Multi-Trailer Stability Detection Using Tractor-Based Motion Estimation

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Solution Overview

Problem

Combination vehicles with multiple trailers face instability issues such as rolling over and jack-knifing, which are challenging for both manual and autonomous operations, and existing stability management systems are inadequate.

Innovation Solution

A computer system estimates the motion of trailers relative to the tractor using vehicle condition signals and relative positions, employing statistical models to predict trailer motion and determine vehicle instability without requiring sensors on each trailer, allowing for preventive actions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sensors are placed on each trailer to directly measure trailer motion, then measurement precision of trailer motion is improved, but device complexity and cost increase significantly

Engineering Contradiction:
Improvetrailer motion measurementVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a virtual model (copy) of the trailer motion system that replicates the physical behavior of trailers. Instead of measuring actual trailer motion directly with sensors on each trailer, the system creates a statistical model that copies trailer motion characteristics based on tractor motion data and relative position measurements, thereby achieving accurate motion estimation without complex sensor deployment on trailers.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical sensor measurement system with a computational estimation system. Instead of using physical sensors mounted on trailers to mechanically detect motion, the system uses processing circuitry to calculate trailer motion based on tractor motion signals and relative position data, substituting physical measurement with mathematical modeling.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If external sensors are placed on each trailer to measure motion, then reliability of stability determination is improved, but ease of operation and communication requirements worsen due to limited trailer communication capabilities

Engineering Contradiction:
Improvestability determinationVSAvoidsensor deployment and communication
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent extracts the measurement requirements from the trailers themselves and concentrates them on the tractor. Instead of requiring sensors on each trailer, the system extracts sufficient information from tractor motion signals and single-point relative position measurements to infer the motion state of all trailers, thereby eliminating the need for complex trailer-side sensing and communication infrastructure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent makes the tractor's motion sensors serve multiple functions: they not only control the tractor but also provide data for estimating the motion of all attached trailers. The single relative position measurement system serves both for positioning and for stability assessment, demonstrating multi-functionality that reduces overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Device complexity

If statistical models are used to estimate trailer motion from tractor motion signals, then device complexity is reduced, but measurement precision of trailer motion may worsen

Engineering Contradiction:
Improvesensor system complexityVSAvoidtrailer motion estimation
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-calibrating the statistical model with training data that captures the relationship between tractor motion and trailer motion under various conditions. The model is trained in advance on datasets containing synchronized tractor and trailer motion signals, enabling it to accurately predict trailer motion from tractor signals alone during actual operation, thereby maintaining precision without requiring complex real-time measurement systems.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4534369B1Determining stability of a vehicle based on a motion of trailers attached to the vehicle
Publication Date: 2026.03.11 VOLVO TRUCK CORP
  • EP4534369B1 patent drawingFigure 1~2
  • EP4534369B1 patent drawingFigure 3~4
  • EP4534369B1 patent drawingFigure 5~6

AI summary

A computer system (1000) comprising processing circuitry (1002) configured to determine whether a combination vehicle (1) is unstable is provided. The combination vehicle (1) comprises a tractor (10) and a plurality of trailers (12). The plurality of trailers (12) comprises a first trailer (11). The processing circuitry (1002) is configured to obtain vehicle condition signals indicative of a status of the combination vehicle (1). The processing circuitry (1002) is configured to obtain relative positions of the first trailer (11), relative to the tractor (10). The processing circuitry (1002) is configured to, estimate a motion (m1, m2) of the plurality of trailers (12). based on the relative positions of the first trailer (11) and the status of the combination vehicle (1).The processing circuitry (1002) is configured to, determine whether or not the combination vehicle (1) is unstable based on the estimated motion (m1, m2) of the plurality of trailers (12).