US-20260126817-A1 - Article Transport Facility

US20260126817A1US 20260126817 A1US20260126817 A1US 20260126817A1US-20260126817-A1

Abstract

In an article transport facility, transport vehicles each include a speed detector that detects a current speed and a distance detector that detects an inter-vehicle distance index corresponding to a distance from another transport vehicle ahead in a travel direction. A control system performs a first target-speed determination process for determining a control target speed based on a distance-based target speed greater for a greater inter-vehicle distance index, the current speed, and the inter-vehicle distance index. The first target-speed determination process includes an acceleration determination process for determining whether to perform an acceleration process for setting the control target speed to the distance-based target speed higher than the current speed. In the acceleration determination process, the system performs the acceleration process when a relationship between the current speed and the distance-based target speed reaches a state satisfying an acceleration condition and the state continues for a determination duration or longer.

Inventors

Atsuhiko Mukai
Makoto Kono
Kazuhiro Iwamitsu

Assignees

DAIFUKU CO, LTD.

Dates

Publication Date: 20260507
Application Date: 20251104
Priority Date: 20241105

Claims (8)

1 . An article transport facility, comprising: a plurality of transport vehicles configured to travel along a travel path and transport articles; and a control system configured to control the plurality of transport vehicles, each of the plurality of transport vehicles comprising: a speed detector configured to detect a current speed that is a current travel speed of the transport vehicle, and a distance detector configured to detect an inter-vehicle distance index that is an index corresponding to a distance from a transport vehicle, among the plurality of transport vehicles, located ahead in a travel direction, wherein the control system is configured to perform a first target-speed determination process for determining, based on a distance-based target speed, the current speed, and the inter-vehicle distance index, a control target speed that is a target value in controlling the travel speed, where the distance-based target speed is a target value for the travel speed and is preset to be greater for a greater inter-vehicle distance index, wherein the first target-speed determination process comprises an acceleration determination process for determining whether to perform an acceleration process for setting the control target speed to the distance-based target speed higher than the current speed, and wherein in the acceleration determination process, the control system is configured to determine to perform the acceleration process in response to a relationship between the current speed and the distance-based target speed reaching an accelerable state satisfying a preset acceleration condition and the accelerable state continuing for a preset determination duration or longer.
2 . The article transport facility according to claim 1 , wherein: the acceleration determination process comprises determining whether to perform a speed maintaining process for setting the control target speed to the current speed, and in the acceleration determination process, the control system determines, in response to the accelerable state continuing for less than the determination duration, to perform the speed maintaining process without performing the acceleration process.
3 . The article transport facility according to claim 2 , wherein: in response to an increase in the inter-vehicle distance index per predefined time being less than or equal to a preset reference value, the control system performs the acceleration determination process with the acceleration condition in which the current speed is lower than the distance-based target speed by a difference greater than a preset determination threshold.
4 . The article transport facility according to claim 3 , wherein: in the acceleration determination process, the control system determines to perform, in response to the current speed being lower than the distance-based target speed by a difference less than or equal to the determination threshold, the speed maintaining process without performing the acceleration process.
5 . The article transport facility according to claim 3 , wherein: the first target-speed determination process further comprises a deceleration determination process for determining whether to perform a deceleration process for setting the control target speed to the distance-based target speed lower than the current speed, and in the deceleration determination process, the control system determines to perform the deceleration process in response to a relationship between the current speed and the distance-based target speed satisfying a preset deceleration condition.
6 . The article transport facility according to claim 5 , wherein: the control system further performs a second target-speed determination process for determining the control target speed in response to the increase in the inter-vehicle distance index per predefined time being greater than the reference value, and in the second target-speed determination process: for the control target speed being the distance-based target speed, the control system maintains the control target speed at the distance-based target speed, in response to the current speed being higher than the distance-based target speed during the speed maintaining process, the control system determines to perform the deceleration process, and in response to the current speed being lower than the distance-based target speed during the speed maintaining process, the control system performs the acceleration determination process with the acceleration condition in which the current speed is lower than the distance-based target speed.
