Container Positioning using Precision RTG navigation

Enabling precise heading and positioning for cranes when GNSS is unavailable. The tracking systems we have sold probably track 35% (22m TEUs) of all UK Lo-Lo freight. We also sell to a major crane manufacturer who sells world-wide and has done for over 20 years. That is simply thousands of tracking systems for cranes.

• The crane is called an RTG which stands for Rubber Tyred Gantry crane. It looks like a large staple but it can dead-lift two 40 tonne containers with a considerable safety margin
• The container yard has a computerised load-out plan which tracks containers with cm precision from arrival on a truck, train or ship into the port The truck, train or ship also has a load-out plan which uploads to the port system on arrival. The RTG receives its work packages from the port-planning computer.
• An RTG weighs 80-140 tons when loaded with a couple of container and it can move at up to 20mph
• In the picture you can see a stack of containers to the right. To the left of that is a container and tug and to the left of the tug is the left-hand leg of the RTG as we’re looking at it.
• The RTG leg sits in a hatched yellow area running the length of the containers. This is a visual check to ensure the RTG is operating in it’s safe area.
• The right-hand side RTG leg is out of line of sight on the other side of the containers; but the area is visible by cameras in the driver’s cab. The driver’s cab is just above the level of the rooftop of the tug.
• On top of the RTG, pictured in a lateral location over the truck is the “dolly” which lifts and lowers containers. The dolly may move laterally so it can lift and lower any container it’s tasked to move
• On the dolly is a precision GNSS system <1cm (3DRMS). There is also a wire out counter to left and right and up and down to the containers. This is also accurate so that the correct container can be correctly located, picked, moved and released in a new location. It is far less likely today that a load-out incorrectly locates a container. However the input data relies on good data input at source. Large container ships get it right otherwise it’s tens of thousands of pounds per day just to sit on the jetty and then there’s the cost/lift and insurance claims from delayed ships/trucks/trains for the time lost while the badly located containers are re-located.
• Big problems occur if someone operates a GNSS jammer or spoofer in the port. It would be almost impossible to move anything and get it right.

Requirement

• A major UK port required a system that would provide the heading and precise positioning of a Rubber Tyre Gantry (RTG) crane if all GNSS was lost
• It had to work 24/7 365 days/year in port weather and lighting conditions
• The system was to provide the operator with a method to continue operations
• The system also has to detect obstacles in the path of the RTG.

Solution

• Forsberg developed the system to assist the RTG operator by navigating using video imagery to within 5cm of the lane guide lines.
• The development provides a visual camera reference of the RTG in relation to a driveline.
• Two cameras mounted on each leg of the RTG continually monitor the direction, angle and accuracy of the container crane within the yellow hatched driveline by image processing techniques.
• The system advises the operator if there are obstacles in the RTG’s path.
• The RTG driver could choose to navigate by one or more of GNSS, optical and laser scanners (LIDAR).
• Any deviation from the required RTG track and required precision visually displays an amber/red traffic light parameters This is displayed to the operator via an on-screen traffic light in the driver’s cab