Downhill Cruise Control Brake Exit Logic for Stable Headway

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Maintaining a stable headway distance between a host vehicle and a lead vehicle while traveling downhill is challenging due to gravitational forces and the need for simultaneous control of propulsion and braking systems, leading to oscillatory control and driver discomfort.

Innovation Solution

A cruise control system that determines axle torque commands based on road grade and compares them with thresholds to adjust braking and propulsion, using sensors and a controller to maintain a predetermined headway distance and minimize oscillatory control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If braking is applied to maintain headway distance on downhill, then collision risk is reduced, but oscillatory control and driver discomfort occur

Engineering Contradiction:

Improveheadway distance maintenanceVSAvoiddriver comfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system determines in advance whether the host vehicle is traveling downhill using sensors (accelerometer, GPS, or road grade sensor) before oscillatory braking occurs. By identifying the downhill condition proactively, the system can prepare the brake exit threshold logic to prevent unnecessary braking cycles, thereby maintaining headway distance while avoiding oscillatory control and driver discomfort.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the axle torque command and compares it with a brake exit threshold. When the axle torque command falls below the threshold and headway distance exceeds a headway exit threshold, the system terminates braking. This feedback mechanism prevents oscillatory braking by intelligently determining when braking should be maintained versus when it should be released, improving both headway maintenance reliability and driver comfort.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If two actuators (propulsion and braking) are used to maintain headway distance downhill, then headway control precision is improved, but system complexity increases

Engineering Contradiction:

Improveheadway distance control precisionVSAvoidcontrol system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and isolates the downhill travel condition as a distinct operational mode. By using sensors to detect downhill conditions and triggering specific logic (determining axle torque command, comparing with brake exit threshold, determining when to terminate braking), the system simplifies the control architecture. Instead of continuously coordinating two actuators in all conditions, the system applies simplified downhill-specific logic that maintains precision while reducing overall system complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

3Stability of the object's composition

If braking is continuously applied to counteract gravitational acceleration, then headway distance stability is improved, but energy consumption increases

Engineering Contradiction:

Improveheadway distance stabilityVSAvoidbraking energy consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

Instead of continuously applying braking to counteract gravitational acceleration, the system applies braking only partially—specifically, when the axle torque command exceeds the brake exit threshold and headway distance is below the headway exit threshold. This partial action approach maintains headway stability during critical moments while avoiding excessive energy consumption from continuous braking, achieving a balance between stability and energy efficiency.

Inventive Principle:

Principle #16Partial or excessive action

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

The system effectively maintains a stable headway distance, reducing the risk of collision and driver discomfort by optimizing braking and propulsion control during downhill travel.

Implementation Method 1

determining an axle torque command to maintain a predetermined headway distance from the host vehicle to a lead vehicle... determining that a brake of the host vehicle is actuated to provide the axle torque command

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

the gravitational forces cause the host vehicle 10 to accelerate toward the lead vehicle

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentUS20250276690A1System and method for downhill headway control for cruise control

Publication Date: 2025.09.04 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A cruise control method includes determining that a host vehicle is traveling downhill and determining an axle torque command to maintain a predetermined headway distance from the host vehicle to a lead vehicle while the host vehicle is traveling downhill. The method further includes determining that a brake of the host vehicle is actuated to provide the axle torque command previously determined and comparing the axle torque command with a brake exit threshold to determine whether the axle torque command is greater than the brake exit threshold. Further, the method includes comparing the headway distance between the host vehicle and the lead vehicle with a headway exit threshold to determine whether the headway distance between the host vehicle and the lead vehicle is greater than the headway exit threshold. Also, the method includes commanding the brake of the host vehicle to disengage to terminate braking.