Rail vehicle (2) for moving in two perpendicular horizontal directions on a rail system (108), the rail system comprising a first set of parallel rails (110) in a first direction (X) and a second set of parallel rails (111) in a second direction (Y) being perpendicular to the first direction (X), the rail vehicle comprising a vehicle frame (3); rail engaging supports (4); and a plurality of wheel modules (5) configured to move the vehicle on the rail system; wherein each wheel module (5) comprises a wheel (6) with a horizontal axis of rotation, the wheel module allowing the wheel to pivot 90 degrees around a vertical axis such that the rotational direction of the wheel may be switched between the first direction (X) and the second direction (Y); the wheel modules (5) and the rail engaging supports (4) are vertically moveable relative to each other between a first position and a second position so to engage and disengage the wheels from the rails.

An automated overhead follower (AOF) system for a picking process includes an overhead rail, a motorized trolley configured to engage the rail and translate along its longitudinal axis in response to position control signals, a light projector connected to the trolley that emits a light beam in response to lighting control signals, and a radio frequency (RF) transmitter connectable to a tray. An electronic control unit (ECU) receives three-dimensional (3D) position signals from the transmitter as the tray moves along a bin aisle, identifies a bin zone in the aisle using the 3D position signals, and transmits the position control signals to a motor to command the trolley to move to the identified bin zone. The ECU also transmits the lighting control signals to the projector to illuminate one of more bins in the identified bin zone.

An automated overhead follower (AOF) system for a picking process includes an overhead rail, a motorized trolley configured to engage the rail and translate along its longitudinal axis in response to position control signals, a light projector connected to the trolley that emits a light beam in response to lighting control signals, and a radio frequency (RF) transmitter connectable to a tray. An electronic control unit (ECU) receives three-dimensional (3D) position signals from the transmitter as the tray moves along a bin aisle, identifies a bin zone in the aisle using the 3D position signals, and transmits the position control signals to a motor to command the trolley to move to the identified bin zone. The ECU also transmits the lighting control signals to the projector to illuminate one of more bins in the identified bin zone.

A service vehicle operates on a rail system of a storage and retrieval grid. The service vehicle is configured for retrieving a remotely operated vehicle for service. The service vehicle includes a first vehicle area in which the remotely operated vehicle can be received by the service vehicle while the remotely operated vehicle is still on the rail system, and a second vehicle area in which the remotely operated vehicle can be supported by the service vehicle for servicing. The first vehicle area is configured as a vehicle pen for holding the remotely operated vehicle before entry to the second vehicle area. The first vehicle area is linked to the second vehicle area for passage of the remotely operated vehicle via the vehicle pen. The vehicle pen includes an entry barrier to regulate entry of the remotely operated vehicle into the service vehicle and the vehicle pen, and an exit barrier on exit from the vehicle pen into the second vehicle area to regulate the passage of the remotely operated vehicle through the first vehicle area and into the second vehicle area.

A service vehicle operates on a rail system of a storage and retrieval grid. The service vehicle is configured for retrieving a remotely operated vehicle for service. The service vehicle includes a first vehicle area in which the remotely operated vehicle can be received by the service vehicle while the remotely operated vehicle is still on the rail system, and a second vehicle area in which the remotely operated vehicle can be supported by the service vehicle for servicing. The first vehicle area is configured as a vehicle pen for holding the remotely operated vehicle before entry to the second vehicle area. The first vehicle area is linked to the second vehicle area for passage of the remotely operated vehicle via the vehicle pen. The vehicle pen includes an entry barrier to regulate entry of the remotely operated vehicle into the service vehicle and the vehicle pen, and an exit barrier on exit from the vehicle pen into the second vehicle area to regulate the passage of the remotely operated vehicle through the first vehicle area and into the second vehicle area.