Hill-Hold Brake Control Without Road Grade Sensing
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Solution Overview
Problem
Existing hill-hold assist systems require road grade sensing, which adds cost and complexity, and do not effectively prevent vehicle rollback on any grade without this information.
Innovation Solution
A vehicle controller is programmed to automatically engage friction brakes when the brake pedal is applied, the vehicle speed is zero, and the accelerator pedal position is below a threshold, regardless of road grade, and to release the brakes when the accelerator pedal position exceeds a second threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If road grade sensing is used in hill-hold assist systems, then the system can effectively prevent vehicle rollback on steep grades, but the system cost and complexity increase
Solution Approach 1:
The patent extracts and removes the road grade sensing component from the hill-hold assist system. Instead of using complex road grade sensors, the system relies on existing sensors (brake pedal position sensor, accelerator pedal position sensor, and speed sensor) that are already present in the vehicle, thereby reducing system complexity while maintaining rollback prevention functionality through alternative control logic
2Reliability
If road grade sensing is used in hill-hold assist systems, then the system can effectively prevent vehicle rollback on steep grades, but the system cost increases
Solution Approach 1:
The patent eliminates the need for expensive road grade sensing hardware by extracting this function from the system. The solution uses only standard sensors already included in the vehicle's existing control systems, thereby significantly reducing manufacturing costs while maintaining effective rollback prevention through intelligent control algorithms that monitor brake pedal position, accelerator pedal position, and vehicle speed
Solution Approach 2:
The system uses the vehicle's existing sensor infrastructure (brake pedal position sensor, accelerator pedal position sensor, speed sensor) to perform the hill-hold function without requiring additional dedicated road grade sensing components. This self-service approach leverages available resources to achieve the desired functionality at lower cost
3Reliability
If the driver manually coordinates brake and accelerator pedals, then the driver can launch the vehicle without rollback on steep grades, but the ease of operation decreases
Solution Approach 1:
The system automatically performs the hill-hold function by monitoring sensor inputs (brake pedal position, accelerator pedal position, vehicle speed) and controlling the friction brakes without requiring manual coordination by the driver. The controller applies brakes automatically when launch conditions are detected and releases them when the vehicle is ready to move, eliminating the need for complex manual pedal coordination while maintaining effective rollback prevention
Solution Approach 2:
The system continuously monitors feedback from sensors (brake pedal position sensor, accelerator pedal position sensor, speed sensor) to automatically adjust brake application during vehicle launch. This closed-loop control ensures rollback prevention while simplifying operation, as the system self-adjusts based on real-time sensor data without requiring manual intervention
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 effectively prevents vehicle rollback on any road grade by engaging friction brakes independently of road grade information, simplifying the system and reducing costs.
Implementation Method 1
automatically engage friction brakes regardless of road grade and continue engagement of the friction brakes despite subsequent release of the brake pedal such that the friction brakes are engaged to hold the vehicle stationary independent of the road grade
Data Source
AI summary
A vehicle includes a powertrain having a powerplant and a transmission. The transmission has an input shaft operably coupled to the powerplant and an output shaft operably coupled to driven wheels. A vehicle controller is programmed to, in response to a brake pedal being applied, a speed of the output shaft being less than a threshold speed, and a position of an accelerator pedal being less than a threshold position, automatically engage friction brakes regardless of road grade and continue engagement of the friction brakes despite subsequent release of the brake pedal such that the friction brakes are engaged to hold the vehicle stationary independent of the road grade. The controller is further programmed to release the friction brakes in response to a position of the accelerator pedal being greater than a second threshold position.