Virtual slots for independent cart system

A system of coordinating traffic flow in an independent cart system, the system comprising:

• a track including at least a first portion, a second portion, and a third portion, wherein a plurality of coils are spaced along each of the first, second, and third portions of the track as part of a linear drive system for the independent cart system;
• a plurality of movers operative to travel along the track, wherein each of the plurality of movers include at least one drive magnet mounted to the mover as part of the linear drive system for the independent cart system;
• a plurality of virtual slots defined along the first portion of the track, wherein each of the plurality of virtual slots:
• defines a space along the first portion of the track,
• has a first spacing defined between adjacent virtual slots,
• are controlled to move synchronously along the first portion of the track, and
• selectively receives one of the plurality of movers from the second portion of the track;
• and
• a controller operative to:
• assign a first mover, selected from the plurality of movers, to a first virtual slot, selected from the plurality of virtual slots,
• command the first mover to enter the first portion of the track as the first virtual slot passes a connection with the second portion of the track, and
• command the first mover to exit the first portion of the track as the first virtual slot passes a connection with a third portion of the track.

A method of coordinating traffic flow in an independent cart system, the method comprising the steps of:

• defining a plurality of virtual slots along a length of a track for the independent cart system, wherein:
• the track includes a plurality of track segments,
• each track segment includes a plurality of coils spaced along the track segment and a segment controller to regulate current in the plurality of coils, and
• the plurality of coils are a first portion of a linear drive system for the independent cart system;
• controlling each of the plurality of virtual slots to travel along the length of the track, wherein:
• the plurality of virtual slots are spaced apart at a first distance, and
• the plurality of virtual slots are controlled to travel synchronously at a desired speed;
• and
• controlling operation of a plurality of movers to travel along the track, wherein:
• each of the plurality of movers includes at least one drive magnet,
• the at least one drive magnet is a second portion of the linear drive system,
• an electromagnetic field sequentially generated by the plurality of coils interacts with a magnetic field generated by the at least one drive magnet on each mover to propel the corresponding mover along the track,
• each of the plurality of movers is controlled to travel within one of the plurality of virtual slots at the desired speed, and
• each of the plurality of movers has a minimum stopping distance greater than the first distance when travelling at the desired speed.