Vehicle Drawn Down State Detection Using Indirect Acceleration

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Solution Overview

Problem

Existing vehicle drawn down state detection devices are inaccurate due to variations in braking force with payload and fail to detect the vehicle's standstill state, particularly when wheel speed pulses are input at varying intervals on uphill gradients, leading to potential vehicle rollaways.

Innovation Solution

A vehicle drawn down state detection device that calculates indirect longitudinal acceleration from vehicle speed changes and determines a no-driving-force state based on uphill travel and engine, clutch, or transmission conditions, avoiding erroneous detection by checking polarity changes in direct longitudinal acceleration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If braking force relationship is used to detect drawn down state, then the detection can be performed, but the detection accuracy deteriorates because braking force varies with payload

Engineering Contradiction:

Improvedrawn down state detection reliabilityVSAvoiddrawn down state detection precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the detection parameter from braking force (which varies with payload) to longitudinal acceleration (which remains consistent regardless of payload). By calculating longitudinal acceleration from vehicle speed changes and comparing it against threshold values, the system achieves accurate drawn down state detection that is independent of payload variations.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If wheel speed pulse is used to detect standstill, then the detection can be performed, but the detection accuracy deteriorates when pulses are input at varying intervals on uphill

Engineering Contradiction:

Improvestandstill detection reliabilityVSAvoidstandstill detection precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the detection parameter from wheel speed pulse intervals (which vary on uphill gradients) to longitudinal acceleration (which provides a consistent indication of vehicle motion state). By using longitudinal acceleration thresholds, the system can accurately determine standstill and drawn down states regardless of wheel speed pulse variations.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If indirect longitudinal acceleration calculation is used, then the detection becomes independent of payload, but the device complexity increases

Engineering Contradiction:

Improvedrawn down state detection precisionVSAvoiddetection device complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical braking force measurement systems with a computational approach using existing vehicle speed sensors. By calculating longitudinal acceleration from speed changes and applying threshold comparisons, the system achieves accurate detection without additional complex hardware, thus reducing overall device complexity while maintaining high precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Accurately detects the vehicle drawn down state, preventing rollaways by restarting the engine or increasing braking force during idle stop or hill hold control, independent of payload and ensuring precise vehicle control.

Implementation Method 1

a vehicle speed detection means for detecting the speed of the vehicle

Methodology Applied

Scientific EffectSpeed detection:

Implementation Method 2

calculating the longitudinal acceleration, which is an acceleration in a longitudinal direction of the vehicle, from change in the speed of the vehicle

Methodology Applied

Scientific EffectAcceleration calculation from speed change:

Data Source

PatentUS9283962B2Vehicle drawn down state detection device and vehicle control device including same

Publication Date: 2016.03.15 ADVICS CO LTD

AI summary

An indirect longitudinal acceleration calculation section indirectly calculates longitudinal acceleration by calculating the longitudinal acceleration, which is an acceleration in a longitudinal direction of the vehicle, from change in the speed of the vehicle detected by a vehicle speed detection section. When an uphill travel detection section detects an uphill traveling state in which the vehicle is traveling on an uphill and a drive state determination section detects a no-driving-force state in which a vehicle driving force is not generated, a vehicle drawn down state detection section detects that the longitudinal acceleration indirectly calculated by the indirect longitudinal acceleration calculation section is oriented in an accelerating direction, and determines that the vehicle is in a drawn down state.