Automatic guided vehicle system and method

Abstract

An apparatus and method for guiding an automatic guided vehicle along a magnetic pathway and more specifically to an apparatus and a method capable of accurately and precisely following a weak magnetic field emitted by a substantially continuous passive magnetic marker having route junctions.

Description

TECHNICAL FIELD[0001]The present invention is directed to an apparatus and method for guiding an automatic guided vehicle (AGV) along a magnetic pathway and more specifically to an apparatus and a method capable of accurately and precisely following a weak magnetic field emitted by a substantially continuous passive magnetic marker having route junctions.BACKGROUND OF THE INVENTION[0002]AGVs having automated guidance systems and thereby capable of operating without a human operator are increasingly common in industrial facilities. AGVs are used for a variety of tasks and functions, of which the most common function is to transport material along predetermined routes. To ensure precise and accurate guidance, AGVs use many guidance methods, including dead reckoning, electrified guide wires, optical systems, inertial guidance systems, magnetic markers, as well as a variety of other systems. Each of these systems has a variety of drawbacks, typically related to system cost and complexit...

AI Technical Summary

Benefits of technology

[0011]The present invention is directed to an apparatus and method for guiding an AGV along a magnetic pathway and more specifically to an apparatus and a me

Problems solved by technology

Each of these systems has a variety of drawbacks, typically related to system cost and complexity.

The largest components of the system costs are the initial installation costs and the cost of each AGV.

Issues related to the complexity of the system typically include limited guide path revision flexibility, high costs associated with any guide path revisions, complex and heavy processor use during operation, and for some systems, limited operational accuracy.

However, the initial installation costs of these electrified guide wire systems within the facility in which the AGVs operate are extremely high in comparison to other guidance systems and an electrified guide wire system has extremely limited guide path revision flexibility and high costs associated with any such revisions to the guide paths.

More specifically, any change in a route the AGV follows requires tearing up the floor of the facility, removing existing electrified guide path wires and replacing them with rerouted guide path wires, all resulting in significant inconvenience or down time for the facility.

Optical guidance systems have made significant strides in improved accuracy, but typically require expensive sensors and controllers with substantial processing power to process the graphical images used in guidance of the AGV, which increases the cost and complexity of each AGV.

Inertial guidance systems, similar to optical guidance systems, have significantly improved their capabilities, however, inertial guidance systems using encoders and gyroscopes also typically require significant processing power.

As such, the guidance systems for these AGVs are generally expensive and complex in comparison to the guidance systems for AGVs that follow an electrified guide wire.

While optical and inertial guidance systems do not require tearing up the floor of a facility to make route changes, similar to most guidance systems, any route changes may require substantial time and costs for the system to learn the new route.

In optical and inertial guidance systems, at least one AGV typically must be taught the new route and in some systems, a new map of the facility must be created, which can be time consuming and require specialized expertise.

As such, the components on the AGV relating to the guidance system may have substantially greater costs and complexity than similar components on any AGV in an electrified guide wire system.

Due to the weaker magnetic field generated by these passive magnetic materials, some AGVs have experienced issues in accurately and precisely tracking the guide paths formed by the passive magnetic materials.

While the installation costs are much lower and route revisions are much cheaper than electrified guide wire systems, the weaker magnetic fields of these passive magnetic materials may limit the ability of traditional magnetic sensors on the AGV, previously used with electrified guide wires, to determine the precise location of the weaker magnetic signal, especially in facilities having strong background or ambient magnetic fields.

One problem with discrete magnetic markers is that the AGV must be presumed to be in alignment with the path defined by the discrete magnet markers.

During operation, if errors compound, such as a heading error increasing to a point where correction is not possible, the sensors on the AGV may be too far displaced from the next marker to obtain a valid reading of the

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