Hill Start Assist Gradient Correction via Pitch Tilt Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hill start assist control (HAC) systems frequently malfunction and exhibit sensitive operations on flat roads due to misrecognition of the road gradient, leading to unnecessary braking and vehicle instability.
Innovation Solution
The method adjusts the road gradient calculation by subtracting the vehicle's pitch tilt due to braking deceleration from the gradient sensed by the acceleration sensor, providing a more accurate assessment of the road gradient to determine the need for HAC intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HAC system uses the acceleration sensor to detect road gradient, then the system can identify hills and provide assist control, but the system misrecognizes flat roads as hills after braking due to pitch tilt
Solution Approach 1:
The patent introduces an intermediary correction mechanism that uses braking deceleration information as a mediator to adjust the acceleration sensor output. The controller calculates the pitch tilt angle based on braking deceleration and uses this as an intermediary value to correct the road gradient detection, thereby eliminating false positive detections on flat roads while maintaining accurate hill detection capability
Solution Approach 2:
The patent replaces the purely mechanical/physical acceleration sensor-based gradient detection with a corrected detection system that incorporates computational correction. By substituting the raw sensor output with a computationally adjusted value that accounts for braking-induced pitch tilt, the system achieves more accurate gradient measurement without additional physical sensors
2Reliability
If the HAC system operates on flat roads due to misrecognition, then unnecessary braking force is applied, but this causes vehicle instability and noise
Solution Approach 1:
The patent applies preliminary anti-action by preemptively correcting the acceleration sensor output before it is used for HAC decision-making. By calculating and applying the pitch tilt correction in advance, the system prevents false activation of HAC on flat roads, thereby avoiding the harmful effects of unnecessary braking, vehicle instability, and noise generation
Solution Approach 2:
The patent implements a feedback mechanism where braking deceleration information is fed back into the gradient detection process. The controller continuously monitors braking deceleration and uses this feedback to dynamically adjust the acceleration sensor output, creating a closed-loop system that eliminates false positive detections and their associated harmful effects
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 approach effectively prevents HAC malfunctions and sensitive operations on flat roads, reducing driver displeasure and vehicle instability, while avoiding unnecessary braking and noise generation.
Implementation Method 1
a longitudinal acceleration sensor (G sensor) is used and a controller of the HAC system is configured to detect and recognize a hill having a designated gradient or more using an acceleration value sensed by the longitudinal acceleration sensor
Data Source
AI summary
A hill start assist control (HAC) method and system for vehicles is provided to prevent malfunction and sensitive operation of an HAC function, generated due to misrecognition of a flat road as a hill when the vehicle is accelerated after braking on the flat road, caused by use of a value sensed by an acceleration sensor in determination of a hill. For this purpose, a corrected gradient, in which a tilt of the vehicle in the pitch direction is reflected in a gradient acquired from the value sensed by the acceleration sensor, is used as an actual road gradient value.