Tugger Train Stability Control for Jack-Knife Prevention

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Solution Overview

Problem

Existing tugger trains lack systems that ensure high stability during a wide range of operations, particularly when trailers are not equipped with braking systems, leading to instability issues such as the 'jack-knife' phenomenon during braking, steering, and driving downhill.

Innovation Solution

A tugger train system equipped with a control unit that utilizes sensors for speed, steering angle, and load weight, along with an inclination sensor, to impose speed and steering limitations to maintain stability, preventing the 'jack-knife' phenomenon by calculating an instability curve and activating opposing torque or braking systems as needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If trailers are not equipped with braking systems, then device complexity is reduced, but stability of the tugger train deteriorates during braking and steering operations

Engineering Contradiction:
Improvebraking system complexityVSAvoidtugger train stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The control unit acts as an intermediary between the towing tractor's braking system and the trailers, coordinating their braking actions through electronic control to achieve stable stopping without requiring independent trailer braking systems

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback from sensors monitoring the tugger train's operational state to dynamically adjust braking force distribution between the towing tractor and trailers, maintaining stability during braking operations

Inventive Principle:
Principle #23Feedback

2Loss of time

If the towing tractor applies strong braking force, then stopping distance is reduced, but the jack-knife phenomenon occurs causing loss of stability

Engineering Contradiction:
Improvebraking distanceVSAvoidtugger train stability
Core Design Contradiction:
Loss of timeVSStability of the object's composition

Solution Approach 1:

The braking force distribution is dynamically adjusted based on real-time monitoring of the tugger train's operational state, articulation angle, and load conditions, allowing optimal braking performance while preventing jack-knife phenomenon

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system applies partial braking force to the towing tractor while coordinating with trailer braking to achieve effective stopping without excessive force that would cause instability or jack-knife phenomenon

Inventive Principle:
Principle #16Partial or excessive action

3Ease of operation

If steering angle is increased to improve maneuverability, then ease of operation is improved, but stability control becomes difficult especially during braking

Engineering Contradiction:
Improvesteering maneuverabilityVSAvoidtugger train stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The control unit preliminarily adjusts braking force distribution before the towing tractor completes its steering maneuver, ensuring stability is maintained throughout the steering process by coordinating brake application with steering angle changes

Inventive Principle:
Principle #10Preliminary action

4Productivity

If speed is increased to improve productivity, then productivity is improved, but stability control becomes difficult especially when braking, steering, or driving downhill

Engineering Contradiction:
Improvetransport speedVSAvoidtugger train stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The system continuously monitors the tugger train's speed, articulation angle, and operational state, using feedback to dynamically adjust braking force distribution and maintain stability during high-speed operations, braking, and downhill driving

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4197866B1Stability control of a tugger train
Publication Date: 2025.07.16 TOYOTA MATERIAL HANDLING MFG ITAL SPA
  • EP4197866B1 patent drawingFigure 1
  • EP4197866B1 patent drawingFigure 2
  • EP4197866B1 patent drawingFigure 3

AI summary

A tugger train (10) comprising a towing tractor (11) and a plurality of trailers (12) connected to the towing tractor (11) in an articulated manner for carrying loads, including: -a speed sensor (21) for detecting a speed of the towing tractor, -a steering angle sensor (22) for detecting a steering angle of the towing tractor, -acquiring means (24, 25) for acquiring information relating to a weight carried by one or more of the plurality of trailers, and -a control unit (40) configured to perform a stability control by imposing a limitation to the speed of the towing tractor (11) based on an analysis of the speed of the towing tractor detected by the speed sensor (21), the steering angle of the towing tractor detected by the steering angle sensor (22) and the information relating to a weight acquired by the acquiring means (24, 25).