Omnidirectional Wheel Vehicle Conveyor Transition Control

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Solution Overview

Problem

Existing omnidirectional wheel vehicles face challenges in precisely navigating and driving onto and off moving conveyor systems without deviating from planned paths, especially when the vehicle's size exceeds the conveyor width or when wheels encounter relative movement, leading to potential dragging or slipping issues.

Innovation Solution

A method involving an omnidirectional wheel vehicle with a control device that coordinates the rotation and speed of at least four drivable wheels to transition smoothly between surfaces, ensuring at least three wheels remain driven to maintain control, allowing the vehicle to adapt to differential speeds and orientations by detecting the rotational speed and direction of wheels on moving surfaces, thus enabling controlled movement on both stationary and moving surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the vehicle uses all four wheels driven on a moving conveyor surface, then the vehicle can maintain better control and stability, but the relative movement between wheels and conveyor causes dragging or slipping that deviates the vehicle from its planned path

Engineering Contradiction:
Improvevehicle control stabilityVSAvoidpath following accuracy
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The vehicle's wheel drive system is segmented into independently controllable units. When transitioning to a moving conveyor surface, the control device selectively deactivates the drive for at least one wheel that is about to contact or is contacting the moving surface, while keeping other wheels driven. This segmentation allows the vehicle to adapt to differential surface speeds and prevent dragging or slipping on the conveyor.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If the vehicle deactivates drive for wheels on moving conveyor surfaces to prevent dragging, then path following accuracy improves, but the vehicle loses some control capability during surface transitions

Engineering Contradiction:
Improvepath following accuracyVSAvoidvehicle control stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The vehicle's drive system dynamically adjusts which wheels are powered based on real-time surface detection. The control device monitors when wheels transition between stationary and moving conveyor surfaces and dynamically switches the drive state of individual wheels accordingly. This dynamic adaptation maintains both path following accuracy on moving surfaces and control stability during transitions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control device implements feedback by detecting the rotational speed and direction of wheels that are freely rotating on the moving conveyor surface. This feedback information is used to adjust the drive control of remaining driven wheels, ensuring the vehicle maintains its planned path while compensating for the loss of drive on the conveyor-contacting wheels.

Inventive Principle:
Principle #23Feedback

3Reliability

If the vehicle maintains driven control of all wheels during surface transitions, then control stability is maintained, but the vehicle cannot adapt to differential speeds between stationary and moving surfaces

Engineering Contradiction:
Improvecontrol stabilityVSAvoidsurface speed adaptation
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The vehicle adapts to differential surface speeds by changing the operational parameters of its wheel drive system. The control device modifies the drive state (activated/deactivated) of individual wheels based on the detected surface movement. When a wheel contacts a moving conveyor surface, its drive parameter is changed to deactivated/free-rotation mode, allowing the wheel to rotate at the conveyor's speed without resistance, while other wheels on stationary surfaces maintain their driven state.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If the vehicle uses free rotation for wheels on moving conveyor surfaces, then adaptation to conveyor speed is achieved, but the vehicle loses direct control over those wheels

Engineering Contradiction:
Improveconveyor surface adaptationVSAvoidwheel control precision
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The control device acts as an intermediary that manages the transition between controlled and free-rotation states. It detects when wheels should be switched to free rotation based on surface movement detection, and uses feedback from the freely rotating wheels' motion to indirectly control the vehicle's overall trajectory. This intermediary control mechanism maintains vehicle-level path following accuracy even though individual wheel-level direct control is relaxed.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3841445B1Method for operating an omnidirectional wheel vehicle, omnidirectional wheel vehicle, and computer program product
Publication Date: 2022.07.06 KUKA DEUT GMBH
  • EP3841445B1 patent drawingFigure 1~6
  • EP3841445B1 patent drawingFigure 7~12

AI summary

The invention relates to a method for operating an omnidirectional wheel vehicle (1) which has a vehicle body (2), on which at least four drivable omnidirectional wheels (4) are rotatably mounted, wherein each of the at least four wheels (4) is designed for advancing the omnidirectional wheel vehicle (1) on an underlying surface (5.1, 5.2, 5.3) and is controlled individually in its directions of rotation and rotational speeds by a control device (3). The invention also relates to a corresponding omnidirectional wheel vehicle (1) and to an associated computer program product.