GPS Line Marking for Sports Fields
Main Points
- The line marking machines TinyLineMarker use satellites to know their position.
- The robots receive correction signals from reference stations in the area.
- This means that the lines are always marked with a precision down to 0.8”.
- All that is needed is the robot and tablet, making it easy to do line marking just one person.
Perfect Remarking
How It Works
TinyLineMarker allows groundsmen and greenkeepers to layout and mark sports pitches in a matter of minutes and to achieve centimeter precision in doing so. But how does the robot achieve its high precision when moving around the pitch and painting the lines?
Read this article to learn how the line marking robot uses satellites and reference stations in order to always know exactly where to mark the lines.
Communication between satellite and robot
There are thousands of satellites orbiting our planet, and more are being put into service every year. We all use these satellites in our everyday lives for many different things; telephone, radio, navigation, television, weather forecasts etc. Our communication with the satellites becomes more and more sophisticated to the point that we all have access to global positioning information in our pocket via our smartphones.
The sports line marking robot TinyLineMarker uses the information from the satellites to place and mark sports pitches of all types. With a tablet, the user can place pitches directly on a map or use the robot to place pitches in a pre-defined location. This is particularly useful if a sports club has fields with fixed goal posts and the field needs to be painted according to these goal posts.
Communication Between Satellite, Reference Stations And Robot
The GPS signal from satellites can sometimes be disturbed. A simple change of weather can cause clouds to disturb the signal that is sent to the robot. This is where the RTK network comes in. RTK means real-time kinematic, and the network consists of multiple reference stations similar to telephone poles placed in many different locations throughout a region. These stations are permanent installations and are used for many different purposes within a region or country such as construction, land surveying, agriculture, machine control, etc. – and now also for sports line marking.
The reference stations constantly receive signals from the satellites in order to detect any offsets, delays or errors due to eg. cloudy weather. If they detect an offset, they are able to calculate a correction and communicate this to the line marking robot in a matter of seconds. Knowing this information, the robot can now correct its position continuously when working. This means that even if the GPS signal is disturbed, the robot will always know its position down to 0.8”, and this is what gives the high degree of precision needed for sports lines.
What Does This Mean for Groundsmen and Line Marking?
The communication between robot, satellite and reference stations means that a groundsman can start the robot on a line marking job, eg. a football pitch, and 20 minutes later, he will have a fully marked football pitch painted in the desired location with a precision of 0.8”. For this, all he needs is the robot and the tablet.
It also means that once he has painted a pitch the first time, he can save it for the coming seasons and save himself a lot of work. When he comes back in 6 or 12 months to do re-markings, he can find the pitch from last season on the tablet and simply press ‘Start’. The pitch will be painted in the exact same location, with the same degree of precision. All pitches can be saved in the cloud so that they are always available for future use.
Additionally, if a pitch needs to be moved or resized or copied to a new location, he can do this from his tablet and simply start the robot on these new and updated pitches.
To see how a groundsman typically uses the robot in his daily work, visit our customer cases page here to see our customer interviews.
RTK vs. Base Station
It is possible to use a base station instead of using the RTK network. A base station is a local unit that you set up next to the sports pitch whereas RTK is a service you subscribe to. The base station has the same purpose as the reference stations, ie. to correct the signal from the satellites. However, as both setups rely on the accuracy of the satellite signals, they both achieve the same degree of accuracy and precision. This is why land surveyors, who rely heavily on high precision in their work, have been using RTK for years.
We asked a land surveyor about his experience in working with both RTK and base stations. According to him, using the RTK network for sports line marking is highly reliable and is neither more or less accurate than using a base station. RTK is simply easier as you only need the robot to mark the lines.
Why a Local Base Station Won’t Work for You
Using base stations can involve challenges to the line marking operation. Watch this short animation to see some of the challenges users may encounter using this set-up.
RTK challenges
Using RTK has the vulnerability of coverage. If RTK is used in an area with little or no cell coverage, the robot will not be able to receive the needed satellite signals. This problem is the same faced by cell phone users / smartphone users who go to remote areas without mobile internet connection. However, practically all of our customers live and work in places where they can connect to the internet via smartphone and consequently, the robot works in these areas as well.
Satellite Signal Issues
Using satellite signals for line marking can be vulnerable close to high structures such as elevated side stands (spectator seating areas) in stadiums and arenas. The local conditions such as how high the side stands are and how many sides are covered may affect the result of the line marking.
