System and method of operating an automated storage and retrieval system
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.
1. An automated storage and retrieval system comprising:
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, wherein the second direction is perpendicular to the first direction;
a plurality of container handling vehicles on the rail system operable to handle storage containers, each container handling vehicle comprising:
a positioning node, and
a local controller adapted to control movements of the container handling vehicle;
a positioning system comprising at least three reference positioning nodes spaced in fixed positions on and/or proximate the rail system, the positioning system being 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; and
a control system adapted to communicate with each local controller in each container handling vehicle and the positioning system, the control system being 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.
2. The system of claim 1 , wherein to instruct the second container handling vehicle to move with and follow the first container handling vehicle comprises instructing the second container handling vehicle to accelerate or decelerate until the second container handling vehicle is at the 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.
3. The system of claim 1 , wherein to instruct the second container handling vehicle to move with and follow the first container handling vehicle comprises instructing the second container handling vehicle to move at a set speed based on the received position data of the positions of the first and second container handling vehicles.
4. The system of claim 1 , wherein to instruct the second container handling vehicle to move with and follow the first container handling vehicle; comprises instructing the second container handling vehicle to move to a position that is at the predetermined separation from the position of the first container handling vehicle.
5. The system of claim 4 , wherein the position at the predetermined separation from the position of the first container handling vehicle that the second container handling vehicle is instructed to move to is a position at a predetermined separation from a future position of the first container handling vehicle determined based on a current speed and heading of the first container handling vehicle.
6. The system of claim 1 , wherein the signal measurements are time of flight measurements.
7. The system of claim 6 , wherein the time of flight measurements are time difference of arrival measurements.
8. The system of claim 1 , wherein the positioning node of each container handling vehicle and the at least three reference positioning nodes are Ultra-Wideband nodes.
9. A method for controlling movement of a plurality of container handling vehicles in the system according to claim 1 , wherein the method comprises:
instructing the first container handling vehicle to move to the target position,
repeatedly receiving the position data from the positioning system of a position of the first container handling vehicle and repeatedly receiving the position data from the positioning system of a position of the second container handling vehicle, and
instructing 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.
10. The method of claim 9 , wherein the instructing the second container handling vehicle to move with and follow the first container handling vehicle comprises instructing the second container handling vehicle to accelerate or decelerate until the second container handling vehicle is at the predetermined separation from the first container handling vehicle based on the received position data of the positions of the first and second container handling vehicle.
11. The method of claim 9 , wherein the instructing the second container handling vehicle to move with and follow the first container handling vehicle comprises instructing the second container handling vehicle to move at a set speed based on the received position data of the positions of the first and second container handling vehicles.
12. The method of claim 9 , further comprising determining the position of the first container handling vehicle and the position of the second container handling vehicle using time of flight measurements.
13. The method of claim 12 , wherein the measurements are time difference of arrival measurements.
14. The method of claim 9 , wherein the instructing the second container handling vehicle to move with and follow the first container handling vehicle; comprises instructing the second container handling vehicle to move to a position at the predetermined separation from the position of the first container handling vehicle.
15. The method of claim 14 , wherein the position at the predetermined separation from the position of the first container handling vehicle that the second container handling vehicle is instructed to move to is a position at a predetermined separation from a future position of the first container handling vehicle determined based on a current speed and heading of the first container handling vehicle.
16. A computer program product for a control system in an automated storage and retrieval system comprising:
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, wherein the second direction is perpendicular to the first direction;
a plurality of container handling vehicles on the rail system operable to handle storage containers, each container handling vehicle comprising:
a positioning node, and
a local controller adapted to control movements of the container handling vehicle;
a positioning system comprising at least three reference positioning nodes spaced in fixed positions on and/or proximate the rail system, the positioning system being 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; and
the control system adapted to communicate with each local controller in each container handling vehicle and the positioning system, wherein the computer program product comprises instructions which when executed on the control system performs the method comprising:
instructing the first container handling vehicle to move to the target position,
repeatedly receiving the position data from the positioning system of a position of the first container handling vehicle and repeatedly receiving the position data from the positioning system of a position of the second container handling vehicle, and
instructing 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.