System and method of operating an automated storage and retrieval system

Abstract

An automated storage and retrieval system includes a rail system with a first set of parallel rails extending in a first direction and a second set of parallel rails extending in second direction. The second direction is perpendicular to the first direction. The system includes a plurality of container handling vehicles on the rail system operable to handle storage containers. Each container handling vehicle includes a positioning node and a local controller adapted to control movements of the container handling vehicle. The system includes a positioning system comprising at least three reference positioning nodes spaced in fixed positions on and/or proximate the rail system. The positioning system is adapted to determine a position on the rail system for each of the container handling vehicles based on signal measurements between the positioning node of each container handling vehicle and the at least three reference positioning nodes. A control system is adapted to communicate with each local controller in each container handling vehicle and the positioning system. The control system is adapted to: instruct a first container handling vehicle to move to a target position, repeatedly receive position data from the positioning system of a position of the first container handling vehicle and repeatedly receive position data from the positioning system of a position of a second container handling vehicle, and instruct the second container handling vehicle to move with and follow the first container handling vehicle within a predetermined separation from the first container handling vehicle based on the received position data of the positions of the first and second container handling vehicles.