface conditions are present), the system adjusts the brake force to an intermediate level between the strong brake force for rocky areas and the lighter brake force for muddy/sandy areas. This parameter adjustment ensures vehicle stability is maintained without excessively reducing startability when conditions are uncertain.
Data Source
AI summary
A braking system for a vehicle, the braking system includes a brake provided in a wheel of the vehicle and configured to restrain rotation of the wheel, and a brake force control device configured to control a brake force of the brake. The brake force control device includes a road-surface condition acquisition portion configured to acquire a road-surface condition indicative of a condition of a road surface where the vehicle travels, and in a case where the road-surface condition acquisition portion acquires a plurality of conditions as the road-surface condition, the brake force control device controls the brake force in a mode different from respective controls on the brake force based on the conditions.