System and method for synchronizing motion of multiple vehicles in an independent cart system

Patent metadata

Field	Value
Publication number	US-11829158-B2
Application number	US-202117411791-A
Country	US
Kind code	B2
Filing date	Aug 25, 2021
Priority date	Aug 25, 2021
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

Synchronization of multiple vehicles in an independent cart system to reduce spacing and increase throughput designates one of the movers as a leader and at least one additional mover as a follower, defining a chain of vehicles. A motion command for the chain is provided to a controller for the leader, and the controller generates a motion profile. The controller passes this motion profile to a controller for each of the follower movers. If the follower is unable to maintain the motion profile for the leader, the controller for the follower generates a message to the controller for the leader indicating a modification to the motion profile is required. The controller for the leader modifies the motion profile and forwards the modified motion profile to controllers for each follower. If all movers are following the modified profile, the controller for the leader may return to the original motion profile.

First claim

We claim:

1. A system for synchronizing motion of multiple movers in an independent cart system, the independent cart system including a track and a plurality of movers configured to travel along the track, wherein the track includes a plurality of track segments, the system comprising:
a first mover for leading a chain of movers, wherein the first mover is selected from the plurality of movers in the independent cart system;
at least one additional mover, wherein:
the at least one additional mover is selected from the plurality of movers in the independent cart system, and
the first mover and each of the at least one additional movers are included within the chain of movers;

a first segment controller, wherein the first segment controller is located in a first track segment, selected from the plurality of track segments, and the first segment controller is configured to control operation of the first mover while the first mover is present on the first track segment; and
at least one additional segment controller, wherein the at least one additional segment controller is located in an additional track segment, selected from the plurality of track segments, and the at least one additional segment controller is configured to control operation of the at least one additional mover while the at least one additional mover is present on the additional track segment, wherein:
the first segment controller is configured to obtain a desired motion profile for the first mover,
the first segment controller is configured to transmit the desired motion profile to the at least one additional segment controller,
the at least one additional segment controller is configured to detect that the at least one additional mover is unable to follow the desired motion profile,
the at least one additional segment controller is configured to determine a desired hold back for the at least one additional mover, wherein the hold back is a value to modify the desired motion profile to a modified motion profile such that the at least one additional mover is able to follow the modified motion profile,
the at least one additional segment controller is configured to transmit the desired hold back to the first segment controller, and
the first segment controller is configured to modify the desired motion profile for the first mover to the modified motion profile as a function of the desired hold back received from the at least one additional segment controller.

2. The system of claim 1 wherein:
the at least one additional mover includes a plurality of additional movers,
the at least one additional segment controller includes a plurality of additional segment controllers,
the first segment controller is configured to transmit the desired motion profile to each of the plurality of additional segment controllers,
each of the plurality of additional segment controllers is configured to transmit the desired hold back determined in the corresponding controller to the first segment controller, and
the first segment controller is configured to modify the desired motion profile as a function of the desired hold back having a largest amplitude.

3. The system of claim 1 wherein:
the at least one additional mover includes a plurality of additional movers,
the at least one additional segment controller includes a plurality of additional segment controllers,
the first segment controller is configured to transmit the desired motion profile to one of the plurality of additional segment controllers located adjacent to the first controller,
the additional segment controller located adjacent to the first segment controller is configured to determine a new desired motion profile as a function of the desired motion profile and of a desired following distance,
the additional segment controller located adjacent to the first segment controller is configured to transmit the new desired motion profile to another additional segment controller located one hop away, and
each of the additional segment controllers are configured to determine another new desired motion profile as a function of the new desired motion profile from the additional segment controller immediately adjacent and of the desired following distance.

4. The system of claim 3 wherein each of the additional segment controllers is further configured to determine a desired hold back as a function of the new desired motion profile for the corresponding additional segment controller and to transmit the desired hold back to the first segment controller via each additional segment controller located between the corresponding additional segment controller and the first segment controller.

5. The system of claim 1 further comprising a synchronization controller configured to determine the first mover and the at least one additional mover to define the chain of movers and to transmit a motion command to the first segment controller for the first mover.

6. The system of claim 5 wherein the first segment controller is configured to obtain the desired motion profile as a function of the motion command.

7. The system of claim 5 wherein the motion command transmitted from the synchronization controller to the first segment controller is the desired motion profile.

8. The system of claim 1 wherein the at least one additional segment controller is further configured to;
determine a following error as a function of a present position and the desired motion profile for the at least one additional mover, and
determine the desired hold back as a function of the following error.

9. The system of claim 1 wherein the first mover and the at least one additional mover are located on one track segment and the first segment controller and the at least one additional segment controller are the same controller.

10. The system of claim 1 wherein:
the independent cart system includes a first track and a second track,
the second track is oriented parallel to the first track,
the first mover and the first segment controller are located on the first track, and
the at least one additional mover and the at least one additional segment controller are located on the second track.

11. A method for synchronizing motion of multiple movers in an independent cart system, the independent cart system including a track and a plurality of movers configured to travel along the track, wherein the track includes a plurality of track segments, the method comprising the steps of:
obtaining a desired motion profile for a first mover with a first segment controller, wherein the first segment controller is located in a first track segment, selected from the plurality of track segments;
transmitting the desired motion profile from the first controller to at least one additional segment controller, wherein:
the at least one additional segment controller is located in an additional track segment, selected from the plurality of track segments,
the at least one additional track segment has at least one additional mover located on the at least one additional track segment, and
the first mover and the at least one additional mover are configured to travel along the track as a chain of movers;

detecting with the at least one additional segment controller that the at least one additional mover is unable to follow the desired motion profile,
determining a desired hold back for the at least one additional mover with the at least one additional segment controller, wherein the hold back is a value to modify the desired motion profile to a modified motion profile such that the at least one additional mover is able to follow the modified motion profile;
transmitting the hold back from the at least one additiona

Assignees

• Rockwell Automation Tech Inc

Inventors

• Huang Yuhong
• Clark Tracy M
• Young Jason A
• Bentley Neil R
• Mendenhall Jesse R

Classifications

• G05D1/0295

  by at least one leading vehicle of the fleet · CPC title

• G05D1/0276

  using signals provided by a source external to the vehicle (involving a plurality of vehicles G05D1/0287; automatically controlling vehicle speed responsive to externally generated signals B60K31/0058) · CPC title

• G05D1/0223

  involving speed control of the vehicle (vehicle fittings for automatically controlling, i.e. preventing speed from exceeding an arbitrarily established velocity or maintaining speed at a particular velocity, as selected by the vehicle operator B60K31/00) · CPC title

• G05D1/0293 Primary

  Convoy travelling · CPC title

• G05B19/4189 Primary

  characterised by the transport system · CPC title