Off-Road Hill Start Assist Without Position Sensors
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Solution Overview
Problem
Existing Hill Start Assist (HSA) systems for off-road vehicles are limited in usability due to reliance on sensed vehicle position angle, which can be ineffective in uneven or hilly terrains with varying traction conditions, such as soft soils, snow, or ice, and do not allow manual control over drive configurations like rear wheel drive, four wheel drive, and all wheel drive.
Innovation Solution
A HSA system for off-road vehicles that includes a brake system with a control unit to maintain braking force when the manual brake actuator is released, operable in ready, activated, and hold states, determined by specific vehicle conditions such as being stopped, brake actuator engaged, and HSA switch activation, allowing manual control without position angle sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HSA systems use position angle sensors to automatically maintain brake on hills, then the system can prevent vehicle rolling, but the system becomes ineffective in uneven or hilly terrains with varying traction conditions
Solution Approach 1:
The patent removes the position angle sensor from the HSA system, extracting the problematic sensing component that limited adaptability. The system now relies on basic sensors (brake switch, accelerator switch, wheel speed sensors) that work reliably across all terrains without requiring accurate position angle data, thus resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The HSA system uses readily available vehicle data (brake switch status, accelerator switch status, wheel speed) that the vehicle already generates during normal operation. By leveraging these existing signals rather than adding specialized position sensing, the system achieves both reliability and versatility across different driving conditions.
2Extent of automation
If HSA systems automatically control brake based on sensed position angle, then the system can maintain vehicle stationary, but the system does not allow manual control over drive configurations
Solution Approach 1:
The system dynamically adapts its behavior based on real-time driver inputs and vehicle conditions. The control unit continuously monitors brake switch, accelerator switch, and wheel speed signals to determine when to activate HSA, allowing the system to automatically maintain brake when needed while remaining responsive to manual driver actions and drive configuration changes.
Solution Approach 2:
The system uses feedback from vehicle sensors (wheel speed, brake switch, accelerator switch) to automatically adjust brake application. This feedback mechanism enables automatic brake maintenance while still allowing manual override through the brake switch or accelerator input, resolving the contradiction between automation and manual control.
3Measurement precision
If HSA systems are designed for paved roads with position angle sensing, then the system can provide precise brake control, but the system complexity increases and limits off-road usability
Solution Approach 1:
The patent replaces expensive, complex position angle sensors with simpler, more robust switches and existing wheel speed sensors. This substitution reduces system complexity and cost while maintaining sufficient control precision for off-road conditions where exact position data is less critical than reliable brake application.
Data Source
AI summary
A Hill Start Assist (HSA) system for an off-road type vehicle includes a brake system for producing a braking force sufficient to maintain the vehicle in a stopped condition, and a control unit in communication with the brake system for controlling a brake modulator of the brake system to maintain the braking force when a manual brake actuator of the brake system is in a released position. The HSA system is operable in a ready state where the brake modulator is in an open condition and the braking force is not maintained, an activated state and a hold state where the brake modulator is in a closed condition and the braking force is maintained. The HSA system is only in the ready state upon determination by the control unit that predetermined vehicle conditions are satisfied.