7 . The article transport facility according to claim 4 , wherein: the first target-speed determination process further comprises a deceleration determination process for determining whether to perform a deceleration process for setting the control target speed to the distance-based target speed lower than the current speed, and in the deceleration determination process, the control system determines to perform the deceleration process in response to a relationship between the current speed and the distance-based target speed satisfying a preset deceleration condition.
8 . The article transport facility according to claim 7 , wherein: the control system further performs a second target-speed determination process for determining the control target speed in response to the increase in the inter-vehicle distance index per predefined time being greater than the reference value, and in the second target-speed determination process: for the control target speed being the distance-based target speed, the control system maintains the control target speed at the distance-based target speed, in response to the current speed being higher than the distance-based target speed during the speed maintaining process, the control system determines to perform the deceleration process, and in response to the current speed being lower than the distance-based target speed during the speed maintaining process, the control system performs the acceleration determination process with the acceleration condition in which the current speed is lower than the distance-based target speed.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Japanese Patent Application No. 2024-193891 filed Nov. 5, 2024, the disclosure of which is hereby incorporated by reference in its entirety. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an article transport facility including multiple transport vehicles that travel along a travel path and transport articles, and a control system that controls the multiple transport vehicles. Description of Related Art An example of such an article transport facility is described in Japanese Unexamined Patent Application Publication No. 3-6603 (hereafter referred to as JP 3-6603). The article transport facility in JP 3-6603 includes multiple transport vehicles each including a distance detector that detects a distance from a transport vehicle located ahead in a travel direction (inter-vehicle distance). The control system calculates an amount of change in the inter-vehicle distance (distance change amount) per unit time based on the inter-vehicle distance detected by the distance detector, and calculates the difference between a preset appropriate distance and the inter-vehicle distance (distance difference). The control system then increases or decreases the acceleration of each transport vehicle based on the distance change amount and the distance difference. The article transport facility in JP 3-6603 thus causes the transport vehicles to travel while changing their accelerations to maintain appropriate inter-vehicle distances. However, when the article transport facility in JP 3-6603 controls a transport vehicle to accelerate by increasing the acceleration in response to, for example, an increase in the inter-vehicle distance, the acceleration can be ineffective in some situations of the travel path for the transport vehicle, such as congestion in an area ahead of the transport vehicle in the travel direction. The transport vehicle may then consume extra energy. To reduce energy consumption, the acceleration frequency of the transport vehicles may be reduced. However, reducing the acceleration frequency can lower article transport efficiency of the transport vehicles. SUMMARY OF THE INVENTION Article transport facilities to be developed include transport vehicles with easily reduced energy consumption and with less likelihood of lower article transport efficiency. In response to this, an article transport facility includes a plurality of transport vehicles that travel along a travel path and transport articles, and a control system that controls the plurality of transport vehicles. Each of the plurality of transport vehicles includes a speed detector that detects a current speed that is a current travel speed of the transport vehicle, and a distance detector that detects an inter-vehicle distance index that is an index corresponding to a distance from a transport vehicle, among the plurality of transport vehicles, located ahead in a travel direction. The control system performs a first target-speed determination process for determining, based on a distance-based target speed, the current speed, and the inter-vehicle distance index, a control target speed that is a target value in controlling the travel speed. The distance-based target speed is a target value for the travel speed and is preset to be greater for a greater inter-vehicle distance index. The first target-speed determination process includes an acceleration determination process for determining whether to perform an acceleration process for setting the control target speed to the distance-based target speed higher than the current speed. In the acceleration determination process, the control system determines to perform the acceleration process in response to a relationship between the current speed and the distance-based target speed reaching an accelerable state satisfying a preset acceleration condition and the accelerable state continuing for a preset determination duration or longer. In this structure, the acceleration process is not performed unless the accelerable state continues for the preset determination duration or longer in the acceleration determination process after the relationship between the current speed and the distance-based target speed reaches the accelerable state satisfying the preset acceleration condition. This reduces ineffective acceleration of the transport vehicles and allows the transport vehicles to travel efficiently. The structure can thus include transport vehicles with easily reduced energy consumption and with less likelihood of lower article transport efficiency. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an article transport facility according to an embodiment, showing its entire structure. FIG. 2 is a side view of transport vehicles included in the article transport facility according to the embodiment. FIG. 3 is a block diagram of the article transport facility according to the embod